Tbi swap build thread

[BigBlocksRule]

There won't be much towing, maybe a car trailer from time to time. I plan to use this as a work truck more than a hauler. Part of the reason for the pass heads is compression bump. Plus, with 4.10 gears, I'll be in the meat of the torque band pretty much all the time.
I started thinking a few years ago about an "old fart truck" for my later years which are slowly creeping up on me. Something to drive around and get in the impatient young kid's way, white hairs sticking out of my ears and nose and a finger in their direction...sure would be nice to have a truck with some cojones as well for when they decide they can't bear to follow an old fart in an old ugly truck and try to pass. I'm actually looking at decals for the dually fenders, something like the old Gentleman Jim and Beau James, except mine will be "Fugg Lee"...
And as long as I stay away from rectangle port heads, I'll have plenty of torque by default, that's the big block way!

[GmtGmt]

can a computer and wiring harness from an early Astro van be used?

[rfmaster]

Originally Posted by GmtGmt

can a computer and wiring harness from an early Astro van be used?

Yes, Astro Van used 4.3L V6 and TBI injection which was controlled by 1227747 ECM - same as in C/K trucks. The harness length and layout is a bit different, but with a little bit of work it can be adapted. Now - if you are planning to use 4.3 (V6) TBI setup on 5.0 or 5.7 V8 you'll have to make several changes.

1) In the ECM EPROM and NETRES must be from V8 vehicle that best matches your engine (i.e 5.0 to 305; 5.7 to 350). It is easier to find matching ECM from V8 truck with correct calibration.

2) distributor must be from V8.

3) Injectors - 4.3L V6 used 46 lb-Hr injectors; 5.0L 55 lb-hr and 5.7L are 62 lb-hr.

4) KS and ESC module - should be of a V8 flavor.

//RF

[SLR_65]

Hi Guys,

I'm still reading through this entire thread, but I thought I'd take a break and outline a project I'm thinking about taking on.

I have two trucks -

A 1974 C-10. It's just an old beater but I love it. It's not pretty but I like that - I can haul anything and not worry about scratching the box! It was an old farm truck before I bought it on an auction. I bought it when my oldest son was 15 (he's now 22) and we spent a year fixing it up (it had sat for 8 years as the farmer had retired and pretty much just abandoned it in a shed). It has a 350 in it, the numbers say it's a four bolt main though we've never had the pan off, and it has 010 020 cast in the block in the timing chain area so it should be a high nickel block. Fixing it up was great fun, we put new heads on it (it had a burnt valve ('74 was the last year for regular gas heads)), an Edelbrock Performer cam and intake, a Mallory HEI distributor, rebuilt the quadrajet, and a few other things. It ran well and actually didn't do too bad on mileage after the cam change. unfortunately it's an old truck and it's developed a really nasty noise down deep so I'm afraid it's spun a bearing or something.

The other one is a 1989 Chevy 1500 with a 305 TBI in it. It also has a 700R4 transmission that has about 4,000 miles on a rebuild in it. This was my father's truck and I inherited it after he passed away. It was a decent enough truck too - I don't do any heavy hauling or anything so the 305 was just fine. Unfortunately I let my middle son drive it to work right after he turned 16 and on the way home he had a pop from McDonalds (he worked there) and it fell over so he reached to grab it and pulled the wheel while he reached . . . and ran right into the back of a parked truck! Unfortunately it's not worth fixing - it'll need a new front clip and some frame straightening and we just had liability on it so insurance isn't paying to fix it and I'm not inclined to want to spend as much as it needs out of pocket. I was able to get the sheet metal out of the way enough to see if it would start and it does start and run fine, the fan isn't bent or anything.

Sooooo, I have an old truck that needs an engine and I have a newer truck that has an engine but is totaled otherwise. My thoughts are to combine the two to get a truck back running. I thought about just rebuilding the 350 in the old truck but I hate to just toss the good engine/tranny/fuel injection from the newer truck and, some day, I'd like to do a t-bucket roadster and the 350/th350 could work well in that. My next thought was to just toss the tbi and use an Edelbrock carb conversion manifold, strip the newer engine down to a long block and install all the pulleys and accessories off the old 350 on to it and then just bolt it up to the th350 and go. I think the only real mod beyond the intake and carb would be to use an electric fuel pump as it seems to me the newer block doesn't have provisions for a mechanical fuel pump (I'll have to hop out to the shed we have it stored in to confirm though). It'd be pretty straight forward I think, but I kinda like serptentine belts and I kinda like throttle body injection and . . . I literally have ALL the parts! I just can't see tossing them! Soooo, I'm in the process of doing some research (I bought the Jags That Run book and have been surfing the net a good bit) trying to talk myself into this project . . . maybe you guys can help with that! ;->

Some random notes so far:

Transmission:
*) I should be able to use the 700r4 tranny.
*) The column linkage on my '74 will work, just the gear indicator will be off?
*) I will probably have to cut the drive shaft? There are several articles on the net on driveshaft shortening, it looks doable.
*) I may need to build or adapt a tranny crossmember.
*) The donor truck is an '89 so the DRAC is part of the instrument panel so I will need to replace it with a separate unit, or is the DRAC separable from the instrument panel?
*) If I can salvage the original DRAC the books says it's programmable - is that easy to do? I think the gear ratios and tire sizes are different between the two trucks. If I can't use or can't reprogram the original one then I'll need to get a DRAC that matches the gear ratio/tire size of the truck it's going into.
*) The Jags that Run manual says all TBI engines thru '92 used a two pulse VSS but on the next page they say that all Chevy trucks with rear wheel anti-lock brakes 1989 and newer use the 40 pulse per driveshaft revolution sensor and I'm sure the donor truck has rear abs brakes.
*) The older truck has a cable driven speedometer so I will need to accomdate that.
*) Jags That Run carries a reluctor ring sleeve assembly that allows for cable drive speedometer gears and a 40 pulse reluctor ring. In addition to this assembly I will need a modified tail house that allows for the relocated 40 pulse sensor. Both items will run $130 delivered.
*) Where is the park neutral switch at? On the transmission or up in the steering column gear indicator?

Wiring:
*) I would like to save some bucks and use the original harness. I'm comfortable with control / sensor wiring and troubleshooting as I do it in my job all the time.

*) After market harnesses are expensive, but the MegaSquirt people have an interesting option - they make do it yourself wire kits for less than $100 and the wires actually have the sensor designation stamped on them (it's just the wire though, no connectors). This would be nice, but the wire colors don't match the stock GM wire colors and I think there's value in maintaining the stock wiring colors so I'm back to trying to salvage my harness.

*) I have a laser printer and they make laser print outdoor labels so I'm thinking I'll just print labels and use them to tag the harness connectors.

Fuel System:
*) I don't know if an '87 fuel tank would work in my '74 truck as they are slightly different body styles and the tanks have different part numbers in the LMC truck catalog (I'm sure that's because of the baffles and stuff, but my older truck is also a different part number than the later '82 -'86 carbureted trucks). I can get a used '87 tank for $65 at the local junk yard (minus fuel pump, darn it!) though.

*) If I can use the '87 fuel tank the fuel pumps are expensive and it's a pain to change them when they go out, so I'm thinking an external pump set up would be better? External pump would entail two pumps and a small reservoir, but all in all I think it would be slightly cheaper and easier to work on in the future.

*) Update, it appears the fuel pump in the '89 could be used in an '87 tank - LMC truck says part number 32-4048 works on '87-'89 models! Though external pumps would be easier to service, if you don't habitually run the tank low in tank pumps usually last quite a while and not having to buy a pump/sending unit combined with a $65 junk yard tank is the cheapest option.

*) Is the fuel gauge sending unit compatible with the gauge in the '74 truck?

Cooling System:
*) I bought the Jags That Run Fuel Injection manual - they had a point I hadn't considered, is the fan, shroud, etc. going to be properly placed to provide adequate cooling? My thoughts are yes, or with a few tweaks it could be made to work correctly. Worse comes to worse I revert back to the old separate pullys, fan, shroud, etc. so this shouldn't be a big issue, just something to keep in mind while it's coming together.

All in all, this looks doable. It's not "easy", but it's not hard either. No real fabrication work, more just getting parts that work and switching them out.

I'd be interested in any and all comments, suggestions, ideas, whatever - I'd really like to make this a smooth going project if I decide to take it on.

Back to reading the thread . . .

Steve

[Jonboy]

Steve, I think you are overthinking it. I just did the same swap: http://67-72chevytrucks.com/vboard/s...d.php?t=433689 , and it isn't that hard. I used a harness from www.fuelinjectionconnection.com ($245 shipped), to save the hassle and headaches of making a harness and using 20+ year old wires. That harness deletes the emissions, making the installation easier.

I used the 700R4 trans, relocated the crossmember back a little bit, and the driveshaft fit perfectly. I also used the 2PRS VSS from JTR ($75), and that will solve the hassle of the DRAC, tailhousing, etc. That will also let you use your existing gauge cluster with no problems. I did use the '74 column shifter, but added a quardant out of a later model truck. P/N switch is at the bottom of the column, inside of the truck. I bought a later model one (for an '87), and moved a few wires around. It's not currently in use, but that's my own fault. That will be fixed when I get the truck back.

I used the accessories from the '74, as I wanted it to look original. That's just my own weirdness there, but it wirks. The fan will fit in the shroud just fine, no matter which set of accessories you choose. I also used an '87 fuel tank, but mainly because I had one. I previously had a '79 C10 with an LT1 in it, and they used an external pump. It was a little noisy for my taste, but it worked fine, with no external sump. I had planned to fix that, but sold the truck first.

My project stretched out over a month, but that was due to a few external factors also (I got my wisdom teeth a pulled, got the flu, it was freakin cold, Christmas and New Years holidays, and then some). I did quite a bit extra too, but figure a couple of weekends to get it done, start to finish. There was a lot of head scratching involved, but I also have a talent for making my own headaches. For whatever reason, I redid almost everything at least twice.

[Chad77]

Well its been a while again! I have my TBI set up running with a hiccup when I had started it for the first time it started and idled good, well scene then I have started it here and their and to day I rerouted the gas lines and topped off the coolant I started it up and now it wont idle unless I have my foot on the gas pedal I dont have a air breather for it and I have yet to drill and weld in the bung for the O2. any suggestions?

[rfmaster]

Steve

Welcome to the board (and the thread)

1) Use in tank fuel pumps if you can - despite the small cost differential they do last longer. In tank fuel pumps are cooled by fuel and tend to be less noisy. Use baffled tanks from 87 (Spectra Premium part number GM1C; fuel sender FG05M driver side, FG05N passenger side, fuel pump Delphi FE0115). IRC, the fuel fill inlet diameter is different than the 73, but should fit existing inlet. If you have 20 Gallon tanks the new 20G gas tank should be a drop in replacement for OE non EFI tanks. In fact you should (must) replace you gas tanks - god only knows ho much crud you have in there (unless previously cleaned out). Also, modern gas (E10, E15) is a nasty mix of ethanol/methanol blend and tends to rot fuel systems from inside out. Not a good thing at all for us trying to keep older vehicles running.

2) 700R4 overall length is 30 3/4”. THM-350 came with three different tail shaft lengths: 6, 9, 12. Passenger cars were equipped with 6" tails while trucks (for the most part) were equipped with 9 or 12". Dim A: for 9" tail is 30-11/16.
http://www.tciauto.com/Products/TechInfo/trans_dims.asp
Measure your THM 350 - if it has 9" tail no drive shaft cutting will be required. Slide the cross member - you'll need extra long drill bit.

//RF

[SLR_65]

HI Jonboy,

Yeah, I tend to overthink things!

Boy, your '74 is a whole lot prettier than mine! Mine is just plain ugly, but I love my ugly old truck! I can haul compost for the garden, or lumber, or the equipment I use for public fireworks displays without worrying about scratching or denting things. And, it's relatively cheap and easy to work on (not that it ever really needed worked on much). It's just been a great old truck! I thought I had some pics on the computer but I can't find them, I'll try to snap a couple tomorrow so you can see what ugly is! ;->

First off, I'm cheap - and I freely admit that! Second off, I'm a do it yourself kinda guy and wiring doesn't intimidate me in the least, in fact I kind of enjoy it, so utilizing the '89s wiring harness is something I'd like to try. If it gives me problems though I think I would look at a prebuilt harness - from what I've dug up on the net it looks like it's hard to find vendors to sell small quantities of the various wire colors needed and the cost of the plugs add up too, so in the end building a harness from scratch, though maybe a fun project for a weekend, probably isn't really justifiable. (you could vary the wire colors but I think there's value in keeping the wiring the same colors just to get away from any confusion in the future)

I actually like the serpentine belt setup and can't really see spending the effort to switch them out. If the fan was going to be an issue though I could - again, the nice part of this swap is that I have both vehicles complete so no nickel and dime junk yard shopping! 8->

I'm going to have to read up on the VSS stuff again. How do you drive your cable driven speedometer with the 2PRS? I thought it screwed in to where a speedometer cable would go but just gave a two pulse output? And it needs internal gears like a speedometer, doesn't it? I see they have a 4 pulse unit that give the output and provides for a cable, but I didn't know if my computer would be happy with that. It may be though as the DRAC is in the speedometer of my '89, it may only use that high 40,000 count signal for the ABS brakes and output a lower count to my computer - I need to find out what the computer is expecting for input. My 700r4 is from a truck with ABS brakes so it has the 40,000 pulse reluctor thingie in it so it doesn't even have the gears to drive a speedometer type setup. It's just got the reluctor ring and the sensor for it plugs into the hole where the speedometer cable would go, at leat I think that's the way it works. I need to dig into this a bit further!

This will probably be an all summer project! I'm a power plant boiler operator and they're saving money by reducing staff so any time anyone is sick, on vacation, at training, etc. my schedule goes nuts. But this isn't my daily driver and it's already out of commission so time doesn't really matter much.

Thanks so much for the help! I'll keep ya posted as I progress into the project (yeah, I've decided I'm going to do it!).

Take care,

Steve

[SLR_65]

Hi RF,

Thanks so much for the reply!

I'm glad to hear I can use the '87 tank in my '74. And yeah, I have the 20 gallon tank (only one - driver's side mounted).

I'll try to check out the transmission tailshaft length tomorrow, but it's a 90% chance of rain all day tomorrow so I may not get the chance.

I'm glad the crossmember will work too - though fabbing a new one wasn't an insurmountable job (I just suck at welding. If I practice for a while I get ok at it, but I gotta practice. Once I quit practicing the skill evaporates and the next time I gotta start all over practicing before I work on my project . . . oh how I envy those who can just pick up a gun and start welding!)

I'm getting excited about this!!!

Take Care,

Steve

[Jonboy]

I thought the '89 might have used a cable driven speedometer. I've never owned one of that body style, it's still a new truck to me. You could locate the cluster out of a 90 4wd or 91 Suburban, and use it. Those use an electric speedometer, and will bolt in place. You will have to repin the connector and run a new wire to the speedometer, though. I've used them with newer engine swaps (LT1) that have the buffer in the PCM, so you will probably have to reuse the DRAC with that cluster.

There is nothing wrong with being cheap (although I prefer the term thrifty), but I also like to think I know when to pick my battles. I went ahead and bought the harness I did because mine was in pieces, and it was only $245. I need to reflash the ECM when I get my truck back to change tire size and kill the emissions inputs, but that is only another $60.

[rfmaster]

Steve

*) Where is the park neutral switch at? On the transmission or up in the steering column gear indicator? - It should be on the steering column next to the firewall.

GM used 90 Ohm fuel level sending since 50's - newer sending units with in tank fuel pump will be compatible.



2PRS is an inline unit, it screws into speedometer cable output port (at the transmission) and speedo cable bolts into the VSS. Run two wires from it - one goes to signal ground while the other is tied directly to pin A10 (assuming 1227747 C3 ECM)

//RF

[SLR_65]

Hi Jonboy,

No such luck, the '89 used an electronic speedo and the DRAC is built into the cluster pcb so it appears to me that I will need to get a separate DRAC also.

> I've never owned one of that body style, it's still a new truck to me.

LOL! It was/is to me too! Remember, I inherited it!

I thought about an electronic speedometer but wanted the dash guages and stuff to stay matching (why, I dunno . . . again, this beast is ugly!). I hadn't thought of finding a used one. I'll dig into that.

So the VSS you have from JTR feeds the cable drive through? It just doesn't seem to say that on their web site, the only one that mentions doing both is the 4 pulse one, but even at that I'm pretty sure that I'm reading that my tranny doesn't have the speedometer / VSS drive gears in it, they've been replaced by the reluctor ring, so I can't just pull the sensor out of my tranny and put a new one in as there's nothing to drive it. It looks like I could put the drive gears back into it though and then use the 4 pulse cable feed through one and a stand alone DRAC. If the 2 pulse one feeds the cable through though then all the better - no DRAC needed! I gotta dig a little more on this . . . still, no matter what, it's not a project killer - it's definitely solvable one way or the other and wont cost a fortune either.

Thrifty, yeah, that's it! I'm just so used to the wife and kids calling me cheap that I've forgotten the proper term! 8->

Picking your battles is definitely a good idea! Time is a big factor in those decisions for me as when I work for myself I work pretty cheap :-> . With this project I have plenty of time so I'm willing to do as much as I can.

I've been playing with tuner pro as at first I thought I would have to have a new chip due to the tire size difference between the two, but now it seems if I get the drive right on the VSS then it will be accurate and no fudging in the chip will be necessary . . . correct?

Turning off EGR in the chip looks like duck soup. Turning off the AIR injection is something of a curiosity to me though. From what I gather many just remove it as it's not supervised by the computer so it wont set a check engine code. However I read on one of the boards that it isn't that simple because when the AIR is turned on the computer fudges the O2 reading coming in - it decreases it because they know it's going to read the extra oxygen they are pumping into the exhaust and that would throw the calculations off so they apply a correction factor to the reading coming in to deal with that. From what I gather the way to deal with it is to raise the Minimum Temp For AIR parameter to the maximum, doing so will keep the computer from ever turning the AIR pump on and thus the correction factor will never be applied. Though I read that it's not noted that way in the xdf file I have for the chip, so if that's true for the 7747 I dunno.

I actually thought about buying a programmer if I needed a new chip as it was about the same price as buying a chip and then I could play if I wanted to. I'm very comfortable with this as I used to play with electronics, pics, eproms, etc. years ago. In fact I still have a programmer but it wont run under Windblows - it wants DOS . . . it's THAT old! I doubt if I will now though as I don't think I absolutely need one to make this project work and I don't really care much to disable the EGR or AIR (maybe if it were free to do so, but I'm not paying much just to do that . . . especially since they keep bringing up emissions testing every couple years. The idea usually gets killed quickly, but you never know. If it ever does get implemented I don't want to have to scramble to find/put back stuff I took off).

TTYL,

Steve

[SLR_65]

RF - THANKS soooo much! I LIKE pictures!!!

[SLR_65]

OK, did a little poking around and I can find the Suburban speedo pretty easily on the net for around $75 delivered.

Finding a DRAC is a bit more of a challenge though! ONE guy on fleaBay is selling them for $100. Couldn't find anything else on the net.

I just need to hit the local salvage yards I think (though they were crushing LOTS of cars a few months ago when scrap metal prices were high). What's a good price on a DRAC? I have no problem installing the jumper switches and doing the calibration myself. Our local salveage guys like to haggle and it's kind of hard when you have no idea of the value!

I like the replacement speedo / use a DRAC idea - just no hassling with the tranny, leave it stock.

[Jonboy]

Check the classifieds here, too. By becoming a supporting member, you can post "want to buy" ads as well.

I would pull the extension housing off of your trans and have a look. If you can run a gear and a speedo cable, the 2PRS will get you all set, without a DRAC. I know you can just disconnect the AIR on an early TPI engine, so I am sure TBI is similar. It will not set a code.

[SLR_65]

Hi Jonboy,

I'm certain I have no VSS drive gears since I have the reluctor ring, though I will continue to dig a bit deeper into this when I have a bit more time.

I'm sure I can install gears with a JTR kit but it'll probably be cheaper to just find a DRAC (or Buffer as they are also called) and change the speedometer. I'm sure my local salvage yard will have something that will work, or Dakota Digital makes a unit that I'm sure will work for $85.

I don't think removing the AIR injection without disabling it in the computer is a good idea whether it's tpi or tbi - basically AIR drumps air into the exhaust so the O2 sensor is going to see more air. To avoid erroneously adjusting for that extra air the computer shaves a little off the input when it's calling for the AIR to be injected (not all the time, just when it calls for the AIR). The AIR is not supervised so it wont set a code. i.e. it's just sending a signal out to open the valve and it's assuming that's being done - whether it is really being done or not. Since it thinks it's being done it then invokes the O2 fudge factor.

I think this is like the use a VSS or not situation - the engine will run and for many people it will run just fine without a VSS but it's simply not running as well as it could be.

Personally I think I'll leave the AIR hooked up for now. If it creates a problem later down then road then maybe I'd look at just disabling it in the chip by raising it's minimum activation temperature. I have the AIR pump already on the engine, it's already in the wiring harness, and the engine runs fine so I'm not going out of my way to mess with it as I just don't see much need to.

Here's an interesting thread on it at the 3rd gen camaro forum:

http://www.thirdgen.org/techboard/di...-pump-air.html

The above is on a different ecu, but somewhere I have a thread on the 7747s and it said literally the same thing.

TTYL,

Steve

[Jonboy]

VSS will trigger more than AIR will. VSS input operates TCC, Evap, EGR, and a couple more acronyms I have forgotten. I think it is much more important than AIR, but that's me.

I had an '81 El Camino that I swapped a 305 TPI into that I drove through most of college. We didn't hook up the AIR, and it ran fine. No code, no problem. My speedo cable had broken at one point, and the CEL set almost immediately. It also ran hotter from the TCC not engaging. Didn't take long to see the need of fixing that.

[rfmaster]

Steve

1) AIR is only active when engine is cold and operating in open loop (O2 is not providing feedback). If you have 7747 ECM there is no AIR related DTC.

2) EGR function can be easily disabled by increasing EGR Temp On parameter to 155C (255 counts). To completely disable EGR DTC in TunerPro uncheck Malf Flag 32 in your Bin file and save.

3) I use flash chips AT29C256 or 27SF512 with a slightly modified G2-0.6 adapter (with ZIF socket) in my 7747, 8746 ECM's. A29C256 is still available from Future Electronics:

http://www.futurlec.com/Memory/AT29C256pr.shtml

4) For greater flexibility I prefer to use GQ-4X Willem Programmer from MCUmall. It is more than you need and BURN2 Chip Programmer from Moates will work just fine for you.

5) I use 2PRS in my conversions - Dakota digital should work as well. IRC, they have auto calibration capability so that you do not have to worry about having correct speedometer gear combination. It can be a real PITA trying to get a right pair of gears for speedometer to indicate correct speed. However, if you have OE mechanical speedometer (73) you must select correct gears. It is not as bad as it sounds - you need to know:

Drive gear teeth count (inside tail housing)
rear end ratio
tire diameter.

plug into equation

http://www.tciauto.com/Products/Tech...eedo_gears.asp

driven gear tooth count.
//RF

[SLR_65]

Hi RF,

Thanks for the reply - though I don't forsee a need to mess with my computer chip, I may just for fun once I get it running.

I don't have speedo gears in my tranny. I can put them in with a JTR kit (just talked to them), but I think the easiest approach is to simply find a DRAC/VSS Buffer and then set the jumpers for my tire size / rear gears. Then just use an electronic speedo since an OEM one that will match my dash both physically and appearance wise is easily available.

I think the DRACs are just a low failure item so there's not much demand for them and they're buried in the dash so the salvage places don't dig 'em out - I'm sure if I go salvage shopping I should be able to dig one up. I'm hoping to do that later this week.

I'm starting to feel pretty comfortable with this - it doesn't seem like there's any major hurdles . . . famous final words, eh?

TTYL,

Steve

[FritzA]

Instead of finding a DRAC you can get a Dakota Digital product that performs the same functions. It is about $75 at Sumit Racing.

[SLR_65]

Well crap! I just swung by my favorite salvage yard. This is a neat old place, I used to go there as a kid with my Dad (and my sons and I just toured it a couple years ago!) and it has cars going back for decades. Has a few rows of 30's/40s/50's era cars and even an old Liberty truck that's been there for as long as I can remember.

Well, it DID anyway! Today I'm greeted by the sound of a crusher running and the field with the really old stuff was empty! They are crushing most older stuff. The really old stuff and the camaros, mustangs, etc. all got sold to an outfit in Oklahoma and they picked them up a few weeks ago!

They aren't closing, they are just starting over. They had no demand for their old stuff so they are scrapping it and focusing on stuff that's about 10 years old or newer.

He didn't have any early '90s stuff any more at all so I didn't get a DRAC. He knew exactly what I wanted and said it would've ran $10, but they crushed those vehicles a week or two ago!

It's truly a sad day here in Steveville!

We have one more salvage yard in town but they've been more of a crush yard than anything for a long time now so I'm not holding out much hope.

About 20 miles south of me is a yard that specilizes in older stuff so hopefully they'll be able to help me.

I'm aware of the Dakota Digital device and may end up using it, but I have a question about it that I'll have to ask them first . . . it only has one 2,000 PPM output and I need two, one for the computer and one for the speedometer. Is it OK to split that line and feed both? On the original DRACs they had two separate outputs for those signals. Even if you can't I'm sure you could use one of the other lines and little more circuitry to divide down what you need, but the original OEM DRACS appear to be very reliable, easily modified with dip switches so you can configure them for new gear ratios and tire sizes, and if you can find one they seem to be CHEAP! It's hard to beat that combination!

A friend of mine is an elctron guru too and I mentioned this to him and he got a twinkle in his eye and started mumbling about pic chips and stuff. Later he wanted to know how many pulses per revolution and my gear ratio and tire size so I'm sure he's cooking something up too so I'll probably have another option. 8->

I'm having trouble finding stumbling blocks / reasons NOT to do this project, so it looks like it's time to order some parts and start stripping the donor truck!

TTYL,

Steve

[lahnen]

read through alot of pages, answered some questions, still unsure on some others. i have a 86 k30 4x4. going to put in a 89 350. will a harness from fuelinjection connection be able eliminate any not needed things, such as the speedo issues im reading about. i would like to just to use the original speedo cable and not have to swap out clusters. originally i planned on trying to use the 89 wiring, computer, and what not, or finding a 87 harness with out buying another truck for parts, but if i can buy a harness that just needs to be plugged in, i'd rather do that route. if theres anything else i'm over looking or left please let me know. i'm also gonna use the new gas tank from the 89 seeing how it has a new sending unit and pump

[SLR_65]

I'm still researching my swap so don't take the following as gospel . . .

*) The wiring harness would provide just what you need to run the fuel injection without having to deal with a 20 year old harness and wiring for other circuits. They can come stock or with the EGR and AIR injection removed. Personally I'm not a proponent of removing the smog equipment - in this day and age I don't think any of us are too far away from local municipalities invoking smog laws and requiring inspections and it can be expensive to replace the smog equipment if you toss it. At the least I'd leave it physically on the vehicle and just disable it.

*) What your speedo options are I think will depend upon what vehicle your 89 350 came from. If it had rear wheel anti-lock brakes then it will have the 40 pulse per driveshaft rotation vss in it like my donor did (all 89 full sized trucks came with abs) and that makes the speedo a little harder to deal with. Jags That Run have some methods to deal with it if you don't want to change the speedo. If the donor didn't have the antilock brakes though then you should still have the speedo drive gears in the tail of the tranny and there are several options to provide for cable driven speedo and provide a vss signal for the computer.

*) I'm not sure an 89 gas tank will fit into an 86 truck. If it will then I'll save myself a few bucks and use mine too!

*) If the tank wont work at least the fuel sending and pump will according to the LMC truck catalog anyway.

Hope that helps!

Steve

[rfmaster]

Originally Posted by lahnen

read through alot of pages, answered some questions, still unsure on some others. i have a 86 k30 4x4. going to put in a 89 350. will a harness from fuelinjection connection be able eliminate any not needed things, such as the speedo issues im reading about. i would like to just to use the original speedo cable and not have to swap out clusters. originally i planned on trying to use the 89 wiring, computer, and what not, or finding a 87 harness with out buying another truck for parts, but if i can buy a harness that just needs to be plugged in, i'd rather do that route. if theres anything else i'm over looking or left please let me know. i'm also gonna use the new gas tank from the 89 seeing how it has a new sending unit and pump

Do you have a mechanical speedometer in your '86. If you do then you can simply insert 2PRS (2000ppm) VSS inline with speedometer cable. Connect one wire to ECM and one to the ground - done. (assuming that you are keeping 86 4x4 trany and x-case and putting 89 350 in place of tired OE)

I do not know what exactly harness from fuel injection connection has (it is probably custom build to order). Generally speaking EFI harness is a stand alone system - only a handful of connections to the fuse box and P/N switch (and brake switch for TS control).

If 89 tanks fits - use it, but make sure to replace rubber hoses with EFI rated SAE 30R9 fuel hoses.

//RF

[lahnen]

yes i plan on using the th350 that i have in the truck already. original plan was to use tbi 350 but to convert it to carb, but figured at $4 gal a few more mpg would be nice seeing this is a one ton dump truck. also with the dump bed i dont think i will have a problem using the 89 tank.