quadrajet on a 250 inline advice

[SSC's76]

i know its a little late in the game here but there is a guy over on one of the ford truck boards using a q-jet on his 300 6. Looks like you may be going another route but there is no reason a qjet would not work properly on a 250.

[sixtyeightchevykid]

one big reeason why i would like to get a New carb is because i would have to rebuild or get the qjet rebuilt and all i have ever had was rebuilt carbs and i have never been happy with them,

[RichardJ]

>>all i have ever had was rebuilt carbs and i have never been happy with them,<<

Rebuild kits usually come with a sheet that explains and gives specs for a variety of adjustments. About half the adjustments are performed on the bench. A rebuilt carb will have those adjustments made for you.
The remaining adjustments are performed with the carb mounted and the last few with the engine running. Those adjustments must be made by you even if it is a good carb pulled off a running engine, even if you rebuilt the carb, even if someone else rebuilt the carb or even if it is a brand new carb out of the box.

Carburetors are not plug-n-play.

SSC76
I would put that Qjet on with the primaries to the outside. It will be running on the primaries 95% of the time and the extra couple of inches away from cylinders 3 and 4 can only help balance the runner length.
Mounted that way will make it difficult to get to the mixture screws.
Is that picture showing a 5 feet long throttle cable? Turning the carb would allow him to shorten that up a great deal.
On that fnord the photo makes it look like the fuel line is connected to the vacuum port on the rear of the carb??

[HEI451]

The best carb for what you want to do is an older Holley "spread bore" that was designed to be a direct replacement for the Q-Jet on Chevy engines, LIST-4360 "Econo-master series, 450 cfm, manual choke, mechanical secs and, NO POWER VALVE to blow out.

These carbs are NOT modular carbs like the 390, they bolt directly to Q-Jet manifold pads, and work well on very small engines. I had one on my Buick all aluminum 215, AFTER using the LIST-8007 390 cfm nightmare, and jetting that 390 to the moon, over and over again. The 450 went right on, worked from the get go.

[sixtyeightchevykid]

Can I get some advice about the carbs that I posted links for?
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[HEI451]

Yes, the LIST-8007 390 cfm ISN'T a good carb for that application, it is too small, and doesn't have the same air circuits as a LIST-1850 does. ANY LIST-1850, from no suffix, to dash 3 will work a lot better than the 390 will.

As far as the Q-Jet, you already have that answer, the ONLY Q-Jet that will work well on that engine is the one from the higher horsepower Pontiac OHC inline 6.

The only other consideration for a spread bore would be the Holley 450 cfm Economaster I mentioned previously.

You can take the great advice already given, or, stay on the "spin my wheels" tack you are now on. Choice is all yours, use the advice given, or, have fun working with a too big Q-Jet carb that won't work.

So, before you say that "HEI451 is an idiot", consider that I worked on Pro-Stock Dominator race carbs at HOLLEY, for 5 years, and have been a Holley tech for over 4 decades.

[sixtyeightchevykid]

HEI451 i have already said that i will not be using the qjet, that is the reason i have been asking for advice on the carbs that i have posted links for, i have also changed to wanting an electric choke. the 1850 carb you are talking about is a manual choke. and is 600 cfm. why do you think i am "spinning my wheels"? for wanting to put a 4 barrel on an inline, or for asking so many questions?

and i admire that you "worked on Pro-Stock Dominator race carbs at HOLLEY, for 5 years, and have been a Holley tech for over 4 decades." but i am not racing my truck, im simply looking for a good new carb that is and will be reliable for a long time, that is electric choke, not a qjet, and will get fair fuel economy.

[sixtyeightchevykid]

i dont understand how a holley 390 can be too small for a 250 inline 6. it came factory with a single barrel that i believe to be around a 250 cfm (i could be wrong).
moving on...
from what i have read on edlelbrocks website and comparing on summit the 1801 and the 1403 are basically the same carb, the 1801 is an Edelbrock Thunder Series AVS Carburetor, and the 1403 is an Edelbrock Performer Carburetor. and i am leaning toward the 1403, because of price, and i would like to be able to tune it myself, it is an electric choke, it is new, and it is 500cfm .
HEI451 is that ok with you?

[425HP409]

Cadillac, Buick and Pontiac used quadrajets on the Buick 4.1L/252CID V6 engines with great success in the early 80's. It was used in many models, even the full size Cadillacs where it was not uncommon to get 24-26 mpg on the hiway with an overdrive transmission. They did have the airflow slowed down in these carburetors so that they would work well at all throttle openings.
The thing that is misunderstood about carburetors is that each one is factory tailored for the cubic inch size, rpm usage and load that each one will be subjected to. This entails the jet size, idle air bleed size, part throttle and full throttle fuel and air circuit size, and cubic feet of air per minute that will be needed at any throttle opening. I have a Quadrajet on my 77 GMC Sprint with a hot 454 with no problems. It idles well, acelerates well, and runs perfectly. Why is this so? It is because I started with a carburetor built for a 454 in a one ton truck. It already had the correct size air bleeds needed for my application, so all I had to do is make minor adjustment to the jets and it works great.
PS. Holley made 390 cfm carburetors for some early small block Fords and AMC engines in the 60's. I can give referrals for where to purchase them.
If I was going to install a Quadrajet on a 250 CID engine, I would start with one designed for that size engine and then maybe have to do nothing else with it.
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[SSC's76]

Originally Posted by RichardJ

SSC76
I would put that Qjet on with the primaries to the outside. It will be running on the primaries 95% of the time and the extra couple of inches away from cylinders 3 and 4 can only help balance the runner length.
Mounted that way will make it difficult to get to the mixture screws.
Is that picture showing a 5 feet long throttle cable? Turning the carb would allow him to shorten that up a great deal.
On that fnord the photo makes it look like the fuel line is connected to the vacuum port on the rear of the carb??

Yeah i'd agree but its not mine so he can figure it out lol. actually when it comes to inlines i like the ford 300 more then any other inline gas engine. much better engine last alot longer more power and better fuel economy out of the box. Of course this all changed when they went injected.

[sixtyeightchevykid]

anyone else?

[sixtyeightchevykid]

anyone running an edlebrock 1403?

['68OrangeSunshine]

Originally Posted by sixtyeightchevykid

anyone running an edlebrock 1403?

I have the EDL-1404 [manual choke] on my modified 292. I like it a lot. It's been going good for over 7 years, with only the occasional tune up.

[sixtyeightchevykid]

'68OrangeSunshine when you say occasional tune up. why do you need to ?

and would you recommend the 1403 ?

[RichardJ]

>>when you say occasional tune up. why do you need to ?<<

['68OrangeSunshine]

Originally Posted by sixtyeightchevykid

'68OrangeSunshine when you say occasional tune up. why do you need to ?

and would you recommend the 1403 ?

The 1403 and 1404 are pretty much the same carb. 1404 is the manual choke version. So yes. I use one and recommend it.
I got this 292 build on the road in January 2005. I re-tuned it in August '05 -- setting according to the Edelbrock Owner's Manual at position "13" to get a leaner burn.
In March 2011, I re-built it again, only changing the step-up springs from Yellow [4" Hg] to Orange [5" Hg]. (This is equivalent to changing the Power Valve on a Holley -- I used to run 8.5" Hg on the 8007.)
The maintenance-free, perpetual motion machine has yet to be built.
In any machine, especially one that runs at a high temperature, and variable to high RPMs --there is wear and tear. The brass holes in the jets and the brass on the metering rods tends to wear down -- opening up and [going richer] with each variation in RPM in a daily cycle. The gasket around the accelerator pump wears out and must be replaced periodically. [The Re-Carb Kit p/n EDL 1477 contains fresh cup gaskets for the accelerator pump. Unless the shaft is bent don't buy the separate accelerator pump kit p/ 1470.]
Also changes in weather and elevation, and changes in plug ranges or ignition components may require re-tuning. Dirt, dust and rust particles may be so fine as to get past your fuel filter and accumulate in the float bowls, sometimes jamming the needle and seat assemblies.
Did that answer your question?
BTW the manual choke version may be $50 cheaper than the auto-choke.

[sixtyeightchevykid]

yes it did, i wasnt sure if the edlebrocks just didnt hold the tune or what for sure, (if that makes sense)

thanks for your help, i only know enough about carbs to get me in trouble so im trying to learn...

['68OrangeSunshine]

OK, so you went with an EDL 1403. If you doing this to a '68, you need some modification to use a throttle cable, since '67s + '68s ['69s?] used a series of levers and/or pushrods.
There is a guy selling a '67 and later-friendly throttle cable on this forum, That saves a lot of hassle.
Eleven years ago, I got a buddy to braze some modifications to a '72 Chevy truck gas-pedal-thru-cable setup. We then used a Lokar style cable from a new hole in the firewall -- running to the right and up and over the valve cover to a Holley-type throttle cable bracket [HLY-20-112]. (Although I used a Jegs-branded copy.) Also I had to saw off the last inch or so to avoid contact with the valve cover.
I'll shoot some pix later, right now I'm up to my armpits in 1040 forms.
Thanks for the PM, but I'm about outta space there, so this is your reply.

[sixtyeightchevykid]

i have been thinking about the gas pedal cable set up. but i have not had time to look and see if my idea will work,ill post more info later. i will use the linkage that came on the 1403 but the problem is it hits on the manifold holding the primaries open. so i will need to run a spacer, not sure if i should get one that is open in the middle or one that has the 4 holes....?

ill try to post pics later of the progress

['68OrangeSunshine]

Hey 68KID,
Did you rig it face-forward or sidesaddle? I run mine sidesaddle with the big red Edelbrock decal and [more importantly] the mixture screws facing the drivers side fender. Very handy position. Main benefit is better distribution with Primaries outboard-- having slightly longer passages to swirl thru. Secondaries are right on top of plenum when you open it up.
If you rig the carb just like on a V8, fore-and-aft then the primaries feed more into the 1-2-3 channels and the secondaries feed into the 4-5-6 chambers. Some people will say it doesn't matter, but to me it's just common sense.
I got my taxes off, but today the clutch (throw-out bearing?) on my '71 Jimmy took a dive at the Home Depot and a nice guy [who said he had a '70 Chevy longbed at home] pulled me 3 miles home on a chain.

[sixtyeightchevykid]

i have it set up just like you have yours, the problem i have is the throttle linkage on the carb hits the intake and i need a spacer tho fix the problem. but there are soooo many different spacers out there and i only need 3/16-1/2 to fix it.

thats too bad about your clutch, it seems like there is always something

['68OrangeSunshine]

Originally Posted by sixtyeightchevykid

i have it set up just like you have yours, the problem i have is the throttle linkage on the carb hits the intake and i need a spacer tho fix the problem. but there are soooo many different spacers out there and i only need 3/16-1/2 to fix it.

thats too bad about your clutch, it seems like there is always something

Thanks. I had it apart today. Funny: all the hairpins are intact, the Z-Bar is seated in its brackets and the block stud is secure, the throw-out bearing spins and is intact, the clutch fork is seated properly, the lower clutch rod is not bent, the upper clutch rod is OK, the clutch lever was seated properly, but the pedal swings to the floor and does not disengege the clutch. Still puzzled. I did crank a few turns tighter on some of the 3/4" tranny bolts [SM465]. Maybe I'll post about it on the 4x4 line.

[sixtyeightchevykid]

huh thats got me puzzled as well, best of luck to you.



i went by a local parts store last night after work and had to order a carb spacer and intake/exhaust gasket. i still need a gas pedal and return spring, i looked at a 94-97 suburban and i think the pedal will work so i might try to get that

[sixtyeightchevykid]

ok well i started to put it all together this morning, it was going way to smooth and i have hit a wall pretty much, first i go to put the intake and exhaust manifolds together (still using the stock exhaust) and the two studs coming out of the exhaust were too long so i cut those to a good length and get the manifolds together and then i notice the faces(or where they meet the head are not even the intake sticks out past where the exhaust is. so debating on having the manifolds surfaced so that they are straight or wait and get split exhaust..opinions?

[RichardJ]

You may have to trim the ears on the intake or the exhaust or both so that they don't interfere with each other. Assemble the intake and exhaust loosely or no more than snug and then bolt them to the head. Snug everything up together before fully tightening.

They originally used both long and short clamps and two studs. The rest were bolts and the two end pins.

With the Clifford and tube headers I am using only short clamps and threaded studs in all holes (8) down the side of the head. Each of the clamps may have to be modified specifically for each location.

In this picture, there is not one nut holding the manifolds in place. They are just resting on the studs. The headers are two piece and the intake makes a third piece that would have to be juggled while trying to start individual bolts. The studs make installation easier and allows for more uniform tightening.