Best investment with a TBI 454

[chillman88]

Hey all,

I bought a 90 suburban with a 454 that will eventually go in my 69 Caprice Classic.

I'm trying to get an idea what would be my best plan of action. I'm just in the idea stage, not quite to planning so ANY help would be appreciated. I have a couple ideas and would like other's opinions. All options will be carb'd (most likely a Q-jet). I'm not keeping the EFI. I know these engines are set up for torque and de-tuned with low compression.

Funds will be quite limited. Unless I can steal a pair of good heads, I'm stuck with either the factory TBI heads or a set of Junkyard Vortec heads. I have read they dont flow much better, but the chambers are smaller which should net me higher compression and a decent ROI.

Option 1.

Slap it in and go (likely what will happen first, then proceed to another option)

Option 2.

Put a set of junkyard vortec heads on it to up the compression, maybe an intake and then run it.

Option 3.

Cam change and factory tbi heads.

Option 4.

Factory tbi heads and different pistons to increase compression.

Option 5.

Highly unlikely, but factory heads and a turbo setup. I've read lower compression is better for boost but I expect the TBI heads to be a major bottleneck here.

What say the masses? I'm not new to wrenching, but new to modifying engine internals.

[kwmech]

Depends on your budget and what you expect overall from the 454. Just bumping the compression between 8.5 and 9.0 along with a mild cam will wake that big block up, even with the stock heads

[chillman88]

Originally Posted by kwmech

Depends on your budget and what you expect overall from the 454. Just bumping the compression between 8.5 and 9.0 along with a mild cam will wake that big block up, even with the stock heads

That's kinda what I was expecting with the Vortec heads. They should bump the compression to about 9 from what I've read.

I'm not looking for a drag car, just something to make it feel a little stronger. The HP spec on this TBI block is stupid low. Something like 230-250hp or so?

I'd love to get 350-400hp, but I am after all going to be dealing with a slim budget.

EDIT: I don't know how low my budget will be just yet. I'm looking at tax return funds for this build.

[kerber63]

I did option 3, then option 5.

I started with a ‘90 motor and got rid of all tbi and emissions junk. I put on a Quadrajet and went with a stage 1 rv cam and stock compression hyper pistons. I kept the peanut port heads - they support decent horsepower, and flow right for huge torque. I was getting ~16 mpg and didn’t feel like I was missing out on anything.

Later, I put a turbo on and tried to run it with mods to my original setup. The change was huge, but it didn’t last long. After I lost the ring lands on the pistons, I rebuilt everything with turbo spec parts - cam, pistons, double pumper, etc. I’m still running the peanut port heads - once the charge is being forced into the cylinders, it overcomes the small port flow problems.

If you’re seriously considering a turbo setup, I’d suggest saving up and doing it all at once instead of doing it in stages like I did. And prepare yourself to spend lots and lots of time thinking through every part and installation.

[DieselSJ]

Originally Posted by chillman88

That's kinda what I was expecting with the Vortec heads. They should bump the compression to about 9 from what I've read.

I'm not looking for a drag car, just something to make it feel a little stronger. The HP spec on this TBI block is stupid low. Something like 230-250hp or so?

I'd love to get 350-400hp, but I am after all going to be dealing with a slim budget.

EDIT: I don't know how low my budget will be just yet. I'm looking at tax return funds for this build.

You get just about a full point of compression with the Vortec heads. Note that you will also need a tune as they like about 30 degrees total timing because the chamber is so good and the stock tune has a lot more timing than that. Intake at the same time - any oval port intake will work with the Vortec heads.

I'm totally on the fence about doing the Vortec head swap or just putting the money into a Cummins swap. Before I do anything, I need an overdrive...

[Tiger Joe]

under 400 hp you can most likely keep the stock heads.

I would definitely be changing out the cam. these cams are really pathetic.

nice cam, true dual exhaust, and I bet you have a really healthy motor, for not a lot of coin.

[chillman88]

Originally Posted by DieselSJ

You get just about a full point of compression with the Vortec heads. Note that you will also need a tune as they like about 30 degrees total timing because the chamber is so good and the stock tune has a lot more timing than that. Intake at the same time - any oval port intake will work with the Vortec heads.

I'm totally on the fence about doing the Vortec head swap or just putting the money into a Cummins swap. Before I do anything, I need an overdrive...

She'll need a tune anyway going from TBI to Carb I considered a diesel swap but I won't have the funds for that. Can you imagine a 69 sedan pulling up to you clattering away? Lol it'd get looks for sure!

Originally Posted by Tiger Joe

under 400 hp you can most likely keep the stock heads.

I would definitely be changing out the cam. these cams are really pathetic.

nice cam, true dual exhaust, and I bet you have a really healthy motor, for not a lot of coin.

I was hoping to have a few different guys say this. My concern is the low compression. Wouldn't a bigger cam lower my dynamic compression, compounding the issue or not necessarily depending on the grind? I have a very basic understanding of cams but they still confuse me.

I'm curious what just a cam change would do for me. I don't want to lose low end though.

[b454rat]

You can run a mild cam with whatever combo and it will run. I built an 84 3/4 ton with a million mile 454 with some type of smog head, small comp cam, headers and stock carb/intake. Truck had 6" lift and 35s, and with 3.73s I could smolder the right rear tire. (one wheel peel lol)

[Tiger Joe]

yes the tbi 454s don't have much compression to play with, they wont support a very big cam. however the factory cam is so pathetic you almost have to start there.

if you are ditching the tbi, i'd look at the Comp Cams XE274H. Guys have had a lot of good luck swapping that cam into low compression 454s.

get a good manifold, carb, cam and headers and you have a healthy motor.

trying to go any bigger than that you're gonna end up rebuilding the motor to bump up compression

[chillman88]

Originally Posted by Tiger Joe

yes the tbi 454s don't have much compression to play with, they wont support a very big cam. however the factory cam is so pathetic you almost have to start there.

if you are ditching the tbi, i'd look at the Comp Cams XE274H. Guys have had a lot of good luck swapping that cam into low compression 454s.

get a good manifold, carb, cam and headers and you have a healthy motor.

trying to go any bigger than that you're gonna end up rebuilding the motor to bump up compression

This is pretty much what I was hoping to hear. A rebuild will happen later but is not in the cards right now. This car has already been sitting 3 years. I want to drive it.

Will this cam require adjustable valves or different pushrods? I thought I read the TBI heads have non adjustable valves from the factory.

[Tiger Joe]

heres the cam specs:
http://www.compcams.com/Company/CC/c...?csid=396&sb=0

you need different springs. the kit is K11-246-3

doesn't include push rods so you could likely reuse your stockers. though id prolly just buy new for peace of mind.

[Captainfab]

I have the XE268H in a 9-1 454 and personally I would not go any bigger with that compression. It runs just fine on 87 octane.

[DieselSJ]

That XE274H looks to be a lot of cam for a 8:1 (or less) engine. I would not go that big with stock compression. With the Vortec heads, yes.

[chillman88]

I started to look into it after CaptainFabs comment. What about the XE268H? I also saw someone recommend Lunati over comp for some reason...

I'd rather not over cam it too much. It's more street than strip but I want a little more oomph than it has now.

[b454rat]

My last 454 had the 268 in it and was definitely a shaker. Sounded awesome, great power, but might be a wee too much for a street truck. Go to youtube and search that cam in a big block, there was a couple and sounded pretty rowdy. A couple steps up from a stock cam will wake a 454 up. I wish I was better situated to build mine...

[Tiger Joe]

Go over to the chevelle website you can search guys ran that cam in low comp 454s with a lot of success. You said caprice which is a little heavier but not much than a chevelle. Still lighter than a truck.

['63GENIII]

Try giving a call to Chris Straub. Im running one of his cams that was designed for the SS 454 engine. IIRC, it was dynoed at something like 450 / 525 in the TBI combo (which I think was a lower compression engine too). Im running this cam in my L29 (with the Vortec heads) and it pulls like a freight train on the "slightly" hotter than stock tune which just eliminated the EGR, rear o2 sensor and gave it fuel and timing maps to work with the rest of the truck.

Non adjustable valve train completely sucks so if you have your heads off for any reason... get them drilled and tapped for the standard BBC 7/16 studs. Don't believe the BS about the Comp Cams conversion studs. They are crap and you can't find 3/8" guide plates to use with their studs anymore.

For using Vortec heads on the older block -

I think that if you have the 1 piece rear seal, you should be fine.

2 piece rear seal requires a slightly different head gasket to be sealed up right.

1 piece rear seal is likely machined for a roller cam retainer plate. This is good. Take advantage of it.

Vortec heads are fine but there is just not a lot of real hard info on them. They were kind of like a GM experiment until the big cathedral port 8.1 came along.

The Vortecs don't respond too well to porting unless you like water injection and the intakes really could use porting due to the ski jump in them.

Once in the chamber, there is the heart shape cast into the chamber that is supposed to promote complete ignition of the mixture. The casting comes to such a sharp point that it will actually slice your hands open if not careful. I looked at this point as a possible source of detonation. This could be why the Vortecs are tune limited to 30 deg. total advance. Exhaust is a different story. The D shaped ports flow fairly well and don't need much work to work well on the street. All in all though, these heads are done at 5,000 - 5,500.

[cadillac_al]

It all depends on how hard you run that Caprice. I have a 70 Impala and I almost never go over 3k rpm's with a 400 sbc. I will bring her up to 5k rpms a couple times a week just to make some hot rod noise. I'm still working on stability at high speeds. Everything in the suspension is new and it is a handful to handle over 80 mph. I don't remember them being like this in the old days but hey, I have bikes and a Camaro for going fast.

I'm looking for a big block just for the big block sound. I'm thinking if I score a truck 454 I may try it in stock form for a while. I'm sure the truck 454 will love cruising under 3k rpms with an occasional 5k rpm blast to make some noise. I guess my old Impala is just a fair weather cruiser that doesn't seem to need high horsepower.

[chillman88]

Originally Posted by cadillac_al

It all depends on how hard you run that Caprice. I have a 70 Impala and I almost never go over 3k rpm's with a 400 sbc. I will bring her up to 5k rpms a couple times a week just to make some hot rod noise. I'm still working on stability at high speeds. Everything in the suspension is new and it is a handful to handle over 80 mph. I don't remember them being like this in the old days but hey, I have bikes and a Camaro for going fast.

I'm looking for a big block just for the big block sound. I'm thinking if I score a truck 454 I may try it in stock form for a while. I'm sure the truck 454 will love cruising under 3k rpms with an occasional 5k rpm blast to make some noise. I guess my old Impala is just a fair weather cruiser that doesn't seem to need high horsepower.

This is kinda how I'm feeling about the car. It'll be fun, but I'm not trying to get any tickets or anything. Might try a strip once but I just want a driver that'll chirp the tires if I open it up. I'm leaning towards the 168H simply because the 174H has a much higher power band. If I was going to put taller gears in it it might not be a big deal, but I'm almost certain it has 2.73s in it now.

I don't think a 4-5k rpm limit will be a big deal. I'm used to Diesel power bands anyway. My old truck is done about 3200rpm lol

[DieselSJ]

Originally Posted by '63GENIII

Once in the chamber, there is the heart shape cast into the chamber that is supposed to promote complete ignition of the mixture. The casting comes to such a sharp point that it will actually slice your hands open if not careful. I looked at this point as a possible source of detonation. This could be why the Vortecs are tune limited to 30 deg. total advance. Exhaust is a different story. The D shaped ports flow fairly well and don't need much work to work well on the street. All in all though, these heads are done at 5,000 - 5,500.

The timing limit really has to do with the efficiency of the chamber and is not related to being prone to detonation. The fuel/air charge is mixed so well that the burn is done faster.

There is actually a lot of good data on those heads over on the 454SS forums.

[chillman88]

Well here we are a year later. Still haven't gotten the engine in. One thing after another...

I'm going to be ordering gaskets and stuff here pretty soon. I will be replacing the timing chain for peace of mind but keeping the stock tbi cam.

Any benefit to advancing it 4 degrees or is it going to be best to leave it straight up and worry about it when I change the cam someday down the road?

[Captainfab]

I see no advantage in advancing the puny stock cam. It is already ground for low to mid range power.

[Warrens69GMC]

Ever hear the name Grumpy Jenkins? this is a good read....

http://garage.grumpysperformance.com...ck-combo.2900/

[Warrens69GMC]

and Vortec pro ported peanut port heads

https://www.youtube.com/watch?v=cSUtmDOxKUs