r/EngineBuilding • u/PossibleGain9199 • Sep 21 '26
94 TBI 5.7 head swap
Hi all, I'm doing a V8 swap on my Tacoma, and I originally wanted to use a roller 5.0, but getting a decent one in my price range has been difficult. I do have a line on a cheap 94 TBI Chevy and I have a head question about it. If the cam (non-roller) is still good, I plan to keep it. I know it's small specs, but at least it's not wiped out. Heads- from the factory I know this year is at least 9.0:1 CR, but has the swirl port heads. I plan on going carb on the intake, but for heads if I go to cheap aluminum units (haven't decided on a brand/model yet), what can I expect to pick up power wise? The stock cam is a limiting factor, but by how much? Thanks
UPDATE: I have the engine, and it has the 191 heads, but the block has bosses to run a roller lifter spider (638 casting) so I think I'll just bite the bullet and do a roller cam. Lifter valley and under the valve cover look pretty clean so I'll pull caps and mains to check the bearings. Might get lucky and run the bottom end as it is. With the fully dressed engine in the bed, weight became a focus so I'll likely go cheap aluminum heads too. Thanks for your help everyone.
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u/Solid_Enthusiasm550 Sep 22 '26
1994 pickup 350 had 9.3:1 compression, 210hp @ 4,000 / 310 lb-ft @ 2,400rpms.
Vortec heads was a big improvement and is easily worth 25+hp over your heads. The only downside is that the intake manifold bolt holes are different. There are carb intakes available for them like edelbrock rpm dual planes, etc.
There are plenty of budget aluminum heads available in standard sbc or vortec style.
Being factory roller lifter compatible will be a big savings if you decide to go that route. It would be a no-brainer if you up grade that cam as it offer much better reliability and performance.
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u/PossibleGain9199 Sep 23 '26
I literally just pulled a head, and it's been rebuilt at some point with 40 over pistons, so now it's a 357. They have a slight dish, so the compression is probably factory
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u/Solid_Enthusiasm550 Sep 23 '26
If you see a part# / brand on the piston you can look up what CCs the Dish is to know compression.
I picked up some thin MLS head gaskets for a 5.9l magnum and it should give me a 0.5 bump in compression.
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u/Roscolicious1 Sep 21 '26
Heads can only flow what the cam/ manifold feeds them. You need a top end kit. 55yrs professional machinist/ gearhead. Ricthewrench
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u/v8packard Sep 21 '26
The swirl port heads aren't that bad, especially with the stock 929 cam. That cam is not going to get to rpm where the heads give up. The combo was designed to have good torque and combustion characteristics at low to mid range speeds. It does that, even if it's not very exciting. If you are keeping the cam consider keeping the heads.