TBI cam suggestions

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09-06-2017
tayto

TBI cam suggestions

I recently accquired a TBI 350 from a 1987 Chev 2500, VIN K (light duty, only had semi floater 14 bolt). Engine has 137,000km Kilometres. I pulled heads and still has crosshatch on the cylinder walls. I am planning on swapping it into my 89 Caprice. It is a roller block, but none of the holes are drilled for the spider. I could drill them by hand but maybe it would be cheaper to go with a hydraulic tappet? Anyway I am wondering if you can recommend a cam for this engine?

It has dished pistons. Do you think it is*worth running a thinner headgasket to bring the quench to the .035-.045" range and bring up the compression slightly? I am on a budget would like to just regasket & cam swap and then put it into my caprice. Thanks!
09-06-2017
dave w

1 Attachment(s)

One budget option would be get all the roller camshaft parts (used) from a Vortec 350, see picture below. Send me a Private Message (PM) if you would like purchase the used parts pictured.

dave w
09-07-2017
donf

I have seen this flat tappet cam recommended several times for mild TBI use when the block is not set up for a roller cam. https://www.summitracing.com/int/par...0032/overview/ Some say that Summit cams are made by Crane. Crane has a cam listed as the energizer 260 with exactly the same specs, and a little better description. I purchased shim head gaskets and valve stem seals on closeout from rockauto a while back. I figure that if I am going in that far I might as well pull the heads and take a peek. If nothing else have them cleaned up and new springs / seals installed.
09-08-2017
tayto

I ended up getting a lightly used LT1 cam shaft for $100 canadian shipped, i have a uaed set of roller lifters with about 50 hours on them and plan to goto the wrecker this weekend to pull the lifter spider and dog bones. Going to measure my piston to deck height a will get a gasket that will put me around. 045" quench. i also got a set of LT1 exhaust manifolds that i can hopefully mod to work with the TBI heads. going to make a single 3" and call it a day. i already modded my small block TBI for a slight increase in flow and pretty sure i have a 16 psi spring somewhere.

dave, i may be interested in a mail order tune for this thing. i plan to run the stock '746 tho... i have a' 7427 but dont want to have to do much wiring aside from repinning thw connector if possible. will be running a 700r4 with lockup controlled by ECU.
09-08-2017
dktool

Quote:

Originally Posted by tayto

Going to measure my piston to deck height a will get a gasket that will put me around. 045" quench.

Correct me if I'm wrong, with full dished pistons you cannot achieve an effective quench.
09-15-2017
tayto

I believe you are correct dean. I measured the old head gasket, it was .015-.017",so I am just going to run that again. I need to see how far the piston is in the hole and then will determine if i need to mill my heads to get my compression in the 9:1 range.
09-15-2017
jim_in_dorris

Sorry to disagree, but quench height is strictly how far in the hole the piston is, and the crush height of the gasket. Stock pistons are installed .025 in the hole, and a crush height of .015 to .017 gives you a perfect .040 to .042 quench. Compression is made up of the piston dish or dome, the distance in the hole for the piston, the gasket crush height, and the combustion size for your head.
09-16-2017
dktool

Quote:

Originally Posted by jim_in_dorris

Sorry to disagree, but quench height is strictly how far in the hole the piston is, and the crush height of the gasket. Stock pistons are installed .025 in the hole, and a crush height of .015 to .017 gives you a perfect .040 to .042 quench. Compression is made up of the piston dish or dome, the distance in the hole for the piston, the gasket crush height, and the combustion size for your head.

Thanks for the clarification Jim, and are you really in Dorris ? I have passing through there a lot in the past couple years, to and from Bend, OR. going again in 2 weeks.
09-18-2017
jim_in_dorris

Yep really from Dorris. LOL. didn't make Bend this year, have some friends in La Pine
09-21-2017
kacy

The limiting factor on the engine is the heads, they just dont flow and need lot of work to be performers. A stock set of older model heads, TPI heads and Vortecs all out flow theses heads stock. The engine in your 89 Caprice should be a roller cam engine, unless it is you daily driver you would be better off rebuilding it, getting a used lt1/4 cam and the heads mentioned above.
09-22-2017
Fast355

Quote:

Originally Posted by kacy

The limiting factor on the engine is the heads, they just dont flow and need lot of work to be performers. A stock set of older model heads, TPI heads and Vortecs all out flow theses heads stock. The engine in your 89 Caprice should be a roller cam engine, unless it is you daily driver you would be better off rebuilding it, getting a used lt1/4 cam and the heads mentioned above.

VERY LITTLE HP difference swapping from the TBI heads to TPI heads on these engines. Even Vortec heads do not see large gains until you go to a substantial cam upgrade, different intake manifold, 454 TBI unit, headers, and larger exhaust. The stock TBI heads can make 300 HP with the right setup.