SBC LT1 / vortec compatability

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SBC LT1 / vortec compatability

Post by prairiehotrodder »

will the cam / lifters and the rods / pistons out of a 93 buick roadmaster LT1 go into a 96-98 350 vortec truck engine ? I have the roadmaster engine and i'm trying to build another ultra low buck JY motor for my sons jr. street drag car 1980 malibu 4 door. I haven't taken the motor apart yet but i 'm thinking it might have factory flat top pistons, powder metal rods and a bigger cam than the vortec truck motor ? can anyone verify this ?
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Re: SBC LT1 / vortec compatability

Post by turbo camino »

Roadmaster didn't get the LT1 until '94. The '94-'96 B body cam is essentially identical to the L31. I don't think the other parts are any different (better) than what would be in the L31 already, either.
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Re: SBC LT1 / vortec compatability

Post by prairiehotrodder »

sorry, my roadmaster is the 94. So the flattops and the better cam is just a myth ?
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Re: SBC LT1 / vortec compatability

Post by turbo camino »

The camshafts are within less than .010" lift difference at the valve and 1* at .050, small enough that it could be down to nothing more than being measured by two different people. Nothing there. Except, some of the early B body cams had a fuel pump lobe. None of the L31s did.

The L31 pistons have a much better ring pack. If the LT1 pistons do turn out to be FTs make sure to verify the compression height, otherwise you could get fooled into trading a small dish with better quench for the same effective compression ratio with worse quench. The L31 dish is not that extreme.
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Re: SBC LT1 / vortec compatability

Post by prairiehotrodder »

well thanks for the info. Good to know. I've mainly been playing with TBI truck motors. The car is limited to 9.0 in the 1/8 mile for the IHRA Jr. street program. Last year it had a stock TBI 350 out of a 94 pickup with headers and a Q-jet on a stock iron 4 barrel intake. It would squeal the tires and went pretty decent for a bunch of wore out junk. I sold that motor and put in another 94 TBI 350 truck engine but this time i swapped in all the vortec roller cam stuff (not the heads). It was slower. I bet the vortec roller cam made 40 less hp than the stock TBI flat tappet cam. Didn't expect that. It still runs fine and we drive it 2 hours to the track. I'm gonna sell this motor and try mixing and matching a bunch more junk and see what happens. Its kinda fun. I have 4 more TBI motors to play with and the vortec motors turn up in my JY once in awhile to but usually they have cracked heads.
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Re: SBC LT1 / vortec compatability

Post by turbo camino »

I bet I know where you got that about the cam being bigger - the 'baby LT1' (L99) had, I believe, the LT4 camshaft but with 1.5:1 rockers for less lift. It was something like 203/210 @.050.

The L31/B-body cams, according to my notes...
191/196 .418/.430 111*
vs
190/195 .412/.423 111*
...not even gonna tell you which is which cause it don't matter.

I have a similar leftover-parts engine. 1995 TBI truck block, L31 pistons/rods, B-body roller cam (got to have that fuel pump lobe), 55cc '113 aluminum L98 heads, Bowtie ZZ4 intake, Qjet.
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Re: SBC LT1 / vortec compatability

Post by travis »

Seems strange that the stock TBI cam was faster, as it is a tiny little thing...like 178/194@.050 or there about with very low lift. Are you running a really tall gear?
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Re: SBC LT1 / vortec compatability

Post by prairiehotrodder »

travis wrote: Tue Sep 08, 2020 3:50 am Seems strange that the stock TBI cam was faster, as it is a tiny little thing...like 178/194@.050 or there about with very low lift. Are you running a really tall gear?
the car has 3.42 gear and a stock torque convertor in a turbo 350.
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Re: SBC LT1 / vortec compatability

Post by 1980RS »

The truck Vortec's are not compatible with the LT1 engine, but you can use the later LT1 cast iron heads and port those to run form the 95-96 B-body cars. Don't go hog wild and port the crap our of them, they don't need it to make good power. Just a good 3 angle seat valve job and bowl porting is all that needed. Do not port match them , you don't need to. If I can run a high 10 sec time with not much port work on a Vortec head, just think how just a little work will do for your engine.
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Re: SBC LT1 / vortec compatability

Post by prairiehotrodder »

just to update this thread, i tore down my 94 buick roadmaster LT1 and it does have flat top pistons. In fact for a very high mileage motor the whole rotating assembly was in excellent condition. No skirt wear that i can see. I'm most likely going to find a TBI 350 (cheap and plentiful) and put in these pistons, maybe a small cam and have fun. If i happen to find a roller block TBI engine then i'll also use this LT1 camshaft as well. The main things i want to get away from is the goofy TBI and vortec heads with their special intake bolt patterns. I know the vortec heads can make power but they are usually cracked and i don't want to buy a special intake.
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Re: SBC LT1 / vortec compatability

Post by BillK »

ph,
I would make absolutely sure that the LT1 cam will work in a "regular" roller engine. I am pretty sure the front of the cam is different for the Optispark. Every cam manufacturer I looked at has a different set of part numbers for the LT1&4 It may be a simple matter of using the correct timing set but make sure and check.
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Re: SBC LT1 / vortec compatability

Post by CGT »

Im pretty sure the difference is the length of the dowel pin. Seems like Ive gotten a late model step nose sbc cam that came with 2 different length pins.
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Re: SBC LT1 / vortec compatability

Post by F-BIRD'88 »

If you got your L31 vortec heads from a known good running L-31 motor the heads are probabily ok.
Its the take off heads from a blown overheated unknown motor (coolant leak) that will likely be cracked. They get sold off.
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Re: SBC LT1 / vortec compatability

Post by F-BIRD'88 »

A 305 sbc would be good (and cheap) for that car.
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Re: SBC LT1 / vortec compatability

Post by mt-engines »

CGT wrote: Thu Oct 01, 2020 3:22 pm Im pretty sure the difference is the length of the dowel pin. Seems like Ive gotten a late model step nose sbc cam that came with 2 different length pins.
correct
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