jtarp

I haven't posted on here in a while, but I have a few questions. I have recently gotten rid of my camaro and have picked up an '86 c10. It has a 350 small block and th-350c trans.(lockup convertor and transgo shift kit) I was told the block came out of a 69 corvette. I am looking to build the motor to 400hp+. So here are my questions.

How can I verify that the block is indeed from a 69 vette? And if it is, is it a good block to start with? Motor does run very well, and it does have a Summit Racing 1103 cam and lifter set in it. Seems to move out decently. It is a 4-bolt main block as I have checked that out. Carb looks to be an Edelbrock Q-jet. Not sure on cfm, but I was looking at the Holley 670 street avenger as a replacement. Intake is an Edelbrock performer. Distributor is some old HEI.

What are your opinions on the lockup convertor type th-350's?

Also it has the factory 2.43 gears and a lame peg legged rear. What would be a good rear set up?

Are the numbers I'm looking for reasonable? And if so what would be a good Head/Cam combo? Anything over and beyond 400 horses would make me happy. I do not have a budget at this time but I guess I would like to keep it under $2k if at all possible. The truck will see track time in the future. Streetablity is NOT a concern.

angel71rs

Any 4 bolt 350 in good shape is good enough for your app, so doesn't matter if it came out of a 69 vette. But if it is, might be worth $$$ to someone restoring a 69 vette. If block deck hasn't been machined, there will be a 3 letter code on the pad in front of the passenger head. That plus casting date and casting number will tell you what it came out of. Just be aware that every sbc came out of a vette... or so it seems to hear a lot of sellers tell it.

Don't have much experience setting up for a truck, but would suggest building for torque, not peak hp. This will help move the heavier truck. So any reputable manufacturer's head with intake ports ~ 170 cc, and a cam ~ 220* @ .050". But aftermarket heads are $$$, so don't know about 2k budget for the build. Consider Vortec heads/intake, Vortec head info here: http://www.nastyz28.com/forum/showthread.php?t=56505

This won't make 400 hp, but will work well with a 3.42 gear, a good all around gear. If you have to have 400 hp, you can still get there with a good 170cc port, or move up to 195/200cc. Combined with a good intake and a cam ~ 230-236* should get there. And you would have to go to at least a 4.11 gear or it would be a dog off the line.

Edelbrock qjets are 750 cfm + depending on the model. Qjets are good carbs, small primaries for low end torque, big secondaries for high rpm power. Just more complicated than Holleys. I ran a factory qjet on a 67 442 and it did great once I got it tuned right, and it came free with the car, so something less to spend $$$ on.

Since you say the motor runs well, you could also consider a supercharger if the compression ratio is suitable. Something like this will get you there and make a ton of torque to move the truck: http://www.summitracing.com/parts/WND-6500-1/

Your cam specs are suitable for a supercharger, but make sure you have a good set of valve springs/keepers installed. A lot of guys will use factory springs with a small cam like that, and it works ok... until you spin it > 5,200 rpm or add a supercharger. Then you can get valve float. Lots of companies have performance springs that will swap right in, no machining needed.

Don't know about lockup th350s, but any stock th350 is going to have a hard time living in this app. Best to have it built to handle the power. Gears/posi install on top of that... old saying... take what you thought you'd need to spend and double it... you'll get close to what actual cost will be.

p.s. a lot of light duty GM trucks/vans of that era use a weak posi unit in the corporate 8.5" diff. I think it was called a governor posi or something. If you find a complete diff in the junk yard with a "posi" pop off the cover and make sure it's not one of those. Check out this pic, governor on the left, desirable clutch type posi middle, std right:

http://rides.webshots.com/photo/1055...41712107SKzSev

jtarp

Thanks for the input man. I really appreciate it. I will however be keeping the truck N/A. I actually have a friend with a set of vortecs sitting around. I believe they are the 906's. So I guess it'd be a good idea to pick them up from him?

I have another question also. Do you know anything about 700r4 transmissions. I know they have a steeper first gear. Are there any weaknesses to them though, as opposed to a th-350?

As for the rear I have decided to go with a set of 3.42's for now. I was thinking about grabbing a detroit true trac as well.

Angelis83LT

One of the weaknesses on the 700r4 is the TV cable imo. the TH350 has a shift detent cable, and the line pressures are controlled through a vacuum modulator if I remember correctly. The 700r4 is all controlled by the TV cable. A miss-adjustment of the TV is all it takes to turn it into a rebuild core. Other than that, I believe there were a few issues with the early 700r4s. Can't remember off hand what they were though.

As for the engine. You need to get the casting number off the back of the engine, and then the engine ID code from the passenger side head. That will let you know when it was made, and what it came out of (once you post the numbers). Another good thing to do is actually take a look and see if you can see any markings along the lines of "5.7" on the block by the casting number. or the like. You would be amazed how many of those "corvette 350" motors are actually 305's...

byrons1502

The cheapest way to get good power is install vortec heads and run the q-jet. They are awesome when tuned right. Make sure the exhaust is at least 2.5 inch or bigger. Good headers. Run the trans till it pukes then get a regular th350 and a small stall. Run 3.73 gears. The motor will not max out at the top end and the taller tires will keep the rpms just right. I used to street race a 85 longbed c10 that has had 9 different engine combos. The most fun was the big block.

rskrause

Good advice here and in the other posts.

Go for Vortech heads and a small cam, build it for torque in the low and mid-range. Cam should not be more than 215 intake duration at 50.

Rich