Help wanted

[jx12ihra]

Hi Folks,I'm a new person to the site,and have been away from 60 degree engines,but do have some knowledge about them.The vehicle 1s a 1985 -10, 2wd,700r4,power and air.The plan for this truck is to be able to drive regularly and bracket race on week ends.I have access to a fresh 3.1 rear drive short block,a t-25 turbo,and a 4.1 limited slip rear from an 87 s-10 4wd.The current engine is a tired 2.8.I need advise on cam and head choices.I am aware that the later fwd heads are far better in terms of flow and power production,but I intend to stay carbed,and computer free.Any suggestions would be helpful.THANKS,jx12ihra

[BMC]

Sounds like a neat start but if you can find a used 3.4L eventually, you can get more out of it.

I believe this site along with older info on the S-series.org site has cam choices and info that would help a bit. Personally, I dont care for automatics....

A 4.1 means you can skip the freeway but a 3.73 may leave you with some freeway wiggle room.

Heads- must use iron for carb. Alloy uses a different intake manifold configuration. Later heads, say about 1986 or 87 started using larger valves so if you get a sete of those and port them out, thats what you can do for a carb motor. If your willing to build a FI engine, you can go either route but plan to spend quite a bit of time building for a one off project.

-BMC.

[jx12ihra]

Thanks,BMC,The 4.1 gear wont be an issue because I will be beefing up the 700r4 to handle the additional power[automatics are much easier to hold consistancy].4.1x.7=2.87final crusing ratio.I noticed that some people have modified the intake top to adapt an m-90,why not a carb.?This would mean a piston change,but could allow the much better cyl.heads.Has anyone be able to retro fit a roller cam and lifters to the early engines?I only need about 370 ft.lbs of torque to run the et I need[7.95 in 1/8 mi.]in a 3100 lb.truck.Thanks again for the help.jx12ihra

[robertisaar]

you're trying to make 370lbs of torque with a carb on top of a modded UIM?

not very realistic. that much torque on a N/A 60* motor is going to be VERY hard to achieve.

[jx12ihra]

Thanks,you are probally right,I've been playing with v8's too long,however with the right turbo it will take more boost than practical for the street.I guess I'LL JUST HAVE TO GO SLOWER.I had not planned on going n/a,and dont really want to go v8,I like to be different.Any ideas will be apperaciated.jx12ihra

[robertisaar]

Thanks,you are probally right,I've been playing with v8's too long,however with the right turbo it will take more boost than practical for the street.I guess I'LL JUST HAVE TO GO SLOWER.I had not planned on going n/a,and dont really want to go v8,I like to be different.Any ideas will be apperaciated.jx12ihra

a 3500 should be able to make that with around 8psi...

[jx12ihra]

3500 olds motor or new chevy? eight lbs is in the range i want to run.I've read some posts other guys have done, and they are quite impressive.Again ,many thanks.

[robertisaar]

3500 olds motor or new chevy? eight lbs is in the range i want to run.I've read some posts other guys have done, and they are quite impressive.Again ,many thanks.

3.5 olds(shortstar) would be a 90* motor, not something we endorse a lot on here. i'm refering to the GM High Value 3500 V6 (LX9, which is the non-VVT version). you probably could use a VVT version if you want to mess with some way of being able to control the cam-phaser, but it only adds another 15 hp compared to the LX9. BTW- LX9 is rated around 220lb-ft stock, LZ4(VVT version) is around 220, HP of the LX9 is between 200-210, LZ4 is around 215-225.

i'd go with the non-VVT for simplicity and run it on TGP code(at first anyway).

with 8psi, you'll be stuffing around an extra 55% of air in(assuming 100% efficiency anyway), so expext around an extra 55% of torque, which is ~340lb-ft. obviously. depending on a few other factors, that could be enough to hit the ET you're looking for. if not, 10psi would take you to 370...