First G body build

[80cutlass355]

Hi everyone,

I recently purchased a 1980 Cutlass Supreme as my first g-body and I'd like to do a somewhat pro street build. Nothing fancy, but something I can take to the strip every once in awhile and still have fun while being a driver as well. I am looking to get pointed in the right direction and get the best bang for my buck as this is going to be somewhat of a budget build. For starters I was wondering if anyone has any input on the motor I have. It came with the car and is fresh with about 2000 miles on it. I was told it should have right around 375hp. The specs are as follows.

SBC 355
.010 nickel block
GM steel crank
aftermarket rods
flat top pistons
64 cc heads that have been shaved
decked block
edelbrock performer intake and carb
double roller timing chain
melling high volume oil pump
.480/.480 cam

This is all the information I have on the motor. Does what is in it make sense? Is there anything I should change? Best changes to make more power? Does it make sense that this motor should be right around 375hp?

The car has a rebuilt th350 with a stage 2 b&m shift kit. It has a non posi original rear end with 2.42 gears. True dual exhaust with H pipe and magnaflow mufflers. The car seems to sit lower then most. I am guessing that the springs are worn out because the are the originals. There are smaller tires on front and there are still some rubbing issues at full crank. I was thinking about getting a posi and 3.73 gears in the stock rear end, but I have read that they cannot handle a bunch of hp especially if they are going to the strip. This build is going to happen in stages so I dont know if I use this rear end for now and then switch to a different later. I would like to put a manual or at least a 4 speed auto transmission in it so I can run 3.73s or 4.11s in it for the strip while still being able to cruise at too high of rpms.

I am new to building a car so sorry if my questions may seem like common sense to a lot of you guys. I look forward to any kind of input you guys have!

Thanks

 

[Carlola]

4 speed and 373's make sense for your purposes. It really depends on how streetable you want this to be. Some will tell you that a properly built 7.5 rear end will hold up fine to your hp range. If your gonna be hitting the strip a lot though, a 9"/12 bolt/8.5 are the upgrade options.

375 ponies sounds pretty good for that set up, maybe a bit of an embellishment.

 

[Fox80]

I think you better find out about the " shaved heads" and the block being decked. If the decked the block to establish the correct deck height that's ok and a must do on any block, but if they cut it to allow the piston to travel out of the block say .005" and cut the heads with the 64cc chamber you will have a pretty high comp. ratio. Not a bad thing at all but if your new to this stuff the tuning on a motor like that becomes critical as well as fuel quality. I would agree with the previous post that power number might be a bit inflated, but still very good street motor. I think personally a 9" rear end is the only way to go bolt in setups can be bought for the same money as guys want for a 8.5" that still has a c-clip style axle in it

 

[80cutlass355]

Thanks for the input guys. I am told that the engine is 10.5-1 compression. I am not sure if that is high or not for one of these motors because again I am new to this. I am trying to get the name of the engine builder so I can talk to him personally. I am from WI and the car runs perfect other then when it is cool out. We have had two cool nights where it was maybe low 60s or high 50s and a little damp out and the car didnt run very good. It kept dying at stop signs, but then the next day when it was warm again it ran perfect. I have done a little research on a 4 speed manual swap and see that it can be done, but what would be the best way to go about this? Also, what should redline be and overheat temp. in an engine like this?

 

[O. D. Showtime]

Welcome to the site...

Your motor combo is very similar to what my son has in his 81 Malibu...he decided to dyno it and it made 375...so I think yours should be right there as well.

 

[80cutlass355]

What transmission and rear end set up does your son have in his malibu?