Hi All,

I finally purchased my IROC project car ('85, 305 TPI engine currently) and I have a couple of quick questions so I can get started. I'm planning on building this car for fun, want to drive it on the street and probably never take it to the track:

1) I haven't decided what kind of engine I'm going with yet (carb or TPI), but either way I'm wondering - is there a recommended "maximum" HP for these cars? I want to put a 383 stroker in, just wondering how much I can build it before I need to start worrying about killing the rear end, suspension, etc. I plan on tying the frame, but I wanted to stay away from any other major suspension/drivetrain mods. The crate engine I'm looking at is rated at 420 HP, which means roughly 380 to the wheels, right? Is that too much?

2) The car originally had a 4-speed automatic in it but the previous owner swapped it out with a 5-speed automatic. I'm thinking about going with a manual instead, I know it's a lot of work but I really want a stick. Any recommendations on what trans to get, where to look, best way to get the clutch pedal assembly, etc.?

3) I would like to know what rear end is in it, I looked underneath and didn't see a tag (unless it's hidden). Is there any way to find out what gears are in it based on the VIN, options, another location for the tag, etc.? And, what gear is recommended?

Thanks in advance for any advice & info.

 

1. Check emission laws first. Then go from there. But realize more HP is more expensive and on the street it can be no fun. Especially if all the power is made in the 4-7K range.

2. I don't understand the obsession with manual, if he already did the swap, then you will the platform and, most would recommend the T-56, for auto I'd stick with a built 700R4.

3. You can find all of your options on a sticker inside of your center console. Decode those and you'll be able to tell exactly what you have. Most likely, it'll end up being an open 2.73 10-bolt, but there were other options.

 

What 5 speed automatic did they install??

 

That was going to be my question. lol

 

Mine too. A 700R5 perhaps?

 

thats a bit of a mystery. now if you are looking to make that much power with tpi, look to spend about $3k for an bigger intake, fuel injection upgrades, new computer prom, and other misc. needed parts. now if you can go carb, thats as simple as an intake, carb, and putting a return style regulator on the electric fuel pump. you have two rear options, 9 bolt borg warner and 10 bolt gm. the 9 bolt is stronger but more expensive to upgrade and isnt common. the 10 bolt is weaker but upgrades are cheaper. mine is handling the power for now. you can run the rpo numbers, or jack up the rear and mark the driveshaft and tires and spin it to guesstimate the ratio

 

The 700r4 has a locking torque converter and can feel like a shift. So 1st, 2nd, 3rd, 4th, then lockup, feels like 5th gear? That's my guess.

 

The guy I bought the car from told me that he had put a 5-speed trans in it. It also has a B & M Slapshifter, which in my very limited experience so far I hate. Would there be some sort of stamping or tag on the trans to try and determine what he put in?

 

Did you drive it yet? Did it have 5 gears?

 

Yes. And Yes. But man, do I hate the slap shifter. Definitely getting rid of that...if the 5-speed auto that is in it turns out to be a good trans, maybe I'll keep it an auto and just do a shift kit.