Bigdream

I have a 1989 IROC Z28 Convertible with a 305. It comes with the 700R4 transmission and what ever rear-end is stock I would imagine.

The 305 is giving me a little smoke every once in a while and I have been told it is probably the Valve Guides. Not a problem, I wanted to replace the engine anyway, repaint it, rebuild or replace the seats and put new carpet in it.

My first question is would I be better off with a built turn key 350 crate motor (420HP - 450 pounds of Torque) OR should I go with a turn key 383 Stroker (400HP - 420 Torque)? I am considering the modifications I would have to make when putting both engines in. I want to keep this as straight forward as possible. Both engines would be carb, and come with a new air conditioning unit (as my current one is the old style).

I have been told that I should also have my transmission rebuilt to take the updated torque, and honestly, I would redo that anyway.

But, what about the rear end, is that going to have to be modified, and although the brakes were just rebuilt 5,000 miles ago, would the stock brakes work (say maybe with the corvette spring put in master cylinder for the rear brakes).

Last question. I am located in Shoreline, WA - do any of the members know a reliable shop or person that could take on the above project?

Thanks,

Donn

Abubaca

iTrader: (3)

-Valve seals are the likely culprit, but if the engine is running well and you don't WANT a new engine, it's not that involved. Doesn't NEED a whole new engine. -But who we kidding!? Go with a new engine!!!! LOL

-With regard to which motor, the specs you listed are pretty similar. It's really hard to say which is better. What are your goals for the car? ....if the quality of the parts are the same, and it's the same builder/shop building the motor, the SUPER general idea would be that the 383 would cost a little more to machine, would typically get a few more ponies and pound feet, and would make power sooner, but not rev as high. But you can change components around to get what you want from either engine really. What you listed shows the 350 with a smidge more power and torque. What's the cost difference? In all likely hood it's just hopped up a little more. Maybe bigger cam...maybe a little more compression? Probably revs higher too. In those power ranges, these aren't exotic engines by any means and should serve you well, so long as they're from a reliable builder.

-On the record, the stock rear isn't up to the task. Off the record, many of us have run stock rears behind lots of power and have had them last a long time. Still, officially they're not strong enough and many people have torn them up. Hard dragstrip launches definitely will kill them. It's all in how you drive it really. I built a similarly powered 383 and I'm still running the stock rear, knowing eventually I'd have to replace it. If you go in knowing it won't last forever, might as well give it a go. If you promise your wife you won't spend another dime once it's done....ehhh....ya might wanna plan for the rear now!

-Assuming you have PBR rear discs, you're fine. ....if you have drums, I wouldn't have rebuilt them in the first place. As for the fronts, I think the SMALLEST front swap is an LS1 era F Body front brake kit, and it's light years better than stock. -And they fit under stock 16" wheels, except for GTA wheels I think, but I assume you've got Irocs. Pretty sure they will NOT fit under 15" Irocs though. While there are better kits out there, the LS1 kit is affordable, easy to do and provides modern braking performance. -Also cheap replacement parts.

Bigdream

Abubaca: Thank you for your reply, and I have done a poor job giving any other information. First of all, let me define what I have found in my recent research.

I will probably go with:
383 Stroker (440HP and 470 pounds of Torque)
Rebuilt 700R4 Transmission (green clutch components) which will handle that power and torque
FI-Tech EFI
New AC components
Leave the rear-end with the stock components for now. This won't be raced or romped - but used for long tours during the summer with the wife.
My suspension was just completely upgraded with KYB Front Strut Mounts, Excel G Front Hydraulic Struts, KYB Gas-a-just Rear Shocks and Eibach Pro Kit Springs. It has about a 1" drop.


All I have to do is decide who I am going have work on this. That... is still being researched. Again, if anyone knows of a trusted shop in the greater Seattle area, I would appreciate the referral.

Abubaca

iTrader: (3)

Sharp looking car!

From what it sounds like, your stock rear should be fine. Just keep it in the back of your head......one day....lol!

...also keep in mind, if you go with EFI, you'll want to upgrade your fuel system. I replaced my old pump with a new high capacity pump. -and also found my stock wiring wasn't up to task of feeding the new pump. Wired in a plug and play racetronix hotwire kit. Easy, and affordable insurance.

....and finally, though I'll admit to being biased, I recommend you look into the Holley HP EFI. As I'm not one to bash products I haven't used, I'll simply say that my research led me away from FI Tech, and I ultimately went with Holley. ...and I will say that probably more than any other part I've purchased, Holley as overperformed and overdelivered, if there's such a thing! ....I had never done anything like installing and tuning an EFI, and they they're system was easy to understand, and tech help was amazing. That being said, I'd go with whatever system your builder is familiar with. Sounds like you don't have a builder yet, but talk to some tuners as well. Whoever will ultimately have their hands on that car.