avati

My '94 Z28 had an oil pump failure, spun bearings, and the engine seized. It is currently be disassembled by my mechanic to assess the total damage, but it looks like the block and heads are OK. The engine is original stock with 180,000 miles, so a total rebuild is certainly the right thing to do. I don't want to cut any corners. I'm looking for suggestions on practical rebuild tips to improve performance without spending a tone of money (not over $5,000).

My mechanic tells me that the LT1 is thin walled, so boring out the cylinders is not wise as it leads to overheating. Can anyone confirm this? What about simply going 30 over? That should be OK, right?

What are some things I might consider to get the most bang for my buck?
Are there some Specific brands of rebuild parts I should consider or avoid?
Should I consider pistons profiles other than stock, or are stock replacements really about as good as it gets? If the rods are in good shape, should I re-use them, or are there new rods on the market that will make a significant enough improvement to warrant the expense?

mrmint69

You can go cheap and find a used lt1 with lower miles or rebuild what you have. There are lots of kits and complete engines out there. Do you want to shoot for about the same hp as you had? My son bought a 98Z for $3500 and the car and engine were in great shape with lower miles. The question is, does the car have sentimental valve? I have heard of stories were someone rebuilds someones motor and then give them a huge bill, mostly for labor and you have about what you had before.

96capricemgr

If it spun a bearing then depending what bearing either a rod or rods are shot and the crank damaged or if it was a main bearing then the block is not really worth repairing.

Since you seem to be paying R&R labor with a low budget like that I would just put a junkyard engine in it. Especially since the mechanic seems a bit clueless with his comments about LT1 overbore. The VAST majority of built LT1s are .030 over which has been the smallblock chevy standard for decades, a handful of guys are using .040 and there are even some .060 over with careful sonic checking of the bores and careful core selection.

avati

The car has definite sentimental value. It was my best friends car, and when he died, it was entrusted to me, so selling it is not an option.

I kind of thought boring 30 over was no big deal. I was not specific with my mechanic, so he may have thought I meant something more radical. He is definitely not clueless.

What I'm really looking for are suggestions on minor modifications that will yield horespower gains.

Examples:
Assuming the crank is still good, Is polishing it after machining worthwhile?
Is there are particular valve spring combo that I might want to switch to?
Piston type?
Cam spec? I've heard about the Comp Cams cc503?
etc.

MachinistOne

The mechanic is not clueless, the LT1 blocks are pretty thin wall - I have had to throw some out because a sonic check showed that they wouldn't even be ok with a .030" overbore. My suggestion is to have the block sonic checked, and honed to the minimum possible oversize.

Polishing the crank should be a part of the process irregardless of desired performance.

Springs depend upon what cam you choose, and what cam you choose depends upon your intended usage for the vehicle, daily driver, weekend racer, Smog concerns, etc...

Pistons depend upon the power level you're looking for and intended use of a power adder.

mrmint69

Need to know your hp goals to really help. If your shooting for 300 that would be very easy. I would hate to see you do all this and wonder later, what if I had gone 350 or even 400hp. I regret it on older cars I never did it to, when I had the chance.