needanother1

Well, I got into my motor and found more problems than I was expecting. Long story, but suffice it to say that the previous owner botched a rebuild on the original engine :mad, and now I have a .030 overbored block with questionable machine work and just a whole pile of really questionable/marginal parts. So:

I'm contemplating swapping in a ZZ4. I thought about a 383, but I'm assuming it would be more $$, and I'm gonna be WAY overbudget on this deal already. I read some of the other threads concerning what fits from the ZZ4 and what has to be changed. My question involves the stock TPI system and computer. I realize that the TPI won't breathe well enough to take advantage of the 5250 RPM power peak, and so it will hold the motor back a little. I might switch to a SR down the road, but right now I'm just wanting to get the thing running again! Will the computer and the 22# injectors function well with the ZZ4? Or will I end up needing to do a chip and larger injectors? What about putting the factory manifolds back on? Is the ZZ4 designed to run with any EGR--- i.e.: could I set everything back up just like it is on my current engine? I'm probably going to go with a dual exhaust system, sans cats, and I might delete the air pump.

Last, do those of you who have done this swap feel like it was an upgrade, or just basically an equivalent replacement engine? The ZZ4 is a lot more money than I planned on having to put back into my engine, but when you've got questionable block, rods, pistons, heads, crank, etc., it sounds alot more reasonable. Thank you for any info!

Jason
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1988 coupe, Z52 auto

Corvette0096

In my case I had the cast heads non roller motor, You are better off getting a zz4 short block and putting on your heads and intake, ZZ4 are the same heads you have now but with no egr passages..I think there short blocks are $1800 or so..

AquaMetallic94LT1

Find a good machine shop and have the parts you have checked out. You may just need to polish the crank, new bearings and new rings to get the short block back together.

You can use the TPI with a ZZ4. The stock programming and injectors will work but a slightly higher idle and more low end spark advance will help.

gtsyellow

aqua hit it right on, why spend $1900 on a zz4 short block when your parts only need to be measured & inspected & possible balanced. once you know what you have you'll be able to make a better choice. also you would need to reprogram for it to run perfect. it would still run on the stock chip but with that much larger of a camshaft it would need some work. since you already have D port heads you can buy manley pro-flo valves for $152, do a 3 angle valve job for $150 blend the bowls for maybe $50 more, hotcam springs, shims, retainers, locks & seals under $100 for all of the junk. right there you will kill a stock out of the box zz4 head. machine shops can easily measure your gaps and how the engine was setup. even if the block is warn you can do .040 over very easily & without any concern. i'd like to say the zz4 is a great engine & it really isn't that bad but you can build a better engine for the same money if you have some idea of what your doing. find out where your at before you go spending $3500 on a crate.

trupp

I recently finished this swap and am happy with the results. It is a big upgrade, at least from an '85 concern. The swap was relatively painless, with the only really difficult part being clearancing the crossmember for the 8" balancer and that wasn't that difficult. For the time being I'm still running the original chip and will upgrade that with an Ed Wright chip when my wallet has regained some thickness. The stock chip doesn't appear to be having any problems with the engine and cam combination. You'll be able to use you current egr setup ie crossover tube. I have taken it out to the track one time since break in which showed I need more traction and the new chip to help make the engine work better. But as it stands it is getting 13.7/13.9 et's and 101/102 trap speeds which equates to approx 265 to 275 rwhp. Good luck with whatever engine you decide on.

gtsyellow

you know jim pace has brand new old stock L98 short blocks for $1300, i just stumbled across them in the new catalog

SuperL98

trupp,
I was wondering about the 8 inch balancer
What did you have to do to the crossmember to make it fit?
Did your stock pulleys mount and line up ok to the 8inch.
Someone said they pulled the 8inch and put the old balancer on,
but I thought these 87 & later blocks where external balanced and you shouldn't change the flexplates and balancers on them.
thanks

gtsyellow

you need a 6-3/4" balancer. i'd just find a good machine shop if i were you, the quality is definatly going to beat a crate motor.

Corvette0096

6-3/4 balancer is right.. Quality? New parts against reused part? Machining the crank gives you less actual oilling surface, Thin cylinder walls,no need to go there. Warranty? Try getting one from a machine shop for 1-3 yrs. My ZZ4 has never burnt a drop of oil or leaked. :smash:

gtsyellow

there is a pretty valid point. unless a rebuild is done right & that would mean balanced & blueprinting of tolerances. real machine work and quality parts the finished product won't be anything too special. some shops around here with less than a perfect rep consider a rebuild new rings and bearings...then it's out the door.