robbkord1

HI, I have three 1988 Chevy vehicles (It wasn't planned, it just kind of worked out that way). I have a C4 Corvette, a 5.7 IROC-Z Camaro and a 2500 truck. The Corvette is the newest (to me). I've had it for a year and a half, but it hasn't been operable for a few months now. Last summer I got it hot (the overflow tank tube to the radiator had become plugged) and it overheated and I cracked one of the aluminum heads. I got both heads repaired and re-surfaced but the car never ran quite "right" after repairing it. Up until that happened I'd occasionally have problems with the battery not staying charged and dying and I had to change the slave-cylinder (I'm on my second one now).
I changed quite a few parts (alternator, battery, EGR valve, IAC, plugs, coil and a new timing chain) on it. It could drive it but I was never confident that it would start back up once I stopped and on several occasions it would die and then I couldn't get it to start again. I began trying to diagnosing it by checking for fuel pressure (which it had) and spark (which it also had). I ran a compression test and had little to know compression in any of the cylinders.
I had a completely re-done set of heads from the camaro so I decided to swap them out with the aluminum set. I had good compression with the cast-iron heads out of the IROC so I was optimistic that I would be able to get them to work.
I was at the final stages of putting the car back together when I found a problem. The original heads on the corvette have angled plugs and the cast-iron camaro heads don't, so I'm asking for any advice going forward. Getting the easy plugs in (3&5 and 4&6) is quite a challenge with the factory exhaust manifolds installed and I'm not sure that this combination will work. I don't really know what to do next (and I'm trying not to break the bank to get this fixed). I've come to the conclusions that I'll need to possibly change to another exhaust manifold/header or to take the aluminum heads back to the machine shop and see if they can be fixed. Does anyone have any ideas that may help??

VikingTrad3r

assuming u r doing the work yourself....(in terms of recommending things that wont break the bank)

i would not mess with any other heads other than whats intended for an 88 vette block.

so first things first, what is wrong with the aluminum heads? why no compression?

robbkord1

Ok, so as I said, I got the heads and the one on the driver's side had a small crack in it. Took them off had the crack fixed and both heads resurfaced (they took off 30-thousandths) and I re-installed them onto the car. Car ran (but not very well, I'd only drive it every so-often because I was worried about it) and then it got to where when I would drive it the car would start up at home (cold) and I could drive it but once I stopped somewhere chances were good that it wouldn't start back up (when warm) or would die when I would be at a stop sign or traffic light and wouldn't start back up. Changed the timing chain hoping that it was part of my compression problem but car would still not start. Ran a compression check and got little to nothing out of each cylinder. After I installed the cast iron heads I ran a compression test and out of #1 I had over 130 and with the stock aluminum heads I had zero out of #1.

JackDidley

130 is low. I never tested my L98 when stock but with flat top pistons and 59 cc chambers, all cylinders were 185, + or - 4.

bjankuski

Put the alum heads back on the vette, there is no reason to run the iron heads. If you had the heads fixed and there is no damage run the alum heads. If you have no compression it is probably a result of incorrect rocker arm adjustment, incorrect timing chain install, or shot rings that leak more when warmed up.

The cast iron heads have straight plugs and 72 degree angles center intake bolts that will not allow you to bolt on your intake without modifying the intake. If you are bound and determined to run the cast iron heads the spark plugs should clear the exhaust manifolds. The 1984,85 and 86 vettes had straight plug heads and the plugs cleared.

VikingTrad3r

i agree here. if u had them "fixed" then take them back and ask them to be double checked if you suspect the problem is in the heads

if it was a reputable shop that repaired the heads then ask them to walk you through thier verification process and then reinstall them.

your suggestion of putting iron heads from another car on the vette makes no sense.

if the heads pass verification test then i would expect an error on the install and yeah, rockers too tight would be a good explanation for no compression if they all had no compression and they were all adjusted using the same incorrect process.

i found that using an oiled .001 feeler was the best way for moi.

if you have done this alot and you know you know you installed them correctly then i apologize if it seems that we are second guessing your install job. it just makes no sense to put thise heads on the car. get the shop to verify the repair thats what id do.

cheers.

robbkord1

Thanks for the advice. I wasn't a big fan of switching to the cast-iron heads but was running out of ideas as to what the problem could be. My Dad, who is one of those old-school car guys (has always had a car/truck from the 1950s/1960s) suggested trying the heads that had been on my camaro. Since I wasn't getting any compression I was hoping that the change would help get the car to run again. I got everything installed with little difficulty (I had to "modify" the intake manifold to fit by drilling the 2 middle holes on each side). I'm going to start taking the cast-iron heads off this afternoon after work and will get my Dad to take the aluminum heads back in to get them re-checked as well.

Hot Rod Roy

Your first question should be "Why no compression?" Installing the iron heads is the wrong answer. The question is still "Why no compression?"!

Who installed the valves into the reworked heads? With zero compression, there is something very major wrong! I hate to say it, but somebody goofed!

Do you have the FSM (Factory Service/Shop Manual)? Are you following the FSM procedure for adjusting the valves/rocker arms?