Lex,

Hope you can answer a few question for me. I don't know much about engine so please give me as much detail as you can.
I am in the process of taking out my 88 Chevy aluminum heads out for rebuild. I drop an exhaust valve.
I only looking to build a reliable and better than stock. I will not drag race so I don't really want an all out rebuild engine.

Went to a machine shop yesterday to ask questions on valve job and bottom end work.

Price: $175 for a normal valve job including 3 angles valve.
$275 for a high performance valve job this would includes the normal job plus setting of the valve springs. I have to give the machinist the spec. on the cam
If the heads need surfacing it will be another $75 for bothe heads.

1) What is all this mean? Do I want to spend an extra $100 for setting the springs, I understand that the setting it will give me same spring rate for each valves.

2) car has 145K miles on it already. Should I just replace the springs? If I use new spring should I get new valves also? With new spring do I still want the $275 valve job?

3) For bottom end, I am thinking of boring it to 0.030 to make it 355 CI. that's means new pistons and rings. Do I need to buy new piston rods? What esle should I do to the crankshaft beside having the shop cleaning/honing it.

Please give me some insight on this issue. What should I do

TIA

 

Need a little more detail, when you say '88 Chevy alum heads, do you mean the alum Vette heads from the L98 TPI motor? If so, these are great heads for a factory casting, better than the 2.02 camel hump 'fuelie' heads everyone thinks are so great, plus the Vette heads have a nice 58cc chamber, i've built a couple motors with 'em, one is pictured below. Boring the block 30 over to 355c.i. will not require new rods, though a nice combo would be the 400 crank and then you could go to 383+ cubes, go with a 5.7" or 6" rod in this case, not the 5.45" 400 rods (there are fans of long-rod theory and short-rod theory, but you don't wanna be Mr. short rod, now do you?). Getting back to 355 c.i., for the crank, have it polished, unless it needs to be cut a bit (i.e. .010), chamfer the oil holes, the usual stuff, but balancing and knife-edging will reduce windage and give a couple potential horsies, plus a more rev-happy motor. If you're looking to go mild, just put it back together with decent retainers and new springs and a standard 3-angle valve job, maybe take .010 off to clean them up, not more than that, these heads can warp if you don't have a solid deck surface, especially on juice. New valves will up the expense quite a bit, assuming you would go bigger, the largest you can go in the L98 heads is 2.00 intake and 1.56 exhaust, but that's enough to take you well into the 11's with some port work and cleaning up the bowls a bit, plus the quench area, etc, allow this head to be pretty detonation-resistant, my last one was at 11:1, with some spray on top of that, ran like a motherf#cker. Hope I didn't miss anything, and if it's a roller motor '87+ let me know, a few cam profiles will work out nicely for you, those motors like lift, but not too much duration, assuming you're running tuned port, if not everything changes of course, but hey, good luck.
- Jon

 

On behalf of everyone on this board that has not rebuilt an engine, I would like to say

"Huh?"

 

Lol gavin.

Are you looking for an explanation? I'm bored. To keep it short -
Lex was asked about a GM motor - not to sure which one. VQT is pulling the heads and may pull the block I take it.

Anyways, Lex is talking about two types of heads - one from a corvette. He goes into the vlavetrain - springs return the vlaves to closed position in a seat. This seat can be machined by a 3 or 5 angle "job" wich improves flow - 5 is better, costs more. He is talking about the displacement of both the cylinder head and block. Then he refers to boring over - .030. This means he is making the cylinder bore larger. So if you make that larger you have to get pistons to fit - they have rings to better seal the piston in the cylinder wall of the bore. The piston rides in the bore and is connected to the rods. Connecting rods can be sized - Lex talks about short and long rods and alludes that the long ones may be better in this application. The motor will rev better - turn rpm's willingly. These rods connect further to a crankshaft. This can be knife edged - to reduce mass and allow easier rotation = less loss, more efficiency. You can get in to balance but that may be a little much.

The top end is the heads and valvetrain.
Bottom end is pistons, rods, crank.

Pretty cool stuff. I'd like to do more if I could find the time. Need to learn though. Should find something I can afford to break.

 

Thanks everyone for replying this post and thanks the moderators didn't lock the post since it is no Lexus related, but I need help.
Everyone are welcome to jump in and give me suggestion

Lex,

Yes it is my 1988 Corvette, Z52, Auto, 3.07.
The car has 145,xxx miles on it and an exhaust valve on no. 2 has drop after I put a 1.6 Comp RR on. The head has a quarter size thickness dent in it near the intake valve so I have to buy a used aluminum head from a 89 Vette.

Again, do you think I have buy new valves or reuse the old valves. I guess new springs is the way to go now.

I don't want to have a stroker 383, I don't race and I want relatively good gas mileage so I think a 0.030 over for a 355 CI will be plenty for me. Therefore, I think that I would stay with the same crank and have them polish it

1) What do I tell the machine shop to to do with my heads? Do I really need to spend the extra $100 for setting the srpings? Keep in mind that I don't want an all out street machine, I don't have the budget for it now. I am willing to spend money to make the car better than stock though.

2) What's the good inexpensive brand spring set? If I have to buy new valves, what brand? What other thing should I buy for the heads. So far, I know summit racing, jegs as the suppliers.

3) How do you take the bellhousing bolts out? I want to take the engine out and leave the trans. in place. we have everything off already except the bellhousing bolts.

I had some answer from the corvetteforum.com but I still like to have your oppinion on this.

Thanks again for helping me out

 

That engine looks like it an 88+ heads with the D shape exhaust ports or is it an after market heads?