I'm getting to the point where I've done just about all the bolt-ons there are for my car, or at least the ones I want to do or can afford. So now I'm looking at the engine itself. With the modifications I've done to the intake and exhaust I'm pumping a lot of air into and out of the engine, but now my heads are probably my bottleneck.

I'm on a VERY limited budget of maybe a few hundred dollars and would like to know what my best option is for getting more power out of these (or other) heads. I've narrowed my choices down to a few options:

1. Get my current heads mildly ported and get a three angle valve job (anyone know how much this would cost?)

2. Score some vette L98 heads from a bone yard or other cheap source and have the same done to them. (how much do the junkyards usually ask for heads?)

I'm leaning towards option 2, even though it would be more expensive, because I'd like the weight reduction with the aluminum heads from the vette and I've heard their combustion chambers are smaller which would bump my compression ratio up, which would be an added plus.

Can anyone give me ideas on what each option would cost me and what I should look out for or search for when looking for vette heads? Differences in years, etc... Any information you guys can add would be a help, I'm just starting my research into this so I don't have that much knowledge yet.

BTW, for information purposes, the car is an 88 GTA, L98, auto, about 112,000 miles but runs VERY strong.

Dave M
88 GTA

[This message has been edited by Dave M (edited January 08, 2001).]

 

back to the top....

[This message has been edited by Dave M (edited January 10, 2001).]

 

again.....

 

I ported and polished mine myself.I'm a machinist by trade so I understood what needed to be done.Standard abrasives offers a "deluxe porting and polishing kit"that will show you step by step how to do it.If your not comfortable doing it yourself,then try a local speed shop,but that can get expensive.If the cost exceeds $500,then you might as well buy new heads.You can get a set of World heads from www.competitionproducts.com for about $500.When I rebuilt my L98,the valve job was $105 and since I did the porting and polishing myself,I had money left in my budget for a torque converter.After market heads will flow better than the stock ported heads,but my fully ported L98 heads keep mee pulling up to 5500 rpm's or so.A big improvment,plus I got the torque converter kinda like a throw in.I think theres an article on porting your own heads in the archives.

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We need Perry Mason

 

You arent going to find Corvette L98 heads in a junkyard unless you are VERY lucky and/or know someone. They are pretty popular. They came on 87-91 Corvettes (and 86 Convertible Corvettes). I'm using them on my car, my dad ported them for me. You could also try some of the GMPP dealers like www.paceparts.com or www.sdpc2000.com or www.salleechevrolet.com for their take-off ZZ4 heads. They're the same, except with better valve springs. I think they go for $600 or so. These heads dont have EGR passages, so if you have emissions testing in your area, you will need to hookup the EGR like Corvettes do. I'm in the middle of modifying my SLP 1 3/4" headers for that right now, and I will have pics available soon. If you can port the heads yourself, or have a friend who can, they're a good deal. If not, the cost of porting, plus the emissions deal, might be prohibitive, and you'd be better off spending the money on a set of Edelbrock Performer heads. They flow better out of the box without porting...


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Thanks guys!

I just read the article on porting and polishing yourself after I posted that message, and I think once I'm ready I'll spring for the valve job and try the porting myself. If I screw up, I have another car to drive and it's just a reason for me to have to buy new heads. It would be a justification to the wife, a.k.a the checkbook holder. If I do my own porting and have a valve job done, that's certainly not going to help my compression ratio, and if anything will lower it. Assuming I currently have a 9.5 compression ratio and get a valve job done and some basic home porting, how much would have to be milled off the deck to bump the ratio up to about 10:1 and how much does milling the deck usually run? Would the same place that does my valve job likely be able to mill the deck for me or does it involve more complicated machinery that the average machine/speed shop wouldn't have?

Thanks,
Dave M
88 GTA

[This message has been edited by Dave M (edited January 12, 2001).]

 

Which heads are you porting? Your stock iron ones or the aluminum L98 ones? You dont want to mill the aluminum ones as they are 58cc's and will raise your compression ratio up from what it is now. The iron ones you can mill, as they are 64cc's. Did you see the porting article at www.sa-motorsports.com ?