The Supercar Registry

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- Technical & Restoration (https://www.yenko.net/forum/forumdisplay.php?f=86)

- - New heads (https://www.yenko.net/forum/showthread.php?t=139385)

I know my thoughts, and sometimes I'm out in left field. I know Mark is pretty damn good with the GM ovals and he posted in this thread:

http://www.chevelles.com/forums/13-p...402-bbc-2.html

Post #24
"You don't put 2.190 intake valves in a 4.155 bore, unless you want to kill the engines potential."

Now would I tell him to toss his L-78 heads if he had them, probably not. Will it make power, YEP, been there done that. I'm was just pointing out for what he's looking at doing, and parts he has, with a limited budget, the $$$ would be better spent to port what he has and keep the 2.06's.

Eric, you know how to make some power too from what I've seen. I just think the return on investment might be better served keeping his 2.06's? This is partly what these forums on different site are meant to do. Open up "friendly" discussions as there are always many different way to reach a given result. And I would have fully agreed with a MIN of 2.19 intake on a 30 or 60 over 4.250 block. But with this narrow 4.155 bore, limited budget, and not shooting for the moon, I just think personally I would go with a port 2.06 over a non port 2.19 in this head ON THE BORE SIZE.

It's ok if we disagree, I'm Canadian and your an American. It happens LOL

I appreciate everyone's input. I took the heads home with me to do some more thinking and research on it. Basically where I am right now is thinking I have three real choices:
1. Try to lap the valves the way they sit and save money for another day.
2. Have my heads done with 2.19 valves. ~$700 or so labor and parts. I'd have less than $1k in the whole set up.
3. Keep trying to find aluminum heads with ~260 - 270cc runners, 2.19/1.72 valves and ~100cc chambers for less than $2k.
I'm going to try for #1, but I think I'll end up with #2.
Don't stop the conversation if you have anything to add. I appreciate any knowledge you guys are willing to share.
By the way, this is the seat that concerns me and the reason I think I need to go to 2.19 intake.
It looks worse than it is, but it's still not good obviously. All the others are clean.

http://i1164.photobucket.com/albums/...9_161947_1.jpg

That seat is toast, don't try to run it like that! Lapping that seat will NOT clean that up! It's right smack dab in the middle of the 45° cut.

You'll either have to (A) sink the valve job to clean that up (BAD idea!), (B) have seats installed (another bad idea as discussed earlier) or (C) have the seats cut for bigger valves.

That's what I figured. C it is.I thought that I might get enough of the seat to seal by lapping it just to run them for a while.
Just out of curiosity, what would happen if I did clean it up a little and ran it? A little loss of compression or something more serious?

Nevermind. I just found this which describes what happens with a bad seat.
"The other common type of valve failure is valve burn, or burnt valves. Essentially this is caused by combustion gases escaping between the valve and valve seat when they are not sealing correctly. The hot combustion gases are forced past the valve which starts to burn away the edge of the valve, progressively getting worse the longer it is left without being rectified. Normally this type of failure affects the exhaust valves only, but it can also damage the intake valves.

A burnt valve will cause issues with your vehicle’s performance and fuel consumption. Rough idle, reduced power, backfiring, and misfire are all symptoms of valve burn."

That seat WILL NOT clean up via lapping -- loss of compression will be the result. TAZ

I didn't think it would completely clean up, but I thought I could get enough of a seat to seal for a while.
I won't run them unless I get the 2.19 valves installed.

Well....that ends the discussion. Reality trumps opinion on this one [img]<<GRAEMLIN_URL>>/rolleyes.gif[/img]

Looks like the bigger valves are the best choice.

Good luck.

-wilma

Agreed. Thanks all. I'll let you know how it turns out.

Just to add one more thing to this... I've been scouring the Web looking for aluminum heads that would fit the bill. I have found zero that would. The closest I could find are Edelbrock heads. They're 100cc and 2.19 intake, but 1.88 exhaust. $2,400 a pair! The bare are $1,600 and need a valve job.
Am I missing something? Looking in the wrong place?