TireSmoke.org

It's not 2009 yet, but it will be by the time the car is back on the road. After testing the compression again with Andy's gauge (showing 150, where other cylinders read 180+), I decided to take the head off.

The head gasket looks to be bad between cylinders 4 & 6, the two cylinders that had low compression. So far, it seems like a simple head gasket, except that there seems to be some scoring on the wall of #4.

I'm not sure what to do next.

I would think if you can feel the scoring, that maybe you should put a hone to it before you put it all back together, but if it's just something you can see, I wouldn't be too concerned. It looks to me like the cross hatching is still there, even where the scoring appears, and if that's the case, I wouldn't do anything but put it back together.

-BP

I'd wana measure the bore dia right at that location.
The discoloration concerns me.

Dave,

I know you were thinking about what to do with the body of your chevelle. I can go look at this for you if you want.

http://www.racingjunk.com/post/1390173/ ... velle.html

Is the motor still apart?
Any progress, or decisions as what direction to take?

Matt, that one sure looks tempting for $2000. And whatever I don't have, I'm sure my neighbor does.

The engine is still apart. I haven't really touched it at all since I took it apart at the end of November. Someone on Chevytalk suggested that I was using head gaskets that weren't up to the task (Fel Pro 8364PT). I called my friend Matt, who used to work for Cometic, and asked him about that and he said. And depending on what answer I find will determine whether I just replace this gasket, or pull the other head and replace both. I know the gasket I used was the part number listed by Edelbrock for those heads on a 400.

After that, I just need to button up the trans. I removed it from the car to try to fix a few minor leaks. I also ordered the correct speedo gear and pulled the tailshaft housing off to install it. While it was off, I noticed the area of the seal is dented -- out of round, although it was not leaking there. What do I do with it? I also got a shiny new aluminum pan, to replace the cruddy, dented steel pan it had. w0w.

-Dave

So I took the heads off my car and took them down to Michael's to get milled flat after the blown headgasket. My 11:1 compression on 93-octane probably isn't going to cut it. I did hear, on several occasions, detonation coming from my engine last year and turned the timing back to try and compensate. Other people (including BP and Fred32v) both suggested throwing more fuel into it to tame the detonation, which should be easy enough to do with the EFI without messing up the idle and part-throttle. I had always heard about backing off the timing, but never heard about throwing in more fuel.

In talking with Michael about it, he thinks I need to lower the compression. With my 64cc heads, I would need a dished piston. That's $600, just for pistons. The associated machine work (putting pistons on rods, deck the block, mill the heads (which I have to do regardless) potentially re-balance the rotating assembly) would be around $400.

So, I'm considering just putting another set of headgaskets in there, crossing my fingers and hoping to get through another year. I know if it breaks again, I'll have yet another wintertime engine teardown next year and then I'll have to spend the money for sure. I just don't want to put another $1000+ into the engine at this point. I'd rather put it towards body/paint, or home remodeling stuff.

Decisions, decisions...

So, we're not too far from the halfway point in 2009 and I've done exactly nothing with my car, except to buy a couple small patch panels at Carlisle. One of these days the motivation will froth over and I'll get it back together.

-Dave

So, after a few more months of in-action, I've finally started to feel motivated to work on this thing again. Or, at least think about working on it. I'm good at thinking about working on stuff.

Doing all the work associated with lowering the compression via new pistons was not sounding very attractive from a time, labor, and cost stand point. I started looking around and decided that I'll try picking up a set of heads with 76cc chambers. I started cruising around Summit, searching first by chamber size. (odd way to look for heads, IMO)

http://www.summitracing.com/parts/AFR-1036/

Changing to these heads also requires me to switch back to a conventional style intake (non-Vortec)

http://summitracing.com/parts/WND-7540/ + required fuel rails (no, for some odd reason, they don't swap)
http://summitracing.com/parts/HLY-534-186/

So, I've listed my Edelbrock heads and intakes for sale on craigslist, thirdgen.org, & stealthram.com. Listed the heads for 750 (1100 new), Performer RPM Air-Gap for 200 (250 new), Vortec HSR w/rails & regulator $450 ($600 new).

http://cleveland.craigslist.org/pts/1222903850.html

I'm hoping to keep the net cost of this under $1000.

-Dave

How much compression do you need to lose? When I was working on my 307 olds heads, guys on forums were constantly complaining about head gaskets being too thick and loosing compression to them. Perhaps there is a mega thick gasket that would knock compression down enough to use the heads you have. .030 off the head was .5 compression on the 307.

I've read about the effects that cam specs have on reducing the effects of higher compression. I think the overlap bleeds off some of the compression. Perhaps you can contact Comp Cams help desk and ask them about it. Maybe between GMJohnnie's idea and a change of cam, you can save a bundle of cash.

Using the various compression calculators out there, I have somewhere around 11:1 compression. The Wiseco piston catalog says 11.3:1 with my pistons and 64cc heads, but they dont take gasket thickness into account.

Actually, the very first gasket I used (spring '06) was a custom 'mega-thick' gasket from Cometic -- a Multi-Layer-Steel (MLS) gasket. The only problem was that no one told me I needed to have a fresh surface on the head AND block. I think I had them made .050" or .060" thick. I put them on, and they leaked water. To get a fresh surface on the block (decking), requires a complete disassembly. I've done reading about this and if you start using too thick of a gasket (combined with the amount of depth the pistons are in the hole), you lose the required quench, which also can lead to detonation. Aye carumba! what a mess!

I suppose I could go to a bigger cam, but does that solve the real problem of detonation? At some point I need either more octane or less compression, I think.

-Dave

OK, then. Sounds like $1000 will buy a lot of octane booster for a whole lot less work. I'll bet you don't put enough miles on that car to use up $1000 worth of octane booster even in your lifetime. Just food for thought.

Can you have the heads opened up? Gardner's?

Detonation, from what I've encountered, is from too much timing and / or not enough fuel. Add more gas or turn the timing back a few degrees if you can't increase the octane.
Like Walt said, you can add a lot of octane booster for $1000. Not to mention the extra time to change all that stuff.

-BP