ProComp/Speedmaster aluminum heads
- Thread starter j par
- Start date
-
j par
Well-hung Member
1 1/2 points of lost compression because of head Flex LOL that's got to be one of the most outlandish things I've ever heard on the internet....I suggest you use "flexseal" for your head gaskets...
j par
Well-hung Member
The best part is 318 has valves that will fly believes it...
j par
Well-hung Member
I had a quench question?...
huh? I said 1.5 points lost?? where???? LOL Jpegusesflexsealforheadgaskets
Phreakish
Well-Known Member
I'm not at all claiming that there's enough flex in an OHV head to account for 1.5 pts of compression.
That number is likely as old as replacement heads for flathead motors, which I could see flexing enough to account for 1.5 pts.
The thing is, most engines could get away with far more than +1.5 points without ever thinking about head material and so alum head makers can make that blanket suggestion without risking much. The +1.5 myth probably also helps sell alum heads because any performance gained would be from the compression, not the head material and no one wants to spend money for nothing..
However, head flex is 100% a thing. All heads 'lift' to an extent when under load, and all metal moves and deforms when under load. How much is highly variable, but alum tends to move twice as far as steel/iron for the same load, so in my mind the extra compression to account for deformation is the only thing which is based on science - but how much adjustment is needed? Likely not much if the engine is worth two ***** to begin with.
yellow rose
Overnight Sensation
LOL 318hasvalveswillfly vs Jpeghasrubberheads
Ok, I've been up since 3 and it took me a minute to get the rubber head thingy but yep, that's funny!!!
j par
Well-hung Member
And you're never ending quest to try and throw a new call name on me continues...Jpeghasrubberheads, wrong guy maynard
you will be always known as 318 has valves that will fly from the day jab called you that... Me Jason and I drive a Mopar and I will always be Jpar...
Oh boy!!!!!! Here we go......LOL 318hasvalveswillfly vs Jpeghasrubberheads
Steve Brulé. (Say Brew-lay)
Car Craft - IIRC, did this as well with Chevy heads from - IIRC, Dart Cylinder Head and also found zero difference between the identical castings they make.
Careful if you drop one of your heads, Jpeghasrubberheads, it will bounce up and hit the cealing in your garage
j par
Well-hung Member
And your promaxx heads you're going to buy before next summer will be made of?...Careful if you drop one of your heads, Jpeghasrubberheads, it will bounce up and hit the cealing in your garage
Post 1046. Quality heads = less flex. You'll certainly add some "bounce" to your car when you install 'em
I have to quit for a bit. my wife is look'n at me shaking her head as I'm busting a gut.....
yellow rose
Overnight Sensation
The last paragraph nails it. There isn't a cylinder head on any engine ever that doesn't lift and flex. There has never been one.
If there was, you could machine the head and block to flat and smooth and not use a gasket.
That's why you need a gasket. The head lifts and flexes and moves all over hell. Without a gasket you'd never get it sealed.
As one more proof I'm not nuts...if you use dead soft copper gaskets you know what a beeeeeeeeotch to get sealed. Not compression sealing, but coolant and oil sealing. That's because that dead soft copper gasket can not follow the head as it moves away from the deck and flexes with every single firing cycle.
My buddy had a blown iron 392 hemi we built and I begged him to let me Oring the the block and heads but some gasket maker promised him his dead soft copper gaskets would seal 10 pounds of roots boost without Orings. So I did it without the Orings.
It was in a roadster. When we fired it up and got it warm I walked around the engine and stuck my hand down by the head/block interface at all 4 corners. He said WTH are you doing...and I say I'm feeling the combustion leaking out past the gaskets!!!
So he sticks his hand down there and he feels it. He was pissed. That very day the engine came out, I took it back to work, pulled it all the way down and did the Orings.
You couldn't feel the combustion leaking at idle any more, but I promised him at full boost and full song it was leaking!
It's just the way that it is.
for me I got one thing out of it all: cheap heads flex like a cartoon, thus the Jpeghasrubberheads
I bet he can grab a hold of his rocker shaft mount pedestal and pull it up about 1.5 inches ????BWHAHAHHAHAAAA
yellow rose
Overnight Sensation
I have never been able to remember names. Ever.
I date this gal way back in 1988 and I took her to my local watering hole. It was my regular spot so I knew most people in there. That particular night, a bunch of people I went to HS with had gotten together and went out for dinner and then stopped by this place.
They weren't in the jock or gear head crowd so they weren't in my peer group but we all knew each other on site.
I saw at least 10 people (gals included) that I knew but couldn't think of their names. My GF was pissed because she thought I wasn't telling her how all these people knew me and my name but I didn't know theirs. A couple people talked to me like they knew me, but I didn't recognize them. They actually were there at a couple of big money street races I won (sometimes if the loose lips learned what was going on we'd get a hundred people out that and that made it all the more dangerous) because they could remember as much as I did and I had no idea who they were.
That was the first fracture that killed that relationship. She never believed much of anything I said after that.
yellow rose
Overnight Sensation
for me I got one thing out of it all: cheap heads flex like a cartoon, thus the Jpeghasrubberheads
BWHAHAHHAHAAAA
Whew!!!! You are ruthless today. Dang.
yellow rose
Overnight Sensation
Phreakish
Well-Known Member
I never would have believed these kinds of anecdotes, but I used to follow the FWD turbo guys and have seen an underhood video (way back before gopros and all the junk they've got today) that showed literal flame blowing from between the block and head as it went down the track. Eventually they added better o-rings and more headbolts and were able to remain competitive with far less boost. Craziness.
-
