I added the CR sheet to see...
Does intake need machining after zero decking block.
- Thread starter dan juhasz
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So I come out this morning place the old head gaskets on the block grab the new 440 source heads and just snug them down 2 center bolts each side. Lay the manifold on no gasket or tray. If I line up the bolt holes to the heads it would really sit askew as pictured . So much so that the intake end bumps into the start of the China wall. If I place the intake so it is even to the heads I wouldn’t be able to start a bolt.
What’s gives here ??
What’s gives here ??
I can't see what your talking about from the pictures. Can you get all 4 corners bolt holes to line up? Is the intake too high, too low? You may not be able to use metal shim gaskets for the intake. I don't know what ascew means either. Not sure if you can look into the runners with a bore scope to see how they line up to the intake port at the head.
Morning when you run those numbers I was going to go with cometic gasket with a 4.380 diameter for the 4.350 bore at ,060 compressed thickness
Thank you
I spelled skew wrong. Can’t post a video. Look at the top of the intake runner to the machined surface of the head
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When I put a new intake on an engine, I usually bolt it to one head only with no gaskets. I also take a cheap electric
endoscope and match up the ports. Then I use feeler gauges to measure the gap between the intake and the head.
You also check the taper in the space if there is any. If it's parallel, all you have to do is purchase the correct thickness
gaskets. if it's off be alot, you'll need to cut the intake surface of the heads. Make sure you check the front and rear!
endoscope and match up the ports. Then I use feeler gauges to measure the gap between the intake and the head.
You also check the taper in the space if there is any. If it's parallel, all you have to do is purchase the correct thickness
gaskets. if it's off be alot, you'll need to cut the intake surface of the heads. Make sure you check the front and rear!
With your gasket dimensions for the Cometic HG, entering the other piston dimensions of 4.300" ring area diameter, the top land dimension of 0.250", and a guess at the chamfer of 0.031" @60 degrees because it would seem that "Maff" is hard for some. It is too difficult to see that a chamfer is the hypotenuse of 0.031" at a specific angle (I chose 60 degrees). Anyway, I get 9.764:1 CR factoring in all of the areas contributing to the overall volume of the cylinder. Ring area volume is 1.392cc and the chamfer volume is 0.046cc for a total of 1.438cc representing a reduction in CR by 0.123:1
One last question same cometic gasket but @ a .050 compressed value would that net me a true 10:1 ratio?
So I believe my original intake bolt mounting holes were drilled wrong on the six pack manifold. I had an iron 440 magnum manifold sitting around so I dropped it on the heads, it lines up perfect side to side with all holes lining up.
So I either hog out the holes on the original aluminum manifold so it will slide over in between the heads or just buy a new edelbrock six pack manifold.
So I either hog out the holes on the original aluminum manifold so it will slide over in between the heads or just buy a new edelbrock six pack manifold.
A 0.050" gasket with all else the same would result in 9.997:1 CR. It is not worth fretting over for that small of a change.
But, if you want to see numbers:
0.060" Thk = 9.674
0.050" Thk = 9.997
0.045" Thl = 10.087
0.040" Thk = 10.200
The 6pk manifold could have been milled and they did not get it correct and that is why it is cock-eyed while the iron 4v fits.
But, if you want to see numbers:
0.060" Thk = 9.674
0.050" Thk = 9.997
0.045" Thl = 10.087
0.040" Thk = 10.200
The 6pk manifold could have been milled and they did not get it correct and that is why it is cock-eyed while the iron 4v fits.
Not fretting over it but I'm taking my time and had a certain 10:1 ratio in mind no gaskets are ordered yet, I want to cross my t's and dot my i's. I'm likely just going to shelve that manifold and get a new Edelbrock. The poor fitment of that manifold clears up a lot of issues I had with I thought were carburation issues, I think I had vacuum leaks to different degrees depending on ambient and engine temps. I really appreciate the help you provided me.
Shorty Thompson
Well-Known Member
Don't zero deck your block. There's so many other things that get affected besides your intake manifold. FYI if you go ahead and do zero deck your block is that your pushrods are now too long. Now you have to drop a cool $2k getting special ones made. Now if they take down the rimmed edges, i.e. front rim edge and rear rim edge it's not going to be a huge problem with the intake. However ! That's yet to be proven to me atleast. Good Luck! Hope this makes you think a little harder on it.
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