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Re: We got our hemi heads back from Modern Cylinder Head.
[Re: Bob_Coomer]
#532956
11/22/09 07:15 PM
11/22/09 07:15 PM
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Joined: May 2007
Posts: 1,087
Northeast, Arkansas
Dodgeman67
OP
super stock
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OP
super stock
Joined: May 2007
Posts: 1,087
Northeast, Arkansas
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Bob I will try to post another topic to get some feed back. But I have two siamese blocks that both would go back standard 4.25 if I wanted to do that, and I have a stock hemi crank and one 4.15 stroke crank, these are Mopar Performance heads about 4 or 5 years old, will have to check the casting number. I also have a set of 13.5-1 Venolia pistons and they are standard bore, and I have a set of aluminum rods for them, so my plan is to build a 426 with one of the blocks. I need some cam recommendations for it if anyone has any suggestions. Back to the plan, we want to build this 426, put these heads on it, get our headers build and get everything worked out and then get the other block on the stand and we will probably sell the 4.15 crank and find a 4.5 or bigger stroke crank and build a 572 or something in that range and pull the 426 out, pull the heads off of it and put them on the big motor. I will keep the 426 short block complete for a back up engine, just in case.  This is out plan anyways. I still need a cam, lifters, push rods, head studs, head gaskets, and a timing chain set, also will have to have a flywheel for an 8 bolt crank, for the power glide, and new slicks. Does it ever end.
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Re: We got our hemi heads back from Modern Cylinder Head.
[Re: Dodgeman67]
#532957
11/22/09 07:25 PM
11/22/09 07:25 PM
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Joined: Nov 2003
Posts: 6,293
Rock Springs
Bob_Coomer
master
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master
Joined: Nov 2003
Posts: 6,293
Rock Springs
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If you are interested in very large solid flat tappet cam and lifter set new in box from Barton (Bullet Cams)...Let me know..
Lifters are the Howards EDM AMC that will also oil through the push rod if you want it too.
I was going to do this and add restricters in the pushrods to fight some of the oiling issues people have had from Hemi from time to time.
[color:"red"]65 Hemi Belvedere coming soon [/color]
[color:"#00FF00"]557" Indy engine 1.07 60ft 144mph in the 8th 2100 lbs package [/color]
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Re: We got our hemi heads back from Modern Cylinder Hea
[Re: Dodgeman67]
#532961
11/23/09 02:06 PM
11/23/09 02:06 PM
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Joined: Aug 2004
Posts: 2,128
sweden
sshemi
top fuel
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top fuel
Joined: Aug 2004
Posts: 2,128
sweden
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Quote:
Very interesting topic guys.
Fred that does sound very logical.
And I assume that's for the exhaust as well, leave them both alone, right.
Bob here is my flow sheet, not as good as yours, but should make go power. I will be posting up more of our combo later to see what yall suggest for a cam for this little engine.
Whats the dimensions and volumes?
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Re: We got our hemi heads back from Modern Cylinder Head.
[Re: Dodgeman67]
#532962
11/23/09 02:13 PM
11/23/09 02:13 PM
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Joined: Jan 2003
Posts: 13,369
Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 13,369
Marion, South Carolina [><]
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Those look nice! Familiar too.  I have the same heads (MP CNC'd by MCH) on my hemi. I didn't touch the ports or valve job when I got em back from Jeff. I just assembled them and bolted them on. They definitely make power.  CHIP
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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Re: We got our hemi heads back from Modern Cylinder Head.
#532964
11/24/09 10:13 PM
11/24/09 10:13 PM
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Joined: Dec 2007
Posts: 486
IL
knyech1
mopar
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mopar
Joined: Dec 2007
Posts: 486
IL
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Quote:
what I always believed
Quote:
Port and polish Often mis-used term. Back in the early days, aport was ground as large as you could get it and then polished to a mirror like finish with the thinking that smooth was better for air flow. It also looked pretty. When flow benches came on the scene, it was discovered that the polishing part was actually hurting the port. The greater the air speed, the more it hurt.
How can that be? There is this thing called a boundry layer which is actually caused by the friction of the air as it makes contact with the port wall. This friction causes the air to tumble at the point of contact. Compare this to a wave reaching the beach. The closer it gets to the sand, the higher the wave gets until it collapses. Now, with a polished surface, the air does the same thing but because of the drag caused by the polishing (yes, drag), the wave height becomes so high that it effectively reduces the size of the port. Eventually, the wave can no longer support it's self and collapses, only to start over again. Now you have turbulence.
Air needs a lubricant to eliminate this drag. The best lube for air is a cushion of "air". Fine scratches perpendicular to the direction of flow act as a tripping point for the air that contacts it. The air tumbles at every scratch forming what is called a "boundry layer" that about the same size high as the scratch is deep. The air flowing in the port uses this boundry layer as it's cushion or lube and therefor is more resistant to turbulence. You can demonstrate this to yourself by pushing your finger over a mildly abraded surface and then a piece of glass.
So after all that, the "term ported and polished" has stuck with us even though "polishing" hasn't been done for over 20 years.
It's like I am reading my Fluid Mechanics book! Great explanation HEMIFRED I love these topics!!
knyech1-
'71 Sassy Grass Demon 340/904. Pump gas, 1.61 60ft, 7.439 1/8 @ 95mph, 11.824 1/4 @ 111mph
"Not too bad for a pump gas 340, full of used parts and hillbilly ported stock heads." - V.B.
'03 2500 5.9L HO 6-spd on 35's. 395hp/755ft-lb at tires.
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