Measured deck height w/ bridge, pistons average ~0.0085" out of the hole. Measured on larger flat part of piston, rocked pistons back and forth, figured the middle for a .0075" to .009" range w/ the average right at .0084".

I have Fel-Pro 1071-1
.039" - .009" = .030" clearance piston to head. Is this sufficient, or do I go for 1071-2 for .051" - .009" - .042"?

Target compression for custom cam per Tony @ AFR is ~11:1, my combo is ~10.93:1 w/ 1017-1, will drop to 10.63:1 w/ the 1071-2.

I just got my AFR heads today, was getting ready to measure dome clearance.... started thinking about what I should expect where and it dawned on me that w/ my piston 'out', the suggested method of mounting the head minus the gasket and turning over would not work! No need to take the gaskets out of package if I should return them for thicker ones.

I read through quite a few posts before bedtime (NOW!), see others have run tight quench, including Wolfplace... I am obviously not a pro engine builder however...

Other combo info:
496
SRP 18cc dome
Scat forged rotating assembly (4.25 crank 6.385 rod)
AFR 305 w/ CNC chamber
Solid roller .715"/.715" 250/254 @.050"

Mike

Measured deck height w/ bridge, pistons average ~0.0085" out of the hole. Measured on larger flat part of piston, rocked pistons back and forth, figured the middle for a .0075" to .009" range w/ the average right at .0084".

I have Fel-Pro 1071-1
.039" - .009" = .030" clearance piston to head. Is this sufficient, or do I go for 1071-2 for .051" - .009" - .042"?

Target compression for custom cam per Tony @ AFR is ~11:1, my combo is ~10.93:1 w/ 1017-1, will drop to 10.63:1 w/ the 1071-2.

I just got my AFR heads today, was getting ready to measure dome clearance.... started thinking about what I should expect where and it dawned on me that w/ my piston 'out', the suggested method of mounting the head minus the gasket and turning over would not work! No need to take the gaskets out of package if I should return them for thicker ones.

I read through quite a few posts before bedtime (NOW!), see others have run tight quench, including Wolfplace... I am obviously not a pro engine builder however...

Other combo info:
496
SRP 18cc dome
Scat forged rotating assembly (4.25 crank 6.385 rod)
AFR 305 w/ CNC chamber
Solid roller .715"/.715" 250/254 @.050"

Mike

Mike,

My combo is very similar to yours, almost identical. Only exception is I run the Voodoo 60234 solid roller.

My piston is .0115 out of the hole, so I used the 1017-2, to have my final quench at 39.5.

Go with the 1017-2. Anything under .050 quench is acceptable. You don't want to run it that close using the 1017-1, especially in a BBC.

You don't have to be dead nuts with the compression, especially if your quench is acceptable.

On my Voodoo cam, it only requires 10.5-1 compression.

Advertised Duration (Int/Exh): 285/293
Duration @ .050 (Int/Exh): 255/263
Gross Valve Lift (Int/Exh): .680/.680
LSA/ICL: 110/106
Valve Lash (Int/Exh): .018/.018
RPM Range: 3000-7200
Solid roller, rough idle. Good cam for Pro street or mild bracket racing applications. Works well in 454-540 cubic inch engines. Needs 3500 RPM or better stall converter, headers, 10.5:1 compression ratio and 4.11 rear gears.

You can see it HERE (http://www.lunatipower.com/Product.aspx?id=2162&gid=290).

I've run several oval track engines at .030 piston to head, a few with less. never saw any marks on the pistons or heads. I don't think based on my experience that the .035 number was given by God with the 10 Commandments. It's just a number that somebody came up with and got published in magazines and books, turned into hot rod law like Power Valves and whatnot. Look at a spark plug gapped at .035 and try to figure how a rod is going to stretch that much. And, don't forget that the block grows with heat too.

I am obviously not a pro engine builder

Mike,

Here is a quote from Joe Sherman, a "Pro Engine Builder" -

"I have never seen any majic in the super tight quinch.The differance from 040 to 050 does not make anymore power. Why bother ?? The only time this stuff is really important is when you only have 9 to compression ( or whatever )When you have enough compression, the last 010 does not do anything."

"My experience is that you still get all the same bennifits of the tight quinch with up to 050 or 055. There is NO reason to take a chance with hitting the head because it will work just as well with 005 or 010 more room."

You can see it HERE (http://speedtalk.com/forum/viewtopic.php?t=6745&highlight=quench).

Simple method to check your dome to head clearance, slide .015" of feeler gauge under each end of the head, then rotate/clearance as necessary.

I have no problems running .030" quench (or less) in certain small block applications, I would not attempt it with a dome piston big block. Rock the piston in the bore and measure the maximum protrusion, that is a real picture before the piston heats up of how close the piston can get to the head. Bet you have .020" to .030" protrusion worst case scenario. Run the thick head gaskets.;)

I'm at .032-.033 with a 4.500 bore and .005 p/w clearance. SRP pistons and steel rods.

It's been over 7000 with no sign of contact at all.

Randy

My 540 is at .028. Pistons are .009 out of the hole with a .037 gasket. They slightly *polish* the head and piston. I have .0045 wall clearance and routinely spin it 7400-7500 for 6-7 years now.

No problem!

JIM

Jim,

That's great, "polished."

LOL

My 540 is at .028. Pistons are .009 out of the hole with a .037 gasket. They slightly *polish* the head and piston. I have .0045 wall clearance and routinely spin it 7400-7500 for 6-7 years now.

No problem!

JIM
=
Or as I like to say,,,
It keeps the rods from stretching :D

I would probably not build it that way on purpose but .030 is a non issue as long as you check all cylinders & don't have ten thou of wall clearance