quench clearance

[352Ford2]

How tight of quench clearance do you think I can run with this combo?

SBF 302, cheap scat steel rods, and not planning on reving over 6 grand


Right now it is looking like the piston is out of the hole 0.014 and felpro claims my headgasket is compressed 0.039 so that works out to be 0.025.

A little tighter than I was planning on, what do you think, get a different headgasket?

 

[eagleautosports]

I know Cometic makes gaskets for this problem. I think they could actually go as thick as .080.

 

[Rick 91GT]

.025" is a little tight but with a steel rod you may be ok, ROL makes a .051" thick graphite style gasket that would get you closer to the norm .035"-.039"

 

[352Ford2]

How tight have people run their quench clearance?

I really would like that as tight as possible (also I would rather not have to get different gaskets.) I would really like to be able to back off the timing and run cheap gas when I am not at the track (its going to have about 9.6:1 CR and iron heads) and running the tight clearance would help that, and make me some more power. Its set up for N2O so the piston to bore clearance is a touch looser (1.5 times speed pro spec) so there will be a touch more piston rock, which isn’t helping me on this issue.

 

[352Ford2]

Update:
I rechecked everything (the measurement I took before were quick and dirty only on number 5 cyl with a straight edge and a feeler gauge). I did it right and used a piston stop and dial indicator.

#1: 0.007 out of the hole
#2: 0.007 out of the hole
#3: 0.006 out of the hole
#4: 0.007 out of the hole
#5: 0.008 out of the hole
#6: 0.007 out of the hole
#7: 0.003 out of the hole
#8: 0.003 out of the hole


so with my 0.039 gasket the quench clearances are 0.033, 0.034, 0.035, 0.038. which is still tight, but I think doable.

It kind of bothers me that two of those cylnders are 4 thou out of the hole less than the others.

ideas?

 

[352Ford2]

ttt

 

[352Ford2]

so only me,rick, and eagle are the only ones on stangnet that care about or check quench clearance?

thats disapointing...

 

[ninety15.0]

What was your method with the dial indicator? .004 is a tight difference, but still a tad concerning. I would double check...do you have the pan on it already?!

 

[352Ford2]

I used the piston stop, set up and zeroed the dial indcator, removed the piston stop, spun the motor and recorded how high it went, I did it a couple times so I am pretty sure its +/- 1 thou

yeah the oil pan is still off

 

[Rick 91GT]

The deck being crooked/uneven really doesn't surprise me much you see that with most of the stock stuff. I had a stock 74 351 that was .014" high up front bank 1, .014 high in the rear on bank 2...twisted.

.033" will be fine, I usually shoot for .038" We have run as tight as .018 on some race stuff but you need to have everything right or.....BOOM!

You could deck the pistons and block to make everything straight or atleast split the difference.