Oval Piston Roll Call!!

K

Kramer

Member
Sep 3, 2014
46
0
6
Hornell, NY
Finally got my truck running last week with .040" over, 15.75:1 cast oval bowl pistons. Ran great for 300 miles, now I'm having injector problems. Should be around 800hp once I get the injector problem straightened out. Not the best fuel economy, but obviously nowhere near broken in, probably haven't even seated the rings yet. I'll report back after I get some miles on them.
 
quinton

quinton

Active member
Nov 28, 2011
1,883
0
36
Granbury Tx.
I've got around 40k hard miles on mine. Ran most of it with a Danville 72mm now have S475. Ready for this years season to start to see what the truck can do now.
 
rgullett83

rgullett83

Active member
Oct 27, 2008
1,607
0
36
Illinois
I have about 80-100 miles on mine since I got it running before Thanksgiving, been at the body shop ever since. Hopefully I get it back soon
 
Ne-max

Ne-max

I like turtles
Nov 15, 2011
3,361
64
48
Lincoln, Ne
Almost a 1000 miles on min . Went 15.5:1. Smokey pig on start up on these low 60 degree nights. Did a compression check last week on passenger side. All cylinders was at 300. Does this sound right?
 
DAVe3283

DAVe3283

Heavy & Slow
Sep 3, 2009
3,729
297
83
Boise, ID, USA
Ne-max said:
Almost a 1000 miles on min . Went 15.5:1. Smokey pig on start up on these low 60 degree nights. Did a compression check last week on passenger side. All cylinders was at 300. Does this sound right?
Click to expand...
I think the cam plays a large role in cranking compression. I have 16.5:1 pistons in mine, but a stupid cam, and I see 350 PSI. So if your cam is aggressive, 300 wouldn't be out of the question. It does explain the smoke.
 
Ne-max

Ne-max

I like turtles
Nov 15, 2011
3,361
64
48
Lincoln, Ne
DAVe3283 said:
I think the cam plays a large role in cranking compression. I have 16.5:1 pistons in mine, but a stupid cam, and I see 350 PSI. So if your cam is aggressive, 300 wouldn't be out of the question. It does explain the smoke.
Click to expand...

I am running a social af9100 with 150% injector .
 
TROJAN366

TROJAN366

Gold Rush
Jan 13, 2012
2,474
1
38
MASS
I have 16:1 with reliefs in my truck. About 100 miles and so far so good. Will update as I turn the tune up and get some miles on it.
 
moparkxracer

moparkxracer

Well-known member
Jun 25, 2010
2,309
33
48
Out and about
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I had 1500 miles on mine before blowing an oil pump. The Pistons went back into the engine when it was rebuilt.
 
Fingers

Fingers

Village Idiot
Vendor/Sponsor
Apr 1, 2008
1,717
96
48
White Oak, PA
The pressure you will see will depend greatly on the length of the connection to the compression gauge. The longer the hose, the lower the indicated pressure. Each cc of additional volume reduces the effective CR by about 1/4 point and thus the indicated pressure on the gauge.
 
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mike diesel

mike diesel

I'm alright.
Sep 6, 2012
4,005
0
36
SLC, Utah
Fingers said:
The pressure you will see will depend greatly on the length of the connection to the compression gauge. The longer the hose, the lower the indicated pressure. Each cc of additional volume reduces the effective CR by about 1/4 point and thus the indicated pressure on the gauge.
Click to expand...

Is there a length of hose that is considered to be some sort of "national standard" or "accurate" when doing a compression test?
 
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