Piston 0.007 past deck height with 198 rods. Go/No-Go?

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csheehy

csheehy

^Yup, that's me
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I've got a 225 with 198 rods and Wiseco PTS536A45 pistons at 3.445" bore - the head and block were just kissed for gasket sealing...

I'm using AussieSpeed's Big Bore gasket that has a 0.060" thickness on the gasket and 0.070 on the ring.

My piston is projecting 0.007" past the block deck.
Is this Okay?

Everything I have read about the long-rod conversion leads me to believe this should be at zero-deck. But I'm not, and the block has never before been cut. This is not a racer - nor will it see high-RPM. Just making sure the tolerances are in spec before buttoning up the engine.
 
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On a steel rod motor you should consider .040-.045 as a minimum. I would use a thicker gasket.
 
I assume open chambers, so what is the depth of the quench pad on the head? Measure each one.
 
You should be good. Not knowing what the closest part of your combustion chamber looks like you may not need them are pistons fly cut?
 
Run it. You have an open chamber head. You'll never get appreciable quench anyway. All using the Wiseco piston does in your case is raise the static compression. Measure how deep the chamber is on the opposite side of the head from the spark plug. Add that figure to your head gasket figure. That will be how far the piston will be away from the head.I don't think there's any way in the world you'll ever be close enough to even THINK about the piston hitting the head. I bet the chamber depth is on the order of .100" or more. Add that to "whatever" your head gasket thickness is and you begin to understand my lack of concern.

That said, your static compression will be high with no quench whatsoever. It will be a premium gas motor for sure and for certain. There'll be no escaping that.
 
Not sure what you are asking. Is it that the piston is 0.007" above the bore with a 0.060" thick head gasket? If so, no problem at all. Mate of mine drag races a 351C, has about 0.025" piston to quench pad clearance, runs to 7k rpm, never had a problem.
 
Bewy said:
Not sure what you are asking. Is it that the piston is 0.007" above the bore with a 0.060" thick head gasket? If so, no problem at all. Mate of mine drag races a 351C, has about 0.025" piston to quench pad clearance, runs to 7k rpm, never had a problem.
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We're not talking about a quench Cleveland head here, either. We're talking about an open chamber slant 6 head.
 
Put a hunk of clay on top of a piston, temporarily assemble, and rotate engine by hand.
Carefully cut through clay with a razor blade. Thickness of squished clay will show your running clearances.
 
Thanks for all the info everyone! Here's where I ended up...

I bought the last two Aussiespeed big-bore cylinder head gaskets (AS0193) in the US (sorry folks) which come in at 0.055" compressed; leaving a confirmable safety margin. The pistons do have reliefs for the oversized (Ford 289) valves, and with .476"/.479" valve-lift - I think I'm all set. Final compression here BTW, is 9.8.

Much appreciate all the shared knowledge!!
 
csheehy said:
Thanks for all the info everyone! Here's where I ended up...

I bought the last two Aussiespeed big-bore cylinder head gaskets (AS0193) in the US (sorry folks) which come in at 0.055" compressed; leaving a confirmable safety margin. The pistons do have reliefs for the oversized (Ford 289) valves, and with .476"/.479" valve-lift - I think I'm all set. Final compression here BTW, is 9.8.

Much appreciate all the shared knowledge!!
Click to expand...

Those gaskets are a waste of money. Almost every head gasket I have here measure 3.55" and those Aussie gasket are 3.6" "supposedly". Imo, all you're doing is giving up a little compression.
 
RustyRatRod said:
Imo
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You could be correct...
For me though, it works. I've got a 3.445" bore, so if your dimensions are accurate, that's right in my ballpark. And dropping a bit of compression, put me exactly where I wanted to be, which is 9.8. For me, it's a perfect fit...
 
csheehy said:
You could be correct...
For me though, it works. I've got a 3.445" bore, so if your dimensions are accurate, that's right in my ballpark. And dropping a bit of compression, put me exactly where I wanted to be, which is 9.8. For me, it's a perfect fit...
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So does my next build. I'm going to use the FelPro Print O Seal. It measures 3.55". I had actually considered the Aussie head gasket for mine originally, as I had the non turbo flat top pistons pressed on. That was going to get compression about 10.3. So I reformulated my plan and pressed on the turbo style dished pistons instead and compression will come in about 9.4. Much more pump gas friendly.
 
Lol
SGBARRACUDA said:
On a steel rod motor you should consider .040-.045 as a minimum. I would use a thicker gasket.
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Lol, the avg. uncut slanty head has the quench in the .150-.160 range, even if the kisses were heavy enough to knock it down by .040 that's .110plus.055minus.007. That's .158, and a long way from any fast burn let alone contact.
 
Killer6 said:
Lol

Lol, the avg. uncut slanty head has the quench in the .150-.160 range, even if the kisses were heavy enough to knock it down by .040 that's .110plus.055minus.007. That's .158, and a long way from any fast burn let alone contact.
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Quench. LOL
 
Killer6 said:
Lol, with the stock slugs so damn far down in the hole on the stk.225, it would be more accurately described as a combustion arena.........
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Yeah. I'm still slap befuddled that I got 175 PSI with pistons almost .180 in the hole. LOL
 
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