Minimum piston/head clearance?
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Registered User
Joined: Sep 2000
Posts: 550
From: KC; Where grandma drives in the left lane
Originally posted by Mindgame
Check with the gasket manufacturers..... detroit, corteco, rol, mr gasket, I'm sure you can find something a bit thicker. If the deck faces are good enough, you can use a copper gasket as they come in a real wide variety of thicknesses.
Important to mic the piston where (along the skirt) the manufacturer specifies.
-Mindgame
Check with the gasket manufacturers..... detroit, corteco, rol, mr gasket, I'm sure you can find something a bit thicker. If the deck faces are good enough, you can use a copper gasket as they come in a real wide variety of thicknesses.
Important to mic the piston where (along the skirt) the manufacturer specifies.
-Mindgame
I wouldn't be at all afraid to run copper gaskets, as both surfaces were milled to accept shim gaskets. I'll get a catalog and find the part numbers for something.
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Joined: Feb 2000
Posts: 35
From: Chickasha, OK
nos,
Well, I have to put my 2 cents worth in here.....
First, I will say I think you will be fine at 0.033-0.035 with your combo. The reason I say this is based on my experiences. I had a 355 that was rebuilt 3 times. Each time I surfaced the deck and used the same gasket. I started with around 0.040 quench, then went to around 0.035, then to 0.030, then to 0.026. And yes, I measured this each time with very good equipment.
Now, my engine was a 355, with TRW 11:1 pistons (LF2304 or something like that). These pistons are some of the heaviest I've ever seen for a 350. They weighed around 600 grams without the pins. I had a stock GM forged crank and Crower sportsman 5.7 rods.
This engine also went through an evolution in the rpm range. It started with a peak rpm of around 7,000. But, by the final rebuild, with the quench at 0.026, I was winding it to around 8,400 through the traps. I did this for a full season, with about 6-8 passes per weekend (depending on how well I did!!!).
To my point. I never had a problem with the pistons hitting the head, until the last season. With the extreme rpm, tight quench, and heavy piston, I found the limit. When I tore the engine down after the last season, the pistons had been 'lightly' touching the head. Funny thing is, it only happened on one side of the engine (I think it was the passengers side). After seeing this, I remembered reading something about this in Smokey's book. Sure enough, in his 'Power Secrets' book he talks about how the pistons on one bank get closer to the head during operation. Has something to do with the rotation, and whether the quench is on the thrust side of the piston. I don't remember exactly, but he talks about it.
Anyway, as you can see, I ran all the way down to 0.026, winding to over 8,000 rpm on a regular basis, with a VERY heavy piston. I did have a good crank and rod, but your crank and rods are good pieces too. And your pistons are MUCH lighter I'm sure. The 6.0" rod helps in that department. So, again, I think you will be fine.
Someone else said it, but I will repeat it. IMO, one thing to watch is to make sure you don't wind it too tight before it reaches operating temp. I think this should be procedure for any high hp engine, but definitely for one with tight quench.
JMHO,
Shane
Well, I have to put my 2 cents worth in here.....
First, I will say I think you will be fine at 0.033-0.035 with your combo. The reason I say this is based on my experiences. I had a 355 that was rebuilt 3 times. Each time I surfaced the deck and used the same gasket. I started with around 0.040 quench, then went to around 0.035, then to 0.030, then to 0.026. And yes, I measured this each time with very good equipment.
Now, my engine was a 355, with TRW 11:1 pistons (LF2304 or something like that). These pistons are some of the heaviest I've ever seen for a 350. They weighed around 600 grams without the pins. I had a stock GM forged crank and Crower sportsman 5.7 rods.
This engine also went through an evolution in the rpm range. It started with a peak rpm of around 7,000. But, by the final rebuild, with the quench at 0.026, I was winding it to around 8,400 through the traps. I did this for a full season, with about 6-8 passes per weekend (depending on how well I did!!!).
To my point. I never had a problem with the pistons hitting the head, until the last season. With the extreme rpm, tight quench, and heavy piston, I found the limit. When I tore the engine down after the last season, the pistons had been 'lightly' touching the head. Funny thing is, it only happened on one side of the engine (I think it was the passengers side). After seeing this, I remembered reading something about this in Smokey's book. Sure enough, in his 'Power Secrets' book he talks about how the pistons on one bank get closer to the head during operation. Has something to do with the rotation, and whether the quench is on the thrust side of the piston. I don't remember exactly, but he talks about it.
Anyway, as you can see, I ran all the way down to 0.026, winding to over 8,000 rpm on a regular basis, with a VERY heavy piston. I did have a good crank and rod, but your crank and rods are good pieces too. And your pistons are MUCH lighter I'm sure. The 6.0" rod helps in that department. So, again, I think you will be fine.
Someone else said it, but I will repeat it. IMO, one thing to watch is to make sure you don't wind it too tight before it reaches operating temp. I think this should be procedure for any high hp engine, but definitely for one with tight quench.
JMHO,
Shane
Registered User
Joined: Nov 2001
Posts: 2,985
From: In a house by the bay
Yeah, I think TRW uses carbide or maybe a little lead in their pistons.
That's impressive to spin such a heavy piston to those kinds of rpm. Wouldn't be my choice in building a dependable motor but you do with what you've got.
I've seen guys run into contact problems in the 0.028 region running close to 8k so maybe there is a hard-safe-limit. I'm sure the amount of crankshaft torsion plays a part too and we all know that's gonna vary a bit so there are variables, just like everything else. Safe is still better but I agree, don't see a problem here.
BTW, my comments on piston checks wasn't meant to be an insult to anyone's intelligence, just a reminder.
-Mindgame
That's impressive to spin such a heavy piston to those kinds of rpm. Wouldn't be my choice in building a dependable motor but you do with what you've got.
I've seen guys run into contact problems in the 0.028 region running close to 8k so maybe there is a hard-safe-limit. I'm sure the amount of crankshaft torsion plays a part too and we all know that's gonna vary a bit so there are variables, just like everything else. Safe is still better but I agree, don't see a problem here.
BTW, my comments on piston checks wasn't meant to be an insult to anyone's intelligence, just a reminder.
-Mindgame
Thread Starter
Registered User
Joined: Sep 2000
Posts: 550
From: KC; Where grandma drives in the left lane
Thanks to everybody for the help! Mindgame, I understand your intent, and thank you for your time. I think I'm going to run this setup and hope it works out . Unfortunately, I do have to pull it in the next day or so to fix a bad pan gasket leak. Figures... I bought the rubber/shim/eyelet gasket and it still needs glue around the vacant dipstick boss.
. Unfortunately, I do have to pull it in the next day or so to fix a bad pan gasket leak. Figures... I bought the rubber/shim/eyelet gasket and it still needs glue around the vacant dipstick boss.
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