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've 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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'68 Barracuda - taking advice on increasing street torque, power, & road handling. Click To See It

If it does not hit the chamber of the head and there is .090" clearance in between piston and chamber then I would not worry about it.

If you really want .000 you can have that much milled off the piston tops.

I wonder what doc and others think about this...


Greg

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It's unclear...what is the compressed thickness of your gasket? I think you are giving uncompressed measurements which don't mean much.

Does the gasket provide full cylinder clearance, or does any part of it overhang the cylinder at all?

If your piston is .007" out of the deck at TDC, and the gasket is .040-.050" thick (compressed), you'd probably never have a problem. That's especially the case on a low revving Six. I might have a different opinion on an 8000RPM small block.

D

My engine was the same, just a little out of the deck. But mine was a race motor so we cleaned @ .015 off the top of the pistons. That being said if you have a compressed thickness of .040-.045 you will likely be fine. Of more concern is if you use big valves or not? If yes then you will need to check the valves reliefs to see if the valve catches the edge of them. Lift is not much of an issue since the reliefs are plenty deep. My .570 lift, .260 @ .050 cam had plenty of room, but the pockets needed opened up a little to clear edge of the valve. ( They are not quite exactly in the right place)

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

I have 0.030" between pistons at TDC and head chamber on 1 engine and around 0.040" on another. Pistons are 0.005" out of hole on one and 0.015" on the other. 6000+ RPM redline and no problems. 0.045" compressed gasket on both. Need to measure piston-valve carefully with the cam you will use and the position you will use it in and have 0.090" or more.

Lou

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Home of Slant6-powered fun machines since 1988

Yes, I have big cams and valve notches on both engines.

Lou

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Home of Slant6-powered fun machines since 1988

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!!

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'68 Barracuda - taking advice on increasing street torque, power, & road handling. Click To See It

Sounds good. Look forward to hearing how it runs.

Lou

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Home of Slant6-powered fun machines since 1988