Hey everyone, i am back with the methanol powered slant six, and i am going to build it right this time, no more stock piston and rods. i am going with the Weisco 3.445 pistons and Molner 7.005 rods. But i only have one problem, i was trying to calculate my C/R and was coming up with some crazy numbers, i wanted to check with the forum and see what you guys say. Current specs without new piston and rods is below. Will i have a problem with piston protrusion with the current amount the block is decked, and will i have piston to valve clearance issue based on what ya'll have found with this setup? This setup has been done many times but cant seem to find clearance info from the forum, must have been lost to time.

New Cam: 254/267 duration .540 lift with 1.5 rockers

Current spec:
Head was milled 0.100
Block was decked 0.040
Deck height 10.642
cyl head cc 40cc
deck clearance .140
using steel shim head gasket.

If I had to guess your pistons will be out of the hole a good bit and your compression will be over 12.5 to 1. My guess!
My block was decked about .020 and my pistons were out of the top of the block @ .010 if memory serves me correct. The valve notches had to be opened up a little as well. They hit the valves. I ended up at 11.5 to 1 with a 56cc chamber

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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

Okay that is good knowledge. I have an extra block laying in my backyard i am probably going to use then. I am looking for 12:1 would be best for methanol.

I'd drop those numbers into a calculator see what it says. Even if you use zero for a deck height,that should be close.Your 40cc head will be the big difference.

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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

With a 40cc head and NO block decking, you will be well over 12:1 for sure. You will need to use your old block that has not been decked. You need to measure and calculate you will break all your nice new parts. Ryan Covalt can get you an 0.080" thick head gasket that would likely let you use your 40 cc head. He may have one on ebay.

Lou

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