For those of you guys using aluminum rods, what are you setting the piston at in the hole? Did you order shorter rods, did you order a .050 head gasket? I am going with a pond block, not sure of the deck with a 4.25 stroke crank and diamond piston, but it should be below zero, I want to order the BME 6.700 rods but the website said that the min. piston to head clearance is .060, what did you guys do and what was your compression height on the piston, thanks in advance. Also will the forged crank need a ton of weight removed?
Find the compressed thickness of the head gasket you are going to use, and subtract that from .060", and that will tell you how far in the hole your mock-up must be(usually .040-.041"). If it is not down .020" @ TDC, then you will need a .060 compression thickness gasket available from Cometic. Joe-JDC.
This message has been edited by MsgtJoe on Oct 30, 2008 3:09 PM
My buddy runs aluminum rods in his Windsor. I believe they are .015 to .020 shorter than advertized, after you've run them a couple hundred passes or more they stretch and come up to length..... then it is time to throw them away! In other words if you order 6.700 rods they most likely will measure 6.685 or something. So you wouldn't have to have custom pin height pistons because the rods are set up to work with them with the standrad pin location for each engine.
Don't take this to the bank but that is how his were.... check and re-check everything! I'm sure a phone call to a maunfacturer would put your mind to ease. GRP, Bill Miller, Childs and Albert, Manley, are all good.....
68 Cougar XR7 street and strip car, 428 4-speed, 3560# of fun, new best 10.43@131.2 1.47 60 ft
With a .040 gasket shoot for .020 in the hole which keeps you with the .060 clearance recommended. You can run it a little closer but not much. Remember that it all gets bigger as it warms up. Knowing the deck height is a must so you know what your CH needs to be. IF your deck height is 10.170(it usually isn't) you would need a piston with a CH of 1.325. You need to know the exact deck height to get it right. Balancing the crank won't be a big deal.
all this with Ross. On learning that the pistons they were making for me were to go with aluminum rods, they immediately told me that they were going to set the pin so that the piston was .010 in the hole. I have not yet explored gasket thickness with Cometic.
KS
