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Posted: Mon Dec 03, 07 5:12 pm
by Blue
In my mind I've got the figure of 60 thou. After a quick whizz round the net I can't find anything to back that up, so don't take that as definite. Still looking, I will need to know this myself soon....
Posted: Mon Dec 03, 07 5:24 pm
by latil
Found this ; You need to install high-quality main studs and billet main caps if
they are available. Mock up the short block and check for counterweight clearance everywhere in the crankcase (especially at the pan rails). Check each individual crank throw, counterweight and rod clearance through a complete 360° of rotation. Minor grinding on the block or rotating assembly is okay. Next check rod-to-cam interference through a full 720º rotation. You need at least .100? clearance everywhere to be safe.
It's from
www.enginebuilder.com
Posted: Mon Dec 03, 07 5:28 pm
by Blue
Blimey that sounds like a lot, just posted the question on Moparts, lets see what comes up from that...
Posted: Mon Dec 03, 07 5:40 pm
by AllKiller
According to Mopar engine Guru Chuck Senatore 60" thou is good .....or
better still machine the crank counter weights
The inside edges of the 2 small counter weights need to be done on a lathe.... at a 45 degree angle 1/4 inch wide.
also some diameter can be taken off the overall diameter of CW's
thus lightening an already lighter set up...
.100" is a good starting point, exact amount depends on piston/rod weight.
Block grinding is easier, but turning down the counterweights is better
Posted: Mon Dec 03, 07 5:46 pm
by Mick70RR
According to a book I have, 50 thou is enough clearance.
Posted: Mon Dec 03, 07 5:56 pm
by Blue
Just got a reply of 50 thou. minimum....
Posted: Mon Dec 03, 07 6:01 pm
by latil
50 thou sounds plenty,allowing for rotational distortion and heat,at 50thou crank movement I would think the mains would be binding or the crank about to break.
Posted: Mon Dec 03, 07 6:06 pm
by Anonymous
440 source say 30 thou , 50 thou sounds good then.
Posted: Mon Dec 03, 07 6:37 pm
by AllKiller
60
From the man that runs Muscle motors
Posted: Mon Dec 03, 07 6:57 pm
by mopar_mark
0.050"/0.060"will be sufficient, there is not a great deal of expansion in that area of the rod. If there was then your rod bolts wouldn't be doing there job......... and your rods would be in "frightened of the dark territory" and no amount of clearance can stop them when they want to punch a hole
Posted: Mon Dec 03, 07 10:49 pm
by Anonymous
Julian , what yer building for the jensen?
Posted: Tue Dec 04, 07 8:28 am
by AllKiller
I bet you'll be happy....quick too
