[AMC-list] AMC Engines

["Bruce Hevner" <390scrambler@xxxxxxxxxxx>]

Couple of things came to mind after I sent last post.

There ARE a few things that are handy to know when building AMC motors.

 

Use small block Ford roller rockers. They are EXACTALLY the same as AMC and
can be had on eBust pretty cheap.

 

Use 343 flat top pistons for a high compression 360. Same bore size, since
the 360 pistons are WAY in the hole the difference in stroke works out just
right for the 360. Gives around 10.8 so be careful and use appropriate cam.

 

BE SURE TO MATCH YOUR STATIC COMPRESSION TO YOUR INTAKE DURATION for maximum
performance!! This is a COMMONLY overlooked planning point and yet is VERY
important !! For instance an Intake duration of 204'@.050 (common for torque
type cams) wants 9-1 while duration of 221"@.050 (typical mid-range) wants
10-1. Putting too much cam in a low compression motor results in a "lazy"
engine. Putting too much compression in a short duration motor results in
spark knock. Checking "cranking compression" can give you an idea of where
you are. Good street motors will crank around 140-160psi.

 

AMC's have a heavy valve train and REALLY don't like RPM with a hydraulic
cam. They WILL float valves about 5800. A solid cam works MUCH better but
does need periodic adjustment and does have the "clatter" of a mechanical
valve train. Generally speaking AMC's like more duration than other motors
of the same displacement

 

Stock AMC iron heads flow quite well but the 5/16 bolts used to hold rocker
fulcrums down limit spring pressure to 250 or so open max. More than that
and the bolts start breaking. So by the time you convert to 3/8 studs and
guide plates and other reconditioning you're not TOO far off from the
Edelbrock head which is a NICE piece of work!!

There was a timing chain kit available to install a thrust plate to control
cam walk. I THINK the seller was Nick Alfano. I HIGHLY recommend this to
prevent the dist gear wear problem!!!
Bruce Hevner

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