should i hold out for a early 360 for my stroker?

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a lot of guys keep saying "get it sonic checked" (me included).....however, please post the acceptance criteria along with the obvious........

FYI, I have a '71 360 that is currently .060" over - however, I would not have punched it over that much prior to sonic checking AND getting the block in the cnc to find out how much it would take to REALLY clean up the bores (meaning get them centered over crankshaft cl) while maintaining at least .200+ on major thrust surfaces....
 
What ever you deside to use. Do not rely on the factory motor mount ears . They stress the block and the 340 , 360's cannot take it. One of the reasons they moved the left side rear ears forward. Always use a motor plate or turn buckles for added support. This is the weak link and why you always see one of these two cylinders fail under torque from flex. Seen many pistons go through the wall on these two cylinder and break the rod. The rod is always blamed but it is the block. One of the reasons Chassis cars use front and mid motor plates. Good R3's don't even have mount ears.
 
Oldmanmopar said:
What ever you deside to use. Do not rely on the factory motor mount ears . They stress the block and the 340 , 360's cannot take it. One of the reasons they moved the left side rear ears forward. Always use a motor plate or turn buckles for added support. This is the weak link and why you always see one of these two cylinders fail under torque from flex. Seen many pistons go through the wall on these two cylinder and break the rod. The rod is always blamed but it is the block. One of the reasons Chassis cars use front and mid motor plates. Good R3's don't even have mount ears.
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Thanks, that give me more to chew on.

My old motor has a turn buckle at the trans to keep the early pos motor mounts from pulling a part.

was looking at one of those strut type motor mount support, but hadn't really notice just what they attach to?
 
kielbasa said:
a lot of guys keep saying "get it sonic checked" (me included).....however, please post the acceptance criteria along with the obvious........

FYI, I have a '71 360 that is currently .060" over - however, I would not have punched it over that much prior to sonic checking AND getting the block in the cnc to find out how much it would take to REALLY clean up the bores (meaning get them centered over crankshaft cl) while maintaining at least .200+ on major thrust surfaces....
Click to expand...

The acceptance criteria is entirely subjective. It depends on what the shop/tester has experienced and what is planned for the build. But, in terms of my specs: The minimum thickness on the major thrusts for me on something that makes under 500hp is .180". Anything expected to make more should be .200 Minor thrust minimum is .150, pin centerlines .090". In terms of blueprinting the bore centers, I am more concerned with centering the bore in the supplied casting core, then exactly where in relation to the center to center distance. IMO it's much more important to have the thickest most stable cylinder walls than to have the bores spaced exactly perfect. If you've tested more than a few blocks, you'll find it' s less common to find any year block that meets the " thicker than .200 on the major thrust" on all eight holes. Most have one or two that are thinner because of shift. You also want to make sure they are thoroughly testing each bore, and the that tester is quality and calibrated to the block in question. My test is 20 points on the bore, plus a scan along each compass point from the bottom to deck surface. I have found testing only points to miss casting issues and rust pits. So I also scan them and I've found rust pits on an otherwise great looking wall that dropepd the thickness from .220-.230 to .130. This was not picked up testing every inch up the bore. If one or two bores are failing, I'll just sleeve those holes because it's $100/hole to sleeve, or another $200-300 after aqusition cost to clean another block, mag, and sonic test.
 
Cudafever said:
Thanks, that give me more to chew on.

My old motor has a turn buckle at the trans to keep the early pos motor mounts from pulling a part.

was looking at one of those strut type motor mount support, but hadn't really notice just what they attach to?
Click to expand...


The struts from Schumacher attached to the mount ear, and I've had to repaired 2-3 of them. The best metod I've used over the years is $8 of chain and turnbuckle off the timing cover/water pump bolt holes. But honestly, the distortion is not a prevelant issue. It IS and issue, but not until you're really making some steam.
 
moper said:
The acceptance criteria is entirely subjective. It depends on what the shop/tester has experienced and what is planned for the build. But, in terms of my specs: The minimum thickness on the major thrusts for me on something that makes under 500hp is .180". Anything expected to make more should be .200 Minor thrust minimum is .150, pin centerlines .090". In terms of blueprinting the bore centers, I am more concerned with centering the bore in the supplied casting core, then exactly where in relation to the center to center distance. IMO it's much more important to have the thickest most stable cylinder walls than to have the bores spaced exactly perfect. If you've tested more than a few blocks, you'll find it' s less common to find any year block that meets the " thicker than .200 on the major thrust" on all eight holes. Most have one or two that are thinner because of shift. You also want to make sure they are thoroughly testing each bore, and the that tester is quality and calibrated to the block in question. My test is 20 points on the bore, plus a scan along each compass point from the bottom to deck surface. I have found testing only points to miss casting issues and rust pits. So I also scan them and I've found rust pits on an otherwise great looking wall that dropepd the thickness from .220-.230 to .130. This was not picked up testing every inch up the bore. If one or two bores are failing, I'll just sleeve those holes because it's $100/hole to sleeve, or another $200-300 after aqusition cost to clean another block, mag, and sonic test.
Click to expand...


i agree, once the block is in the cnc (after the sonic check), then some of the holes can be centered (or biased)to be in the "meat" of the casting vs centering over the crank centerline if need be (depending on core shift).......
 
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