No crank spacer with 5.3L/4L80E conversion?
07-01-2005, 05:13 PM
#51
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Ok guys, looks like Lance might be on to something. 
I measured the offset of a 5.3L flexplate and the offset of a standard SBC flexplate.
The 5.3L offset from the crank mounting surface to the converter lug mounting surface is ~.553"
I just happen to have a standard SBC flat plate on a 4.3L engine laying around.
Doing that measurement the same way it measured .278"
That is a difference of .275 or just over 1/4". That is exactly the amount of space I need to have just a hair over 1/16" space between the converter and flexplate.
I think I might have found the culprit
Thanks everyone, I will have to get a new flexplate now though. NEXT DAY AIR!!!!
I'll let you know how it works out.
I measured the offset of a 5.3L flexplate and the offset of a standard SBC flexplate.
The 5.3L offset from the crank mounting surface to the converter lug mounting surface is ~.553"
I just happen to have a standard SBC flat plate on a 4.3L engine laying around.
Doing that measurement the same way it measured .278"
That is a difference of .275 or just over 1/4". That is exactly the amount of space I need to have just a hair over 1/16" space between the converter and flexplate.
I think I might have found the culprit
Thanks everyone, I will have to get a new flexplate now though. NEXT DAY AIR!!!!
I'll let you know how it works out.
07-06-2005, 06:27 PM
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WELL....the saga continues. 
The flexplate I got for an old school SBC has the right holes for the converter but, NOT the right holes for the crankshaft. I did not realize the crank bolt pattern was different. Either that or I got sent the wrong flexplate by accident which wouldn't surprise me at all. 
Why would the crank bolt pattern be different, did Chevy really change them and if so what year did they do that?
Here are some pics of what I'm talking about. The top picture is the bolt holes lining up with the PI converter lugs. That is the GM small bolt pattern. The bottom picture is the crank spacer sitting on top of the new flexplate. You can see how the crank bolt holes don't line up at all. The hole in the center of the flexplate that the spacer snout fits through is also very big compared to the "LS1" flexplate. Actually, the '92 4.3L flexplate I measured has the smaller crank bolt pattern and hole in the center like the "LS1" flexplate. That's why I thought any SBC flexplate would do.
The flexplate I got for an old school SBC has the right holes for the converter but, NOT the right holes for the crankshaft. I did not realize the crank bolt pattern was different.
Either that or I got sent the wrong flexplate by accident which wouldn't surprise me at all. Why would the crank bolt pattern be different, did Chevy really change them and if so what year did they do that?Here are some pics of what I'm talking about. The top picture is the bolt holes lining up with the PI converter lugs. That is the GM small bolt pattern. The bottom picture is the crank spacer sitting on top of the new flexplate. You can see how the crank bolt holes don't line up at all. The hole in the center of the flexplate that the spacer snout fits through is also very big compared to the "LS1" flexplate. Actually, the '92 4.3L flexplate I measured has the smaller crank bolt pattern and hole in the center like the "LS1" flexplate. That's why I thought any SBC flexplate would do.
07-06-2005, 07:36 PM
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wouldnt 1/4" more
bottom the converter out and equal 0 clearance?
1 1/8 - 7/8= 1/4"
sounds more like you need 1/8 extra instead of 1/4
Ive seen so many numbers about this stuff
on the tci site
one page says 1 1/8 then another says
1 1/64
which is it?
if 1 1/64 is the correct measurement
1 1/64 - 7/8= 9/64
which is just 1/64 more than 1/8 clearance
well within tolerance
bottom the converter out and equal 0 clearance?
1 1/8 - 7/8= 1/4"
sounds more like you need 1/8 extra instead of 1/4
Ive seen so many numbers about this stuff
on the tci site
one page says 1 1/8 then another says
1 1/64
which is it?
if 1 1/64 is the correct measurement
1 1/64 - 7/8= 9/64
which is just 1/64 more than 1/8 clearance
well within tolerance
07-06-2005, 07:48 PM
#57
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gamedawgx53 - Stop it, you're trying to confuse me.
When I use the spacer and GM "bent" style flexplate the flexplate is like 1 5/16" away from the block which puts the flexplate and converter too close by 3/16 of an inch. No good.
When I use just the bent flexplate and no spacer I have 7/8" from the block which leaves a 1/4" gap. No good.
When I use the spacer and "Flat" flexplate it is 1 1/16 or so away from the block which give me a 1/16-3/32" gap between the converter and flexplate. That is within spec. This is the solution. 
I think I found a flexplate that will work and I'm going to call about it tomorrow. I want to find a flexplate that requires no reaming out of the holes and works with the PI converters with the small GM bolt pattern. I'll keep you guys updated.
When I use the spacer and GM "bent" style flexplate the flexplate is like 1 5/16" away from the block which puts the flexplate and converter too close by 3/16 of an inch. No good.
When I use just the bent flexplate and no spacer I have 7/8" from the block which leaves a 1/4" gap. No good.
When I use the spacer and "Flat" flexplate it is 1 1/16 or so away from the block which give me a 1/16-3/32" gap between the converter and flexplate. That is within spec.
This is the solution. I think I found a flexplate that will work and I'm going to call about it tomorrow. I want to find a flexplate that requires no reaming out of the holes and works with the PI converters with the small GM bolt pattern. I'll keep you guys updated.
07-06-2005, 08:16 PM
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buddy Im just trying to help
below you mean without the spacer...correct?
below you mean without the spacer...correct?
When I use the spacer and "Flat" flexplate it is 1 1/16 or so away from the block which give me a 1/16-3/32" gap between the converter and flexplate. That is within spec. This is the solution.
This is the solution.
07-06-2005, 08:59 PM
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Originally Posted by gamedawgx53
buddy Im just trying to help
below you mean without the spacer...correct?
below you mean without the spacer...correct?
I was just messing with you about the confusing part.
