496 clearance problems - Team Camaro Tech
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post #1 of 9 (permalink) Old Nov 12th, 05, 04:27 AM Thread Starter
 
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496 clearance problems

Hi Guy's, I am currently building a 496 bbc with Gen V1 block, Eagle 4.250 crank,Eagle rods 6.385 & 060 SRP pistons, & as suggested by SRP to check for sufficient clearance between counterweight on crank & bottom of piston with a minimum of 060", to my surprise the very front c/weight slightly scraped the piston skirt (only one), with most other c/weights only given approx 040" clearance in the area below the piston pin, just curiuos to know if this is to be expected when building stroker big blocks. Appreciate some advice if anyone has had similar experience, thanks.
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post #2 of 9 (permalink) Old Nov 12th, 05, 07:43 AM
 
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Unhappy Re: 496 clearance problems

I would not have thought your crank would have kissed one of the pistons with your longer rods so I figure the crank is the problem!!

If they said it was good to go with 1/4" longer rods and it kisses a piston, send it back and get in their face!

AND I say this b/c several companies say the rod the crank is made to work with if you look. And this is not just a balance issue, but a clearance issue at BDC.

Been there and have cam-cut my crank..

pdq67



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post #3 of 9 (permalink) Old Nov 12th, 05, 08:21 AM
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Gary
 
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Location: Long Island
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Re: 496 clearance problems

Quote:
Originally Posted by pdq67
I would not have thought your crank would have kissed one of the pistons with your longer rods so I figure the crank is the problem!!

If they said it was good to go with 1/4" longer rods and it kisses a piston, send it back and get in their face!

AND I say this b/c several companies say the rod the crank is made to work with if you look. And this is not just a balance issue, but a clearance issue at BDC.

Been there and have cam-cut my crank..

pdq67
Hi PD, we see this all the time, I answered his identical post over on the Chevelle site. The pistons don't have enough "radius" machined into the skirt as the c'weights pass them. The brands don't matter we see it with ALL different ones. It's simply "vendor-issues", as we call it. The pistons don't usually hit under the pin bosses. Cruise on over, I explained it in more detail. Thanks, Gary in N.Y.
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post #4 of 9 (permalink) Old Nov 12th, 05, 05:48 PM Thread Starter
 
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Re: 496 clearance problems

Thanks Guys your help is greatly appreciated, my clearance between c/weight & pinboss is virtually .040" but as mentioned i have more of a concern with the radius on the piston skirt brushing the c/weight, now i know this is a not an uncommon occurence i will show your comments to my machine shop who had suggested taking some metal off the effected c/weights, again i appreciate your feedback as i live downunder & it's good to have you guy's to communicate with, Thanks.


Tuffss

68 SS Camaro 406 P/glide 4500 conv 4.11 9"
11.80 114mph
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post #5 of 9 (permalink) Old Nov 12th, 05, 06:55 PM
 
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Smile Re: 496 clearance problems

Well put a shrimp on the barbi for us!!

Glad to help.

AND I would strongly consider a hand contour job on the piston skirt bottoms along their sides if you haven't balanced her yet!

BUT the pin boss deal is critical so please go over to Team Chevelle where I asked Gary about that.

Darn, I would like to visit your place before I die!!

pdq67



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post #6 of 9 (permalink) Old Nov 14th, 05, 04:41 AM Thread Starter
 
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Posts: 34
Re: 496 clearance problems

G'day guy's it's me Mr 496 with another issue of rod side clearance i am coming up with 030" between a pair of rods to me this seems a bit too much any of you guy's had similar results, again these are Eagle H beam rods with an Eagle 4340 x 4.250 stroke crank, starting to get a bit frustrated now what with the other issues i had posted previously i hope these stroker big blocks are worth it.
Thanks Guy's.
Tuffss
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post #7 of 9 (permalink) Old Nov 14th, 05, 05:49 AM
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Gary
 
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Re: 496 clearance problems

You'll be fine there, no problem. Thanks, Gary in N.Y.
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post #8 of 9 (permalink) Old Nov 14th, 05, 01:27 PM Thread Starter
 
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Re: 496 clearance problems

Thanks Gary much appreciated.

tuffss
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post #9 of 9 (permalink) Old Nov 14th, 05, 05:05 PM
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Al
 
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Location: Vancouver, USA
Posts: 10,511
Re: 496 clearance problems

I had the issue of the counterweights hitting the pin bosses on my 383 SBC. The fix was to remove material from the counterweights. It still internal balanced just fine. Eagle 4340 crank, BTW.


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