Too much Big end clearance ? - Team Camaro Tech
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post #1 of 5 (permalink) Old Aug 10th, 03, 02:00 AM Thread Starter
Join Date: Apr 2003
Location: birmingham england uk
Posts: 29

When rod bolts have been torqued there is still play () up & down with d.t.i. on rod cap this is only on my original rods, 2 rods have been replaced with standard sealed powers (due to spun shells) which when torqued have zero play crank still turns ! will it be acceptable to have rod caps ground 1.5 to 2 thou to tighten things up or is new rods the answer. The crank has been ground and all big-end journals are correct size for new shells. can i take the cheap route ?
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post #2 of 5 (permalink) Old Aug 10th, 03, 02:03 AM Thread Starter
Join Date: Apr 2003
Location: birmingham england uk
Posts: 29

HI forgot to put in amount of play 1.8 to 2 thou.
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post #3 of 5 (permalink) Old Aug 10th, 03, 04:03 AM
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Join Date: Feb 2002
Location: LR AR
Posts: 2,372

The big end of the connecting rod will need to be resized. This involves more than just grinding off the rod cap mating surfaces. Replace it or have it resized.
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post #4 of 5 (permalink) Old Aug 10th, 03, 04:04 AM
Join Date: Aug 1998
Location: Waldorf Md. USA
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You need to take your rods to a machine shop and have them measure the inside diameter of the big end with the bolts torqued. This is a VERY VERY critical dimension and needs to be checked with a very accurate bore gauge such as the one on a Sunnen rod reconditioning machine. Just grinding the caps will leave the rod out of round and will result in bearing failure. If your original rods are indeed too big, they can be resized to the proper dimension by grinding the cap and the rod, then honing back to the correct size on the aforementioned Sunnen Hone.
I would like to repeat...the dimensions and straightness of the big end bore of the rods are probably one of the most critical in the entire engine.
Hope thihs helps,

Bill Koustenis
Advanced Automotive Machine
Waldorf Md
1971 Chevelle "Heavy Chevy" original owner

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post #5 of 5 (permalink) Old Aug 10th, 03, 10:00 AM Thread Starter
Join Date: Apr 2003
Location: birmingham england uk
Posts: 29
Red face

I guess this was cause of original failure, had knocking from low revs when reving to 2000 and easing back (no load, car on driveway in neatral), stipp down revealled no 1 & no 8 shells badly chewed up from spinning in rod and crank looked like it had been attacked with an angle grinder ! took a .050" grind to clean up. sick thing is all damage was done on my driveway i had never driven car. I think damage was done when i raised rev limitter from 4000 to 6000, i also used a flushing oil & changed from a 20/50 to a 15/40 (both mineral), wish i'd bought the 400 cu" rods & crank now for a 383, have allready borred it .030" over for flat tops would'nt of been much dearer having seen summit racing pricerecently.
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