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If you decide to resize them also change the bolts to new as extra insurance.
 
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So if I found a shop to resize/hone the rods,how is it done? are all the rods honed to the largest rod?
Or are the caps shortened down/squeezed together closer and then honed to the regular 2.3247 specs?

The bolts are taken out of the rods, then the rods and the caps are put in a special grinder and the ends are ground off a couple of thousandths. Then the rods are bolted back together and honed on a connecting rod hone back to the correct size. They will also have to take the rods back off the pistons to do it properly.



The crush in the big end of the rod is what holds the bearing in place. The little tangs are strictly for alignment and have nothing to do with the bearing spinning.



By the time you are done with it you will still have a 40 year old set of mismatched rods. I dont know about in your area but I get $160 to resize a set of rods. By the time you buy a set of rod bolts you will be getting pretty close to what you can buy new rods for like Gary said :(
 

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Discussion Starter #64
Some just cut the cap, some will push the bolts out and also cut the rod face depending on the finish and flatness, but basically they make the hole undersize and oval and hone it back to round and in spec.
You'll want ask them if they target minimum, or maximum on the bore spec so you can determine clearance ahead of time....or you can tell them you need it at the high or low end of spec to get the clearance you want.

Personally, for typical use I'd want the rod oil clearance at .0018-.0023"
Got it.!

Wonder if its worth it to resize these mismatched rods (6 of the strong newer 2 weaker older style). i dont want it to just run. Want it to last.
 

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Got it.!

Wonder if its worth it to resize these mismatched rods (6 of the strong newer 2 weaker older style). i dont want it to just run. Want it to last.
I would replace the two oddball weaker ones if you got spares, since they have to remove the pistons anyway.

a good point has been made about replacing the bolts with new, and how close that whole process gets you to the cost of just buying new, better sportsman style rods from SCAT or Eagle.

Bill is absolutely right about the difference in methods, I should have been more clear about that.
 

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Discussion Starter #66
I would replace the two oddball weaker ones if you got spares, since they have to remove the pistons anyway.

a good point has been made about replacing the bolts with new, and how close that whole process gets you to the cost of just buying new, better sportsman style rods from SCAT or Eagle.

Bill is absolutely right about the difference in methods, I should have been more clear about that.
My thoughts exactly. All that labor or go for Scat or eagle. Thats whats happened to this country. When I was younger,We used to have machine shops on every corner. My dad was a machinist. Now its cheaper to buy new.
Anyway, what causes a rod to have such a large opening? Dosent look like anything spun on it and ate it up.
 

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Just mileage, but also detonation and lugging the engine pounds the rod out-of-round.
Rarely ever will you find a 50,000+ mile stock connecting rod that is still round on the big end.

Just at a 600 rpm idle that rod has gone up and down the bore 10 times in ONE second....now think about that at 50,000 or 100,000 miles and cruise rpm of 2000+ RPM. Millions of cycles
 

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My thoughts exactly. All that labor or go for Scat or eagle. Thats whats happened to this country. When I was younger,We used to have machine shops on every corner. My dad was a machinist. Now its cheaper to buy new.
Anyway, what causes a rod to have such a large opening? Dosent look like anything spun on it and ate it up.
Back when you were younger, it was re-use stock or spend serious coin for Carrillo or Oliver or Crower H-beam race parts....there was no Sportsman rod to be had at an entry level price.
 

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Discussion Starter #69
Just mileage, but also detonation and lugging the engine pounds the rod out-of-round.
Rarely ever will you find a 50,000+ mile stock connecting rod that is still round on the big end.

Just at a 600 rpm idle that rod has gone up and down the bore 10 times in ONE second....now think about that at 50,000 or 100,000 miles and cruise rpm of 2000+ RPM. Millions of cycles
Wow!! Engine beats itself to death.

Do the new scat or Eagle Rods last longer. Does the big end stay round for more miles?
 

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I went ahead and tried a different brand .010 bearing set. King brand. Got the same results. Plastiguage shows only about .002 clearance for the rods and .0015 for mains.
Why would you change that? Those are perfect. Run a stock volume oil pump, and you will have excellent oil control, and good pressure hot idling in gear.
 

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Discussion Starter #71
Why would you change that? Those are perfect. Run a stock volume oil pump, and you will have excellent oil control, and good pressure hot idling in gear.
As was stated further in the post, a real bore gauge showed plastigauge was very wrong. Some of the clearances are too large and some of the rods have to be resized. Trying to figure out where to go from here. Its cheaper to go with new rods and pistons.
 

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As was stated further in the post, a real bore gauge showed plastigauge was very wrong. Some of the clearances are too large and some of the rods have to be resized. Trying to figure out where to go from here. Its cheaper to go with new rods and pistons.
Hi Rich, one more time, new rods are the right way to go, the set I'm working with here would most likely go without rebalancing the unit! Depends a little bit on your existing rod weights?

Thanks, Gary in N.Y.

P.S. If it were up to me I would go with the new pistons AND rods, get away from the press-pin platform. You'll end up with a much lighter piston with a much lighter ring pack as well. Those TRW slugs you have now weigh about 670 grms, good "boat-anchors" or "ash-trays" maybe! Will definitely require rebalance of rotator with rod and piston change though!
 

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Discussion Starter #73
Hi Rich, one more time, new rods are the right way to go, the set I'm working with here would most likely go without rebalancing the unit! Depends a little bit on your existing rod weights?

Thanks, Gary in N.Y.

P.S. If it were up to me I would go with the new pistons AND rods, get away from the press-pin platform. You'll end up with a much lighter piston with a much lighter ring pack as well. Those TRW slugs you have now weigh about 670 grms, good "boat-anchors" or "ash-trays" maybe! Will definitely require rebalance of rotator with rod and piston change though!
You have a set you’re selling?

This TRW set is going on eBay.
 

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Discussion Starter #74
I think I finally found the answer to my question “ Where does the oil clearance come from, ground into the crank or built into the bearings”
I found the factory specs for a stock 396 crank. The oil Clearances are ground into the crank. The crank journals are not exactly 2.750 and 2.200
Here:
“ The main journals were 2.7482 to 2.7492 inches. The rear main journal diameters are 2.7478 to 2.7488 inches. The rod journal diameters are 2.1988 to 2.1998 inches. ”
 

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You have a set you’re selling? This TRW set is going on eBay.
Hi Rich, contact me with a "PM", parts aren't a problem!

The rod journal diameters are 2.1988 to 2.1998 inches. ”
That .001" difference in those journal sizes is going to be reflected in the brg clearance UNLESS you start mixing/matching brg sizes! The crank grinder should have done a better job for you?

Thanks, Gary in N.Y.

P.S If you're more comfortable talking just "PM" me a number where I can reach you? Looks like you may be fairly close by to me, I'm out on Long Island.
 
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