When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
There have been many posts regarding this type of combo. There is one currently on ROP. Many suggest that you can't use "Chevy" pistons without mods and that you should use/need custom ones. I'm here to tell you that's simply not true.
This thread is also directed at SBOrule, even though he's no longer here. I just thought I'd disproof his bs once and for all.
And actually the valve reliefs and their angles are of no conseqence anyway. The valve hits the flat part of the piston.
Thanks for your time gentlemen.
Last edited by cutlassefi; December 13th, 2012 at 05:34 PM.
It isn't brain surgery, just basic math. Since then some new products have been introduced, but the fact that nobody makes a bolt in aftermarket SBO rod is one thing that makes using the SBC stuff attractive.
So it comes down to the correct p/h and bore size with correct rod length ?
1/2 the stroke + rod length + pin height must equal the deck height +/-. Ideally, near zero or a tad below. Deck height on a SBO is 9.925-9.330. Bore size has nothing to do with the rod length, p/h, or stroke.
I only mentioned bore size as there is many choices for the sbc. std 350 is 4 inch .060 is .003 bigger than stock olds 350 etc. etc. I know the bore has nothing to do with it.
Both of my stroker builds used custom pistons. Because of different strokes, different rod lengths, pin heigths needed, compression wanted, ring packages and also get into less weight, better strength thru latest design, gas ports & etc.
I don't believe in decking the block any more than needed to have a .010-.012 piston hgth. I also want the longest rod, a good rod to stroke ratio and etc.
So to me that justifies the extra money for customs.
Last edited by 380 Racer; December 14th, 2012 at 01:39 PM.
Small block Chevys use offset connecting rods--Oldsmobiles do not. Does this cause problems when using off-the-shelf SBC pistons in an Oldsmobile? For example, I have a converted diesel I'm looking to put a 425 crank into. Obviously, that throws everything out of whack...
The formula to determine compression distance is deck height-rod length-1/2 stroke. Diesels have a deck height of 9.33". The preferred rod length for LS engines (no offset) is 6.125". Stroke is 3.975". Run the formula and you come up with 1.2175" for compression height.
Looking through Diamond and J&E's catalog there's nothing that matches up (Diamond has Chevy pistons with 1.2175" compression height, but the bore diameter is wrong. DSS pistons (Summit Racing) has a piston for a Pontiac with a 1.222" compression height (.0045" too tall), but the pin diameter is .990" whereas the LS rods are .927"--some .053" difference!
Bottom line...you have to do lots of digging to come up with an off-the-shelf upgrade for Oldsmobiles. Biting the bullet and forking over the extra bucks for custom pistons is just the cost of doing business...
Small block Chevys use offset connecting rods--Oldsmobiles do not. Does this cause problems when using off-the-shelf SBC pistons in an Oldsmobile? For example, I have a converted diesel I'm looking to put a 425 crank into. Obviously, that throws everything out of whack... No it doesn't. The rods are offset, not the pistons.
The formula to determine compression distance is deck height-rod length-1/2 stroke. Diesels have a deck height of 9.33". The preferred rod length for LS engines (no offset) is 6.125". Stroke is 3.975". Run the formula and you come up with 1.2175" for compression height. You're taking into account that you wouldn't be milling the deck at all. I think you might want to being it's a diesel block.
Looking through Diamond and J&E's catalog there's nothing that matches up (Diamond has Chevy pistons with 1.2175" compression height, but the bore diameter is wrong. DSS pistons (Summit Racing) has a piston for a Pontiac with a 1.222" compression height (.0045" too tall), but the pin diameter is .990" whereas the LS rods are .927"--some .053" difference!
Bottom line...you have to do lots of digging to come up with an off-the-shelf upgrade for Oldsmobiles. Biting the bullet and forking over the extra bucks for custom pistons is just the cost of doing business...
Not always necessary. Ponder this;
Grinding the crank to a stroke of 4.05, (you have to grind it to SBC size anyway) Then an LS 6.125 rod which is a centered rod. Add that to a DSS LS piston with a cd of 1.173, comes to 9.323, or pretty close to the stock deck height. Hmmm, you need to think outside the box.
And again the valve reliefs would be inconsequential.
It isn't brain surgery, just basic math. Since then some new products have been introduced, but the fact that nobody makes a bolt in aftermarket SBO rod is one thing that makes using the SBC stuff attractive.
I understand I'm a year behind...ha. SO, on these rods, are we looking at a 2.00 or 2.100 big end? I can only find 2.00 rods in the 6" variety so that might answer my question anyway. I think the cheapest way to go is probably an inexpensive 6" rod with a 2.00 big end and a CP piston??
Im having a combo of SCAT 6.200" long rods with 2.100" big end for Chevrolet ( SCAT 2-ICR6200-7/16), and SRP 4.125" bore flat-top pistons for Chevrolet ( SRP 231307). Con.rods narrowed from big-end, and crank journals just driven undersized, so not stroked.
It makes 362cid, ends up .0125" below zero-deck on non-cut SBO deck-height, and following weights:
Last edited by Inline; May 22nd, 2019 at 11:12 PM.
Also....I can only assume the math doesn't add up, but Imma check it anyway and see what y'all think. Why can't we use a 1.88 Honda sized rod end Chevy 6.00 Rod?
Last edited by brownbomber77; May 23rd, 2019 at 06:24 AM.
Took 2 min to search.. But there it is, 6.000" long rod with 2.100" big-end, if you were after those, and for cheap..
What are you actually trying to do?
And about it, some have used honda-sized rods. You can use virtually everything as long as it matches closely to deck-height of 9.330” and few other dimensions. Just takes time and effort to search. It doesnt matter if rods are from Lada and pistons from Ssangyoung as long as they meet few criterias.
December 13th, 2012, 05:28 PM
