Cam Interference Issues on Strokers?
05-14-2007, 10:15 PM
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Cam Interference Issues on Strokers? This is a theoretical question... I have built my fair share of Gen III/IV engines as well as old Gen I SBCs as well. Many of you probably know that one of the items that is routine to check when building a stroker SBC is connecting-rod-to-cam clearance. Obviously, the raised cam introduced in the Gen III helps widen this gap substantially, BUT...
Is there any point where this clearance becomes important to check in LS-style engines? I've never tried to run anything larger than a 4.00-inch crank in an Gen III or IV, and I'm simply wondering about the potential danger of not checking this clearance when building a *really* big stroker.
To envision what I am talking about, the area of the rod that should come closest to the cam is not the beam of the rod, but rather in the vicinity of where the threads of the rod bolt end ("top of the rod bolt threads" if you want to call them that). I figured there would be a lot of engine builders on here who may have shoehorned 4.125 or even 4.25 stroke cranks into a Gen III or IV block who may have run into this issue, especially when using an aluminum rod, which tend to be physically larger in dimensions. This would require either clearancing of this area of the rod and/or use of a smaller base circle cam.
I would like to assume that since the likes of the LSX block and other aftermarket blocks do not have a "raised" cam provision, this clearance is fine no matter how big of a crank you throw in. Anyone with experience on this subject? Thanks for your help.
Is there any point where this clearance becomes important to check in LS-style engines? I've never tried to run anything larger than a 4.00-inch crank in an Gen III or IV, and I'm simply wondering about the potential danger of not checking this clearance when building a *really* big stroker.
To envision what I am talking about, the area of the rod that should come closest to the cam is not the beam of the rod, but rather in the vicinity of where the threads of the rod bolt end ("top of the rod bolt threads" if you want to call them that). I figured there would be a lot of engine builders on here who may have shoehorned 4.125 or even 4.25 stroke cranks into a Gen III or IV block who may have run into this issue, especially when using an aluminum rod, which tend to be physically larger in dimensions. This would require either clearancing of this area of the rod and/or use of a smaller base circle cam.
I would like to assume that since the likes of the LSX block and other aftermarket blocks do not have a "raised" cam provision, this clearance is fine no matter how big of a crank you throw in. Anyone with experience on this subject? Thanks for your help.
05-15-2007, 12:21 PM
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Brian is correct.
With our 4.125 stroke crank in an LSX block we didn't have any problems.
This is with a lobe of .525 and duration above 280 degrees @ .050.
This was also with GRP Aluminum Rods.
This is a picture without the cam bearings installed.
We are checking several cams.
I will post if we find anything different.
With our 4.125 stroke crank in an LSX block we didn't have any problems.
This is with a lobe of .525 and duration above 280 degrees @ .050.
This was also with GRP Aluminum Rods.
This is a picture without the cam bearings installed.
We are checking several cams.
I will post if we find anything different.
