[87iroc]

I am building a late model roller block based 383 for my Camaro.

I am going through the initial mockup before sending it off to be balanced.

Bottom end will be a Scat Crank, Scat 3/8" capscrew rods, and Speed Pro Hypereutectic pistons. The cam will be a 224/230 @.050 cam from Comp. It is currently a standard cam, not a small base circle. I had hoped that with the Scat Rods I would be OK with it.

I started working on clearancing and did the 1/2 rod first. This is what it looks like after grinding...



Here is what it looks like from the Scat w/o Grinding...



Did I grind too much? Near as I could tell, that got me between .050 and .060 clearance to the lobe on the cam. I am grinding the #2 rod right now for clearance and it is taking what seems like a bit more than that...but probably not much. The engine spun over fine before I started grinding...but had less than .030 clearance...I'm guessing I'm grinding .020 or .030 off of it.

Thoughts? Do I need to just drop back and tradfe in my cam for a small base circle? The semi scary thing is the bottom of the rod capscrew is barely the .050 from the cam I think...I can't grind that!!

Thanks

Greg

[ericnova72]

Torque the rod up and grind it with the capscrew in it so that the screw will match the rod clearancing that you have done. This is regular standard procedure, you're doing fine so far, the amount you are removing from the rod and will remove from the screw hurts nothing.

Small base circle not mandatory but it certainly makes things easier, you might not have had to grind at all depending on the cam profile.

[CNC BLOCKS NE]

We have used the Scat Procomp rod with the 7/16 bolts and any time we have used a flat tappet cam we have alwyas had them ground on a 1.130 base circle and never had any clearance issues.

If your cam is a roller you should be fine.

[87iroc]

Thanks for the info guys. I have a roller cam and I am having clearance issues as I hadn't had it ground on a small base circle.

Anywho, I'm going to keep moving forward. I'll grind it down to clear...then when I get done, I'll torque the road bolts(I'm probably going to buy a stretch gauge) and then grind the bolt flush. That should help me be sure it always ends up in the same spot.

[CNC BLOCKS NE]

Interesting as most roller cams are ground on a 1.060 base circle.

[87iroc]

Originally Posted by CNC BLOCKS NE

Interesting as most roller cams are ground on a 1.060 base circle.

Not this one evidently.

I'll have to measure it when I pull it back out.

Hopefully I did alright. I got it all clearanced today. Only did the 4 as bad as that pic shows. 1,2, 5,6 looked like that. The others, I took a little off both sides to try to simulate the same weight reduction...but didn't grind into it as far.

I got a PM on another board telling me not to do it because the rod will break. Sure hope they're wrong.

[ericnova72]

Yes, the other board is wrong, and you are correct on which ones are the worst clearance offenders. Those who say the rods will break due to this clearancing have obviously never built a 3.75" stroke SBC. Don't even worry about it.