69ZZ

Im in the process of building a sbc 383.Today i dropped in the 2 first piston/rod assembly and noticed there was very little clearance between the rod shoulder and cam lobe.
I know the clearance should be a min of .050".Is there a way to mesure that clearance?...cause its very hard to tell by looking at it with a mirror and flashlight.
Im using a comp cam XR288HR with Eagle 6.00 H-beam rods..

Thanks...

TwoFast4Lv

iTrader: (8)

Those rods should clear fine. I am running them with a 3.75 stroke and over .600 lift and 247 .050 duration

It can be a PITA but a feeler gauge has worked for me in the past

elky489

iTrader: (1)

It depends on the cam,if its a reduced bace circle camshaft...I always put alittle clearence in the rod at the rod bolt area,thats the tight point...Its going to be the worst on 2 and 5.I sudgest you clearence them now so if you ever want to do another cam change you wont have a problem......If you need to know where i will take some pics of a couple clearenced rods and post them up for you....

69ZZ

It's a regular SBC cam with no reduced base circle...this brings me to think that if i give the required clearance on the rod im afraid it will upset the rotating assembly balance..but i could be wrong ....what do you think??

elky489

iTrader: (1)

It would eb a good idea to atleast check them afterwards...No more the .5 grams off between the rods....But you have to d this and its worse because u have a 6 inch h beam rod...**** i had to clearence my 5.7 rod motor with a 530 cam...

TwoFast4Lv

iTrader: (8)

I am running regular base BTW if that helps

elky489

iTrader: (1)

iT REALLY JUST DEPENDS ON THE CAM AND WHERE IT GOES IN AT AND HOW AGGRESIVE IT IS...opps sorry about the caps

TwoFast4Lv

iTrader: (8)

Yeah we build a few engines a years. ALL are strokers and this is some thing that is checked Last one we had problems on was a Stock rod 383. The 434 is the only one with a small base circle.

It is actually duration and lobe placement more then lift that causes the problem. You see as lift goes up the base goes down to get the higher lift You can only go so high over stock lift before you HAVE to start cutting the base to get more lift.

So Basicly Check it and see where it is at.

BTW the last engine we built hit the rollers at 540RWHP and 637RWTQ friday Just your basic 10 second 4,000lbs street car! He is one happy customer

69ZZ

thanks for the info....after all this is done i hope to be able to get at least 480-500 HP...ill be using AFR 195 with an rpm air gap intake topped with a Demon 750..exhaust will be 1 3/4 long tubes...
Wish me luck

78LT383

Have you had the block line honed or bored? This will move the crankshaft up slightly and reduce your clearance. Also, every rod is a tiny bit different, and every rod P/N certainly is different. Kudos to you for measuring, although as you now see it's always better to measure before balancing.

The traditional method is to use a feeler gauge.