i am building a 383 stroker and i need to make clearance between my rods and cam.how do i grind on the rods for clearance? how can i balance my engine myself?

 

you can't balance it your self, other than static weight but that isn't really balanced. if you have clearance issues between cam and rods you need small base circle cam and rods that use bolts instead of the nut bolt arrangement. if you already have that then use a grinder to grind on the rods, or a sander whatever works for you

 

here is what i do......i pre assemble engine just use front and rear bearings and torque crank for checking purposes i install the cam and timing chain , gears etc.....then i install each piston rod assembly in its respectible cylinder and torque them in ( i do one at a time its easy to turn engine over by hand with a crank socket) rotate crank slowly to see where cam hits the rod.....then use a grinder to grind clearance on rods ....usually its at the top where the rod bolt head meets the rod shank ....a word of caution here i would use good high quality bolts (arp) and don't grind to much off may cause a very weak area if you detenate the engine much....but like ede said if your cam is new or you need to order one go small base circle

 

IMHO, grinding on the rod bolts is not a good idea. The rod bolts must endure a LOT of stress, especially at high RPM.

Either get a small base circle cam like Ede mentioned, or if you're not willing to part with your cam , get a set of Eagle H-beam rods. They will clear large cams using up to a 3.80" stroke crank.

Only problem you may encounter with the rods is they use floating piston pins. In my case, I had to buy another set of pistons.

 

i take it you have not seen a lot of race engines being built..........grinding on rod bolts is a last choice by all means but there are times to do so.........basically i haven't had much trouble with rod and cam lobes but i have had to notch the pain rail on the block with some combo's. i am a machinist (auto), engine builder , my brother and i got street cars running in low to mid 6''s in the eight mile my recent progect was refreshiing a gene fulton motor 706ci pro mod motor a friend bought to grudge race with

 

You're right, I haven't seen a lot of race engs being built, only abt a dozen or so true racing engs.
I HAVE seen, on numerous occasions however, what happens when rod bolts fail and it's never pretty.


It's the ONLY choice unless a small base circle cam or stroker rods are used.


I've had a lot of trouble with cam/rod clearance. Been down the rod grinding road. I've watched the heads of ARP bolts turn slightly triangle shaped and sink into the rods when torqued after they had been ground for clearance.


Anyone thats every built a stroker has done that. Nothing difficult abt it.


I've been a mechanic for over 25 years. I've repaired all sorts of high perf engines. Everything from 125cc motocross engs to aircraft engs that cruise at 600 MPH.

The one thing I have learned; needlessly compromising the integrity of a critical, high stress componant is never a good idea, period.

 

no need to fight guys.i am going to go the stroker rod road. i appreciate the help,thanks guys

 

demon138>> you're welcome.

 

its all good.....this is what this site is all about different opions and suggestions......we all are right to some extent i agree but in this day and time the aftermarket is flourisded with many opions , its all money

 

Um, well, I've built a few 383s myself, too. I've ground material off the rod bolt head and the shoulder of the rod itself that the rod bolt head clamps down on to gain necessary clearance. Haven't blown one up yet.

In fact, I do it exactly like Billy describes. I hand-grind everything myself, taking off material ONLY where absolutely necessary. Checking and rechecking over and over. When I'm done you only have about .025" of clearance between rod bolt and cam lobe, which seems to be plenty- never had a contact issue.

Let's not get ahead of ourselves here, though. I'm not talking about shaving off 3/16" or anything like that. That's just nuts. Some combos you would just have to take WAY too much off to be safe. Really it depends on your exact combo of cam (big roller cams have more interferece problems) and rods (beefy aftermarket rods have more interference problems). Usually you jsut look at it and you brain will tell you: 1. No freaking way or 2. Damn, it's jsut barely touching. Decide from there. Consult a machinist if you can. I've gotten so I can make those kinda decisions myself successfully, but I consulted second opinions early on.

 

I started off with the rod and cam almost touching. I couldn't get a .002" feeler gauge in there.
I was shooting for .050" min clearance like Lingenfelter recommends in his book ( there's numerous other sources that say .050" min also).

Ground the rods just like Billy was saying, except I removed the rod and filed on it away from the eng. Cleaned, re-lubed, and re-installed, re-checked, repeat.. (this gets old after abt the 10th time)

If I had been shooting for .025" clearance, I might have been OK with respect to rod bolt/rod integrity, but .025" seems a little too close.