i just got my rotatig assembly together and turn it over by hand to check clearence's, it appears that the rod for the # 1 piston is hitting a lobe on the cam, anyone else had this problem? what cam will fit without problems? its a 383 rotating assembly and the crank is a scat

 

You need to do something with the rods. What part is hitting? If it's the usual situation, it a corner of the rod bolt head. This may be ground a bit if needed. Some rods have much better clearance than others. The design of the big end is the main issue, also the bolts - cap screws are better because they do no protrude from the "shoulder" of the rod.

Lunati "Pro-Mod" rods fit great. At ~$700 they are an excellent rod. More expensive than what most people here use, however.



Rich

 

Well worth it

 

thats exactly where its hitting, who else makes a rod that will fit and how much and where should the rod be clearenced

 

You could also change the cam to one ground on a small base circle.

 

that sucks, I hope you get it fixed soon!

 

You can grind on the head of the rod bolt.

Rich

 

I used a small base circle cam and the macine shop still had to grind on the rod bolts for clearence.

 

How much grinding before balance is a concern?

If you change rods you need to rebalance.

This is not some weird problem, it is a known concern when building this sort of engine, most guys just select parts with it in mind and avoid actually hacing a problem.

 

I wouldn't worry about balance with grinding the head of the rod bolt.

Rich

 

I agree. You should be fine. Just pull the rod out and "clearance" it. Grind at the spot that interferes. Also double check the other rods and grind on the ones that are almost hitting.

Funny thing about the Lunati ProMod rod. It has nice cam clearnace but it doesn't have very good block clearance, (at the inboard bottom of the cylinders). It's the first rod I used that ever hit at that area. Surprised me.

Karl

 

looks like going with a small basecircle is the answer right now, anyone got any idea who would have the best price for a custom grind?

 

I don't like small base circle cams unless it's the only way. They are weaker and prone to breakage, though with an HR it probqbly won't be a problem. You realize you will also need new pushrods? You best bet is working on the rods. I expect that any of the cam grinders will have the ability to grind the cam. Also note that the valve timing changes, albeit subtly, with a different base circle.

Rich

 

I've asked this before... not sure if you read, but I know you have a bias for rotating assy. components made outside of the US however I'm still not sure why other than your claim the materials used are of a cheaper quality...
Do you have any reports or has there been anyone on this site who have used Eagle or CompStar components report any breakage that could be blamed on the quality of the part?
Many engine builders I've talked to have used the above mentioned parts with great success in high hp engines and they have also claimed that people are paying more for just a name like Lunati.
What's your take?

 

Most of the bottom end parts people buy are way overkill anyway. How many people have seen stock crank or rod breakage? Actually, the stock stuff is good. OTOH, if you are talking a hi-po build (not a mildly modified motor) better parts are needed. There is a difference between ultimate mateiral strength and utility of a part. There are QC and inspection issues as well as finishing. The good parts have spot on dimensions, are straight, flawless material, and so on. Politics aside, what you need depends what you are building.

WRT the Compstar line, poltics aside, what Callies is doing makes sense. The forgings are Chinese but they are finihsed and inspected here. Eagle also has a good rep. I'd stay away from the others, as much because of lack of familiarity asanything else. For me personally, USA all the way.

Rich