[61-63]

I bought Eagle H beam rods for the 421 I am putting together and let my machine shop guy put the rotating assembly together after the block and crank and balancing work. It turns out Eagle rods tend to be wide and material needs to be taken off to get the rod side clearances right. I didn't know that and neither did my machinist guy. So I'm going to have to take it apart and take some material off of the sides of the rods to get the clearances up. Thankfully I went with floating pistons which will make this much less troublesome.

Oh, the side clearances are .005 now. Too tight.

Thank you to my friend Mike Garblik for leading me through this deal.

[tom s]

Even good builders that build pontiac engines screw up!Over the years I have had two very good builders miss checking ALL rods side clearance.Both of them made it good.If using BBC rods it is usually never a issue as they are already more narrow than a pontiac.FWIW,Tom

[JLMounce]

I feel like this has less to do with having a chevy machinist put the engine together as it is that the machinist was lazy and assumed clearances would be right...without actually checking.

[Tim Corcoran]

Originally Posted by JLMounce

I feel like this has less to do with having a chevy machinist put the engine together as it is that the machinist was lazy and assumed clearances would be right...without actually checking.

Exactly

[PAUL K]

You are saying your side clearance is .005 currently?

Might be an illusion but the clearance on the number 7 & 8 rod look a bunch larger than .005.

I've built hundreds of engines with Eagle rods and have never had an issue with not enough side clearance.

I'd just like to make sure something isn't being over looked.

[Scott65]

Most comments I've ever heard, and my own personal experience is the Eagle rods on the Pontiac crank having too much side clearance. Good catch though.

[25stevem]

I agree, I have never seen those Rods, even there dedecated Pontiac Rods having too little clearance.

If your Crank was cut I would check that the journal to Crank cheek radius was not so big that the rod bearings where now riding up on that radius and eating up the side clearance.

[slowbird]

I agree with Paul, 7/8 looks to have decent clearance in the pic.

[mgarblik]

Originally Posted by 25stevem

I agree, I have never seen those Rods, even there dedecated Pontiac Rods having too little clearance.

If your Crank was cut I would check that the journal to Crank cheek radius was not so big that the rod bearings where now riding up on that radius and eating up the side clearance.

Yes, be sure to check all the things we discussed. Rods facing the right direction, chamfered bearings, if needed. All that stuff. Making extra clearance by removing material from the rods, is a last resort and we really didn't discuss that. Call or text if we need to discuss more.

[61-63]

Originally Posted by mgarblik

Yes, be sure to check all the things we discussed. Rods facing the right direction, chamfered bearings, if needed. All that stuff. Making extra clearance by removing material from the rods, is a last resort and we really didn't discuss that. Call or text if we need to discuss more.

I will. I need to get the thing home and start checking things. I'll be back.

[PAUL K]

You might also first ask the gentleman that assembled the engine in regards to the side clearance.

In addition to the above, also check that the small end of the rod isn't rubbing against the inside of the wrist pin housing support area.

[61-63]

Originally Posted by PAUL K

You might also first ask the gentleman that assembled the engine in regards to the side clearance.

In addition to the above, also check that the small end of the rod isn't rubbing against the inside of the wrist pin housing support area.

The .005 number I posted came from standing there watching him tap on both rod ends on each throw, pushing them apart, and then sticking a feeler gauge between the rods. He did this on all four throws. He said since those gaps check .005 with a feeler gauge they are probably ?? .006-.007 in reality and that is fine. I am going to check everything when I get the block home.

I appreciate your input.

[Formulajones]

Originally Posted by JLMounce

I feel like this has less to do with having a chevy machinist put the engine together as it is that the machinist was lazy and assumed clearances would be right...without actually checking.

Exactly. Every set of aftermarket rods I've ever used, whether it be in a Pontiac, a Chevy, or a Ford, had to have the big ends checked and sometimes were slightly out of round so they had to be cut, and every single set needed the small ends honed to size for the pins. That's just accepted procedure as far as I'm concerned, new rods or not, and the rest of it like side clearance is just crossing your T's and dotting your I's. But I've never had a set that was too tight in that regard.

[PAUL K]

Originally Posted by 61-63

The .005 number I posted came from standing there watching him tap on both rod ends on each throw, pushing them apart, and then sticking a feeler gauge between the rods. He did this on all four throws. He said since those gaps check .005 with a feeler gauge they are probably ?? .006-.007 in reality and that is fine. I am going to check everything when I get the block home.

I appreciate your input.

Interesting, then I'd guess the .005 is an accurate number. Fwiw it's odd the rods needed to be tapped (also understand it could be a figure of speech) as normally they slide back and fourth easily. I'm sure with Mike's guidance you will get it figured out and hopefully it's something that is easily corrected.

Good luck and please keep us posted.

[Skip Fix]

Check to see if the crank filet is wider on those or they need a narrow bearing. I had that issue with a couple of cranks

[72projectbird]

Funny how Chevy guys always get blamed when mistakes are made, but when a Pontiac is assembled and makes good power it's because the builder is a "Pontiac" machinist.

An engine is an engine regardless of brand. Check all clearances in accordance with the build at hand and everything will turn out alright.

[johnta1]

Funny how Chevy guys always get blamed when mistakes are made, but when a Pontiac is assembled and makes good power it's because the builder is a "Pontiac" machinist.

Some of those chevy machinists don't realize the Pontiac driver side of block is behind the passenger side.

(not that some Pontiac people may not either?)

[NeighborsComplaint]

My gut says the fillets on the crank are too small a radius. By tapping the rods from center to get the clearance, he is displacing the soft bearing material to try and convince you he didn't screw up.

[KEN CROCIE]

Pop a cap and see if the chamfer on the bearing is towards the crank

[Schurkey]

Originally Posted by NeighborsComplaint

My gut says the fillets on the crank are too small a radius. By tapping the rods from center to get the clearance, he is displacing the soft bearing material to try and convince you he didn't screw up.

Too LARGE a radius???