Lapping piston rings

[Monte Howard]

It's a BBC rod, but built .500 longer. Not a big deal.

[QUOTE=Monte Howard;493093]It's a BBC rod, but built .500 longer. Not a big deal.[/QUOTE

It's only .010 longer.Instead of 6.625 is 6.635 The standard Chev bearing is the same size as a .050 under Pontiac journal. Easy to get bearings, that's the big advantage. The BBC rod is 50 grams heavier as well.
No great injustice here so relax.

[carl hinkson]

Originally Posted by Dragsinger

My understanding is that rings are "lapped in" during the manufacturing process. The rings are mounted on a mandrel/fixture and "stroked" through a hardened liner/cylinder.

My experience shows that cylinder wall finish, hone finish, is a vital key to a good seal.

Also, precision piston ring grooves are vital.

Back in 68 no one was using MM ring packs like what are available today.

Mahle now offers a 1MM 1MM 2MM ring pack and Mahle rings from what I have seen seal up good on start up.

To achieve good ring seal plate honing is a must which was not used way back when.

A good hone is a must with the proper abrasives.

No matter what you use for a ring its not going to seal if the cylinders are not round once the head is bolted on or the proper finish is not used for the final honing.

Richard Maskins has a good view on honing.
https://video.search.yahoo.com/video...t=mozilla&tt=b

Here are some pics of cylinders that were not plate honed and I don't care who's ring are used in these engine that are not going to seal. Look at the blowby under the top rings.






Shadows under every bolt hole when the torque plate bolted on.

[Jim Kaekel]

[QUOTE=Dwight Southerland;493003]If you can change your mindset to be satisfied with "competitive" not "ET killer", that is the first step to having the inspiration to do your own engine work. After a few serious builds and intense striving for information and skill, it is amazing how much you understand. You then have a reference base of knowledge that helps you to glean more information from everything you read, even advertisements.

That is outstanding advice for anyone that doesn't have a "bottomless pit for a budget".

[Alan Roehrich]

[quote=Todd Hoven;493117]

Originally Posted by Monte Howard

It's a BBC rod, but built .500 longer. Not a big deal.[/QUOTE

It's only .010 longer.Instead of 6.625 is 6.635 The standard Chev bearing is the same size as a .050 under Pontiac journal. Easy to get bearings, that's the big advantage. The BBC rod is 50 grams heavier as well.
No great injustice here so relax.

Todd, pretty sure he meant it is 0.500" longer than the stock big block Chevy rod, which is 6.135" long.

The FE Ford was also allowed to use an aftermarket big block Chevy connecting rod before the aftermarket made rods specifically for them.



On the original subject, these days most of us try to get our piston company representative together with our ring company representative, and make sure the ring grooves and rings are well matched. I've found that my friends at JE and CP have no problems talking to Keith at Total Seal, and making my pistons match my rings really well. I do not do much to my rings or ring grooves when I get my parts.

[Mike Pearson]

Alan
Who do you talk to at JE. I need to get 2 pistons to replace 2 that were damaged

Thanks,

[Bob Mulry]

Originally Posted by Rich Biebel

The BonAmi trick was a Pontiac approved fix attempt for oil burning engines. I recall hearing of it and to this day if I hear the name BonAmi that's exactly what I think of. Add some to your oil to get your rings to seat.

Just a quickee................

It doesn't go in the oil!!!!!!!!!!!!!!!!!!!!!

Remove the spark plugs and put the BonAmi directly into the cylinders and crank her over....Use air to blow out whatever you can from the cylinders.....Start it up....Let it run for a bit....Change oil and filter...See what you got....Sometimes better...Sometimes not...It's just a bandaid..

GM also had TSB's about helping ring seal and oil consumption by using GM Top Engine Cleaner in Gas & Diesels.....Gas it went down the carb and diesels it went in thru the glow plug holes...

Just a crutch...

Bob

[goinbroke2]

We called this "flinting" an engine when we did it to 6v53detroits. They would idle so long they would gum up and when you stepped on it there was a cloud you could see for a mile plus it had no power for a while. Once it got real bad we'd pull the air filter and at a fast idle throw a handful of scouring powder in. Couple rev's and see how much it smoked, maybe do it again.

Worse case scenario, we sent the engine to second line for rebuild.

[Larry Hill]

The NHRA approved rod list for the Pontiac 350, 389, 400,421,428, 455, it looks like all the OEM rods were the same size. 13 rods are listed on the approved list with only two rods as super stock only. Of the remaining 11 rods, nine are listed as the OEM size. Crower makes two, Oliver has three, Eagle has one, Childs and Albert has one, and Carrillo makes two.


It looks to me a lot of venders make a rod for that engine. It ok to grind the crank .049'' under (NHRA allows -.070'') to 2.200'' crank pin size but nobody makes a rod bearing -.049'' under that fits into a 2.375'' housing bore. If I read the rules correctly spacers are not allowed in stock.


So if good bearings are not available just ask NHRA for a new rod, AKA the FE ford rule.

[nolongerracing]

Mopar ask for the same thing for the dragpaks. At least the Pontiac uses a corporate bearing size.

So if good bearings are not available just ask NHRA for a new rod, AKA the FE ford rule.[/QUOTE]