194.5 ci rod compared to the 389ci rod
 

Does anyone know if the 194.5 ci 4 cylinder used the same rod as the 389ci ?

Im asking because the 4 cyl doesnt share its journal with another rod like the 8 cyl does. So would having an offset on the rod big end , would it send it off center from the piston pin?

When i rebuilt mine i used Eagle H beams. Theres an offset on the big end. When i installed the rod and piston it put the rod up against the piston boss at the pin. So i had to mill material off the side of the rod to clearance it.

Does the stock rod have this offset?

Can anyone post a couple of pictures of an actual 4 cyl rod showing the big end to show if it has an offset?

Thanks .

1966 Pontiac Chassis Parts Catalog says 1958-62 Pontiac V8 and Tempest 4 use the same rod, 532294. It lists 541000 for '63 V8 engines, but does not include a listing for '63 four cylinder engines.

Charlie, as Bill said, the rods are the same. Did you try & swap the installed direction on the Eagle rods? I know the only thing different with the 4 cyl. is the bearings had a small chamfer put on one side where they would normally be up against the next rod. This chamfer was for clearance on the cranks rod radius.

I dont have any rods that are that old. Do you know if those rods are the same as a 1970 rod? Im trying to figure out if there is an offset on them.

Thanks

Yes, and it helped but i still had to clearance them at the pin. Do you have a rod you could post a pic of? I would like to see one .. You see, im using a big block chevy eagle rod in mine because it has a 2.200 big end. Where the pontiac rod does not come with that size . So im checking if there is an off set on the 4 cyl rod like the rod i have. Im thinking maybe that was why i had the problem..

Thanks

I don't have any stock rods that are out of engines right now. Your issue may be with the BBC rods being used in the Pontiac. The factory 4 banger rods are the exact same rod as used in the Pontiac V8. Are the rods you are using a full floating pin? There is no offset that I know of on the factory rods.

Yes full float. Yeah ill have to check out a stock rod and see. I wish someone here had a picture. lol

Thanks

I have a 4 cylinder torn down and i will take some pictures for you tomorrow.

Thank you !

If you don't find an answer, I'll need to search for the PMD blueprint of '58-'62 rods.

You're welcome! This rod and piston was pulled out of a 61 4 cylinder. Let me know if you need more pictures.

the pad between the nuts seems thicker than a 389 58-62 rod?Tom

Can you take one exactly like this?

Here you go. I hope this helps. one from each side

It helped alot thank you!

Looks like there is an offset on the stock rod..

What do you guys think?

Yes there's an offset, its more noticable in the second picture.

Yes i thought the same thing..

Kind of seems like theres a bigger off set on the eagle rod?

This is a 1965 389 rod. It surely looks different from the stock 4cyl rod posted . At teast i think so. I guess the design change as the years went on?

Here are pictures of a factory 1962 forged rod - pulled from a 389. There is offset which is more evident when looking at the side clearance of the bearing insert which is installed.

The reason you see a big visual difference is that the early rods through 1962 were forged and then the switch to cast in 1963 (except for a few high performance engines, of course). Early forged rods were no stronger than the later cast because they still Rockwell test quite soft, but they do tend to fail less catastrophically (stretch vs. break) so we used to run them before the aftermarket finally started producing a reasonably priced forged alternative.