Inliners International Forums General Discussion Hi Performance Pontiac OHC rods vs Chevy 250

I edited this post and title. Did it to help anyone that needs the info in the future and to make it easier to find.

Check out the beefy rod on the left in most picture. It is from a 230, 250 Pontiac inline OHC engine. See how beefy it is in most areas compared to a stock 153/ 250 rod?
It is marked with GM on one side. Does anyone have anymore of these?

None of mine look like that.

They look like a good alternative for the 230/ 250 chevy engines.

I pulled a set from a later '68 I think OHC Pontiac that had GM on them just like that. I remember they looked beefier than regular Chevy rods but not sure if it's the same as your photo.

Ditto. Looks like Cammer rods to me also. Pontiac had the right idea!

Sprintbird and Stroker6,
I think you are on the right track. Got any pics?

I have been told a long long time ago to use Pontiac OHC 6 4 bbl engine rods, because they were supposed to be stronger.
Never got a chance to look @ them.

Check the Pontiac 6 forum.

MBHD

Once again I am frustrated in the lack of information available on connecting rod specs. There is plenty of detailed info for pistons, cranks, cams, lifters, rockers, valves, springs, etc. But rods? Some stuff for Vs but we should be able to find all specs for every rod ever used in a production engine. Thank God for oral tradition! My books don't help.

I found them:

http://i965.photobucket.com/albums/ae131/strokersix/DSCN37001.jpg

Stroker, I'm having difficulty reading your post.

The link worked fine, but I can't see if there is anything below it (there is a scroll bar on the bottom and right, but neither will move for me ).

What did you find them for?

They have the same dimensional sizes.
Small end pin .927
Big end made for a 2" crank pin.

Nex, I found them for Tom since he asked for a photo.

Beware not all OHC rods are beefy like these. I have a set of early ('65?) ones that are light and these later ('68?) ones that are heavy. I don't know if it's a production date difference or if it's 1 barrel versus 4 barrel or 230 versus 250. Maybe some Poncho guys will jump in with the details.

Did some more checking on these rods. They may be beefy but they are made out of inferior material compared to the Chevy's.
Took a small ball peen and struck each one. The pontiac rod has a dull thud. The Chevy rod has a tool steel ring to it.

I might be the new guy, but I find that funny, they are both made of drop forged steel (per the service manuals). Plus remember the Pontiac engines from the factory made peak power a good 1,000rpm higher than the chevy (and even the base engine made more HP). They used beefier forged rods.

Here are a few pictures of the rods out of my '69 Pontiac OHC

Notice the camshaft oiler groove on the OHC rods? Pontiac must have left that feature in for some reason. Or Chevy designed the rods. Probably left there so the rods can be used in other applications with cam in block. Maybe marine engines?

I've heard not all Pontiac's had that oil groove. I've read it was phased out by '69, but my block and head are both '69 date coded, so... I can only correlate the rods to those dates.

My best engineering guestimate is that they are there to spray the accessory drive internals. The distributor drive gear and fuel pump eccentric.

I worked on a Cosworth Vega in the '70s and they had what was referred to as a small journal, 6 cylinder version of a Z28 (or pink)rod. They were subjected to peening and magged. What I remember is that they looked a lot like the ones you are showing, but 35 years does cloud the memory a bit. We turned that motor near 8grand repeatedly. The aftermarked sold the rods under the same part #s as with the Chevy11. Built and ran a few Chevy11s in out 2.5litre boat but always went to the after market with them and remember the notes referring to the Cosworth.

Good to see you found your way over here SilverBuick! I saw this thread and immediately thought of you and here you are already...

Hi Pete, I've browsed this forum for information for quite a while now. This thread is why I finally signed up, took a day though for the admin approval though.