Moz Ray

According to the 1978 GM Chassis & Parts Catalog:

62-67 (283, 327) ................................3864881*
62-67 (327),
68-78 (350) (Exc. H/PER., SP H/PER) ......3916396

*Use with 2.00 inch dia. standard crankshaft pins.

I assume the 3864881 Rods apply to SHP 327s and are correct for my application. It appears the way the applications for the 3916396 Rods are shown, that they apply only to Non-SHP 327s. Is this correct?

The Block has been bored out to accept 4" Dia Pistons. The Crankshaft cleaned up at .010"/.010". Will the 3864881 Rods work with this setup? Thanks.

1965 L79 327 ci/350 hp Hi-Perf with Hydraulic Lifters and A/C

MikeM

'62-'65 283, 327 rods were common

'66 327 rods had the outer radius of the crank journal shoulders on each side of the beam beefed up with additional metal. This may have included 283, don't know.

I wouldn't assume anything from that parts book. 327's used a different size crank pin prior to '68 than the 350 engine. The part number shown in the '78 parts book may/may not be a current number or the original number. They change, just like the weather.

If you have an L-79 engine, it should be 4" standard bore from the factory.

Moz Ray

The Crankshaft is an original with Part# 3838495 (ID# 2680). Before posting, I checked with NCRS.org: Part# 3864881 is correct. The Rods were beefed up sometime after 1966.

MikeM

If NCRS.ORG tells you the 327 rods were changed sometime AFTER 1966, you should ask for your money back. The 327 rods were changed between the '65 and 66 models.

The number you posted sounds like it might have been a '67 Z 28 rod which will fit a 327. Same forging as the '66 327 rod, just different strength.

Moz Ray

Which Rod then is correct for my car (bought nothing yet)? Thanks.

From NCRS.org:

"The small bearing rod went through a number of design changes from '55 to '67, which was the last year that GM built small bearing small blocks. The final version, 3864881, went into production in the late '66 or early '67 model year."

"A little more research reveals that there was another 2.00" journal connecting rod. This rod was GM #3927145. It was manufactured from the same forging as the GM #3864881. However, it was manufactured from selected forgings, it was hardened to a greater Rockwell hardness than the 3864881, it was fully shot-peened, and 100% magnaflux inspected.

Some sources indicate that this rod was used for 1967 Z-28. However, GM sources don't indicate that and I don't think that it was ever used in PRODUCTION for that application. I believe that this rod was released in 1968 as a SERVICE-only piece and, primarily, for use on 1967 Z-28 applications in order to improve durability.

Unfortunately, this rod was discontinued from SERVICE in May, 1985 and I don't think you'll find many NOS examples around. However, it should be possible to use a GM #3864881 rod (no longer available from GM but not that hard to obtain) and "create" from it a rod with nearly the same attributes as the 3927145. I still think that going aftermarket is the best bet, though."

VetteRed1965

The second generation rod is the one you want.It is more beefier.

Moz Ray

Is that Part# 3864881?

DZAUTO

Anyone have a GOOD picture to post of the more desireable, beefirer rod?
Next, does anyone have a SINGLE used 327 rod they will part with? I need just one.

Tom Parsons

MikeM

The part # on the rod you need for your engine, according to the April, '67 parts books is indeed the 3864881. It apparently is the same number as late as 1978 according to your book. In the years since, that number could have changed a half dozen times but I don't have a book later than '78 to confirm that. A current replacement rod may not even resemble the original. I don't know but things change.

Like Tom says, if someone could post a picture, it would make it easy for you as any SBC rod that resembled the picture would work for your engine as long as the journal size was correct.

There is no part number stamped on the rods.

VetteRed1965

I dug out my 327/365HP rods here are the pictures

Heres a few pics of the 2nd generation rods

Loren Smith

There's some posts in the archives about the weakness of the factory rods, at least the earlier ones. How about buying a set of these for a low cost, stronger alternative?:

http://store.summitracing.com/partde...W&autoview=sku

590 grams, press fit

http://store.summitracing.com/partde...W&autoview=sku

535 grams, floating

claf

I asked many of the same questions about a year ago when I was building up a 340 HP solid lifter engine. There were some very helpful posts with pictures of all the alternative (stock) rods. When looking at the various rod pictures it is obvious which ones are the strong ones. I ended up using stock 66 Vet rods in my 62 engine. Not sure how to word a search, but they are in there somewhere. Bob

knight37128

All small journal rods from GM are junk.

They will break and tear your block up (just a matter of time).

Spend a little more money and have a good set of rods.

Oliver, Crower, and Carrilo make small journal rods that are far superior to the GM ones.

CWPASADENA

I have done mid year small block engine restorations for more then 30 years and I have not used stock Hi/Perf GM 327 rods for the last ten years or so. All rods have a finite number of cycles they are good for and with used rods you do not know where they have been or how hard they were RUN. I am now using aftermarket rods with press in pins. They are much better and after you go thru a set of original rods, not that much more money. There are several manufactures of GOOD aftermarket rods. You do not need the ultimate in rods unless you are going to race the car and that is a whole different subject.
What ever you do BE SURE TO BALANCE ALL THE COMPONENTS. I have in stock a set of NOS Hi/Perf GM 327 small journal rods but I will not use them.
Good luck, CWPASADENA

MikeM

I'd agree with CWPASADENA if I was in his situation of rebuilding/guaranteeing engines for others. But I'm not. I do my own work. That is a valid point also about connecting rods having a limited cycle life. I don't know what the limits are. Never seen it published but it wouldn't suprise me if it wasn't beyond imagination. I also agree that it's necessary to re-balance the rotating assembly anytime you sub the original internal parts for aftermarket or even OEM.

From what I have seen, many of the mass quality engine rebuilders like "Jasper" use the '66 later rods in their rebuilds. Those rods are getting pretty hard to find anymore. They use the OEM rods and guarantee the engines.

Back when everybody and their brother had a 327 SHP SB replacement engine in their '55-'57 Chevy (including me), I never heard of anyone having connecting rod trouble. Maybe a few other problems but not broken rods. Never. A lot of those engines saw 7200 rpm on a regular basis.

Now, if you opened a car magazine and started reading about Joe, The Boy Racer and his engine buildup, you'd see that the racers preferred something a little more robust than the stock rod.

When the '67 Z 28 came along, Chevrolet released that same "junk" rod for racing only they shot peened it to remove stress and put a special heat treat on it. These were engines that ran at 8000 rpm most of the time doing road race duty.

I built a '63 L/84 engine a few years ago. Used '66 rods. The big ends were round (reasonably), balanced them and put them in the engine. I don't ever take the engine over 6000. Don't intend to and I'm not the least worried about anything breaking. That's not to say it won't. Even new parts fail. Seasoned parts at least have a history.

I have an L-79 engine I'll probably do this Summer. I'll do the same deal on it. I don't expect any problems, either.

If you're going to thrash the engine on a regular basis or race it, you should consider the high dollar rods. To me, spending $800-$1000 on a set of connecting rods for several thousand miles a year conservative driving is a pure waste of money. There's lots of ways to throw money down a rat hole building an engine and there's lots of ways to avoid it. Just depends on what results you're looking for, how much you know and what kind of guy you pick for your machining work. So, do you want to be Joe, The Boy Racer or do you just like to drive 'em without abusing them.

Moz Ray

Wow! Nice pics. Gotta couple of pics of my own of GM# 3864881. They are the later beefed-up Rods from the 1970s as I understand, and do have the "little hump of metal adjacent to the bolt seats on each side of the rod." Thanks for eveyone's input.








A couple of links here at the Forum:

http://forums.corvetteforum.com/c1-a...ine-parts.html

http://forums.corvetteforum.com/c1-a...ween-327s.html


From the 2nd Link:

"The improved small bearing rod that went into production in '67 is 3864881, and as far as I know they are still available. I would buy a set of these rods or equivalent aftermarket replacements or aftermarket racing rods such as the Crower Sportsman for all earlier 327s, espcially SHP/FI, and as far as I know this rod will also work on 265 and 283 SBs.

The early rods should be okay on a medium performance engine (redline 5500 or less) as long as they pass a magnaflux inspection, but given the price of inspecting a set of rods, a new set of 3864881s or equivalents might be cheaper.

The 881s are identifiable by a little hump of metal adjacent to the bolt seats on each side of the rod. This feature is missing from the earlier rods, and it's clear by visual inspection that the 881s are stronger in this area. It was not unusual for the early rods to crack and break at this point in engines that were run hard.

A magnaflux inspection revealed that the #7 rod on my '63 L-76 was badly cracked in this location when I took it down for a rebuild at 115K miles. I don't think it would have take many more excursions to 6500 revs for it to have broken."

Moshe

ragtopman

....and if I may ask a question seeings that this thread is about rods. Who knows anything about the large journal, small bolt rods that were used in the 67 L-48(Camaro SS)350 engines?? They are a factory 'dimple' rod and hard to get.