CRG Discussion Forum
Camaro Research Group Discussion => Originality => Topic started by: 69er on March 23, 2007, 07:47:17 PM
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I'm not sure if I did this right.
did the 69 z28 come with 'O' rods that were pressed pins?
I'm getting to ready to buy some and the seller showed me the manual
that gives the pressed specifications. I'm not sure if he is right or not.
69er
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footnote pic
69er
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these pics from a chevrolet manual indicates that the 302 for 1969
came with interference fit pins for the connecting rod. I'm
confused.
69er
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Nope; 69 302 had full-floating pins with 'pink' rods.
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The "clearance" note is in the wrong column - typo in the manual; many of the 302 specs in the Service Manual are either wrong or not shown at all.
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I talked to the machine shop owner from tennesse who has the set of pink rods
for sale about the misprint in the chevrolet manual. He had no comments about the
misprint. He seems to recall that in 1969 the z28 could be ordered with the optional
offroad camshaft. And with this option came the full floating pins and stronger valve
springs. He sent me some additional pics of the large journal part of a pink rod.
He explains that in the picture you will see a relief notch in the rod cap next to
the bearing tang slot. He said that this was consistent with pink rods used in 302's,
he also says that he has never seen this notch in other small block connecting rods.
The rods he is selling have a pressed fit pin and have this notch where the bearing
tang lock is located, and have the cast letter 'O' on the bottom of the rod cap.
I have attached the pic for your review.
69er
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The rods in the 69 302 were full floating rods. Means the wrist pin floats in the rod and the piston. Floaters had the clips on the ends of the wrist pin to hold it in. The other rods had the wrist pins pressed in. Also I don't think you could order the off road camshaft from the factory. I believe it was over the counter.
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All 69 Z28s had floating rods. We have rebuilt more than anyone in our years of experience. There is also traces of bronze babbot coating in the small end of the rod when you find originals, and paint on the side beams of the rods.
Jerry
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And the factory only installed the "346 camshaft,
JM
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Jerry -
If you were going to rebuild a 1968 302 engine, would you go with floating or pressed fit pins?
Paul
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pressed,
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Why? Originality? Performance? Other...?
Paul
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I personally believe they are safer. No clips can come loose to score your wall up. I think the floating pins were more designed for racing to be able to take apart easier when you are changing piston/rod combinations more frequently. But that is just my opinion.
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Is it true that only pink rods had the notches located in the rod cap?
Maybe someone can look at a set of pink rods that have'nt been installed
yet to see if they have the notch, or just an ordinary set of connecting
rods to see if they have the notch.
Jerry would pressed pins be advised on a 1969 z28 302 rebuild?
69er
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I would do pressed, it's one less thing to worry about. Those sprial locks have broken before and when that happens, you have a wrist pin in the cylinder wall. Not a good thing. Like Sam said, it's a safety thing.
There will be no difference in performance. We have several Z28s in the field that can drive to the track and run in the 13 second zone all day with street tires and closed exhaust. Open headers and tires, look out!
Jerry
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Jerry, so do the 69 z 302 rebuilds you do get converted to pressed pins
from floating pins?
And what do you think about that notch in the rod cap?
Any truth to it?
Maybe you can look at a set of connecting rods.
69er
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Jerry, so do the 69 z 302 rebuilds you do get converted to pressed pins
from floating pins?
And what do you think about that notch in the rod cap?
Any truth to it?
Maybe you can look at a set of connecting rods.
69er
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Don't really even need the pink rods either. I believe it takes some machine shop work to make those pink rods compatible for pressed in pins. Maybe Jerry can help here.
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My "68" L30 shortblock is sitting in my garage soon to go to Jerry's, so I took a look and pulled one of the rod caps off. What I found was all of the rods have the "0" cast on the bottom of the rod cap, the rod that I pulled the cap off has the notch in the cap and the notch in the rod and it looks like the number 207 is cast on the rod by the rod cap. Hope this helps, RonM.
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Does your L30 have small or large diameter journals?
69er
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It has the large diameter journals, RonM.
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I have not idea about what notch you are talking about?? Only thing on the end cap is a machined boss area that is used to machine or grind down when you balance the engine.
And basically, all of the large journal rods are the same. Once you shot peen, mag and install good ARP rod bolts, you have a pink rod. One of my race engines does not have pink rods and it has several hundred runs on it.
JM
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Jerry I tried to draw an arrow to show where this notch is. The gentleman
from tennesse has indicated that pink rods from the 302's were unique in
that the rod cap had this notch (relief) opposite the bearing lock groove.
The arrow is pointing at the notch (relief) in the rod cap.
Maybe you can look at some of your connecting rods at your shop and
see if his comments are correct or not concerning the notch.
69er
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That notch is intermittent on all connecting rods. Even some of the small journal rods have it. Makes no difference to the functionality of the rod at all.
JM
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Just get a set of the new GM powered metal rods. As strong or stronger than any of the old style rods and they are new.
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Kurt -
What is the GM part number on these rods? Thanks in advance.
Paul
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Kurt,
Just a special note on the powdered rods. They are not all they're cracked up to be. Not good at all for racing applications or aggressive street use. There have been many rod failures in the Stock Eliminator ranks with the late model Firebirds and Camaros that run these rods. Many have switched to the older style rods having them shot peened with good rod bolts. These engines are not even twisted that hard, about 6000rpm. Ask any professional engine builder, they will tell you the same thing. NG. Better off getting a set of 3/8" rods and building them, and it will be much cheaper.
Jerry
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Thanks Jerry!
Paul
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Thanks! Hang out with the engine crowd and you hear what works. ;)
I hadn't heard any negative on them and I know some PM rods can be very tough, obviously not true for these rods!
You also stated something else I very much agree with. Take a good set of rods and prep them properly and run them.
Seems like a good alternative to spending the big $$ on NOS pink rods. :)
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I was on Camaro travel today and had a chance to make a few phone calls while at the airport.
In so many words, the PM rods are garbage. This is what I was told by two very well respected engine builders. Bub Whitiker from Burtonsville machine was one of them. Bub builds some of the best stocker and NHRA engines in the country, and is very well respected by many throughout the country. He installed the PM rods in one engine and the rod exited the oil pan and destroyed the engine. He'll never use them again. This has happened to many others running the late model LT1s at the track.
My other machine shop that I use for my restoration engine machine work throws them in the dumpster. I am not making this up. This is exactly what he told me. That's all they are good for according to him.
Bottom one is this, buy a set of 3/8" rods that are shot peened, magged with ARP rod bolts and you're ready to go. Costs for a set of rods like this runs $250-300. You can't beat that. I can even get them done if you wish. That's what we do here at CHP.
Also think about this, NHRA's Stock Eliminator class is one of the best test beds for much of what we do today in the hobby. For years, I've had stock 3/8' rods in my 302 race car. The onboard Racepac data logger computer does not lie about rpms. Two of my engines are abused to as high as 8600 rpm. No other engines take this asbuse unless it's a pro stock or modified eliminator engine. They rev highrer but remember they have light-weight aluminum rods.
Hope I've cleared this up.
Jerry
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For years, I've had stock 3/8' rods in my 302 race car. The onboard Racepac data logger computer does not lie about rpms. Two of my engines are abused to as high as 8600 rpm. No other engines take this asbuse unless it's a pro stock or modified eliminator engine. They rev highrer but remember they have light-weight aluminum rods.
Jerry
8600 RPM! Nothing beats a 302! :) ;) :D ;D
Paul
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A few years ago I was lucky enough to observe one of Jerry's engines on the Dyno. It was amazing to see the horsepower (458) and the high RPM's (8100) the 302 was putting out. I think they did over 18 runs that day I was there. I have the data sheet of one of the pulls. I only wish I had brought my video camera. >:(
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Bring that video camaro to a (NHRA) DIV-1 points meet. Then you will see what the 02 is noted for!! ;D :)
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Jerry,
I'm agreeing with you.
I wasn't clear enough. I've heard of some PM rods from other OEM's that reputedly hold together. Obviously that isn't true of the Chevy PM rods. :(
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I dont want to continue to stir the pot regarding wheter or not 1969 z28's
came with full floating piston pins or not. But, I have a comment then a question
for Jerry or someone else with connecting rod knowledge.
The first comment I have is that this morning I met with the owner of Watson Racing
and Engineering in Concord California. He has been in the racing business for over 30
years. His comment regarding whether the 1969 z28 came with full floating rods were
interesting. According to Mike Watson, he seems to recall that some 69 z28's came with
full floating pins that were shipped to certain dealerships and ordered differently. Other
69 z28 came with the pressed pin version. In his own experience having ordered a brand
new1969 z28 along with his friend and upon tearing down the engine one had full floating pins
and the other did not. It was his opinion that GM quality control of components was very loose.
When 302 engines were being built to meet demand and the rods available were pressed pins,
they would use those rods, production would not stop. According to Watson Chevrolet may
have said one thing, printed it on paper, but in production it may have been something else. He
provide me with an example, how two people that he knew (racers) both had bought new 1969 z28's.
One was very fast and the other was okay, he did'nt understand why that would be the case.
So, they tore apart both engines and sent both camshafts out to be measured for lift, duration and
overlap. What they found was that one camshaft had a different overlap than the other by about
2 degrees. His point was that Chevrolet did not have tight quality control over production. Machining
quality was very poor, hence a major cause of many 302's blowing up. He also commented that
Chysler was the worse for quality control and not doing what they said on paper. I dont know if
this makes sense, maybe some one can comment on that. In my own research I'm just not sure what
to believe anymore.
Watson Racing and Engineering also informed me that if he was restoring someones 1969 z28
instead of spending alot of money on checking the rods and balancing. He instead would purchase
a brand new set of Manley connecting rods, keep the old rods in a box. His feelings were that
using Manley connecting rods provided the stability and quality needed.
So my question is if your rebuilding your 30 year old 302. Is it smarter to use a brand new connecting
rods like the Manley and keep you original rods in a box. I would like to know what Jerry does.
If the rods you get in someone's engine are pressed pins do you have them floated? If they are the floating type
due you reuse them or do you use another quality supplier of connecting rods like the Manley?
asm69
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It is common knowedge and a fact that the 302 was built with full floating piston pins. :)
The 30-30 has such long seat to seat duration that 2 degrees of overlap is not much I would think.
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Everyone is entitled to their opinion, and I always try to share my experiences and knowledge with anyone who asks.
Would I use the Manley rods in my stock 302 engine........no, absolutely not. The Chev 3/8 rods are excellent if they are shot peened and magged. My NHRA Stock Eliminator car is a test bed for these engines and in the 14 years that I've been running this 302 combination............up to 8600rpm, I have never broken a connecting rod in any of my engines. Now, does an enthusiast who is restoring his car need to install Manley rods..........no. That's a waste of money. Save this $$ for something that you really need in your resto project. You can buy a set of good GM 3/8" rods ready to go for about $250. The Manleys are much more $$.
Don't believe me, talk to Bub Whitiker of Burtonsville Machine or Gary McGlasson of McGlasson Racing engines. These are two of the best engine builders in the country with impeccable reputations for building race engines and stock eliminator engines. They will tell you the same thing about GM connecting rods and the applications.
Read the Chevrolet AMA specs and NHRA stock eliminator manuals. All of the 1969 302s got the full floating pins. We have rebuilt more 302s than just about all of the shops in the country. We have never found pressed pins in a 1969 302 engine. Over the past four or five years, we've rebuilt and restored at least 70-80 302s. I have four 1969 302 engines in my shop right now! All have full floating pins.
I have no reason to make any of this up. I am just stating what is published and written............and what our experiences have been.
Jerry
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I should also point out that there are no noticable performance gains in ET at the strip or on the street with full floating pistons. Both work and run well and we build them both ways.
Regarding what was said about some 302s running better than others. That was the case with many performance cars built during the late 1960s. This depended on engine break in and engine tolerancing more related to deck heights and piston to cylinder wall clearance, core shift, etc. Maybe John Z can shed more light on this.
Many seem to think that becuse these cars were built during the late 1960s, it was the "Stone Age" with cavemen working on the cars........and anything went on the assembly line. Not the case. There were strict qualtiy control procedures that had to be followed. I know this from interviewing many of the Norwood workers who were transferred to the Baltimore plant in the late 1980s. This was at the time when I began writing the first 1967-68 Z28 Camaro fact book.
Having lived the era as teenager during that time, my perspective is that the cars were for the most part, very nice and consistant. And to think that GM gave a five year 50,000 mile warrantee makes a statement about how confident GM was about its product.
Jerry
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When you say 3\8 inch is that the bolt size used?
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Yes, 3/8" bolt size, started in '68. Before that 11/32" was the rod bolt size and there were plenty of connecting rod failures with the smaller rods.
Jerry
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Here's a photo that compares the "early" and "late" small-block rods - note the "bump" adjacent to the rod bolt seats on the "late" rods on the right; the "early" rods without the added material at the bolt seats are a time-bomb in a performance engine. NOTE: These are small-journal 327 rods with 11/32" bolts, not large-journal 350/302 rods.
Note: These engines weren't built by neanderthals with bastard files and sledgehammers; considering the technology available at the time, they were amazingly consistent, even though each engine plant built 5500 engines of 35-40 different suffix configurations per day, every day. Some were a little better than others as a result of more favorable (and random) tolerance stacks, but nowhere near what some people would have you believe. I was there, and the people spouting "internet legends" were not.
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Thanks for the info. That clears up some questions I had. I sometimes hate to ask fearing they are stupid questions,but if they are not asked people are unsure.
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Thank you Jerry and John. I believe your comments are accurate and correct.
So, Jerry when restoring a 1969 z28 and using the GM 3/8 rods, would you
float them by using a bushing or float them by honing the correct clearances
in the connecting rod?
Thanks again for your comments. I'm just trying to build the engine correct
to the era and have it be reliable. (non-racing, street use, Occasional burn outs).
asm69
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So if they are 3/8 bnolts does that mean they have the extra bump by the rod bolt seat as john Z showed us?
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John,
You could not have made a better statement about GM's engine program. I get these questions everyday at the shop with many who own the cars saying, "well this car has this item on it and I know it's original to the car because that's the way it was the '60s." Most of my customer base didn't even have a driver's license when the cars were new. Most are in their late 30s to mid 40s, which is good for the hobby because it means these cars made an impression on younger generations.
Regarding the connecting rods, you can build your engine in many ways. Bush the rods or use originals with the factory babbot material and fit the pins to the rods. In many cases, we go back together with a pressed pin. Why, because many of the 69 302s had sprial lock failure with pins coming out and digging into the cylinder walls. Not a good thing........and it's one less thing to worry about when you're building an engine. It's a little added insurance building them with pressed pins.
Jerry
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The bumped rods that John showed us here are the early 11/32 rods. All of the 3/8 rods have the beefed up material in that area.
I am writing another article for CRG called "The Z28 Camaro, A Racer's Perspective." A lot of the artilce will go into great depth on the engine assemblies, what was good and what was not good. Most if it is written in rough draft now and I will finish this project as soon as I can get the revised 4th edition 1969 Camaro book text to the printer.
Jerry
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Thanks Jerry looking forward to the article.I have a set of 11/16 with the O on the rod cap,is that normal?
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11/16 or do you mean 11/32?? These are to small journal rods........last used in 1967.
Jerry
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I mean 11/32
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I would say that's normal. The smaller rods are not that great though, even if you have the versions with the beefed up areas near the rod bolt. The "O" stamping on the cap is not consistant.
For a resto piece the 11/32 rods are okay. But, if you're building a '67 302 that you will wind it up now and then, I would recommend the Manley rods.
Jerry
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Pressed pins are fine but if there not fit properly they too can wander out.
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Anyone have the part # for the GM rods Jerry recommends?
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Pressed pins are fine but if there not fit properly they too can wander out.
They'd have to be done by Bubba - I've been building engines for 40 years, and during 38 years in Manufacturing with GM and Chrysler, I've never seen one single warranty claim where a pressed pin moved and gouged a cylinder wall.
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They'd have to be done by Bubba - I've been building engines for 40 years, and during 38 years in Manufacturing with GM and Chrysler, I've never seen one single warranty claim where a pressed pin moved and gouged a cylinder wall.
[/quote] I have.I've used C-clips since the 70s with zero failures, As long as they are positioned correctly and not over stressed during install.