Pat,

Great technical breakdown on the holley single vs Q-Jet.

quote:

The part number H260 is a Crane Cam # for a "high lift" application such as the L34 would have called for at that time period. I don't know if Crane Cam was a supplier to GM for camshafts like TRW was for the pistons? If so, that would establish all the internals as stock L34 application for this blocks build date

http://cranecams.com/pdf/Page318-329.pdf

On page 2 of the PDF, page 320 of the catalogue Crane Cams lists part number 3883986 as "Replacement for factory 350 HP 396 cu. in. camshaft."

This is the only cam in this section of the catalogue that has a GM part number. To me this looks like Crane Cams was producing the L-34 cam for GM in the 60's.

Funny as I looked through these sheets. They all denote hydrolic lifters. Did'nt Some hi-po motors get the solid lifter?

The L-78 had a mechanical lifter, but the L-34 had a hydraulic lifter.

Really coming along here guys.. Thanks for all the hard work. I personally have been busy with other stuff but am pumped this is moving along!

quote:

Funny as I looked through these sheets. They all denote hydrolic lifters. Did'nt Some hi-po motors get the solid lifter?

As I read this I couldn't stop wondering what cam that the 4P Big Block cars had. Do they have the L-34 cam with hydraulic lifters? Do they have the L-78 cam with solid lifters?

Andy V.
Do you know what cam and lifter combination your cars has? Does your car also have the same L-34 cam that my car has?
Doug

Doug,My car was not part of the engineering dept rebuild group of cars. It is,(I believe),a dealer display car like the Matt Murphy car. The original engine (and trans) had been sold before I got it back in 1979. Previous owner said that it had "the big one with the factory alum intake and holley carb". That would be a solid lifter engine.

A L78 camshaft that I have has traces of a purple paint stripe behind the fuel pump lobe.The only markings on the end is a "4"and a "1".It has GM cast in it and near the center is cast"4366". It is my understanding that the 325 hp cam would have cast 4365 at this location. I don't have any notes collected on the L34 cam,but if it was made by Crane it may or may not have the last four digits of the GM casting number on it.You might check to see.

looking at the camshaft chart that is posted,the pt no 3904362 is the same that I have in my notes as going with the 4366 cast marked 375-396 cam.

These two auctions might help shed light who knows Whadda you guys think

cam #1

cam #2

The L-34 cam in an early version because it has the wide oil groove in the last bearing journal.

The L-35 cam looks like a later version.

Tom, If you could get with Tony and help finish
One Last Race and then at the end of the book put all of this valuable Information you have gathered in the last 5 years. You would make a small fortune. Da Weave could put new tires on that bus and go around the country picking up all of us for that BIG PARTY at Carlisle!
Imagine... All of this information at your fingertips.
Just kidding Tom, Like you don't have other things to do

My dreams match yours.. the wallet, the time and the fact that we learn so much, so fast, are prohibiting us right now...I fear a book would be in need of revision before it hit the shelves

But not forever

Thank you Doug.. very good

I would think that that camshaft was replaced at one time and the owner decided to put in Crane's factory replacement cam.

Its not unusual for a an older engine like that to have worn out a cam lobe/lifter which required its replacement and Crane was very popular back in the day. Looks like an L-34 to me...

I don't think that the cam was replaced. With the oil groove in the end of the cam it was probably original to the engine. After 1966 there would be no reason for Crane to add that step to their machining proccess. It would only cost them more money to produce the cam. GM engineering knew about the design change and that is why they put it in their power book so that people that ended up with the cam as NOS would know how to use it by changing the cam bearing.

The groove is required for the 65-66 blocks due to the drilling of the oil gallies being different. (961,962 blocks for the 396) You can use the grooved cam in the later blocks by doing the bearing modification. You cannot use non-grooved cams in the earlier blocks. Andy V

Actually, the drilling of the oil galleries that feed the lifters didn't change (the two feed holes at 11 o'clock and 1 o'clock at the top of the bearing bore in the block).

The '65-'66 engines used the cam with the groove in the rear journal and the 3-hole bearing with the groove on its I.D. Oil for the lifters traveled in the passage created between the groove in the cam journal and the groove in the I.D. of the bearing to the two exit holes in the top of the bearing which aligned with the two oil feed holes in the block to the lifter galleries.

For '67, the groove was removed from the cam journal, a machined groove was added to the I.D. of the cam bearing bore in the block, the groove in the I.D. of the bearing was removed, and the two exit holes were removed from the top of the bearing shell, leaving just the feed hole at the bottom. Oil for the lifters traveled from the feed hole around the outside of the bearing shell in the groove in the bore in the block to the two exit holes in the block that fed the lifter galleries.

Hey! now I get it! Thanks John I was fuzzy about what they did after.. but being behind the bearing makes sense

Make that...X2 !! Thanks,John Z,for that excellent explaination on the oiling upgrade! Was that the only change made to the block to go from the 961 style to the 406?

Andy V

Yes, that was the only significant change (essentially a re-run of the mistake they made in the '55-'56 265 oiling system that they corrected in '57 with the 283). Photos below of the '65-'66 grooved cam journal, the '65-'66 grooved-I.D. 3-hole cam bearing, and the '67-up no-groove 1-hole cam bearing.







Here's the 3-hole bearing:

This message has been edited. Last edited by: <JohnZ>,

John

Does that mean that I need to have a cam with a groove and a bearing with the 3 holes for a 961 block?

Can I use a cam without the groove in a 961 block if I use the bearing with just one hole?

Is the note in the GM book about plugging and redrilling the bearing only supposed to apply to a cam with the groove when it is used in a block other than the 961, 962 block?

Doug

Another little piece of the puzzle from an article back in 93 that Doug unearthed. Its all part of the old and not so accurate info of the past but this whole EQ line matches Dougs car correctly AND it certainly wasn't pulled out of thin air.. Every bit inches us closer to the truth

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