1969 L88 camshaft

[J W.]

Does anyone know if any camshaft manufacturer is making an exact replica of the 1969 L88 camshaft GM part# 3928909? Apparently Crane Cams did but they went bankrupt in Feb 2009.

[Michael H.]

Re: 1969 L88 camshaft

I'm not sure who makes the 68-69 L88 cam now but I think you would be looking for a 3925535?? I don't recognize your 3928909 number as an L88 cam.

[J W.]

Re: 1969 L88 camshaft

From what I can gather from past threads, 3928909 was likely used in 1968-69 L88's. 3925535 may have been an over the counter item. I believe the specs are the same (.562/.584). The 3959180 ZL-1 cam may or may not have been used in 1969 L88's after the switch to open chamber heads.

[Michael H.]

Re: 1969 L88 camshaft

From what I can gather from past threads, 3928909 was likely used in 1968-69 L88's.

I don't know if the 909 was ever available in service, if there is such a thing, but I doubt it. I'll see if I have any info on it.
I have a stack of GM cam prints for that era but none that I remember are listed as cam #3928909.

Is it possible that the number we're looking for is 3928991 instead of the 3928909 previously mentioned? I do have some info for a 991 that is shown for 69 (only) L88.

[J W.]

Re: 1969 L88 camshaft

I got the 3928909 from Alan Colvin's Corvette by the Numbers book and have seen it in some previous threads. Since no one is manufacturing an L88 cam as far as I can tell, I may need to have one custom ground if I can get all the specs. I am looking for a .560/.580 lift cam. The ZL-1 cam is available from Comp Cams but has too much lift (.629/.605) and probably was never used on an L88 anyway. Do you have detailed specs on a .560/.580 lift L88 cam?

[Richard F.]

Re: 1969 L88 camshaft

Crane was making that cam. I ordered one from Summit when the word of Crane's demise got out. They had it in stock, and I got it in three days. Maybe they still have some in stock. I'd also try Jeg's if Summit is out.

[Michael H.]

Re: 1969 L88 camshaft

I got the 3928909 from Alan Colvin's Corvette by the Numbers book and have seen it in some previous threads. Since no one is manufacturing an L88 cam as far as I can tell, I may need to have one custom ground if I can get all the specs. I am looking for a .560/.580 lift cam. The ZL-1 cam is available from Comp Cams but has too much lift (.629/.605) and probably was never used on an L88 anyway. Do you have detailed specs on a .560/.580 lift L88 cam?

I just looked at the numbers for both the 3925535 (68 L88) and the 3928911 (69 L88) cams. The specs for both are the same EXCEPT for a slight difference in lift. The 535 cam shows .562"/.584" lift and the 911 shows .560"/.580".
That's a VERY slight difference and it doesn't really make any sense unless the entire profile/ramp speed was changed, without changing the actual duration specs. (different pos/neg accl numbers)

Personally, I wouldn't waste much time trying to find a 911 cam. If it was used for production for the 69 model year, it was probably never released for service.

[Duke W.]

Re: 1969 L88 camshaft

Between my '80 P&A catalog and 2nd edition Chevrolet Power Manual there is no listing for 3928909 or 3928992, but are these the "ID number" - the finished camshaft number, which should have at least the last four digits in the blank or the actual cam/pin assembly number, which is what was sold over the counter?

Any reference to service parts will be for a camshaft assembly consisting of the finished camshaft and indexing pin. The finished camshaft part number/"ID number", and cam/pin assembly part number are often sequential, but can also vary by several hundred.

Any of these big block racing cams should only be used for restoring authentic L-88 or ZL-1 engines. Their extreme overlap is intended for headers and open exhaust and operation from 4500-up. Idle and street manners are absolutely terrible, and one would be lucky to get 10 MPG in the best of circumstances.

Duke

[Michael H.]

Re: 1969 L88 camshaft

Between my '80 P&A catalog and 2nd edition Chevrolet Power Manual there is no listing for 3928909 or 3928992, but are these the "ID number" - ?

Duke

The number comes from a list of GM cams by part number for a complete/finished cam. All of the numbers shown are the same as those shown in the GM parts books, except the 911.

I have a ton of GM info from the late 60's to about early 70's and the 3928911 is mentioned only ONCE in all of the paperwork. I know for sure it was not a part released any later than about early/mid 1968. I seriously doubt the part/number was ever available/shown for service. It's also possible that it never even made to production but I don't know that.

Every piece of info I have from that era shows only the 3925535 for 68 and 69 L88. (possible/likely early 68 used the 67 cam)

[Duke W.]

Re: 1969 L88 camshaft

Duke

The number comes from a list of GM cams by part number for a complete/finished cam.)

That's the catch! The "complete finished" cam is not what was in any over-the-counter parts source. The only way a camshaft could be purchased was as a camshaft-pin assembly, which was NOT the same number on the casting, which WAS the "complete finished camshaft" (less indexing pin).

If anyone has a ...535 "assembly", what is the "ID number", which is the part number of the camshaft drawing - the complete finished camshaft less the indexing pin.

The above is a subtle point that no one seems to grasp.

Duke

[Michael H.]

Re: 1969 L88 camshaft

The above is a subtle point that no one seems to grasp.

Duke

All of the other cams on that same sheet, about 15 of them, all show the original GM part number that's also shown in the original paperwork and the parts books. (and in all of the HD paperwork I have) The 911 is the only one that isn't a common GM part number. Also, the specs on the 911 are different than those shown for the 3925535.

I'm going to do a little more research on this because I find it interesting.

[Michael H.]

Re: 1969 L88 camshaft

If anyone has a ...535 "assembly", what is the "ID number", which is the part number of the camshaft drawing - the complete finished camshaft less the indexing pin.

Duke

Duke

I think your right. I think the 3925535 and 3928911 are the same cam. I just dug out more paperwork and the 3925535 is shown as the "service" part number for 3928911. (upper LH corner of sheet) That doesn't necessarily mean it's different than the production cam though, as you mentioned.
There is/was no such thing as a 3928911 in service.

[Tom M.]

Re: 1969 L88 camshaft

Between my '80 P&A catalog and 2nd edition Chevrolet Power Manual there is no listing for 3928909 or 3928992, but are these the "ID number" - the finished camshaft number, which should have at least the last four digits in the blank or the actual cam/pin assembly number, which is what was sold over the counter?

Any reference to service parts will be for a camshaft assembly consisting of the finished camshaft and indexing pin. The finished camshaft part number/"ID number", and cam/pin assembly part number are often sequential, but can also vary by several hundred.

Any of these big block racing cams should only be used for restoring authentic L-88 or ZL-1 engines. Their extreme overlap is intended for headers and open exhaust and operation from 4500-up. Idle and street manners are absolutely terrible, and one would be lucky to get 10 MPG in the best of circumstances.

Duke

Duke, your right about 8-10 mpg, And the idle is bad, But it's a pure race motor no doubt about it

[Joe L.]

Re: 1969 L88 camshaft

Does anyone know if any camshaft manufacturer is making an exact replica of the 1969 L88 camshaft GM part# 3928909? Apparently Crane Cams did but they went bankrupt in Feb 2009.

J------


Only two camshaft part numbers were ever available in SERVICE for PRODUCTION standard L-88's. The first was GM #3879605. It was used for 1967 and 1968 Corvettes with L-88.

The second was GM #3925535. It was used for 1969 L-88's and it became SERVICE for 67-68 when the 3879605 was discontinued in August, 1968. The GM #3925535 was finally discontinued without supercession in September, 1996.

There was once another camshaft available in SERVICE for L-88's. However, it was not designed for use on PRODUCTION-standard engines. It was GM #3925533 and it was designed for use with gear drive (reverse rotation), but otherwise had the same specs as the 3925535.

The ZL-1 camshaft was GM #3959180. This was a standard rotation camshaft for chain drive. I have no information that any PRODUCTION or SERVICE L-88 used this camshaft. Of course, anyone could have installed this camshaft in an L-88 post-factory.

[Michael H.]

Re: 1969 L88 camshaft

J------


Only two camshaft part numbers were ever available in SERVICE for PRODUCTION standard L-88's. The first was GM #3879605. It was used for 1967 and 1968 Corvettes with L-88.

The second was GM #3925535. It was used for 1969 L-88's

I think the 3879605 was used for 67 and early 68. The 3925535 was then used for the rest of 68 and 69.