Big Block Rocker Arm Configuration

[Larry T.]

I am in contact with someone about purchasing a set of rocker arms. The ones I am looking at have the "L" marking and they are supposed to be originals of part #3860308.

The same person has a set that he says are "the Heavy Duty Rocker arms/nuts/balls/studs and top lockers, "F" Marking at the end of the rocker."

Can anyone shed some light on the rockers with "F" markings, I am not familiar with these.


Thanks.

[Clem Z.]

Re: Big Block Rocker Arm Configuration

I am in contact with someone about purchasing a set of rocker arms. The ones I am looking at have the "L" marking and they are supposed to be originals of part #3860308.

The same person has a set that he says are "the Heavy Duty Rocker arms/nuts/balls/studs and top lockers, "F" Marking at the end of the rocker."

Can anyone shed some light on the rockers with "F" markings, I am not familiar with these.


Thanks.

"H" marked are the best from chevy

[Joe L.]

Re: Big Block Rocker Arm Configuration

I am in contact with someone about purchasing a set of rocker arms. The ones I am looking at have the "L" marking and they are supposed to be originals of part #3860308.

The same person has a set that he says are "the Heavy Duty Rocker arms/nuts/balls/studs and top lockers, "F" Marking at the end of the rocker."

Can anyone shed some light on the rockers with "F" markings, I am not familiar with these.


Thanks.

Larry------


The GM #3860308 are good rockers. They were used for 1965-E1969 SHP big blocks, including HD (L-88). They were replaced by the GM #6258611 in November, 1972. The 6258611 were discontinued some time ago, too.

However, as clem mentions, the "H" stamped rockers, aka GM #3959182, are the best. These were originally used on later 1969 L-88, all ZL-1, and 1971 LS-6. These are still available today in a unit which includes the 3959182 rocker arm + rocker ball and nut and known as GM #12368082. A kit of 16 of these is available under GM #12368085 and GM lists for less than 100 bucks. So, why pay likely more than that for a set of the old 3860308?

[Larry T.]

Re: Big Block Rocker Arm Configuration

Thanks Joe. I have the "H" rockers on my car right now. The reason I am looking at the "L" rockers is they just seem hard to come by and were original equipment for my L72 engine.

Do you have any idea what the rockers with an "F" are? I am trying to get a picture and will post if I do.

[Joe L.]

Re: Big Block Rocker Arm Configuration

Thanks Joe. I have the "H" rockers on my car right now. The reason I am looking at the "L" rockers is they just seem hard to come by and were original equipment for my L72 engine.

Do you have any idea what the rockers with an "F" are? I am trying to get a picture and will post if I do.

Larry------


I don't ever recall seeing any "F" stamped rockers. I've seen "Z", "M", "X". It's possible that the "F" were the non-SHP rockers, GM #3860305.

[Ronald L.]

Re: Big Block Rocker Arm Configuration

I asked this in a similar way a while back...

Were the M rockers used originally on the 66 427? 390HP???

[Clem Z.]

Re: Big Block Rocker Arm Configuration

why would anyone want inferior rockers on their engines when the 182 (H) are still available ???

[Joe L.]

Re: Big Block Rocker Arm Configuration

I asked this in a similar way a while back...

Were the M rockers used originally on the 66 427? 390HP???

Ron-----


I don't think so but I would not rule it out. 1966 L-36 used the GM #3860305 rocker arms. These are the arms that I do not know what character was stamped on them.

I do know that the "M" stamp was used on the GM #6258611 rocker arms. These were released about 1972 and became SERVICE for 1966 L-36 but were never originally used on the 1966 L-36 application. However, it is possible that there were other predecessor rocker arms that used the "M" stamp. I doubt it but it's possible.

[Ronald L.]

Re: Big Block Rocker Arm Configuration

Thanks Joe, I'll go with they were replaced in 1975-6, they look new with very little break-in wear. If I recall, the original 427's for this time period did not have the slotted ball. These M's do....

[Larry T.]

Re: Big Block Rocker Arm Configuration

Here is a picture of the rocker I was told had an "F". I am not sure I would call this an F. Does anyone recognize this part?

Larry

[Bill M.]

Re: Big Block Rocker Arm Configuration

1966 L-36 used the GM #3860305 rocker arms. These are the arms that I do not know what character was stamped on them.

I have a rocker arm from a '67 L78 that has no letter.

[Joe R.]

Re: Big Block Rocker Arm Configuration

I have a rocker arm from a '67 L78 that has no letter.

Bill,

Did you mean to say 65 L78?

Joe

[Bill M.]

Re: Big Block Rocker Arm Configuration

Bill,

Did you mean to say 65 L78?

Joe

Joe:

My post was very unclear. What I should have said was that I have an early rocker arm with no letter on it...

My '65 has an L78 out of a '67 Camaro. The heads are '68 rectangular port, the intake manifold an L72(?). It's a mutt.

Bill

[Wayne M.]

Re: Big Block Rocker Arm Configuration

FWIW, I have a set of rocker arms, springs valves, guides out off of oval port '68 heads # 3917215, dated A 68. No stampings.

Looking at the service catalogs (P&A30 series), the first time a stamped letter is referred to is in the Oct 1 '66 (1st issue 1967), with an "X" indicated for the hi-perf rockers # 3860308. Nothing for the lo-horse versions # 3860305.

Then My July '69 Rev. P&A30 says Z or L stampings for the ..308. Same thing in a Rev 10-1-69 catalog. And same again in Rev 1-1-70 catalog.

[Ronald L.]

Re: Big Block Rocker Arm Configuration

I would appreciate the source you have to get this GM set as indicated for about $100...