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Old 05-29-2012, 08:13 AM
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1965 327 rocker arms

Hey all, I have a question about the use of self-guiding rocker arms on a set of 462 camel hump heads.
Can I use the new style centerbolt style aluminum rockers with these old heads?
The ones that I would like are these http://www.jegs.com/i/JEGS-Performan...rentProductId=
The reason I'm asking is the 462 head doesn't have slots for the rocker arms so a guide plate really would be wasted machine work. If I can use these it would save another tear down.

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Old 05-29-2012, 08:18 AM
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why won't standard rockers work?
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Old 05-29-2012, 08:23 AM
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Quote:
Originally Posted by ap72
why won't standard rockers work?
I have increased the valve spring pressures to 335# open at .540 lift. I'm not comfortable running with stamped steel considering I LOVE to buzz this little motor. So, looking for a set of rollers. The 462 head has push rod holes so I thought I could also save the guide plate deal too.
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Old 05-29-2012, 08:36 AM
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Just a brief clarification. I have some Crower aluminum rockers. When installed, the bottom of the rocker arm comes in contact with the stand where the stud screws into. I was hoping to find a set of rockers with a lower profile at the bottom so clear that casting. Going to a +.100 pushrod forces my roller over the tip of the valve at max lift.
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Old 05-29-2012, 05:03 PM
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You will find that most of the aftermkt aluminum rockers hit on GM stock press stud heads.. If the heads are cut and tapped for screw in studs. The stud boss must be shortened. (about .240" or so, depending on guide plate) If not, the rocker will bottom out on the stud also.
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Old 05-30-2012, 02:36 AM
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Thanks to all. Looks like I won't be changing anything out just yet.
Thanks again.
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Old 05-30-2012, 07:21 AM
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Quote:
Originally Posted by 65_SS
Hey all, I have a question about the use of self-guiding rocker arms on a set of 462 camel hump heads.
Can I use the new style centerbolt style aluminum rockers with these old heads?
The ones that I would like are these http://www.jegs.com/i/JEGS-Performan...rentProductId=
The reason I'm asking is the 462 head doesn't have slots for the rocker arms so a guide plate really would be wasted machine work. If I can use these it would save another tear down.
The best plan is to do as BOBCRMAN suggests: mill the stud bosses and use threaded studs w/guideplates.

You cannot use two types of alignment at the same time. There are three types of push rod alignment used on the SBC:

1. Cylinder head guide slot, integral to the casting
2. Guide plates
3. Self aligning (SA) rocker arms

Be sure that if the heads were originally designed for non-SA rocker arms, and you've installed guide plates and screw in studs, that you enlarge the push rod guide slot in the head so it no longer tries to do the alignment job. This can be done by hand filing or w/a 1/2" drill bit.

Vortec and other production heads that use SA rockers do not have a problem in this area- the alignment slot is already large enough to allow using guide plates w/no other modification needed. Aftermarket heads that come w/guide plates are also already clearanced so there is no problem w/the guide slot in the head.

So remember: Heads can use guide slots, OR guide plates, OR self aligning rockers, but only ONE of the three at any given time.

Question: Why are your heads lacking the factory pushrod guide slots, if they aren't prepped for guide plates? Usually that's the reason (installing guide plates) that anyone would enlarge the factory guide slots, being as how most times SA rocker arms aren't used on these heads (although there's no real reason they couldn't be).

Last edited by cobalt327; 05-30-2012 at 07:26 AM. Reason: Add question
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Old 05-30-2012, 07:37 AM
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Question: Why are your heads lacking the factory pushrod guide slots, if they aren't prepped for guide plates? Usually that's the reason (installing guide plates) that anyone would enlarge the factory guide slots, being as how most times SA rocker arms aren't used on these heads (although there's no real reason they couldn't be).[/QUOTE]
The 1965 head, 3880462x has a hole in which the pushrods pass through, not a slot. I don't think there is a need for either guide plates or "captured" rockers. If the heads were not already in the car, machining would not be an issue. I was mis-lead by an "Engine builder" who told me that I didn't need to machine anything to use these rockers. Well, he was wrong and now I'm looking into something that will cut friction on the valve stem down until I feel like taking the motor out again.
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Old 05-30-2012, 07:54 AM
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Cracks?

I've seen a few cracks in camel bump heads between the 2 center exhaust valves. I am not a Chevy expert , just have a 350 In one of My T buckets, and 3 more in the shop for projects because they are an easy install. The machinest reworked the T engine with screw in studs and i installed roller tip rockers, new cam an a 2 4 manifold. . I have read a lot of recomendations to forget about doing machine work on camel bump heads, they say find later better heads to upgrade.
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Old 05-30-2012, 07:56 AM
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Quote:
Originally Posted by timothale
I've seen a few cracks in camel bump heads between the 2 center exhaust valves. I am not a Chevy expert , just have a 350 In one of My T buckets, and 3 more in the shop for projects because they are an easy install. those engindes will just get installed stock. I have read a lot of recomendations to forget about doing machine work on camel bump heads, they say find later better heads to upgrade.
The reason I'm keeping it is that the 1965 chevy II SS is completely numbers matching. This turns a $10K vehicle into a $40K vehicle. Take off the heads and flush down a pile of money. Concours car with all original equipment.
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Old 05-30-2012, 07:58 AM
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Quote:
Originally Posted by 65_SS
The 1965 head, 3880462x has a hole in which the pushrods pass through, not a slot. I don't think there is a need for either guide plates or "captured" rockers. If the heads were not already in the car, machining would not be an issue. I was mis-lead by an "Engine builder" who told me that I didn't need to machine anything to use these rockers. Well, he was wrong and now I'm looking into something that will cut friction on the valve stem down until I feel like taking the motor out again.
If the slots aren't close to measuring 7/16" x 11/32", someone has taken a drill to them, either in anticipation to using guide plates, or to use SA rockers. Or they didn't know to use a Lewis tool or hand grind the slot for use w/1.6 ratio rocker arms.

In any event, there needs to be one of the three methods (above) used to guide the pushrods.
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Old 05-30-2012, 08:05 AM
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Quote:
Originally Posted by cobalt327
If the slots aren't close to measuring 7/16" x 11/32", someone has taken a drill to them, either in anticipation to using guide plates, or to use SA rockers. Or they didn't know to use a Lewis tool or hand grind the slot for use w/1.6 ratio rocker arms.

In any event, there needs to be one of the three methods (above) used to guide the pushrods.
They are not slots, they are holes that are cast into the head. They vary in size because they are rough cast but measure around .487. This would accomodate most common pushrods. My original question was can I use a SA rocker without machining the holes open, or leave the holes alone and use a standard rocker.
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Old 05-30-2012, 08:19 AM
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Quote:
Originally Posted by 65_SS
They are not slots, they are holes that are cast into the head. They vary in size because they are rough cast but measure around .487. This would accomodate most common pushrods. My original question was can I use a SA rocker without machining the holes open, or leave the holes alone and use a standard rocker.
I do not think you are looking at the place where the p-rod passes through the head. The photo below shows the p-rod slots (red arrows). The red X is not a guide hole.



If this isn't what your heads look similar to, shoot a photo and let us see.
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Old 05-30-2012, 08:24 AM
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As far as using SA rockers, the p-rod guide hole needs to be about 1/2" in diameter, and has to be centered so there's no interference between the casting and p-rod at any point of the valve opening and closing cycle. If 1.6 ratio rockers are used, the hole may need to be clearanced w/a grinder.
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Old 05-30-2012, 08:37 AM
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Quote:
Originally Posted by cobalt327
I do not think you are looking at the place where the p-rod passes through the head. The photo below shows the p-rod slots (red arrows). The red X is not a guide hole.



If this isn't what your heads look similar to, shoot a photo and let us see.
Dude, the heads that you are showing is NOT a 3880462x cylinder head produced by General Motors from 1963-1965 specifically designed for the fuel injected engines found in Corvettes and an occasional Chevy II with the L-79 option. The pushrod "holes" are ROUND. Same location, unmachined but round. I can't shoot a photo unless I pull valve covers. Can't do that until I get home.
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