65 rocker arms

[Jimmy Roggenbuck]

I would like to find out if there is a "correct" type of rocker arm that goes on a 65 327/350 that is specific or preferred. The other question is are there push rod guide plates that are also yo go on the heads?
The rocker arms that were on it were on it are harland sharp roller rockers and I asked a mechanic and he recomended to not put them back on because of the amount of adjusting they require and to go back with stock rockers and nuts
Is there a place to find them and what ratio are the rockers
I have found some in summit catalog just not sure how to go. This car is a driver right now.

[John H.]

Re: 65 rocker arms

Jimmy -

Stock stamped rockers are 1.5:1 ratio (they actually measure slightly less than that, but that's the design number). If you currently have Harland Sharp roller rockers (which are nice pieces), I'm assuming you also have screw-in studs and guide plates; if the pushrod slots in the heads haven't been enlarged for clearance, you should be OK with stock rockers and no guide plates. The Harland Sharp roller rocker poly-lock nuts won't clear stock valve covers, and the stock ones will. I'm pretty sure the stock rockers are still available from GM; if not, there are plenty of stock replacement stamped rockers available elsewhere, as kits with new rocker balls and nuts.

[John H.]

Re: 65 rocker arms

Jimmy -

Stock stamped rockers are 1.5:1 ratio (they actually measure slightly less than that, but that's the design number). If you currently have Harland Sharp roller rockers (which are nice pieces), I'm assuming you also have screw-in studs and guide plates; if the pushrod slots in the heads haven't been enlarged for clearance, you should be OK with stock rockers and no guide plates. The Harland Sharp roller rocker poly-lock nuts won't clear stock valve covers, and the stock ones will. I'm pretty sure the stock rockers are still available from GM; if not, there are plenty of stock replacement stamped rockers available elsewhere, as kits with new rocker balls and nuts.

[Jim T.]

Re: 65 rocker arms

I am no expert here but from all that I have read Harland Sharp roller rockers have been available for a very long time. One area that the Harland Sharp rockers are probably more accruate is the ratio of being more accruate that the stock Chev rocker. I am sure there are a lot more comments on this. Your engine used hydralic lifters, so once the Harland Sharp roller rockers are adjusted there should not be any need for additional adjustments. The first factory Corvette with full roller rockers was the 96 LT4. I have one and haven't done anything as far as adjustment since it was new and no adjusting is required.

[Jim T.]

Re: 65 rocker arms

I am no expert here but from all that I have read Harland Sharp roller rockers have been available for a very long time. One area that the Harland Sharp rockers are probably more accruate is the ratio of being more accruate that the stock Chev rocker. I am sure there are a lot more comments on this. Your engine used hydralic lifters, so once the Harland Sharp roller rockers are adjusted there should not be any need for additional adjustments. The first factory Corvette with full roller rockers was the 96 LT4. I have one and haven't done anything as far as adjustment since it was new and no adjusting is required.

[Clem Z.]

Re: 65 rocker arms

if the heads are stock 65 you can not use guide plates unless you modify the heads. the 65 heads use a double D shaped hole to guide the pushrods. to use guide plates you must enlarge these holes for pushrod clearance and install screw in rocker studs to hold the guide plates. harlan sharp roller are fine and there is no problem adjusting them. the adjustment can be made with the engine cold and not running. if your guy does not want to do them find someone who is familiar with adjusting roller rockers. all SB chevys use 1.5 rocker ratio if you want to change.

[Clem Z.]

Re: 65 rocker arms

if the heads are stock 65 you can not use guide plates unless you modify the heads. the 65 heads use a double D shaped hole to guide the pushrods. to use guide plates you must enlarge these holes for pushrod clearance and install screw in rocker studs to hold the guide plates. harlan sharp roller are fine and there is no problem adjusting them. the adjustment can be made with the engine cold and not running. if your guy does not want to do them find someone who is familiar with adjusting roller rockers. all SB chevys use 1.5 rocker ratio if you want to change.

[Joe L.]

Re: 65 rocker arms

John------

The original style rocker arms used for all 1955-1987 Corvettes are no longer available from GM. They were replaced for PRODUCTION and SERVICE by GM #10089648. These are a guided-type rocker arm. Their tip design has a "depression" in it to locate the valve stem tip. Although the tip design is different than the originals, it's virtually impossible to discern when installed on the engine. Plus, these rocker arms are great----they eliminate the need for guide plates entirely.

These rocker arms were first used in PRODUCTION for 1988 Corvettes and other small blocks. Although Corvette engines for 1988-96 have have what appear to be guide plates installed, these are NOT guide plates. They're plates used as a production assembly aid, but they're not hardened and have larger slots. Guide plates should NOT be used with engines equipped with guided rocker arms. The Crane-manufactured aluminum roller rocker arms used on 1996 Corvette LT4 engines are also of a guided design.

One problem with the guided rocker arms: they are impractical for use on engines with mechanical lifters since valve adjustment using a feeler gauge is difficult or impossible. I think GM "forgot" about this need when they discontinued the non-guided type rocker arms. But, I don't suppose that they're very concerned with providing SERVICE parts for this application.

The best original-style, non-guided rocker arms for small blocks available today are the "Nitro-Carb" rocker arms manufactured by Crane Cams. These are virtually identical to the original GM pieces and are far stronger and more durable.

[Joe L.]

Re: 65 rocker arms

John------

The original style rocker arms used for all 1955-1987 Corvettes are no longer available from GM. They were replaced for PRODUCTION and SERVICE by GM #10089648. These are a guided-type rocker arm. Their tip design has a "depression" in it to locate the valve stem tip. Although the tip design is different than the originals, it's virtually impossible to discern when installed on the engine. Plus, these rocker arms are great----they eliminate the need for guide plates entirely.

These rocker arms were first used in PRODUCTION for 1988 Corvettes and other small blocks. Although Corvette engines for 1988-96 have have what appear to be guide plates installed, these are NOT guide plates. They're plates used as a production assembly aid, but they're not hardened and have larger slots. Guide plates should NOT be used with engines equipped with guided rocker arms. The Crane-manufactured aluminum roller rocker arms used on 1996 Corvette LT4 engines are also of a guided design.

One problem with the guided rocker arms: they are impractical for use on engines with mechanical lifters since valve adjustment using a feeler gauge is difficult or impossible. I think GM "forgot" about this need when they discontinued the non-guided type rocker arms. But, I don't suppose that they're very concerned with providing SERVICE parts for this application.

The best original-style, non-guided rocker arms for small blocks available today are the "Nitro-Carb" rocker arms manufactured by Crane Cams. These are virtually identical to the original GM pieces and are far stronger and more durable.

[Jimmy Roggenbuck]

Re: 65 rocker arms

What is the proper adjustmet on these type of rocker arms? Do you tighten down the nut or allen screw first and how tight on each do you go cold and not running? thanks for the input.

[Jimmy Roggenbuck]

Re: 65 rocker arms

What is the proper adjustmet on these type of rocker arms? Do you tighten down the nut or allen screw first and how tight on each do you go cold and not running? thanks for the input.

[Mark Ring]

Re: 65 rocker arms

Jimmy,
I have to agree with Joe on the Crane rockers. The less expensive rockers are not heat treated the same as the original GM pieces. I bought some less expensive aftermarket stamped rockers and the wear was excessive on a few of them for the amount of miles on the engine. There are also cheap rockers being sold today for use in "claimer" motors that look good but aren't fit for long pieriods of street type duty because of the same reason. I have no experience with needle bearing rockers but I might have heard the needle fulcrum bearings were not advised for hydraulic cam duty in street motors for durabillity reasons. Anyone else heard that? Something about needing lash (mechanical lifters) for the needle bearings to survive?

On the rockers you have now, the allen screw is what holds the setting. To adjust them, you back out the allen screw, then adjust the valves with the large hex, then tighten down the allen screw to hold the adjustment. They will not need further attention.

-Mark.

[Mark Ring]

Re: 65 rocker arms

Jimmy,
I have to agree with Joe on the Crane rockers. The less expensive rockers are not heat treated the same as the original GM pieces. I bought some less expensive aftermarket stamped rockers and the wear was excessive on a few of them for the amount of miles on the engine. There are also cheap rockers being sold today for use in "claimer" motors that look good but aren't fit for long pieriods of street type duty because of the same reason. I have no experience with needle bearing rockers but I might have heard the needle fulcrum bearings were not advised for hydraulic cam duty in street motors for durabillity reasons. Anyone else heard that? Something about needing lash (mechanical lifters) for the needle bearings to survive?

On the rockers you have now, the allen screw is what holds the setting. To adjust them, you back out the allen screw, then adjust the valves with the large hex, then tighten down the allen screw to hold the adjustment. They will not need further attention.

-Mark.

[Clem Z.]

Re: 65 rocker arms

if needle bearing rockers would not survive on hyd lifter there would be no LS-1 or LT-4 engines.

[Clem Z.]

Re: 65 rocker arms

if needle bearing rockers would not survive on hyd lifter there would be no LS-1 or LT-4 engines.