I've inquired on a number of boards about this topic, and I've gotten a number of varying replies. I want to install a set of 1.6 roller rockers on a stock headed 1985 truck 350 (perimeter valve cover). I've been told:
- you will need tall valve covers
- you can get away with just double gaskets
- you will need to machine the heads
- you will need hardened/longer pushrods
- you will need guideplates

Obviously some are true and some aren't. I just want to bolt them on, and double gasket the valve covers and go. Can I?

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1985 Z28, Jasper Class 1 350, Edelbrock Performer intake, Dual snorkel air cleaner, K&N, Edelbrock headers, Catco 3" cat, Hooker 3" cat-back, Richmond 3.73's, Transgo shift kit, JET Stage 2 chip, Hypertech coil, Lakewood LCA's, Powertrax locker, SSM subframes, Centerline Auto Drag's

 

i researched this once and this is what i was told by summit and comp cams.the broach hole where the pushrod goes thru the head may need to be elongated. check after install the clearence beteween the retainer andthe valve guide, check spring bindand i'm sure other people can help. i decided to change cam and springs instead.

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86 camaro 405 sm. blk. th 350 tranny 3.42 gears

 

Let me cut through the BS. First, is this on a stock cam/head engine? If so, you will need tall valve covers only with full roller rockers or rockers that use poly locks (ratio doesn't matter). Double gaskets is a cheap man's idea, don't even think of doing this. Hardened pushrods are only needed with guide plates, OEM cylinder heads have drilled slots to help align the valvetrain. IMHO, you only need guide plates with aluminum heads due to the softer material than cast iron (cast irons don't need guide plates unless they have no drilled slots for the valvetrain). Longer pushrods are only needed if the base circle of the cam was reduced. Machining the heads is needed when you upgrade to larger diamter springs, rockers don't need machining. All this is from a valvetrain point of view only.

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George P. Lara
1984 "L69" A4
1994 LT1 M6
Member:
SCCA, SCFB, SC3GFB

 

Your valve cover needs will depend on what rockers you use. Without more details I can't predict that. Roller-tip rockers like COmp will fit under the stock ones; full roller ones, which use Poly-Locks, probably won't.

You don't need longer pushrods no matter what. You have to change pushrod length when you make a BIG cam change, or change to a roller system. You aren't doing either, so your same length pushrods will work fine.

There's about a 50% chance you will have to alter the heads. There's no rhyme or reason to what heads will work and what ones won't; I've even seen motors where one head would fit and one wouldn't. The problem is very simple: The rocker ratio is the ratio of 2 distances. One is the distance between the center of the stud and the center of the valve. You obviously don't change that by replacing the rockers. The other is the distance between the pushrod seat in the rocker and the rocker stud. That is the one you do change. Specifically, it shortens, such that the pushrod ends up closer to the stud. The pushrod is guided by a slot in the head that has about .010" of clearance to the rod from side to side. However, sometimes it isn't long enough in the direction toward the stud to accomodate the pushrod's new location. When that happens, the pushrod will be forced up out of the cup in the end of the rocker, and something will be destroyed rapidly. Could be the pushrod or the rocker, but something will wipe out.

There are several possibilies:

1. Your heads will accomodate the rockers, in which case, you're done.

2. Your heads will not accomodate the new pushrod pocation. In this case, you have some choices: either you can buy the "Louis tool" from Comp which is basically a drill bushing that positions a drill bit perfectly to elongate the slots; or you can just drill the holes out to a huge size, and install screw-in studs and guide plates. Either requires removing the heads unless you don't mind getting metal chips into your motor (I don't really consider that an option). The Louis tool is like $30 or 35. I would recommend that you get one of those at the same time you get the rockers, test fit the rockers and check REAL CAREFULLY for interference at the end of the slot, and either use the tool or return it.

If you decide to put in screw-in studs and guide plates, AND you get non-hardened guide plates, you might want to get hardened pushrods. Otherwise the stock type ones will work fine. Your old ones might be worn enough at the ends to where they won't fit into the new rockers properly, so I would strongly recommend getting new ones no matter what, they don't cost very much and that will eliminate them as a possible source of problems.

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"So many Mustangs, so little time..."

[This message has been edited by RB83L69 (edited January 18, 2001).]

 

Thank you

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1985 Z28, Jasper Class 1 350, Edelbrock Performer intake, Dual snorkel air cleaner, K&N, Edelbrock headers, Catco 3" cat, Hooker 3" cat-back, Richmond 3.73's, Transgo shift kit, JET Stage 2 chip, Hypertech coil, Lakewood LCA's, Powertrax locker, SSM subframes, Centerline Auto Drag's

 

Just a little side note. I'm running Harland Sharp full roller rockers with polylocks in my 69 Camaro with standard height Edelbrock elite series valve covers with no clearance problems.

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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."

 

I just put 1.6 stamped roller rockers on my 87 T-A with a 305. I put in screw in studs, guide plates and hardened push rods. It all lookde good with no clearance problems anywhere until I went to put on the valve covers. I have at least a 1/4" gap that adding another gasket will not cure.
Ben


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'87 T-A 305 TPI
IN PEICES RIGHT NOW

 

Just FYI, i ran harland sharp 1.5 full rollers w/ poly-locks with stock 85 camaro valve covers and had no problems either.
...ed

 

I've put Comp 1416s on a number of cars, which are what I'd suggest for your application. Don't bother with the stamped sheet metal kind, they are BS; and roller-fulcrum ones are total overkill. Those will basically always fit under the stock valve covers with no mods whatsoever. Like I said, about half the heads I've worked with have had to have the slots elongated.

I have a set of Comp 1102 stainless roller rockers on my 400 with a set of stock 85 L98 valve covers, they fit with the drippers ground off, the breather oil spearators smashed, and the thick ROL gaskets. My heads have had enormous holes installed in place of the slots, with studs & guide plates.

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"So many Mustangs, so little time..."