Tim H

Will A set of Harland Sharpe roller rockers go right on a set of 993 heads without guide plates?
I am also going to use Milidon tall valve covers.
I am not going to race this car but a burn out or two might slip out on the street!

1979toy

The short answer is - maybe.
I just put 993 casting heads on my '79 L48 in addition to a Comp Cams XE262 cam and a set of Erson roller rockers. This combination did not work. One pushrod contacted the inside edge of the pushrod hole and bent the rod causing other grief.
The pushrod holes in the head are not real exact at the edges. This is fine for a stock cam and sled type rockers. When you add a high lift cam it causes the pushrod to travel closer to the inner edge of the pushrod hole as the valve is lifted. On my engine I compounded my problem by using pushrods that were truly 5/16ths diameter. Later I measured my stock pushrods at 19/64ths diameter. Added together on my engine it was enough to cause one pushrod to hit.
My feeling on the subject now is that, yes it might work, but you are making an expensive gamble.

Tim H

OK OK I have a performer cam or less.
I just want to pick up a Jegs book and order some 1.5 roller rockers without too much grief!
Its a small block Chevy for goodness sake.
I want to put them on,adjust and drive what is the %100 sure way without guide plates and head work. :cry

mountainmotor

A "Lewis tool " has been made for increasing the pushrod to head clearance.A rocker change alone is not worth the money or trouble for a performance increase.I think though that 1.5 Comp Roller tip rockers will go on w/o any trouble. I would by a set of headers and get the ignition advance curve dialed in along with optimum jetting of the carb first.

Is this motor assemled?


[Modified by mountainmotor, 7:12 AM 11/18/2001]


[Modified by mountainmotor, 7:14 AM 11/18/2001]

Gordonm

You do not need a set of full roller rockers for this motor. Save your money for something else. A set of Comp Cams roller tip rockers will work just as well and give you the same HP. It sounds cool to say I have roller rockers but it adds no horse power and no one can see it anyway. Until you have over 300 pounds of open spring pressure roller rockers are not needed.

Tim H

It clearly states in the Comp cams roller tip add in Jegs they require guideplates.
The self align ones cost $191 where Proform true rollers self align only cost $169.
This is another one of those questions I never get a clear answer to.
First was would 255-60s fit on a 79 vette, well 15 answers later no answer.
Then I ask what chrome pulleys would fit the water pump,crank,and power streeing? Just plaine ole chrome no aircraft quilty,no titanium just chrome,again no clear answer.
Now a simple rocker arm change and no clear answer.
I might as well work on my cutlass at least I know what fits and doesn't plus part #s. Im about to give up,If I can't get answers to a Chevy question the project is not worth it! :mad

Gordonm

I can tell you that 255 60 15 tires will fit on a 79 Corvette. They were an option that year on the car so they will fit. Why are you changing rocker arms anyway. I know the stock ones are not true 1.5 they are more like 1.47 or about there. Yes you should have guide plates with the Comp Cams rocker arms.

1979toy

If this stuff was easy everybody would own a HotRod Corvette! Suck it up and work with it.
Roller rockers - After my problem mentioned earlier I e-mailed manufacturers and suppliers and got differant answers from them even. It is not an exact science. If you use the Louis tool mentioned above you need to remove the heads to keep shavings from getting in to the engine. If you're going that far you may as well install guideplates. FWIW - I ordered new roller rockers last night and plan to install them on my 993 heads with the same Comp Cams XE 262 as before. Still no guideplates. Keep your fingers crossed!
Chrome pulleys - The water pump pulley on the Corvette is unique to it. I don't know of anybody offering them in chrome. I don't know if any of the other pulleys are differant or not. The way to be sure that they work would be to remove your pulleys, take them to your local chrome plater and have them show chromed.
255/50r-15 tires - These tires were first offered in 1978. When they were installed on the assembly line the front wheel wells were trimmed to allow full travel of the suspension and steering. If your car was ordered with these tires then the wheel wells have been trimmed. look at the flange or lip inside the wheel well. There is some debate about weather all 1979 and later cars were trimmed in the wheel well or not.
I hope that some of this helped.

mountainmotor

You want answers but we need a little more info on the situation! I asked if the motor was assembled.You did not answer.If it is not assembled you can use the Louis tool.What retainers are you using or planning to use?Not all roller rockers are designed the same.Some when used with the wrong retainer will unload the keepers.Are you aware self aligning rockers require specific retainers?Regardless that Jegs says a guide plate must be used it is not necessaryAre you aware that although Jegs say guide plates must be used that has nothing to do with the area the Louis toll is used for clearance?Do you have the screw in studs needed to place the guide plates?YES you can run comp 1.52 roller tip rockers on your heads w/o additional clearance if a good pushrod is used.Good meaning a better than stock that will not bend at high RPM.If you choose to use guide plates and screw in studs pushrods with a hardened end will be needed because they will rub against the plate itself.Are you aware of the possibility of pulling the studs out is there w/o pinning them or machining the heads for screw in studs?

Tim H

OK I give up!
I worked 66 hours this week and had some extra car money.
The big bowtie decal at Auto zone is looking better all the time and I know it will fit in the back window,and the chrome plated plastic chain that goes around the licence plate.
I'll be right back im going to town! :bs