Pushrods?

[Zektor]

Hi All,
I've just received my Comp Cams Magnum Roller Rockers for my 1982 Corvette. The blurb that comes with the set states that you must replace the pushrods when installing these roller rockers or the setup can be prone to failure.

Has anyone else changed their pushrods? If so, how easy are they to replace... Do I have to remove the intake manifold???

Cheers
Dazza

 

[69MyWay]

You need "hardened" push rods.

You really should also do a measurment to see exactly what length.

Call Summit racing, etc, and order an adjustable push rod.

Install it in the engine (you don't have to take the intake off).

You will rotate the engine around after adjusting the valve and watch to see that the roller tip is centering on the valve stem. After you have adjusted the push rod to the length that causes the rocker tip to travel the best on the valve stem tip, then remove it, measure it, and call Summit back up and order a set of new hardened push rods that length. That will insure long trouble free operation from your new roller rockers.

 

[Zektor]

The Comp Cams Roller Rockers I have got are the ones that are a direct replacement for the standard pressed steel rockers. I think they can be used with standard pushrods (They basically shouldn't be under any more strain than using the standard rockers).

I'm not planning on revving the car any higher than stock redline so surely standard pushrods will suffice? No?

Another question, does the 1982 Corvette engine use pushrod guides?

Cheers
Dazza

 

[69MyWay]

If you are now installing full roller rockers they are not a direct replacement for your stock stamped steel units.

Unless you have the high dollar self aligning models, they must use push rod guides, and thus then need for hardened rods. The stock rods will desintigrate as they can't handle the heat and friction and pressure from operating against the push rod guides.

I do not believe your stock heads have the push rod guies. At best dedicated holes in the head casting. but they will not act as a guide for the travle (side to side) of the rocker.

You can run them with out the guides and the hardened rods, but I would not suggest doing so. The problem is (high revs or not), when you have failure it will most likely take the rest of the engine out with it. A terrible costly price to pay for not setting them up in the first place according to manufacturer specifications.

My buddy put a set of Crane full rollers (1.6) on a beefed up 350 without hardened rods. He was running the Edelbrock aluminum heads that come with nice push rod guides.

In about 500 miles the engine developed a terrible noise, then started running rough, etc.

When we opened it up, there was metal shavings all in the block from where the stock rods got eaten up against the guides, and he had three bent push rods.

 

[Jack]

measure & get new pr's regardless

You need "hardened" push rods.

You really should also do a measurment to see exactly what length.

Call Summit racing, etc, and order an adjustable push rod.

Install it in the engine (you don't have to take the intake off).

You will rotate the engine around after adjusting the valve and watch to see that the roller tip is centering on the valve stem. After you have adjusted the push rod to the length that causes the rocker tip to travel the best on the valve stem tip, then remove it, measure it, and call Summit back up and order a set of new hardened push rods that length. That will insure long trouble free operation from your new roller rockers.

DAZZA:
;stupid DITTO ... DO follow Chris' measurement advice here ... otherwise you may not be satisfied. While the stock pushrods may (or may not) be strong enough for whatever valve springs you have ... it's a coin toss if they're the proper length for use with rr's. There's also a good chance your 20-year-old pr's have considerable wear at tips /may be beginning to collapse-fracture there ... don't scrimp here. A good set of 1010 pr's hardened for guideplates are only about $25 a set & will do the trick with most street vs's. Your 82 probably didn't come with gp's ... BUT you may need to install gp's too. ... as is often the case with rr's.
JACK:gap

 

[Stallion]

What parts of the engine are pushrods? Do they interact (or are the part of) with the cam? Thanks!

TR

 

[Jack]

What parts of the engine are pushrods? Do they interact (or are the part of) with the cam? Thanks!

TR

Elliptical cam lobes push up on lifters ... lifters in turn push up on PUSHRODS ... pushrods in turn push against the "lever-like" rocker arms ... rocker arms in turn push down upon the valve stems ... thus opening the valves.
JACK:gap

 

[Zektor]

Ok! Ok! I'm with you!!!

I've read a little more of the blurb and it does state that I need to use pushrod guides with these roller rockers (#1412-16). So it looks like I might as well do as you suggest... fit hardened pushrods and pushrod guides.

Ok, new question then... Thanks for your help as regarding fitting the pushrods... knowing that I do not have to remove the intake manifold will save a lot of work... But, what is involved with fitting the pushrod guides? Is this easy? If I buy some will they bolt straight on? ...do I need to buy all the bolts to fit them etc?

Cheers for the help guys... good job I asked on this forum before steaming in to fit them INCORRECTLY!!!! I hate to think!!!!

Cheers
Dazza

 

[billybob]

Just my thoughts,

While having her opened, sure its only the valve covers at this point, why not do the lifters at the same time? and while your in there do the cam and damper :L

Ok seriously though, I personally hate part upgrading. Unless you have a major need to install the rockers, I'd hold off and match up a set of lifters, cam, springs etc till you get $$ to do it.

Bill

 

[8T8T2]

If I remember right the 82 has 3/8 in. pressed in rocker studs. I may be wrong here and maybe more experienced mechs. can join in but you need threaded studs. They need to be removed and reinstalled to hold the guide plates on. This will require head removel and shop work done. Tapping holes ect. if you have this done go with 5/16 studs.
Please check into this more.

 

[Stallion]

Elliptical cam lobes push up on lifters ... lifters in turn push up on PUSHRODS ... pushrods in turn push against the "lever-like" rocker arms ... rocker arms in turn push down upon the valve stems ... thus opening the valves.
JACK:gap

Okay, so pretty much pushrods are part of that cam chain reaction towards the valves. Thanks!

TR

 

[Jack]

Re: Ok! Ok! I'm with you!!!

But, what is involved with fitting the pushrod guides? Is this easy? If I buy some will they bolt straight on? ...do I need to buy all the bolts to fit them etc?Dazza

Dazza:
SBC pushrods are typically 5/16" diameter. It's nearly certain ... your heads have pressed-in rocker arm studs. Guide plates require OEM studs be removed (all 16) ... and replaced with screw-in studs that have a hex-shoulder to retain the guide plates. The stud-holes in head (8 per head) must be drilled and tapped. Typically the stud-holes are tapped for 7/16"- 14 ... while the upper ends of studs where the rockers arms slide on are typically threaded either 3/8"-24 ... or 7/16"-20 ...YOUR 1412 rockers require the 3/8"-24. The heads can be drilled & tapped while on engine ... but I DO NOT recommend it.

Here's a thought ... consider exchanging the 1412-16 rr's for "self-aligning" 1417-12 ... such change MIGHT eliminate need for guide plates. Call Comp Cams 1-800-999-0853 and ask if such an exchange will work for you. G'luck!
JACK:gap

 

[cntrhub]

Just remember EOIC + "As Soon As" + Stop!

Zek, Eventually you are going to have to adjust the pushrods. Here is a real simple way of doing it. It is one of the most accurate adjustments also. It's an old NASCAR engine assembly trick. Begin with any cylinder you want. Rember to stop turning the crank...."As Soon As"....you see one of the pushrods begin to move. This is key to remember.
OK, here we go: EO = Exhaust Opens. IC = Intake Closes. Lets say, you start moving the crank (pick a cylinder).... now keep turning the crank and watch for the intake's rod (for example) start to close. As soon as you see the slighest movement of the, "Intake Close" (IC)...STOP! Now set the exhaust pushrod to specs. Say the adjustment calls for one full turn (stock adjustment) from zero play. Without making too drastic of a move to unseat the rod from the lifter, start moving the pushrod up and down. Keep doing this until there is just the slightest up and down movement. Then, begin spinning the pushrod as you keep tighten the rocker nut. When you can no longer spin (a subtle touch as you tighten very slowly) the rod, stop. Place the wrench at a known starting point, and turn the rocker nut 360 degrees... and stop. One full turn is a standard adjustment for a stock engine. Consult with the performance specs of their adjustments. It might be less or more turns....depending, etc. Solid lifters on the other hand, will take a different adjustment approach.
Now turn the crank, and watch for the exhaust just begin to open (EO). As soon as you see this happen, stop! Set the intake valve to specs in the same manor stated above.
You've completed an adjustment of one cylinder. There are 7 more to go. This is a lot quicker and more accurate (bottom of heel) than finding TDC of each cylinder. Hope this helps.

 

[Zektor]

The Final Word...

Hi Guys,
Right, I've changed my set of #1412-16 roller rockers for a set of 1417-16 roller rockers. The only difference I can see is that they have "washers" either side of the roller to stop the rocker from "walking" off the edge of the valve stem. Because my '82 'vette does not have guide plates and I didn't fancy getting a load of machining done to the heads. I thought this would be the best option. I've also got a set of Power Push Rods which are of stock length and unhardened material. The guy at "Real Steel" (my local tuning outfit) said that I should not use hardened pushrods without guide plates... he said they would be harder than the head material and would cause damage.

So, in the end, I've got stock pushrods (new) and a set of Comp Cams #1417-16 roller rockers. I can fit these in my head with no modification to the heads themselves and the pushrods will remain in alignment because of the "washers" either side of the rollers. Because my camshaft is totally stock, the guy at the tuning outfit said to spend anymore money on pushrods that I don't need is a waste of money. He said that the stock rods will be fine with my particular setup.

Anyway guys, thanks for all your help... I could of made a very costly mistake. Cheers to you all.

By the way, if anyone else can think of anything else I may of missed before I start work on the car... please tell me!!!

Cheers
Dazza