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AFR 190 heads (late style), '88 350 block, stock rocker arms, 0.51/0.52 lift hyd roller cam

I have problems with determining right length of pushrod. I started measuring pushrod legth with stock length pushrod, but rocker arm touched the valve spring before rocker tip touched the valve tip. I tried with longer pushrod and found pushrod length, when rocker tip touches the valve tip at the intake side at zero lift and moves exhaust side of valve tip at max lift (but rocker arm slot hits the rocker arm stud). Isn't it correct geometry ...or is it? I've read, that valvetrain geometry is correct, when rocker tip starts from intake side of valve tip (at zero lift), then moves to the exhaust side (at half lift) and finishes at intake side of valve tip at maximum lift.

I can't find that lenght of pushrod in my valvetrain. Is the problem in stock rocker arms? AFR says, that you can use stock rocker arms. If problem is in rockers, then should iI go with roller tip or full rollers?

Or is there problem in my method of determining right valvetrain geometry?

Have somebody experienced same problems with AFR heads and stock rocker arms?

Thanks, guys!

Damon

I have used those heads with stock rockers. The stock lenght pushrods worked just fine for me. I was also pushing about .500 valve lift. Like you, with longer pushrods I was running out of travel in the rocker arm slot before getting to max lift. I kept using the stock pushrods, therefore, and have no problems to report from doing so.

Rocker geometry is one of those things where you'll get different answers from different people. I try to start the rocker tip toward the intake side, have it go as far to the exhaust side as it will go at about 2/3 max lift and them come back slightly as it reaches max lift. This setup minimizes the travel of the rocker tip across the valve tip at high lifts, where spring tension is highest.

rjmcgee

My Pro Action heads have 1.460 diameter springs and I ran into trouble with the stock rocker arms. They wouldn't clear the spring with anything resembling correct valve train geometry. Comp's magnum roller tipped rockers fixxed the problem nicely. Also used one of their length checking pushrods to determine the correct pushrod length.

I stole this picture from one of Vader's posts I found with a search, it is how I set up my valvetrain geometry.

max_est

Thanks, guys!

It seems like I should buy a set of new rockers that will clear valve springs with right valvetrain geometry.

But it's strange that nobody has practiced this kind of problem before with AFR's and stock rockers. At least search didn't give me answers.

RB83L69

Surely you must be joking.... nobody in their right mind would do that. That's about as sensible as putting AFRs on a TBI 305 and leaving the stock exhaust manifolds on it.

Get those stupid worthless things off of there, and put something worthy of $1500 heads on top of them. Get your money's worth out of the heads by opening the valves. Then worry about push rod geometry. As it is, push rod geometry is a far lesser problem tnan the flaws of stock rockers.

Vader

Just to expound upon that a bit, the stock rockers would likely have problems with even "perfect" length push rods, since the stud slots in the stock rockers are likely far too short for a cam with a 0.510" lifts. That's all aside from the fact that the stock "forged rubber" rockers aren't going to do the rest of the combination any justice.

And please, stop calling me "Shirley"....

max_est

Will Comp Cams roller tipped Magnums be OK? Or should I step to the full rollers (Pro Magnum)?

Vader

The Comp roller tips will be infinitely better than the stock rockers. However, the fact that you were using stock rockers indicates that you are not using push rod guide plates. That would mean that you would need to get self-aligning rockers. I'm not sure if the roller tips are avaialble in that design from Comp.

max_est

Actually I _am_ using guideplates. My engine had non self-align rockers and guideplates (and some crappy 181? heads with 1.84/1.5 valves) when I bought it. I bought late-style AFR 190's that have guideplates also. So I'm thinking, should I buy roller tip rockers (and save some money) or go with full rollers (then I should buy also taller valvecovers). Car will be daily-driver. Cam has 0.503/510 lift (CC 08-503-8).

rjmcgee

The Comp roller tips fit fine under my stock sized valve covers.