I'm helping a friend assemble his 350 and I ran into a situation I've never experienced before. In an attempt to do his valve adjustment, I have the rocker completely bottomed out on the stud and I still haven't taken the slop out of the assembly. The cam is a Comp Cams retrofit roller assembly purchased as an kit complete with the cam, retro-fit rollers, and the proper push rods. At first I thought that maybe the wrong pushrods were packaged. I pulled out my trusty Manley pushrod length checker and it's perfect. What's going on? We are running guide plates and it appears that possibly we could get the adjustment by removing them but this is not a self guided system. I'm really at a wits end. Can anyone help?

 

Part numbrs for everything......


The more detail the more help.

 

What heads?

If they're stock, how far did they cut the bosses down, for the screw-in studs?

How long are the valves?

 

The heads are Protopline Vortec 906 Replacements. They have super thick decks which I suspected was the problem but they didn't come with special instructions. The heads came from the factory with screw-in studs. The cam is the HR260H, I believe. I know it's a .500 lift with a short duration. Something in the order of 210 degrees @ .050 lift. It's cut on a 110 LSA. The cam was installed with number one piston at TDC as checked with a dial indicator. The piston is still at TDC waiting for adjustment of the number 1 intake and exhaust.

 

stupid question but are you sure the lifter is ok, and that the pushrod is in straight?

 

How could you check it if there's slop at that length?

 

The pushrod is in straight and the plunger is right up against the plunger retainer in the lifter. The lifters are new so I'm confident there is no issues with the lifter. I'm leaning towards the fact that Protopline heads have such a thick deck, I've got a clearance stack up problem. I think RB83L69 is going there with the comment on the bosses. I have a set of Topline Vortecs on my motor but they were milled for a 60cc chamber when I assembled them. My buddy assembled them right out of the box.

Apeiron, I'm not sure about your question. The Manley checker is a device that insures the geometry of your setup. It replaces the rocker and slides down the rocker stud. If you have a gap on either the valve tip or the pushrod, you must lengthen or shorten your pushrods accordingly. The checker sat on the valve tip and pushrod perfectly with no gaps on either. That tells me my geometry is correct. Longer pushrods might cure my adjustment problem but it would mean the roller on the rocker would be loading the outer edge of the valve tip creating wear problems.

 

Are the screw in studs installed with a flat washer and lock washer, if so this will make the stud to high. Just a thought, my TF heads came with both but instructions said to only use one or the other.

 

No washer, just the guide plate. I'm know I'm hoping for a miracle here but it's not rocket science. That extra thick deck has raised the whole valve train up to where I've run out of usable rocker stud. It's time to pull the heads, disassemble, and have the bosses milled. Bummer !! I really like the Protopline but that extra thick deck comes with a price. Not only with the valve train but the weight. We've had the head off and on about 5 times helicoiling some stripped block deck threads. Those hefty 47 pound beasts are no fun to take on and off.

 

I am running the pro topline vortecs 906 replacements, mine weigh 54lbs each, little harder to pick up with 2 fingers. I am running a 264HR roller cam, but it's a factory roller block, I noticed too that I used up alot of threads on the screw in studs, but I was done adjusting with around 10 threads out the top of the comp cam rocker arm nuts, it looks real funny with all that stud sticking through like that though. I am using 1.52 comp roller tip rockers. were the lifters pumped up, I still need to pump the lifters up and re-adjust, my heads were done by tri-state heads.

 

this is very interesting!
i have a set of topline vortec heads for the 383 i am building also.
i haven't had the chance to mock the engine up yet,(still need pistons & bearings)but i'd be VERY interested in what you find out about this!
i can't help but think that if the thick deck was the problem,pushrod geometry would be affected.i would definately get the lifters pumped up first,and if that didn't help,try some longer pushrods before milling the stud bosses!
keep us posted!