dual pattern cams
 

Hello all!!
I ususally spend most of my time on mercurycougar.net, but am kind of embarrased to ask this question, as it has been beaten to death over there.
I have 1965 289 block that I had bored .030 over, and installed an edelbrock performer rpm cam. It specs at .496 int and a .520 exh.
I am having a very hard time keeping pushrods and now roller rockers in this stupid thing!
My question is this:
For those of you that have dealt with a dual pattern cam before, is it necessary to perform valve adjustments differently than with a less agressive cam? I followed the directions in the 68 Ford manual to the letter, and got 8 bent exhaust pushrods.
I replaced the damamged pushrods and adjusted the assembly again, this time only taking the slack out of the rockers, not the pushrods. Thirty minutes runtime later, I get a horrible knocking noise and a broken roller rocker. The only thing I can think of is that I need to do a 'hot' adjsutment, with the engine running and tightening only until there is no more rocker noise.
Does any one here have advice??

Re: dual pattern cams
 

Really basic question here....."It is a Hydralic cam??".

Now if it keeps bending the pushrods and the lifters are Hydralic.....I'd check the push rod length. If that is OK....check for valve spring coil binding. Crane has a good explanation on their site on the correct, and more importantly, the easy way to check this. Crane also talks on one of its sites...don't remember which one about coil bind. Bring the adjusted rocker to full lift and measure the distance between the coils on the valve springs.

The dual pattern shouldn't make any difference.

I adjust mine with the engine off. Spin the push rod till it doesn't turn and add 1/3-1/2 turn. I have never had a problem.

Re: dual pattern cams
 

Yes, it's a hyd cam. I built the whole engine while attending the auto tech program at BSU.
Initially, (The first time I did it) I started on hte number one cylinder, set 'zero lash' I.E. barely any drag on hte pushrods, adn then rotated the crankshaft 90 deg, and did the next cyl in the firing order.
At that time the engine had not fired, and I think the lifters had not pumped up enough upon fireing, and that is why ( I thought) the first set got bent.
We check for spring binding, no problem. Installed second set, adjusted 'loosely'(only taking slack off of rocker, not p/r) and all seemend well. Until I heard the noise, etc...
Now I am waiting for the replacement roller from summit, so I can try it again. My thinking was that also since I had comp cams "289/302" pushrods, that difference in length 6.876 (comp) VS 6.805 (edel 289)
may have been the problem. If the difference in pushrod length could have been that big a problem, then perhaps the difference in lobe height .520-.496 = .024 might require a 'hot' adjustment, I. E. motor running.
I am at a complete loss here. None of this should have happened 'by the numbers'.

Re: dual pattern cams
 

They are stock valves, right?

Re: dual pattern cams
 

Yup, new, but stock valves. Stock 1.6 ratio rockers. I guess I'kk have to spend the money and get the adjustable pushrod checker thingy set up. I was hoping it may have been something that could be cured by a different procedure......

Re: dual pattern cams
 

Read the link from Crane about how to check the pushrod length.

Blacken the top of the valve stem with a magic marker and you run the valve through a complete event and you can see where the rocker is rubbing on the valve stem. It is fairly easy with an adjustable pushrod.

Re: dual pattern cams
 

Alright... I was just wondering as I was told with my Windsor Jr heads (1.94/1.6 valves) not to run over a .500 lift without putting the butterfly cuts into the pistons.

Re: dual pattern cams
 

When I built the motor, I used speed pro flycut pistons. The basic set up is all edelbrock. Rebuild kit thru summit, rings bearings, etc, edel cam pn7122, matching valve springs, and timing gear set. THe Edel dual quad package and a retro fit duraspark ignition. New stock size valves etc. NOthing real special, just a healthy little Ford motor to go in front of a four speed. At this point though I don't think it will ever run right!!
:confused: :mad: :confused:

Re: dual pattern cams
 

Did you check the piston to valve clearances???

Re: dual pattern cams
 

No, I didn't check that value.

Re: dual pattern cams
 

thats what i was thinking too gearhead, cause if the springs aint stackin out and the pushrods a lil too long its gotta be taggin the piston in some way,and i did read where he said at one point it bent all the exhaust pushrods.... like not enough relief cut..dunno just kinda confusing why its doin this with all the things he has tried so far :confused:

Re: dual pattern cams
 

What heads are you running? Are you running guide plates? If they're the early heads with the pushrod slots and you're running guide plates, the might be binding the pushrods..

Also, check the clearance from the underside of the valve spring retainer to the top of the valve guide.

If the exhaust valves were hit hard enough to bend the pushrods, it would bend the valves too, I would think. Compression test would show it..

Re: dual pattern cams
 

They are the stock heads that came on the motor. The machine shop billed me for milling them, but I am not sure how much he took off, and that could be part of the problem. THe first set of tubes that I bent were the comp cams 289/302 which were longer than the Edel recc ones. Since I installed the shorter tubes, the motor had been running fine, until this stupid roller crapped out. I have a replacement on the way, and when it gets here I will be able to determine if there was any other damage. I have NOT been hot rodding the motor, I have been trying to break it in nicely, so that I can dump the clutch later with a clear conscience. But, when or while, the roller was crapping out, I had a BAD knock going on. I don't know if a valve may have stuck, or WTF. I guess I'll just have to wait and see when the new roller shows up. By the way, it was a proform rocker. They are less expensive than most. I'm hoping this was a unique experience, and that the rest of them don't crap out later!

Re: dual pattern cams
 

maybe you got lucky and just damaged 1 rocker when it bent the pushrod, ive done that at times on my race motors..which i never get that lucky .... lol

Re: dual pattern cams
 

Where did the rocker break?

Re: dual pattern cams
 

THe rocker broke right behind the stud (7/16) around the 'side' kind of. On the end that faces the spring, almost in half. I'm thinking I broke more than a rocker to do that much damage. Tomorrow I'm going to see if I can rent a space to tear the head off, and see what's what.

Re: dual pattern cams
 

If you damaged the valves, a compression test will show it without having to pull the head. Breaking a rocker arm usually means something bound up. Check the condition of the rocker stud too. Also make sure you put the rocker arm on right, I've seen people put the rocker arm on wrong, trunion facing the wrong way. Make sure the poly lock is in the right side of the trunion.

Re: dual pattern cams
 

I'm also afraid that the gas in the tank may have been bad as well. I think what happened this time is that this one valve varnished and got sticky, thus causing the piston to hit the valve and break the rocker. I'm too deep into the project to quit now, off comes the head, back to the machine shop. Plus a new piston....(probably)

Re: dual pattern cams
 

Do a compression test... and if one hit and broke the rocker, why did the other pushrods bend? Did you check for coil bind right after the car was running, or after it sat for awhile? The lifters will bleed down if it sits.

Re: dual pattern cams
 

I'd also check, as Dark Knight stated on post #12. Is the spring retainer hitting the top of the valve guide.

One more.....you bent all the exhaust valve push rods....The cam is in time??

Take a compression test.