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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?
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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......
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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
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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!!
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Re: dual pattern cams
Did you check the piston to valve clearances???
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Re: dual pattern cams
No, I didn't check that value.
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Re: dual pattern cams
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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!
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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
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Re: dual pattern cams
Where did the rocker break?
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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.
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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.
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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)
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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.
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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. |
Re: dual pattern cams
The cam was installed "straight up". A compression test is scheduled for this weekend. My local go to guy also seems to think that it may be a spring that bound up some how, he advises against pulling the head just quite yet. The engine does (did) have almost three hours runtime on it, still early in the break in period. I just got the replacment rocker today, I hope to have it running again this weekend!!
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Re: dual pattern cams
I hate to say it but pulling the heads to check for valve train- piston damage is not premature at all from what I've read so far. Something is badly wrong here. I suspect valves kissing the pistons for some reason or coil bind as previously suggested. My advice is not to pussy-foot around on this. Take the heads off and see what the heck happened. With my advice and a couple of bucks you can get a cup of coffee.
Rev |
Re: dual pattern cams
Well, just to keep interested parties up to date: I did a compression test, and #8 is about 30 lbs less than #7. So it seems that I got very lucky and only have a mildly bent valve. I now am trying to find some garage space to pull the heads off and help keep everything as clean as possible.....
I will update when I have more info, thanks to all here who have tried to steer another Ford back onto the road instead of the scrap yard!!) |
Re: dual pattern cams
Did you run the test on all the cylinders? Might want to. Hopefully it didnt damage the piston to much...
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Re: dual pattern cams
Update!
Well, I pulled the head, and there is not a hole in the top of the piston. There is a definate area of contact, but no visible cracks. So, Monday it's back to the machine shop to see what all is going on....... |
Re: dual pattern cams
Upon further inspection, ther is or was, no direct between piston and anything. The first impression was wrong. Something only happened to the valve itself, or the valve spring decided to bind up. I can pick up the head on Friday, it should be running again Friday after noon. :-)
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Re: dual pattern cams
Cool, did they change the springs or retainers? Valve guides might have been to tight too..
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Well, the head is back. The only thing we determined that could have caused a valve to stick was the quality and quantity of bad gasoline on a brand new motor. Since there is no evedence of any contact between the piston and the valve, this is what I'm going to work with. I know everybody says that it is very unlikely, and I certainly agree. But what else is there? If there is no contact, then what is wrong? Look in my '68 part 2' pictures, and keep in mind that this engine only has two to three hours run time.....
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Re: dual pattern cams
This reminds me of a time just after I had installed new CC Magnum roller tip rockers on my 306. At that time I was using 351W heads that still had pressed in studs. After I had adjusted the rockers 1/2 turn down after 0 lash, I took it out for a test drive.
It seems that I did not tighten down the locking screw tight enough, at least on one valve. One of the rocker polly-lock adjusters loosened enough for the push rod to come out of the socket and hit the rocker arm just next to the push rod socket. This caused all manner of hellish noise as the extra force on the rocker actually pulled the stud out of it's pressed in hole, about half way. Fortunately , nothing got bent. All I had to do was get the stud pressed back in and make damned sure that I tighened all the polly-locks down enough. I now after adjusing the valves and tightening down those allen screws, come back with a socket and give those adjusters a slight nudge tighter (not enough to twist off a stud please). I'm just wondering if something similar could have happened in your case. If you have screw in studs or bolt down pedestals, there wouldn't be the give that my stud pulling out allowed. Something else would have to give. My guess would be a bent push rod and/or that broken rocker arm. I don't know that this occured in your case, but it would offer a possible explanation as to what happened in your engine. Rev |
Re: dual pattern cams
I've had a rocker arm stud pull out as well on a set of 68 302 2v heads... my solution was to tape off everything around the hole where the stud was and I tapped out the hole for a screw in stud and was real careful cleaning up the mess of tap shavings. Worked great and never had to even pull off the head.
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Re: dual pattern cams
I'd still bet that the retainer hit the top of the valve guide... or coil bind.. You MIGHT want to check the cam for damage or rounded off lobes...
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Re: dual pattern cams
Well, while I was at the machine shop, the guy pulledd off all the springs and we checked each valve for ease of movement. They each were very, very sticky. I do have screw in studs and guide plates. Unfortuantely, they didn't keep my old valves for me to see. But they said the one that I thought was bent came right out. In my mind I can see the valve gunked up enough to not close all the way. I'm going to try and get it back together today. I'm going to spray some foamy lube on the top of the valve spring to try and get the gunk off the head of the valve, and see if it will run. Again, other than the one pushrod and broke roller, we can't find any evidence of impact any where. IF the valve didn't close all the way, not because it was bent, but because of gunk, it would also show lower compression. I know it sounds like BS, but I'm at a loss.
We'll see what happens when I fire it up tomorrow !!) And, why don't my links work properly down here????? |
Re: dual pattern cams
Fresh heads shouldnt have been gunked up from bad gas though...
Try putting [url] in front then the same thing with a / in front of url after the link. |
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I know the heads shouldn't be gunky, but did you see those pictures?? If you cut and paste, the link works fine.....
PS, the machine shop only took off .006 from the head, just enough to true it up...... |
Re: dual pattern cams
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But your rocker arms wouldn't be railed would they? One of my friends about 10 years ago had a hard time getting his 289 to run after it was rebuilt... After a couple minutes, I pulled off the valve cover to discover that there were railed rocker arms that were put on the engine. He was lucky that he didn't lose any retainers as the rails were pushing on the valve spring instead of the rocker pushing on the valve. A quick replacement, and the thing ran like a charm. |
Re: dual pattern cams
Nevermind... just took a look at your pics.
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Re: dual pattern cams
Well, in order to avoid further breakage, I sent an email to Edelbrock customer service, with my specs and part numbers. Apparently I ordered ( I have no idea how I did it) The wrong valve springs. The ones I have fit the bill as far as specs go, but the coils are thicker than for a Ford motor. Also, the Edelbrock timing gear set that I used was for 84+ motors. So, fellow Fordsmen, take note, 7811 is for newer motors, 7820 is for the earlier stuff. They both "FIT" but the 7820 has a different thickness, to work better with a single piece fuel pump eccentric. I used the 5794 springs, and I should have used 5722. IF you go to summit and look at the suggested parts for the 7122 cam, it will list the correct parts.
Thanks to all who looked at my post, hopefully someone else gleened some usefull info as well!!) |
Re: dual pattern cams
Hopefully it runs goos once everything is fixed. :D
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