Just got a call from my mechanic regarding the trouble with my '73 mustang. After paying some "mechanic" (I use that loosely) to put in a new cam and lifters, I have had to take it to another shop and have them get it timed correctly. Theyc alled me today saying that it is running great but that there is alot of upper end noise or lifter noise. They have checked everything minor and think that when the motor was rebuilt last, they may have gotten the valves ground down a little too much or not "true". What they suggested I do is they want to put in an adjustable set of rocker arms to take up any slack (they are telling me that every lifter is rattling). They cannot guarantee it will fix the problem but they are pretty confident that it will. They say if it doesn't then the only thing left is to take the heads off and have them reground and just rebuild the top half of the motor. I told them I would rather do that now instead of the rocker arm thing, but they said they think the adjustable rocker arms are the way to go and will fix the problem.

What do you guys think, any advice is appreciated.

Thanks,

I think if you grind the valves, they grind the face and seat, which would cause the opposite problem. The top end of the valve (the part that touches the rocker) would now be higher.

Did your first mechanic put new pushrods in? Are they the right ones? Are the rocker nuts tightened down all the way? Are you getting enough oil pressure to pump up the lifters? Did your second mechanic take a look at the cam? Was it wiped from idling during the break-in? You had those metal shavings, remember?

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'73 Convertible, 351C 2V
'91 LX Convertible 5.0
Member: Valley Forge Mustang Club
"I may not have gone where I intended to go, but I think I have ended up where I needed to be."
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What i did to alleviate buying shorter pushrods was to buy the conversion kit from CompCams that converts the nonadjustable valvetrain to fully adjustables. At the bottom of the following link is the kit. Its $40 or so but much better IMO than nonadjustable valvetrain. Pretty much any headwork or cam swap will change the preload and longer or shorter pushrods are needed.
http://www.compcams.com/Technical/CurrentCatalog/HTML/318.asp

If you had shavings, i'd be taking the car back the "the mechanic" and have him put a dial indicator on the rocker arms and go through the firing sequence to ensure that a lobe isn't wiped. If so i'd be raising some hell on him getting you a new cam.

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Originally posted by traumastang:
...They cannot guarantee it will fix the problem but they are pretty confident that it will...

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That's what bothers me the most. These guys sound like they don't have any better idea than the first guy. I would start with checking the cam with a dial indicator like buening said.

buening - If your preload was too high then your lifters were compressed too much. Yours didn't start making noise until your push rods wore. Traumastang is saying, "they are telling me that every lifter is rattling," which implies too much slop in the valve train. I would check to make sure all the correct parts are in and the cam is good before I changed to adjustable rockers.

I am going to call comp cam (the ones I bought the cam from) and see if they sent me the correct lifters (although it did come in a kit with the cam). I was curious, could the 1st mechanic have also put the rods in wrong? I read in one of my books that it says if you reuse the pushrods they shold be marked and put in the exact same lifter journal.

Another question, do you think I should just pick up the car (they say it is running good, just has lifter rattle) and install new pushrods in it? I am wondering if I should have put new pushrods in it when I had the cam installed.

That one comment ddenton made about having enough oil pressure to pump up the lifters also has me thinking. When I was driving the car, before any work was done, my oil pressure guage would go up to high normal and then once I hit high speeds it would come down to just a bit over midway. Could I have an oil pump going out or working "half-ass".

I am going to go down to the shop that has it now and ask some of these suggestions you guys have asked me and see how I feel. I already checked into renting a garage and doing the work myself with the help of my brother (who is alot more mechanically inclined then me but lives in Indiana). I might just take the heads off and have them checked then put in new valvetrain components for the money I would spend.

Thanks again for all your help guys, it is making me feel a little more sure of myself.

The cam is a Comp Cams 280H and from some posts on the 351C forums, other guys have had problems with noisy cams from Comp. The opinion is that the closing ramp is a little too fast for the 351C valve size and "bangs" the valve shut, instead of easing it down gently. Either that or my valve guides are toast and the valves are just rattling around in the heads. Won't know 'til I pull them this winter...

Do you think I would be ok to drive it with a little lifter rattle until this winter. Because in November I was going to garage it (one of my renters will be moving out and has a huge morton building on the property) and redo the entire motor and have the heads check.

The only thing is I would rather get it running now but hate to throw money at a "patch fix" if it would be ok running for a month or two until my garage becomes available. (think of all the questions you guys will be getting when i try and do some mechanic stuff myself).

Thanks again,

I just got off the phone with a guy from Comp Cams (my new cam was one of their CL32-241-4) and told him what my mechanic is suggesting with the adjustable rocker arm setup. He said that actually should have been considered when any cam other than stock was put in. He said that on that cam the back end of the lobe is actually a smaller lift than the stock cam, so if all my lifters are rattling like the mechanic says then he said adjustable rockers should have been installed.

I asked about just getting the correct pushrods and he said that would fix it too but he said it is much more complicated and labor intensive (have to get a pushrod measuring device and what not). His recommendation was to put the adjustable rocker arms in and that way if I have trouble down the road it can easily be adjusted again. The only other thing he suggested was sticking with stock length on the pushrods but getting hardened ones because of the stud mount rocker kit that uses guide plates.

This sound right to you guys? I mean the part about the cam lobe being smaller on the back-end. That would make all my lifters rattle then correct?

Thanks again,

quote:

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Originally posted by Hemikiller:
...The cam is a Comp Cams 280H and from some posts on the 351C forums, other guys have had problems with noisy cams from Comp. The opinion is that the closing ramp is a little too fast for the 351C valve size and "bangs" the valve shut, instead of easing it down gently...

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Traumastang... "He said that on that cam the back end of the lobe is actually a smaller lift than the stock cam" this is the same thing hemikiller said above.

Go with the manufacturer's recommendations.

quote:

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Originally posted by traumastang:
The only other thing he suggested was sticking with stock length on the pushrods but getting hardened ones because of the stud mount rocker kit that uses guide plates.

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Does your heads have guide plates??? Guide plates are used on adjustable valvetrain heads. They are not on your heads if yours are non-adjustable. The kit that they sell is just a spacer and a nut. The nut fits tighter than the stock nut, thus making it similar to a locking nut. Basically it holds the adjustment instead of rattling loose like the standard rocker nuts. I went with standard length non-hardened pushrods on my setup. There is another conversion made by Crane that utilized guideplates but i am not aware of CompCams making them.

Hardened pushrods won't hurt your engine, but they are higher priced and are overkill if you don't use guideplates IMO.

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1968 mustang j-code sprint.13.69@101 306cu.in, stock ported heads,weiand exellerator,650 holley DP,hedman hedders,comp 292 Magnum cam,4-speed,8 inch 4.11 detroit locker...................................................................1966 mustang coupe project.289 4 speed,3.20 rear http://mustangsandmore.50megs.com/MembersPics/mustangboy.html

Yea I spoke with my mechanic and told him what the Comp Cam guy said. He said he was glad to hear it because they was basically at a loss to why it would cause that kind of problem. The adjustable kit he is getting comes with studs, rocker arms and guideplates. I ordered some hardened pushrods (stock length as Comp Cam recommended) and they was only $27.50 with S+H from Northern Auto Parts Store (they are comp cam brand).

Once this is done and it gets back to me (next week I am hoping) it shouldn't take me a day to install the interior (new carpet, headliner, refinished 1/4s, console, ect.). So maybe I will get to take it for a cruise once before the weather turns to bad ehehe. Then the only thing left is to install new brakes, then suspension and it is completed except for the little stuff.

Thanks for your guys help as I would not have known what direction to take with all this stuff. BTW, if I can help you guys with anything let me know, I am a registered trauma nurse specialist and I build custom computers/networking solutions during the week (this hobby has paid for most of my car stuff so far). Just let me know if you need cheaper parts or any tech help and I can help ya get em