I posted this in the engine forum and only got 1 response in a week. So I will try here.


I have a 79 f150 with a 351m all stock and original. I have just changed the lifters and now some of the rocker arms are tapping and i can't get them to stop. Following a master mechanics instructions I torqued them down to 22 foot pounds. And still they tap. It runs better now with more power and a smother idle. He told me that the valve springs need to be replaced but I wanted to ask here first to be sure. The heads are the pedestal mount type. Should I rebuild the heads or try and change the valve springs? Any help would be great.

Thanks

 

In my experience the rocker arms and their pivots are most probably worn beyond the service limits. This causes the arms to be too loose. I have in a pinch added thin washers under the nuts for a temporary fix but you are really asking for trouble in the long run, such as bent push rods or a dropped valve.
If you have the resources by all means have the heads reworked.

 

<TABLE width="100%" border=0 itxtvisited="1"><TBODY itxtvisited="1"><TR itxtvisited="1"><TD vAlign=top itxtvisited="1">The 351M has torque in place rocker pedestals, it does not have adjustable rockers w/ studs. the only way to adjust this engines preload is to change pushrod length or shims under the pedestal.

Some how I don't think you problem is in your pushrod length, you may have a couple of bad lifters ( NEW= Never Ever Worked). not all new part are trouble free. hows the oil pressure? there's only a couple of things that will cause rockers to make noise, low oil pressure, bad or collapsed lifters, bent pushrods, worn out or not seated pedestals.


just a thought, if you want adjustable rocker arms, Crane Cams makes a conversion kit, It worked ok on a 460 i had years ago.
Crane Cams # 52655-16



Hope this helps you

</TD></TR></TBODY></TABLE>

 

Today I pulled the lifters again and found nothing to indicate a bad lifter. I also took the push rods to the shop to check them. Everything is good with the push rods. Which makes me think I would need the heads worked on.

Would the Edelbrock heads (part # 61629) be a good option? Are there other heads that are not pedestal mount that I could go with new or used? I dont care if I have to change the heads I just want a reliable motor.

 

Yes the Edelbrock heads would be a good choice. this info is from Jegs.com,
These heads would be the modern equivalant of the ausie heads. Good luck solving your problem. -RW Looks like their less $$$ at Summit,

<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 10px"></TD></TR><TR><TD style="PADDING-RIGHT: 10px; PADDING-LEFT: 10px; VERTICAL-ALIGN: top; PADDING-TOP: 0px">Edelbrock 61629 - Edelbrock Ford 351C/351M/400M Performer RPM Heads


<TABLE width="100%"><TBODY><TR><TD>


Until now, there weren't many options available when it came to aftermarket head selection for the Clevelands. Now, that's all changed with the Performer RPM head for 351-C. Designed to work with the 351-C, 351-M, and 400-M, they feature very streetable 190cc intake runners with 2.05" intake and 1.60" exhaust valves that provide more than enough volume for outstanding power to 6500+ rpm. Not only do they offer superior flow over a stock Cleveland or 351/400-M head, but they also offer the flexibility to work on the standard 302 or 351 Windsor block to build your own version of a Boss 302, or the infamous "Clevor" engine! The intake and exhaust ports are in the stock location to further add to the streetability of these heads, and can be made to breathe even better with minor port work.
Note: When bolting on to 289/302 engines using 7/16" bolts, use stepped head bolt washer kit #350-9680.

</TD></TR><TR><TD align=middle><FORM onsubmit="getElementById('AddtoCart').disabled = true;" action=/webapp/wcs/stores/servlet/OrderItemAdd method=post> <TABLE cellSpacing=0 cellPadding=2 width="100%" border=0><TBODY><TR><TD class=itemBlockLTop></TD><TD class=itemBlockTop colSpan=4></TD><TD class=itemBlockRTop></TD></TR><TR><TD class=itemBlockLeft rowSpan=2></TD><TD class=itemBlock rowSpan=2>Edelbrock #350-61629


Performer RPM Head - Complete Ford 351C/351M/400M
1/pkg
More Details </TD><TD class=itemBlock align=middle width=30><INPUT maxLength=2 size=2 value=1 name=quantity> </TD><TD class=itemBlock align=middle width=80>$979.99
Ships
08/17/08 </TD><TD class=itemBlock vAlign=center align=middle width=100><TABLE><TBODY><TR><TD></TD></TR><TR><TD vAlign=top align=middle></TD></TR></TBODY></TABLE></TD><TD class=itemBlockRight rowSpan=2></TD></TR><TR><TD class=itemBlock vAlign=bottom colSpan=3><TABLE><TBODY><TR><TD> </TD><TD vAlign=top></TD><TR></TR></TBODY></TABLE></TD></TR><TR><TD class=itemBlockLBottom></TD><TD class=itemBlockBottom colSpan=4></TD><TD class=itemBlockRBottom></TD></TR></TBODY></TABLE></FORM></TD></TR></TBODY></TABLE>Bolt-on power, right out of the box.
These Edelbrock Performer RPM aluminum cylinder heads feature threaded inserts in the rocker studs and exhaust manifold bolt holes for superior strength and durability, plus hardened seats, bronze valve guides, and fully machined valve cover rails for a more consistent gasket seal. They offer improved power throughout the rpm range for greater throttle response and top-end horsepower. The intake and exhaust runners are CNC-machine profiled for superior flow and performance. </TD></TR></TBODY></TABLE>

 

Why did you only change the lifters? Or did you change the cam too? Maybe the cam is possibly going flat.

 

I thought about that also. Just not sure on how too "check it" without opening the motor. I have thought about changing the cam also. I got a pretty good deal on the lifters so I figured I'd try that first. But I just i need a cam.


Cam Suggestions?

 

The only real way to check is to pull the cam. You'll be able to see a "flat spot" on the cam. It will look like two high points on the cam lobe with a flat spot in between them. I had good luck with a Comp Cams 268H cam in my 302. Changed to a 274XE later on though.