I have recently purchased a 1979 F250 4x4 351m/400 4spd . Has alum. intake , rv cam not sure exact size and a edelbrock 4bbl carb . Had a problem with timing and back firing so i dug a lil deeper an found a prob . #1 cyl . bent pushrod, collapsed valve spring and 0 compression .removed head and the valve is intact and seems everything else is not damaged . I checked all other cyl and compression ranges from 120 to 130lbs and valvetrain seems to be ok . am stuck not sure where to go from here . do i replace the heads or replace valve springs and retainers ? i want to keep the cam, i liked the performance . i am just not sure what i can do to fix it and keep it from happening again.

 

It's easy to set here and type and spend someone else's money. But if it had good oil pressure and was running OK before the bent pushrod. You could roll the dice and replace the pushrod and spring and see what happens. If it don't work out then you get to start breaking out the $100 bills.

 

thanks . Upon further inspection I found that lifter has a half moon belly on it so I've decided to go with new cam , lifter and timimg kit . I figured its best to fix it properly instead of a band aid . I love the truck an wouldn't mind some power under the hood . Now I am trying to decide what cam size to go with . Thanks for ur help and any suggestions u may have on good size cam to use would b appreciated

This is my current project

 

Thats a pretty solid looking old truck.
If you lost a lobe and lifter there is a REAL good chance it might have scored the #1 and #5 cylinder walls and messed up some bearings and no doubt hurt the oil pump.
I've lost a lobe or two over the passed 30 years and it almost always damages other stuff. At any rate there are iron filings in your engine and it needs torn down and cleaned out.
The problem all of us old school guys have with running flat tappet cams is there hasn't been a flat tappet lifter made in the US of A since 2015. The reason is the lifter manufactures depend on volume and all the OEM's now use roller lifters. So if you buy a flat tappet lifter it's going to come from Mexico, Taiwan, or China. Exception being some high end race only lifters that cost as much as a set of rollers.
I'm trying not to type a book so I will just post a couple of links for you to look at. Buy a set of these if you are going back with a flat tappet cam. https://www.ebay.com/itm/16-Sealed-P...4AAOSwAVlb~YyL
If you get them specify in the notes to the seller you will only accept made in USA lifters, ink stamped Johnson HT900.
Everyone has their own opinions on oil, I use this oil but I'm not saying anybody else needs to. There are several good articles here to read through. https://tech.drivenracingoil.com/faq...et-rod-owners/
If you should decide to go with a roller cam I would recommend you get at least the lifters from https://www.tmeyerinc.com/ or Cam Reseach ? Custom Ford Camshafts | The experts in custom-ground Ford camshafts they know Ford engines and will sell you lifters that are compatible with the Cleveland oiling system.

 

THANK YOU . I am gonna check em out . i did get the engine disassembled down to block w crank and pistons. to my suprise there wasnt any damage except to lobe cam an lifter. valve was intact an pistons had ne damage or to cyl walls . it hadnt been driven much at all since i first noticed performance issues.

 

AFTER LOOKING AND A LIL BIT OF RESEARCH ALONG WITH ALMOST $200 LESS THAN THE MANUFACTURERS WEBSITE I DECIDED TO GO WITH THIS .

COMP Cams K32-241-4 Xtreme Energy 212/218 Hydraulic Flat Cam K-Kit for Ford 351C, 351M-400

 

Good Luck!

 

Yes, let us know how you like the new cam. And good news is that this time you'll know exactly what is in the engine!

Are you familiar with the full initial cam break-in procedure for flat-tappet cams? I wonder if the old cam wasn't done properly by the PO and you suffered the consequences.

Paul

 

The guy that put in my timing chain and cam used oil with zinc in it and then after the initial run up and 2000 rpm break in I had the oil changed and put in zinc oil again. My old cam was missing a lobe and the tappet had the moon crater in it. Run good now and I am happy. If I ever have to do it again I will put in roller tappets. I like this forum you guys are good and I thank all that has helped me along in the past.

 

i am a little bit past halfway on the rebuild . so far all has gone fairly good . in have familiarized myself with the specifics of cam break-in. thanks for the heads up because until now i wasnt sure about the break-in . i should have it up and running in a few days and wil;l let ya know how things go .