[font size="1" color="#FF0000"]LAST EDITED ON 30-Sep-01 AT 03:06 PM (EST)[/font][p]I just replaced the oil pump and rear main last night in my truck. Upon startup she ticks realy bad. I took the rocker covers off today and checked out the valve springs and all. Well...come to find out the valve stem seals have disinigrated and pieces of them are just laying inside the springs. (explains the smoking and pieces of plastic(?) in the bottom of the oil pan too) How hard is it to replace the valve stem seals and set the valve lash on these engines? I have both a Chiltons and Haynes book and both have a section on how to do it but I just want to make sure the average mechanically inclined person can do this. I don't want to screw up the motor by trying it. Oh yeah...I was also reading that they won' need adjusting. The hydraulic lifters will take care of that. Is that true?

Robert

1978 F-150 4x4 Stepside 351M

Please don't pull out in front of me! The last thing I want to do is play identify the pieces with you or your car.

 

It's not tough with the right tools (valve spring remover, air compressor) but you will have to reset the intial lash on the valves, also not a tough job. I'd suggest you look at the archives, there are several posts on correctly setting the valve lash on these engines.

 

You wouldn't happen to know which archive it is would you? There's about 1000 archives under the 67-79 list. I'm goin cross eyed trying to look through them all.

Robert

1978 F-150 4x4 Stepside 351M

Please don't pull out in front of me! The last thing I want to do is play identify the pieces with you or your car.

 

Here, this may be easier than trying to find it:

Make sure the rocker you're adjusting is on the base circle of the cam. Tighten the rocker down until there's no up & down play in the push rod (zero lash) then go another 1/4 - 1/2 a turn more so it compresses the lifter assuming they're hydraulic. You don't need to prime the engine first. Repeat the process for each rocker by following the firing order of the motor or you can bring #1 cylinder to TDC on compression stroke then adjust #1 I & E, #4 I, #3 E, #8 I, #7 E. Then turn the crank 180 deg and adjust #3 I, #2 E, #7 I, #6 E. Then turn the crank 270 deg and finish with #2 I, #4 E, #5 I&E, #6 I, #8 E.

As far as replacing the valve stem seals you need to find a way to keep the valves from dropping out when you pull the keepers & retainers. The best way is compressed air thru a plug hole. There are other ways involving stuffing rope thru the plug hole but I've never done it. You'll also need a tool like this:

[link:www.autospecialtytools.com/cgi-bin/dyn*****?doc=../catalog/search/z3bb51398RA.dht|Skyway Tools]

Universal Overhead Valve Spring Compressor
ISN KD Tools 2078 Item #1903
Price: $25.95
Shipping: $4.50

 

I have a valve spring compressor simlilar to the second one there. I don't have hydraulic lifters on my engine. I've heard about using the sting thing but wouldn't it get caught inbetween the piston and cylinder wall??


Robert

1978 F-150 4x4 Stepside 351M

Please don't pull out in front of me! The last thing I want to do is play identify the pieces with you or your car.

 

Well ya got me there. I've never owned an engine with solid lifters before and I just don't have the specs for cold lash on a solid lifter 400. I don't think I've ever seen any pusblished. You may need to consult the lifter or cam manufacturer. The adjustment sequence should be basically the same however. I assume if you use a large enough rope, like 1/4" or better you probably wouldn't get it caught.

 

Bill, as far as know, these engines (as with most fords) are non-adjustable. If he doesn't tighten the bolt down all the way, it will work loose over time and really cause problems. I have heard of adding shims under the rocker pedastel, and the ford recommended longer or shorter pushrods. But these normally are not necessary unless an improper valve job was done, or a cam with a different base circle is installed.

 

You're right. If he has non adjustable r/a all he can do is either use different pushrods or shims so he shouldn't have to worry about setting lash.

 

See...that's what's confusing me. The Haynes says they don't need adjusting while the Chiltons says they will. Also a lot of people and the Haynes book are talking about hydraulic lifters and all. As far as I know I have solid lifters ( I think). Just to make sure though how do I tell if they are hydraulic? I'm starting to get a little confused here.... Which is correct? Do I or don't I adjust them?

Robert

1978 F-150 4x4 Stepside 351M

Please don't pull out in front of me! The last thing I want to do is play identify the pieces with you or your car.

 

Well first off no 351M/400 engines ever came with solid lifters stock. Second if you have solid lifters then you must have adjustable rocker arms in order to adjust the lash. Third all 351M/400 engines came with non-adjustable r/a stock. So if you have non-adjustable r/a then you have hyd. lifters and no adjustment is necessary or possible. If you have adj. r/a then you may have solid lifters but maybe not. The only way I know how to tell is to visually inspect the lifter. If you have non-adj. r/a then tighten them down and forget about it.

 

Ahhh...ok. I think I got it now. As far as I know everything in the motor is still stock. So I just put the new valve stem seals in and put it all back together and forget about it then eh'? Ok, cool. Thank you guys very much. You all have been a BIG help!! =)

Robert

1978 F-150 4x4 Stepside 351M

Please don't pull out in front of me! The last thing I want to do is play identify the pieces with you or your car.

 

If everything is stock and went back together the same way it came apart there should be no problem.

HOWEVER, Pedestal mount rockers from Ford MUST be adjusted if ANY work has been done. Some builders just tighten and go and this can lead to a lot of damage.

You adjust pedestal mount rockers just like stud mount except when you get to the actual tightening you can only turn the bolt 1/4 to 3/4 of a turn as the bolt reaches 20 pound feet of torque. If more than 3/4 of a turn, add shims if less than 1/4 of a turn you need a longer push rod.

 

I was told by guys who do head work, if a certain amount of material is taken off the valve face, then the same amount is ground off the valve tip to try and keep the valve stem height the same during a rebuild.

 

Well...in the researching and all I've decided to take the heads to the local engine shop and have them do a 3 angle valve job on them. I'll do the head porting and all myself but not the valve job. I do appreciate your guys' help though. I'll keep all this saved for when I get around to the 460 I'm droping in next year. Thanks again!

Robert

1978 F-150 4x4 Stepside 351M

Please don't pull out in front of me! The last thing I want to do is play identify the pieces with you or your car.