So over the last year I rebuilt the engine in my 1980 Ford f-350. It is a 351m and so I got it put together and sent it to a shop to get carburetor tuning done and when I got it back, it had some valve noise. I pulled off the covers and haven’t seen anything wrong. What should I be checking for? Since I rebuilt the engine could the pushrods be too short?

 

I am guessing you checked the oil level and it is in the safe zone?
What is the oil PSI when you hear the noise and dont say the factory gauge is in the middle we need real numbers so you may need to install a mechanical gauge for testing.
I dont know if your valve train is adjustable or not but how much lifer preload did you put on them?

Now I am going to the dark side.
New cam & lifter installed did you use break in oil that has high level of zinc and at oil changes too?
Could be the cam has gone fat and is putting metal throughout the motor.
How many are making noise?
Dave ----

 

The pushrods could be too short if the guy that did the cylinder heads didn't get the valve stem height correct, or you put in a aftermarket cam with a different base circle.

Have you ever rebuilt a small block chevy or other engine with an adjustable valvetrain? That is the procedure you need to use, even though your valvetrain is not adjustable. If you pretend it is adjustable and check the lifter preload, that will tell you if the pushrods are the problem.

What you will do is pick a cylinder, and run it around till it is TDC firing. You then back off both rocker arm bolts on that cylinder till there is play in the pushrod. Then slowly turn the bolt back down till you just get rid of the pushrod play. Then watching your ratchet, count the number of turns till the bolt is tight. If you can never get the play out before the bolt is tight, obviously the pushrod is too short. Or if the play is gone just as the bolt tightens, it's too short. The best place to be is you turn the bolt 1/2 turn after the play is gone, and the bolt tightens. 3/4 is ok, 1 turn will still work. Over 1 turn, and the pushrods are borderline too long.

What you are doing is plunging the pushrod into the lifter. The lifter works to take up the slack. But if you are out of range of the lifter, you will get noise.

And don't forget, we have had a rash of poor quality camshafts and lifters that have hit the market the past few years. You may have gotten one of those.

 

no, this is my first engine rebuild. I will try the procedure when I get the chance and let you know what I find

 

So I’m supposed to tighten it down and torque it? If so what are the torque specs? Cause I had a Ford shop manual for it but I can’t find it right now.

 

Find it here,https://www.garysgaragemahal.com/351m-and-400.html
https://www.garysgaragemahal.com/1980-evtm.html

This may help too.
https://www.google.com/search?q=how+...hrome&ie=UTF-8

 

25ftlbs, found it here,
https://www.ford-trucks.com/forums/3...procedure.html

 

When you are checking the pushrod length, you are just worried about when the bolt stops by hand. You do not need to worry about the torque until final assembly when you have things figured out and are ready to button things up.

 

So I checked the pushrods on one cylinder and it was within the thresholds. So what should my next steps be?

 

You check both the intake & exhaust push rods and when you say with in spec what was that?
You have the intake manifold off and as you were spinning the push rod with your fingers and was taking up the play when it stopped spinning when you tighten the rocker nut you could see how far the lifter plunger was pushed down?
If not how did you check how far the plunger got pushed into the lifter?

I would check 2 or 4 more valves to make sure they are the same.
If so I would think you could torque the nuts to spec.
At this point if you can I would place the valve covers on the motor maybe with 1 or 2 bolts and start the motor and see if you still have noise.

BTW did you find why the valve train was making noise and what did you do to fix it?
Dave ----

 

Steps for Stock 351M (Non-Adjustable System)

1) Remove Valve Covers: Remove the 10-bolt valve covers to access the rocker arms.

2) Inspect Components: Check the fulcrum (pivot) and rocker arm for wear. Because this is a stock system, there is no adjustment mechanism; you simply tighten the bolts.

3) Torque Sequence: Torque the rocker arm fulcrum bolts to the factory specification (usually around 25 ft. lb.,but verify with your service manual).

4) Replace Components: If clearance is incorrect, the issue is likely worn components or incorrect push-rod length, requiring replacement, not adjustment.

 

The problem is he replaced the cam with I think a non-stock one so that could change the push rod length and why he needed to see what the lifter preload is.
Once he knows the preload is good he can follow your post.
Dave ----

 

Most likely the problem is that the valve-train was not set up correctly at assembly.

He took it to a shop for carb work and they most likely rev'd the crap out of it and the valve-train is now making noise.

If he kept the POSITIVE-STOP feature, spinning push-rods and using a shim kit isn't going to fix it. Shimming is a final fix for roller rocker arm sweep after arriving at correct valve-train geometry.

What cam, lifters and rocker system was used? How was the valve-train initially setup?

 

I dont know and I dont think he said other then not stock IIRC
We (I) also dont know if this made noise before or after the shop had the truck. It could have been that way when he screwed the motor together?
But making noise is not right and he needs to fix it or other bad things can happen.
Dave ----

 

Does the engine run ok? Idles a little rough? They have been having terrible problems with defective new camshafts and lifters the past few years.