About 2 years ago I turned my 351m into a 408. I did a complete rebuild. I don't drive it much at all. If it sits for a couple of days when I start it, for a second or two I can hear what I think is the lifters until oil pressure pumps them up and then it gets quiet. It doesn't do it if I drive it often. So I thought I had a bad lifter, so I replaced the lifters and broke them in. I have the same noise. So maybe it's my oil filter? I use a Napa Gold 1515 filter. Or maybe it's my valve setting? Do I have them set too tight causing the lifters to leak down? Due to the heads and block being milled I had to use different pushrods and shims to get the rockers to push on the center of the valve stem. I forgot to mention that the truck's timing is not very advanced, about 8 degress BTDC but it fires right up. I've got a good battery, good starter, good coil, wires and plugs, so two pumps of the throttle and just tap the ignition and she comes to life. I think if it cranked over more before starting I wouldn't hear the noise because oil pressure would be building before it was running? That actually leads me to the second part of my thread which is questions about harmonic balancers on 351/400s. I sometimes wonder if the ring on the balancer has slipped and my timing marks are incorrect.
1: Are there differences between a 351m and 400 balancers?
2: If a rotating assembly has been balanced, can the harmonic balancer be swapped for another? As in can I put a FluidDampner balancer on there?
When the truck is warm and idling in gear I get a harmonic sound throughout the truck. Maybe I have my idle set a tad too low, but this dang thing makes so much torque that if the idle is higher it takes a lot more brake pedal pressure to keep it stopped at the lights. It just wants to go.


Thanks in advance for your help!

 

1977/79 F100/350 351M/400: Three possible harmonic balancers: Year? 2WD or 4WD? A/T or M/T?

There will be a FoMoCo ID number stamped on it...post what it is.

 

Lifters leak down no matter what spring pressure you have. But what lifters did you use? I see roller rockers so I'm guessing roller lifters?

On the damper, you can replace it on a balanced engine. That's not the best thing as the old one was part of the balance, but they shouldn't have changed it much just so you can change if needed.

 

The truck the engine is in is a 79 F150 2wd 351/c6 that is now 408.
The numbers from the balancer that was used to balance the rotating assembly is D2AE-CA. The other balancer I have is D5AE-AA.

The engine has roller rockers but has a flat tappet Comp Cam. The lifters I just removed were Comp and now it has OEM from the local parts store.

 

My catalog starts at 1980, but the 80 - 81's used D5AZ 6316-A for a 351M and D2AZ 6316-C for a 400.

 

D5AZ-6316-A .. Harmonic Balancer / Marked: D5AE-6316-AA / Obsolete

1977/78 F100/350 351M A/T / 1979 F100/350 351M A/T & M/T / 1980/81 F150/350 351M A/T & M/T

 

Well at least it seems I sent the correct balancer to the machine shop. The thought had entered my mind that I might have somehow mixed up the balancers. I need to take a closer look at my crankshaft pulley. Maybe the harmonics are from there. Hopefully not from my rebuilt transmission. My alternator belt flaps around when the engine is reved. I originally thought it was because I upgraded to a 3G alternator and it wasn't lining up, but I no longer think that's the case. I've got another pulley I'll try although that still doesn't mean that the ring hasn't slipped some. I once had a Corvette have the balancer come apart.
So any thoughts on the lifter noise? Does anyone else have this issue? Guess I'll have to pull the valve covers off and check the rockers when it's cold and see if I've got some slack in the valvetrain. It's a pain to get that passenger side valve cover off with the a/c box there.

 

Could it be the rockers? I know roller rockers make some noise.

 

Did you check how much preload do you have on the lifters ? When you found your push rod length did you remember to add the preload figure to the length you came up with before you ordered the new ones ?