440bb 40psi cyl6 not firing help!!

[pnora]

What makes you think the head is messed up? Maybe just need new valves and an adjustable rocker assembly?

For one I do not ever remember seeing valve stem heights that bad. Two you obviously have cylinder leakage. Three it will never be right in the condition it is in. Myself I would do the leakdown test. If its valves then I would pull the heads. I would then measure the cam lift to get an ides of what is in there. If what we see now on the heads is any indication of how the rest was done you no doubt have a time bomb.

 

[dadsbee]

I have to agree, intakes rarely stick.. it's always the exhaust valves. Give one of those low intake valves a few raps with a wood or brass hammer. If it doesn't come up to the height of the exhaust stem.. the head needs serious WORK.

Here's my 383 head... rebuilt in 1976. This shot is from 2017 when I was doing seals All stem tops even..

 

[Dave6T4]

@PRHeads ?
Looks like the valves are sunk. Back in the day a shade shop would take the assembled head to a belt grinder and equalize the valve stems lol. But they're pretty out of whack.
Rocker shaft shims are ok for the correct application( head milled, pushrods too long,.. less lifter preload for higher rpm etc..) but not too sure what the builder was shimming for

When I pulled my heads down last year on my 440 in my '67 R/T, I found shims under the rocker shafts. I had this engine rebuilt about 35 years ago by a reputable local builder. This guy was well known in the area for building performance engines. I figured he shimmed the the rocker shafts to get a few more rev's before lifter pump-up. I reassembled it without the shims. This engine has run 70,000 miles without a hiccup. I had to swap heads side for side, because the alternator bolt snapped off, and we could not get it out. The other side head still had a good threaded hole. What a PITA!

 

[TruckManiaMike]

For one I do not ever remember seeing valve stem heights that bad. Two you obviously have cylinder leakage. Three it will never be right in the condition it is in. Myself I would do the leakdown test. If its valves then I would pull the heads. I would then measure the cam lift to get an ides of what is in there. If what we see now on the heads is any indication of how the rest was done you no doubt have a time bomb.

after doing some research I have to agree with it being sunken exhaust valve seats. Is there a way I can measure the cam lift without taking it out? Would the fix for the heads just be hardened exhaust valve seats to be machined in and new exhaust valves? (As long as intake valves aren’t leaking during leak down test)

 

[dvw]

Years ago while working with Dave Koffel his 440 dually tow vehicle started missing. Checked itout and found low compression in a few cylinders. I pulled the rocker covers. The stems looked like the heads in question. Once the heads were off it was easy to see. The exhaust valve seats were receded. Some a 1/8".
Doug

 

[pnora]

after doing some research I have to agree with it being sunken exhaust valve seats. Is there a way I can measure the cam lift without taking it out? Would the fix for the heads just be hardened exhaust valve seats to be machined in and new exhaust valves? (As long as intake valves aren’t leaking during leak down test)

You can measure the lift with a dial indicator off the lifter. Heads are hard to tell until off apart on the bench. I would think that valves, seats, and guides most likely will be needed. Mag first to make sure there are no cracks.

 

[12icer]

If it were my call I would pull the heads two cylinders side by side with low compression most times is the result of a head gasket leak or crack.
As for shims I never use them if you have a problem in the geometry of the valve train you are using something not correctly installed or adjusted since you have the covers off get a 100 foot piece of paracord put in the plug hole of at BDC turn till it s against the valves of any cylinder with 15# lower than the highest cylinder and take the springs off and test them.
If all of them are ok as you work through them setup rotate each cylinder up to both valves on baseline and air test it.
Spray atf around the valve stems and something that smells different in the exhaust and intake outlets.
Any cross between cylinders on the air test gonna be head gasket most likely.