Whow, this became a real HOT topic
To be a little more accurate with my words, the valve guide clearances were not measured with a dial indicator or any other measuring device. I apologize, for me checking means that a measuring device has been used.
So the actual reading was not checked, it was only estimated being enough by wiggling the valve from the head. That MIGHT have been the Achilles heel at this proven engine combo.
Here in surroundings area are a couple of 440 rebuilds with almost similar basic components, using 440 Source heads at look-alike-restored-cars
. Edelbrock, Indy, Procomp etc heads that look like a brick have not been an alternative for those cars. Basicly so far there has not been any big unexpected issues with these heads. Changing the retainers, valve locks and at some cases also springs has saved from many headaches.
Here's some more facts from the motor (or fuel for the fire for all 440 Source bashers
)
The 2 broken guides shown are flipped upside down, the top of the valve seals were not hammered off and then they slid down the guide.
Three of the broken valve guides were intakes, one exhaust.
- Valve springs in this combo are Comp dual valve springs, seat load 130 lbs @ 1.85 and 320 lbs at max lift of the valve. Valve springs were carefully shimmed like GomangoCuda noticed from the wear of spring pockets
- Retainers are Comp's chromemoly steel 10° Super Lock and guide clearance at max lift was checked, not close
- Roller rocker arms with 1.6 ratio
- Rocker arm geometry was corrected with .030 shims under the rocker shafts.
- Cam is not very radical, a hydraulic flat tappet Comp XE284H
- With 1.6 rockers, intake valve lift .541 and exhaust valve .544
- Lifters, Comp High Energy. Preload 3/4 turn, ~.040. With ½ turn they were noisy, a little more preload was added.
- Pushrods are 3/8" diameter. Therefore the picture shows some significant clearancing for the pushrods. Pushrods are .080” wall chromemoly steel tubing and they all are straight as an arrow, no bend rods.
- Motor was driven less than 1000 miles after a complete rebuild
- Valves have not hit pistons, at least no sign of it
- Over rev, more than possible knowing the driving habits of owner
About tight valve guides [Email]Jeff@MCH[/Email] wrote earlier here at Moparts
https://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=6665484&Main=6663766 Quote:
ive never really seen tight guides though i ream them when i port them... out of the box they ream them from the port side up towards the valve top and sometimes there is a burr turned up above the guide which will restrict oil from getting in to lubricate teh valve/guide,,, ive told brandon about it and i believe he has fixed it with recent "batches" of heads
My original question was, has anyone else had similar problems with these heads and have you used some standard replacement guides or some custom fabricated guides to fit the Source heads? I did not find any direct replacement guides for these heads from 440Source website. Maybe I will give them a call.
Three of the broken valve guides were intakes, one was exhaust
After all comments, the final diagnosis for the broken valve guides is still open? 
