I have a customers car we did a conversion in ...'71 Torino with a pullout from a 2001 WS6 T/A with 55k .
Well after the startup it had a miss ,upon insection of plugs I installed new plugs & wires .....still misses ? Off comes the rail & injectors as the last 2 donor motors had ALOT of trash & rust type sediment in them & they were NASTY ! AHA This is surely the issue ...yes I already checked spark / fuel pressure & they were good .
After a good cleaning & checking injectors spray ,all were good .....#7 is still missing ? Off comes valve cover & rockers on # 7 & I put some compressed air on the cylinder & AHA ....#7 exhaust valve is stuck so I pull springs free it up & it still will not seat so we have a valve issue .
Off come heads for a rebuild & there were 4 bad valves .I fired it back up today & # 7 is still missing .Compression test is next since valve would not seat before & check .....well # 1 is 75-80 lbs,#3 is 25 lbs ,#5 is 25 lbs ,#7 is 0 lbs.So I am thinking this motor has serious issues broke ring land or collapsed ring ?
My machinist says sometimes after having the engine down on a roller cam motor for the head job you need to bleed the valves ? I will losen rockers a lil & try this next .ANYBODY had this issue before ?
This is a first & I have done several head & cam setups on other builds & never had a issue with this .THANKS for all input !

 

What cam is in it? Have you checked for prooper push rod length? Could be they are too long holding everything up.

 

EVERYTHING is stock down to the manifolds .

 

Does the plungers move on them? They may be froze.

 

Just pullin it back in now to pull the valve cover & start checking .I am going to pull rockers off # 7 & check compression again , then try to bleed the lifters.Something is a miss ? 25lbs on # 3 & # 5 should not fire normally .

 

# 7 is bad broke ring land / ring ?will not hold 20lbs compression ,3&5 are not much better but they would fire .

 

Definately bleed the lifters. They are probably holding oil and hanging the valve open. Or, since the heads were rebuilt you need to make sure the machine shop set the valve stem heights correctly. Or, try a .025" shorter pushrod and see if that helps.

 

If it was a ringland you should have seen it because it would be the top ringland and look something like this.....


EDIT: This is easily visible with the piston in the bore since it is the top ring....

 

Top of piston was good ,no sign of any concern in anything I could see.Even after the head job was complete & # 7 was still dead I even pulled rockers on #7 to assure the valves were closed then applied compressed air to it ....after pulling the dipstick you could feel the air coming out it .Also there was NO swishing of air you get from releasing the air chuck on a good cylinder ,# 7 would not build any pressure.Compression test netted 3 tests with 0-10 lbs & 1 test almost reached 20lbs .
There was no way to do a compression check on # 7 as I found the stuck exhaust valve , I even freed the valve but it would still not seat or pull any vacuum .All cylinders looked real good ,# 7 did have a minor 1/8 " wide lil scrape ,you could feel it with your finger but it would not hang a nail .I have seen much worse & run with no issues .
The salvage yard refuses to help any on all this & I have referred customers spending over 15k at his yard on pullout combos, radiator & fan combos , I spoke with Brandon @ Searcy Salvage to try & get a lil help on at least the short block but no luck as he assurred the customer this was a good pullout but clearly was not..It will be on the customer but is definately not the norm for these engines .