I have a 408 stroker and i have zero compression on bank 1 bank 2 reads 180psi in all four cylinders. So I assumed a head gasket. But when i loosened the rockers for cylinder one and tried the leak down test my dad said he seen the spring go up a little on the exhaust valve and when I went to move the rocker it was so tight I couldn't which tells me that it did move back up. With the rockers off the cylinders builds between 200 and 220 psi on each cylinder on bank one. So my question is why? Why doesn't bank 2 have compression with the rockers on but bank 1 only has it with rockers off? Pushrods are the same length nor bent, no broken springs or valves and lifters are fine and im assuming no bent valves because i would assume i wouldn't have compression either way. Its almost like the valves are being stuck open but its a brand new head. Now the pcv was hooked up wrong by the shop and I did burn through about a quart and a half of oil in only about 250 miles. And 5 and 7 plugs were black but 1 and 3 were same as 2, 4, 6, and 8. So what could it be?

 

Lifters could be pumped up and stuck open so valves won't close

 

Why did you start another thread on the same issue? The members asked you valid questions and you said you did all the things they suggested. Now your saying it has no compression on bank one. WTF Refer back to your other thread and read it carefully. There is solid advise in there. I would get rid of the pcv valve all together and just put a breather on the intake and the valve covers. The reason the members asked you to show pictures of the plugs is because black means fuel and crusty brown is oil. If your not going to do the things you say you did how do you expect to find the answer? Good luck I'm done.

 

started a new thread because i couldn't find the other one i still can't won't show up for me when i click on it it showed it was removed. They're black I know the difference between brown and black im not stupid if I said black then they're black. And as far as i remember I said the compression was fine which it was now i have no compression so totally different issue then what I was having before. Before i had 2 black plugs rest were fine. But also had compression and drive fine now after sitting for a few days have no compression so once again totally different issue then before. So no need for the attitude considering im not the only one with a bank with no compression it would be worthy of a new thread anyway. Telling me to do all those things and having people skip over it because it's labeled about bad spark plugs won't help some one with a complete bank down now will it? Regardless of the thread issue its a totally new problem even after trying everyone help and recommendations new **** still happened and now no compressiom.

 

how does one fix that or what causes that?

 

These are the two bad ones. They still fire so it's not the plugs brand new wires and everything i was told on the previous post. I can't find that post it won't show up for me for some reason Idk why. So I started this one sorry for the confusion.

 

You need to check every pushrod for the correct length, You could be running one head that been milled more than the other making the pushrod length different from one side to the other.

 

makes sense but why with the pushrods and rockers out does the valve move up when air is put in? Makes it seem like the valve is stuck open but its a new head and only 250 to 350 miles on it

 

Bent valves would be the only reason I could think of, It should only take light spring pressure to keep the valve up.

 

but when I put air in it closes and stays close then i have compression. So a bent valve wouldnt allow me to have compression no matter what right?

 

depends. if the guide is worn and the valve is just slightly bent, it might be able to tweak around enough to seal with a little encouragement.

your thought process kind of concerns me, though, because you mentioned you already checked compression in the other thread and you seem to act like it was fine. now it's obvious there is another issue. you gotta relax and take your time, be thorough.

who did your heads?

 

the other thing i would check for is to see how recessed the exhaust valves are. if the place didn't install new seats on heads with worn seats and worn valves, well...

 

I know it sounds like I'm crazy but I had someone there with me and he seen the same thing the first time I had 125psi in cylinder 1 and like 40 in 3 and 0 in 5 and 7 and now I do it i have 0 in all four. So not my thought process its legit how it happened and kept happening until I tried the leak down test and introduced air into then I pushed up the exhaust valve that sealed it and allowed 220psi with out the rockers installed with rockers installed still had 0 psi. Confusing I know.

 

also this head was brand new from Texas speed and checked by the machine shop just incase...

 

Were the heads a matched set or did you buy one head?

 

OP, are you running short travel lifters or the ls7 lifters?

 

i had to only buy one head but the machine shop supposedly milled them to match

 

as far as i know plan ls7 lifters

 

Just a guess but I would say bent valves from one head being different from the other. One head being milled more than the other could cause PTV clearance to be to close on just one bank and the other side just kissing the valves enough to put a slight bend in the valve causing them the hang open slightly. If you don't want to pull the head to check the valves then install a light weight checker spring and see if the valves seat easily.

 

What the cylinder looks like valves look fine though... Both 1 and 7 look like this so i assume all of them do