Hot Boat

Well I think I found out why my #8 intake valve hit the piston. when I was prepping th block to install the head for some reason I was playing with the lifters and luckly found that the #8 intake lifter seemed tight.

Needless to say it took me 4 hours to get that piece of $hit out. to say it was stuck is an under statement. I was unbelievably frustrated. But I got it. I started at 7:00pm and it got out at 12:30am

So the big question is why did the lifter seize?????. it is all roughed up in the edges just below the oil port. by the way it is a Iski. hydraulic roller ... I also noticed when I was cleaning my roller rockers that one of them is not rolling like it should . I dont know if that was the rocker from that lifter. I will replace that rocker.

after the lifter got out I inserted a good one into the bore and it went in just fine. so all what I will do is just hone out the bore.

when I lost the lifter my oil pressure was 60 psi and oil temp was 220 degrees.

so why did this happen ???????????????????

Tantrum

Glad to hear you got it out......
From how Im understanding it the lifter was bent. Im still thinking the valve siezed up first and the lifter bent trying to push the valve down.
If the lifter came apart I would say that caused the valve damage but thats not the case.
Well you comming to Skaterfest with us now?
Ill call you in a bit, Im at the office.

rws

iTrader: (3)

There is a chance that the clearance between the lifter and the lifter bore was not enough .Bore size should be .8437 the lifter to bore clearance should be at least .0007- but not more than .0027 . Perhaps the lifter that seized slipped through quality control.Check it out and let us know.

Rob

Tantrum

rws; wouldnt this have been caught on the dyno?

Paul, what does the push rod look like?
If the exhaust valve bent and was stuck in the closed position, the pushrod should be bent as well from trying to force the rocker arm up/valve down.

The exhaust valve could have bent from;
Exhaust (water) leak, water splashed the valve, seized it and then bent.
#8 & #7 are where you going to have cooling problems if your going to have them because they are at the end of the circulation path.
Tolerances on the head or valve were off.

Im thinking it was that SHIMPY exhaust.

DanB

My guess is you dont have a lot of hours on the motor. One of the things some engine builders miss when blueprinting a block is the lifter bores. They need to be aligned and checked for size and sleeved or honed if too far out of whack. If the lifter seized going up, it hangs up the valve and then then piston hits it and all kinds of $hitty things happen. Mike all the bores and lifters is the safest bet.

Dan

bobby daniels

For what its worth I agree with Tantrum ,,,,plus the lifter bore size is critical you need to check everyone and use a brake hone to clean them up if bad (little as the hone will not angle it right)
GOOD LUCK !!!!!!!

Tantrum

How did the rocker search go?

Back4More

Happened too me also with Isky lifters.
One was just a tad bit larger in dia. than the rest and it found the smallest lifter bore in the block by .0003
Just lucky i guess 256:1 odds and we hit it right on...I have the intake valve here on my desk as a reminder.
BTW we didn't change the rocker and that one let us know about it the next time out...so it was good you changed it.

44MTI

I'm just wondering what type of block you are running. I had the same problem with some motors that I had built by a machine shop which I trusted. Mine were Merlin Pro-blocks. About a yr. latter I came across an instruction sheet from world products which stated in a marine application you need to install bronze guides and allow extra clearance.

Hot Boat

The block is a gen 5 merc 454. it was a warranty block from merc that i got from Ron Spoal (sp) performance. It was completly redone and every inch of it checked.

Performance marine in lake George builds 1400 hp blower motors and they use the merlin block with brass lined lifter bores. Thats all I can tell you.

I called Iski cams today and they were surprised to here what happened to me. mostly because the lifter seized on the sides . not the top and bottom. The want me to send them the lifter and they said they might send me a new one free of charge. Do you think they might cover the $350 in parts and machine cost.