valves question

a couple of questions and after looking back at last weekends race right before i loaded up i serviced the car from an easter weelend race and found that i had a burnt push rod i replace it loaded up and went racing the car made two runs no problems BUT i noticed that the push rod i replaced after each run the adjustment was a little tighter i thought maybe i missed the adjustment just a little but it left me scratching my head because i dont miss on the valve adjustment but i thought maybe i did do to the long nights

( TIT VALVES ) no sign of the seat none of it is there


question do you think the valve was stretching each time a little causing it to get tighter on the adjustment seams to me that was the sign i just never had any thing like that happen

and the other question what would cause it

the motor was not lean

its not been over reved

nor did it run any longer than normal

on that run it shook i peddled it once when i slapped the throttle it went pop pop and i lifted and shut it off

the motor looks brand new on the inside even that hole except the hole in the piston no signs of ever being lean are hot


thanks jim

 

Jim,

I had the exact same problem two weeks ago. Thought I was losing it and triple checked it but sure enough, the valve head was distorted. There was nothing wrong with the seat or anything else. Pulled the head and replaced the valve and the lash was back to normal. This was on a stainless valve, 24 passes with light spring pressure.

Tom

 

mike it was through the intake i thought i blew the burst panel but it wasnt that. detination i have ran this tune many times wasnt leaning on it was rich if any thing i checked the plugs each time new set each time wasnt no where near lean only burning half way around only 30* of timing i was wondering if it may have been a valve failure i will deffintly check the nozzles the whole thing has to come a part now for sure i found the seat it jumped over to the other side and so did the valve stem it just leaves me confused i tuned the same way i always do its got me puzzled

ps it was the intake valve mike

 

Mike,

On my issue, it was the leanest hole as we were tuning and watching the plugs. The plug out of this hole had heat only on the base and half-way down to the first thread. Didn't see any sign on the plug of detonation. We did increase the nozzle in that hole by four after the valve change and it equalized the plug readings in all eight holes.

Even though it was leaner than the rest, we still were not leaning on it that hard. The only thing I thought could have caused it was the leaner condition but the plugs and temps (~1k) didn't seem to indicate it. We had 34* total on a BBC wedge with 7* taken out at the hit and not ramped back in until 2.5 seconds. If it as detonation, where else would I see the indication? Thanks.

Tom

 

Jim what heads are you using?

 

older bae fuel heads

 

I have the same heads on a car I work on and thought I had a valve problem and pushrod issues as well. I found out it was the bubber line feeding the port. It looked fine on the outside but when I looked on the inside the line was delaminating. It looked like it had torn on the inside and was blocking the flow.