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valve train problem
My 427 was making a loud tapping when I backed it out of the trailer at the Dender tour last friday . Drove a very short distance to get gas, thinking it was a sticky lifter and returned to the trailer, still making noise. Shut it down and did not go on the drive. Removed pass VC and found adj lock nut off, adjuster backed off a couple turns, pushrod loose. Determined push rod still in lifter, so put it all back together and it ran fine.
Back home on monday I took it out for a drive to continue carb tuning and it ran ok except for carbs still not right. to be cont. |
Cont:
This am I was working on carbs, and started it up to adj linkage and noticed #2 stack had fuel /air mix blow out stack, engine started and idled a little rough, so I was adjusting linkage syncing carbs and #2 intake ( the one where the adjuster had come apart) would draw air at same volumne as others, than go to zero and make noise, then draw normally again. It does this very evenly, repetedly , about the same time working as not. If I try to accelerate it backfires thru the carb. Obviously a valve train problem, but one I havent run into before, Roller lifters. Letting it cool down before I dig into it. Any ideas? |
2nd post lost?
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3 Attachment(s)
I believe I've found the problem, but first a correction: the problem cyl, #2, is not the one that had the loose adjuster, that was #1.
#2 intake has a broken main spring. This I'm sure happened when I had a heated discussion with a Nissan GT-R regarding hp/weight ratio's of our respective vehicles. My rpm was below 5500 when I capitulated to his arguement ! Now I'm wondering if I should replace all springs, and if there's a better type I should switch to. ? |
Motorhead,
Are those K-Motion springs? |
ok...i'll bite...
obviously more going on than ...oops i broke a spring... were they the right springs and set up correctly for the combo. do you know what heads are on it? do you know what cam is in it? do you have the cam card? if the cam still has all of its lobes, then just buy the correct springs for the cam and this will be best done with the heads off. if you don't have all of the tools to check installed and compressed heights i would take them somewhere and have them put on. but back to the broken spring and the backed off adjuster. do you know where the timing was set to? detonation can back off adjusters and in severe cases break stuff.......some investigation beyond a forum posting should be undertaken to really check things out.. jus' sayin' |
Motorhead,
We saw your car coming out of the trailer - beautiful! To add to your list of things to pay attention to I propose adding this phrase from your first post "Roller lifters." If those are solid rollers, please check them while you are diagnosing. They aren't good for more than 3-5 thousand miles before needing replacement/rebuilding. If they're hydraulic, ignore the preceding caution. Here's hoping you find the root cause and get it behind you expeditiously! Tom |
Rodney: don't know whose springs they are, came with the motor/car when I bought it 12 yrs ago. Car has been drivable just in the last 3-4 mo's.
I rebuilt the eng, changed cam to hyd roller, changed induction to webers. |
FWB:
Got spring specs from Barry R, along with cam and lifters. Heads r e-brocks, big valves. Local shop did all the spring measuring and set-up. I know they checked for binding, installed height and open/closed pressures, etc,etc. The adjuster problem was my bad, just adjusted day before, missed re-checking that nut. Now I had not thought about detonation, but just before the spring broke i was running at 55k rpm and noticed my a/f ratio was at 15-16 :1, so I backed of the gas. 5500r's shouldn't hurt anything, but that lean could have done it. |
Tom:
Thanks for the kind words. The lifters are hyd. Too bad I didn't get a chance to meet you at J-ville. Maybe at the RR. You planing on going ? |
Motorhead,
I hope to be at the RR! Tom |
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