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On route to a local show it starts making a noise and down on power. Oil pressure was / is fine. Pulled over first opportunity and looked for anything obvious and found nothing. Closer to show ground than home so carried on at low speed. Loads of mates there and some are mechanics and they all seemed to favour a loose spark plug. Running the car and pulling the leads off one at a time directed it to cylinder 3. Left that lead off and made it home. Just checked the plug and it was tight, gap was good at .035 and a little funky but nothing unusual. Checked for spark while it was out and all good. Loud crack on start up and excessive motor vibration on tick over.
Checked exhaust manifolds for any cracks and found none.
For OP's sake, I hope his problem is as minor as yours was. What would casue one pushrod to bend? I am not insinuating any skepticism. I just want to learn.
Thanks all. It's a bit late now here in Blighty and I had a consoling beer so I'll take a look tomorrow. It's the other side to where the smog pump is thankfully as for maybe 3/16ths clearance you have to move the smog pump to get the valve cover off!
Appears to be #3 exhaust valve. Is it the normal amount of movement when the valve is closed? Before you take anything apart, I would rotate the engine by hand until TDC on #3 power stroke and wiggle both rockers on that cylinder. They should move the same. If 3E is significantly looser remove the rocker and pull the pushrod for an inspection. If all looks good adjust the valve and proceed.
Factoid is right. But go slow and pay attention to unusual play here and there.
I see you have the poly-locks on the rockers. Make note when disassembling, if that #3E nut is wonky or if the set screw is wonky.
After removing rocker, invert and inspect the pushrod pocket. Also inspect the rocker ball. Any galling? Rocker slot look ok? Rocker stud flush with head? Appear to be straight?
Then pull rod and check both end tips. Note if you can see light through it.
Sometimes its hard to spot a broken spring because it is still under pressure. Use a flashlight and look real close. A broken spring often times retains its normal appearance.
Appears to be #3 exhaust valve. Is it the normal amount of movement when the valve is closed? Before you take anything apart, I would rotate the engine by hand until TDC on #3 power stroke and wiggle both rockers on that cylinder. They should move the same. If 3E is significantly looser remove the rocker and pull the pushrod for an inspection. If all looks good adjust the valve and proceed.
Originally Posted by HeadsU.P.
Factoid is right. But go slow and pay attention to unusual play here and there.
I see you have the poly-locks on the rockers. Make note when disassembling, if that #3E nut is wonky or if the set screw is wonky.
After removing rocker, invert and inspect the pushrod pocket. Also inspect the rocker ball. Any galling? Rocker slot look ok? Rocker stud flush with head? Appear to be straight?
Then pull rod and check both end tips. Note if you can see light through it.
Sometimes its hard to spot a broken spring because it is still under pressure. Use a flashlight and look real close. A broken spring often times retains its normal appearance.
Thanks guys.
I have mates that come to me for advice on C3's but tonight I've realised that I know about as much as Pudding, one of our Pug dogs..
My hats off to you guys and the automotive knowledge ya'll posses
OP Stuart:
I'm assuming your 71 LT1 has Solid aka Mechanical flat tappet lifters.
When you do look under valve cover ... if, IF you do Not find problem w/ valves/retainers/springs/studs/rockers ... But you Do find PushRod is VERY loose and / or bent ...
... Do pull that PR ... then Do also peer down through PR hole in head ... Do look closely at that lifter ...
... Do Verify the lifter's retainer clip is securely in place ... compare to another lifter.
Also, OE specs for 71 LT1 show its PRs have a hardened steel insert in the rocker arm end ...
... suggest check both top & bottom of PR to ensure any insert is securely in place ... if not, you must find it!
fyi ... clip/snap-ring retains lifter's guts & PR cup within lifter body. They can & do come loose ...
... If it's Not securely in place you MUST find it before it falls-slips down into oil pan-oil pump!
As you remove the pushrod, rotate it as you pull. Pushrods have been known to "stick" in the lifter and pull it out of the bore at the same time. Rare, but it happens. And from experience, getting a lifter back into the bore is not much fun with the intake installed.
remove all the spark plugs when rotating the engine by hand. It will make it easier to turn and you wont risk over tightening the crank bolt breaking it off in the crank.
Well I'd read each diagnosis and method of getting to the route cause the my mechanic 'old school Ernie' told me to keep my hands off it and he'll do me a home visit sometime this week. I think that's probably wise but at least I can look over his shoulder and critique his work
I took the cover off the yellow one and compared and none of them have the range of movement as E3
OMG, the suspense is killing me! Hopefully I can pass along some of my unused good luck from June and July.
Caught a leak in ourhome heating oil tank, by absolute luck, when only a few gallons had leaked out. (For those in the dark, oil (AKA diesel fuel) is commonly used in New England for heat and hot water.)
Had what could have been an extremely serious bike vs vehicle event, and SBDU bike and I were able to dodge the fates. Still can't believe I walked away, and the bike will live to be ridden again (needs a fork). I've ridden it for close to 40 years, and it ALWAYS goes where I look. I saw an out, and the bike went there.
Last edited by Dirty Dalton; 07-22-2019 at 04:17 PM.
07-21-2019, 01:02 PM
Motor went clackety clack
