93fxdl
Posted a lot
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Posts: 2,000
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Probably talking carp, but many years ago there was a v8 powered cortina, I saw being raced, would pull out of the pits sounding spot on, a lap or two later would limp in, missing and sounding sick, a few minutes later, running fine until pushed, tappets were pumping up and holding some valves open. Ttfn Glenn
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Have you checked the valve clearances? You can shim the pedestals to adjust them. Made a difference to my old Schuler Super Ranger, I think it is also possible to get the timing chain to jump and they will still run but be very very flat - mine did this
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sowen
Club Retro Rides Member
Posts: 2,245
Club RR Member Number: 24
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High rpm misfire under loadsowen
@sowen
Club Retro Rides Member 24
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Is it consistent, as in will it do it every time at the same rpm? hot and cold? any gear? I would still recommend a cylinder leakage test, much more info than a compression test. Couple of things to look at if you are sure it is not fuel injection or ignition related. Blocked exhaust Fuel pick up in tank Its tough to diagnose without experiencing the fault A little hard to fault find with it stripped down! I want the car up and running quick and also want to cure some of the oil leaks so the decision was made to pull the lot out and give it a thorough health check It's without fail, under load going over 4k rpm. More noticeable now as I'm trying to tune the Megasquirt so am it pushing harder. The exhaust system has been off, mainly due to not fitting properly where it's hit the propshaft and axle. As I say the fuel system is entirely new, fuel tank, lines, filter, there is no part of the original carb system left. I've even replaced the poor charging alternator with a newer 100amp alternator incase it didn't like the weak 13volts the original one was putting out, 14.1volts now with no change. I was going to do another 1st-2nd blast with a camera running, decided against just incase. I may have a video somewhere on a dashcam that might demonstrate the noise? If I have time tomorrow evening I want to strip both heads to check the valve seats and springs. So far what I've found is the internal condition of the engine is good for 97k miles, bores still show the honing marks, plenty of life left in the camshaft and the chain isn't too slack. Nothing obviously untoward which is a relief, less money to spend!
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Last Edit: May 5, 2015 22:16:45 GMT by sowen
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sowen
Club Retro Rides Member
Posts: 2,245
Club RR Member Number: 24
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High rpm misfire under loadsowen
@sowen
Club Retro Rides Member 24
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Probably talking carp, but many years ago there was a v8 powered cortina, I saw being raced, would pull out of the pits sounding spot on, a lap or two later would limp in, missing and sounding sick, a few minutes later, running fine until pushed, tappets were pumping up and holding some valves open. Ttfn Glenn That's interesting to hear, luckily I've got a good spare cam and lifters stashed away which I've been considering swapping over just incase the lifters are playing up? I think they're meant to pump up around 6000rpm anyway assuming all is good? Have you checked the valve clearances? You can shim the pedestals to adjust them. Made a difference to my old Schuler Super Ranger, I think it is also possible to get the timing chain to jump and they will still run but be very very flat - mine did this Not checked them yet, will add to the list of things to do when the heads go back on
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I know someone who fitted solid lifters to theirs, they took them back out as they were too noisy.
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sowen
Club Retro Rides Member
Posts: 2,245
Club RR Member Number: 24
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High rpm misfire under loadsowen
@sowen
Club Retro Rides Member 24
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Clearly I wasn't looking hard enough at the camshaft, I guess I've found the problem now!
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820
South East
Posts: 790
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Thats good, probably caused by poor quality or overdue oil change. Time for a fast road cam, new followers and uprated springs. Have you checked the mains bearings, crank, big and small ends and pistons? Surely time for a 4.6
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Last Edit: May 6, 2015 22:09:32 GMT by 820
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sowen
Club Retro Rides Member
Posts: 2,245
Club RR Member Number: 24
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High rpm misfire under loadsowen
@sowen
Club Retro Rides Member 24
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Thats good, probably caused by poor quality or overdue oil change. Time for a fast road cam, new followers and uprated springs. Have you checked the mains bearings, crank, big and small ends and pistons? Surely time for a 4.6 I have a spare cam and lifters I fitted new to my old V8 a few thousand miles before parting it out for worn rings and crankshaft that'll be going in. The overall plan with the car is to drop a more modern V8 in eventually so no point in spending too much more time and money on the original engine. It will be put into storage with plenty of oil down the bores just in case
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That's a very un-lobey lobe! Glad you are getting it sorted. As someone else said, check your big ends and mains in case all that swarf found its way past the filter. Have you checked the valve clearances? You can shim the pedestals to adjust them. Made a difference to my old Schuler Super Ranger, I think it is also possible to get the timing chain to jump and they will still run but be very very flat - mine did this Any pics of the Schuler MrDodgerover?
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Koos
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Any pics of the Schuler MrDodgerover? Will see what I can dig out, it still around but not on the road or owned by me any more. It was with out a doubt the quietest, best handling range rover classic I have ever driven, sadly it had lost the performance engine somewhere along the way.
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