Dizzy demise saves engine
Discussion
For those of you who followed the Le Mans posting recently and particularly for those who’s company and help I had the benefit of on the club trip to Le Mans, I said I would let you know the outcome of the strange failure of the distributor drive which lost half its teeth at 5000 revs behind a Pagani Zonda. (Photos on Stigs web site).
The engine is now in pieces in the workshop of Repower in Worthing and shows significant signs of wear. The feeling is that at the current rate of wear it is possible it could have seized within the next 500 miles. Had it not been for the damage to the distributor drive (not a bronze one), I would of course have continued to Le Mans and done much more damage to it. The crankshaft (a cast one) is badly scored and the main bearings are very worn with evidence of having welded themselves to the crank. Even the new roller cam which is 1000 miles old has to be replaced which is irritating in the extreme.
The cause? It is believed that this is caused by cold oil. The engine will run quite cold in the winter, down to 40 –50 degrees C on the motorway and the oil cooler has no thermostat control. With viscous oil trying to force its way through the (necessarily) small oil filter, it goes instead through the bypass and returns unfiltered to the engine. This is possibly the cause of the excess wear to the old cam and follower, the particles from which probably contributed to the continued wear.
Does anyone have any experience of this?
I noticed the factory track car used an oil cooler cover and wondered at the time why. Perhaps I should have asked.
The engine is now in pieces in the workshop of Repower in Worthing and shows significant signs of wear. The feeling is that at the current rate of wear it is possible it could have seized within the next 500 miles. Had it not been for the damage to the distributor drive (not a bronze one), I would of course have continued to Le Mans and done much more damage to it. The crankshaft (a cast one) is badly scored and the main bearings are very worn with evidence of having welded themselves to the crank. Even the new roller cam which is 1000 miles old has to be replaced which is irritating in the extreme.
The cause? It is believed that this is caused by cold oil. The engine will run quite cold in the winter, down to 40 –50 degrees C on the motorway and the oil cooler has no thermostat control. With viscous oil trying to force its way through the (necessarily) small oil filter, it goes instead through the bypass and returns unfiltered to the engine. This is possibly the cause of the excess wear to the old cam and follower, the particles from which probably contributed to the continued wear.
Does anyone have any experience of this?
I noticed the factory track car used an oil cooler cover and wondered at the time why. Perhaps I should have asked.
Nick - glad you got to the bottom of it, but I suppose it's less than ideal news.
Still, it could have been a LOT worse and is the engine had thrown a leg out of bed then yuo'd be in BIG trouble.
Interesting about the Dizzy not having a bronze drive?Good tip for other builders I guess.
Anyway, hope you have it back on the road soon. As a footnote, I always make a point of getting the oil up to temp. before even starting a journey. Still, not a lot you can do if it's getting that cold on a winter run
Still, it could have been a LOT worse and is the engine had thrown a leg out of bed then yuo'd be in BIG trouble.
Interesting about the Dizzy not having a bronze drive?Good tip for other builders I guess.
Anyway, hope you have it back on the road soon. As a footnote, I always make a point of getting the oil up to temp. before even starting a journey. Still, not a lot you can do if it's getting that cold on a winter run
On the subject of the dizzy drive gear you should not run a steel gear with a steel cam. Some manufacturers claim otherwise depending on the core material of the cam.
The bronze gear, whilst being required for the steel cam, becomes somewhat sacrificial and wears at a terrific rate.
Comp Cams now have a plastic dizzy gear they claim overcomes both these problems.
I think I will try one when I build my engine.
Steve
The bronze gear, whilst being required for the steel cam, becomes somewhat sacrificial and wears at a terrific rate.
Comp Cams now have a plastic dizzy gear they claim overcomes both these problems.
I think I will try one when I build my engine.
Steve
The oil bypass is in the filter housing the adaptor plate fits too.
On advice from the Chevy Talk forum I have blanked mine off.
The valve is a disc of SRBF or glass fibre held down by a spring. Just dig it all out and put a nut and bolt through the hole and lock it up with thread lock/sealer.
You can buy a kit to do this but the bolt works fine.
Steve
On advice from the Chevy Talk forum I have blanked mine off.
The valve is a disc of SRBF or glass fibre held down by a spring. Just dig it all out and put a nut and bolt through the hole and lock it up with thread lock/sealer.
You can buy a kit to do this but the bolt works fine.
Steve
Steve
Sounds like a good idea but l wonder why the thing is there in the first place? What would happen if viscous oil had to go through the filter? my assumption would be that the flow would be reduced but that must be better than pushing unfiltered oil through the engine. Repower were a bit concerned about the small filter that is used to fit within the chassis gap. A larger filter could be used to give more area for oil to pass through so l intend to use a remote filter when l refit the engine and dispense with the small filters.
Sounds like a good idea but l wonder why the thing is there in the first place? What would happen if viscous oil had to go through the filter? my assumption would be that the flow would be reduced but that must be better than pushing unfiltered oil through the engine. Repower were a bit concerned about the small filter that is used to fit within the chassis gap. A larger filter could be used to give more area for oil to pass through so l intend to use a remote filter when l refit the engine and dispense with the small filters.
Even in the winter my oil temp was above 70 when the car was warmed up after about ten minutes.
Today isn't that warm and its overcast here, it was 78 on the motorway, and I have a huge duct taking the air straight through the oil cooler.
I have to admit I have installed the sensor so it reads the temp just before it goes to the oil cooler.
I think mine is set so that it comes out of the oil filter and then through the cooler, so that the accusump pumps straight to the bearings. But I'm not 100% sure as it was a long while ago that I had to think about it.
I do know that my sensor is in the sandwich plate, which way is this oil going?
Today isn't that warm and its overcast here, it was 78 on the motorway, and I have a huge duct taking the air straight through the oil cooler.
I have to admit I have installed the sensor so it reads the temp just before it goes to the oil cooler.
I think mine is set so that it comes out of the oil filter and then through the cooler, so that the accusump pumps straight to the bearings. But I'm not 100% sure as it was a long while ago that I had to think about it.
I do know that my sensor is in the sandwich plate, which way is this oil going?
Ultiman
The bypass is there to cope with old ladies and lazy blokes who forget or can’t be bothered to change the filter, which then blocks up completely.
The guys in the States say there is a risk of splitting the filter if you rev too hard, with a high flow pump and its very cold. We don't do that do we?
Having invested a fair few pennies on my motor I am thinking I will fit a double filter remote mount which I saw recently on GTRCLIVE’s motor.
Ultimaandy
The oil passes from the pump into the side of the filter and up the middle so if you have a sensor in the side of the adaptor you will be on the flow into the filter.
Steve
The bypass is there to cope with old ladies and lazy blokes who forget or can’t be bothered to change the filter, which then blocks up completely.
The guys in the States say there is a risk of splitting the filter if you rev too hard, with a high flow pump and its very cold. We don't do that do we?
Having invested a fair few pennies on my motor I am thinking I will fit a double filter remote mount which I saw recently on GTRCLIVE’s motor.
Ultimaandy
The oil passes from the pump into the side of the filter and up the middle so if you have a sensor in the side of the adaptor you will be on the flow into the filter.
Steve
Roller cams require a bronze Dist gear unless the cam has a melonized gear pressed on to it in it's manufacturing process.
www.compcams.com
www.compcams.com
Ultimapaul said:
Simon - that was 'Teflonise' and that is why the car wouldn't stick to the road properly 
Sorry TC if you ever pop in ..... you have been the butt of a few jokes lately, no harm intended!
Paul
Actually though, God bless ya Tuckshop, if it be known I actually miss his ambient atmosphere while he posted here. After all, his views were both totally original and exclusive. Also his views showed us things that we have never thought about audio-wise. Woks the matter with that? (Ok Stig were 1 all)
Maybe in years to come Ultima Ltd will view his modifications as VAN GOGH style works of art?
There again, maybe not. His repitition in the forums without his presence, unlike his modifications or his road-holding, seems to have stuck for ever, and so rightly so.
Tuckshop - You are long gone, but not forgotten.
May the hoard of a thousand lowly Metro drivers be upon you wherever you may be and bring you God Speed (er slowness and safety I think), after all God went up the mountain in his Triumph, so the bible said, so I can only asume it was a Triumph Herald...
...mustremembernottopostwhenpissedonafridaynight...
I got the oil cooler kit for my Sports from Kenlowe. The sandwich plate for this has a built in thermostat. The downside is that this sandwich plate is a smaller diameter than a sbc oil filter so needs an adaptor plate. I still managed to fit a Pennzoil filter supplied from the factory, but had to use an oil seal from a smaller filter. The Pennzoil filter has two oil seal grooves so the smaller seal fitted no problem.
Sorry for the confusion, the newer style roller cams have a hardened gear pressed on to the cam during the mfg process. These cams still require a special distributor gear, though no longer bronze as before. The dist gear you must use on the dist shaft is material is called Melonized steel according to the GM Performance parts book. Don't know what that means I assume a treatment of sort harder than bronze, but not so hard as the gear for a non roller cam. If you don't want the problem again check with the cam mfg and make sure you have the proper dist gear.
jeff
jeff
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