Hi Guys thanks for you reply's re Oil Temperature / cooling / gauge etc. I have had to put that on hold at the moment as I now have a more pressing problem.
Driving along the other day it started to stutter and power dropped considerably. I got it home ...just !
It runs ok in the garage if I keep the revs up but won't idle and back fires some-what into the carb. Spark plugs and ignition seem fine . The inlet and exhaust valve gaps were a bit tight ! Adjusted but no better. I I got a compression tester on the off side head ( 130/140 psi ) but there is steel work obstructing my access to the other head. However I brazed a connection into an old spark-plug to get access ...... showing an iffy 40 psi.
I'm reluctant to take the head off but this sounds like a burnt out valve to me.
Any thought or suggestions would be most welcome
Thanks
Dave Ward
Valves on my Bra CV3
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Re: Valves on my Bra CV3
I don't know if they are available in this country but many years ago, I bought a fitting that screws in a spark plug hole and it takes an airline connection
With the suspect cylinder at TDC (Top Dead Centre) with both valves closed put the car in gear with the handbrake hard on.
Turn on the air, ejection of air from the carb = inlet valve, from the exhaust pipe = exhaust valve and from the breather it = pistons/rings.
It would be fairly easy to make a suitable adaptor.
I bought my adapter in Germany in the seventies, it was originally sold to enable valve springs to be changed without removing the cylinder head.
With the suspect cylinder at TDC (Top Dead Centre) with both valves closed put the car in gear with the handbrake hard on.
Turn on the air, ejection of air from the carb = inlet valve, from the exhaust pipe = exhaust valve and from the breather it = pistons/rings.
It would be fairly easy to make a suitable adaptor.
I bought my adapter in Germany in the seventies, it was originally sold to enable valve springs to be changed without removing the cylinder head.
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DaveWard
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Re: Valves on my Bra CV3
Hi , Many thanks , will try that. I have a spark plug that I have drilled out and brazed a fitting In...it will help to confirm one way or the other. If this suggests ok I will check the carb. out
I managed to get a better reading from the compression test and both seem to be 110 plus
Many thanks
Dave
I managed to get a better reading from the compression test and both seem to be 110 plus
Many thanks
Dave
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billp
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Re: Valves on my Bra CV3
sounds more like water in the carb to me. I'd clean out the float chamber and make sure that the jets are all clean first, before delving into the motor.
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DaveWard
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Re: Valves on my Bra CV3
HELP ......... please
After more investigation .... checking again the plugs, leads, carb, and another compression test ( 100 O/S ... 90 N/S ) there was nothing obvious .
So I tried running with just one spark lead connected ...O/S runs reasonable , N/S runs but doesn't sound quite ride with occasional back-fires ??? !!!
Another issue I have discovered is the breather / oil filler return has been blanked off and if the cap is opened while running there's quite a bit of pressure in there and it blows oil droplets out !!! ... I'm obviously going to have to refurb the breather but what do you guys do regarding the return pipe ?? I only have a small pancake air filter unit and while I could modify it to take a return pipe I suspect it wont like this sort of pressure being injected into it.
Having studied the problem regarding removing a head I'm going to need to cut the body work out a bit !!! So last resort
Any suggestions would be much appreciated,.
Thanks Guys
Dave Ward
After more investigation .... checking again the plugs, leads, carb, and another compression test ( 100 O/S ... 90 N/S ) there was nothing obvious .
So I tried running with just one spark lead connected ...O/S runs reasonable , N/S runs but doesn't sound quite ride with occasional back-fires ??? !!!
Another issue I have discovered is the breather / oil filler return has been blanked off and if the cap is opened while running there's quite a bit of pressure in there and it blows oil droplets out !!! ... I'm obviously going to have to refurb the breather but what do you guys do regarding the return pipe ?? I only have a small pancake air filter unit and while I could modify it to take a return pipe I suspect it wont like this sort of pressure being injected into it.
Having studied the problem regarding removing a head I'm going to need to cut the body work out a bit !!! So last resort
Any suggestions would be much appreciated,.
Thanks Guys
Dave Ward
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Re: Valves on my Bra CV3
What problems removing the head? If I was going to do much work on the engine I would just remove it completely, quite a simple job.
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Davidm
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Re: Valves on my Bra CV3
Dave
Have you measured the crankcase pressure with the engine running through the rev range ? It should be at least 50mm water gauge less than atmospheric. (I have just refurbished a breather and this resulted in more than 300mm water gauge vacuum !). The only flow of air into the crankcase should be slight leakages past seals and pistons.
With a breather working normally you would expect splashes of oil coming out if you lift the filler cap.
Davidm
Have you measured the crankcase pressure with the engine running through the rev range ? It should be at least 50mm water gauge less than atmospheric. (I have just refurbished a breather and this resulted in more than 300mm water gauge vacuum !). The only flow of air into the crankcase should be slight leakages past seals and pistons.
With a breather working normally you would expect splashes of oil coming out if you lift the filler cap.
Davidm
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howardjs
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Re: Valves on my Bra CV3
Hi Dave,
Blocking the breather return pipe usually results in oil oozing out of the crankcase from wherever it can. I would unblock the pipe and connect it to a catch tank. The breather one way valve must also work or the crankcase pressure will build up even more.
I'm guessing that you have 2 ignition coils, one for each plug, otherwise, with the normal double ended coil, disconnecting one plug would break the TH circuit. The engine then could not run at all. So perhaps you have one weak coil, or, HT leak somewhere.
Regarding the engine, as has been suggested. Removing the engine is probably preferable to cutting the bodywork. The biggest job is disconnecting the exhaust and carb connections After that just 4 bellhousing bolts and front engine mounts.
Probable worth doing to check valve seats and do a decoke etc.
Good luck
Howard
Blocking the breather return pipe usually results in oil oozing out of the crankcase from wherever it can. I would unblock the pipe and connect it to a catch tank. The breather one way valve must also work or the crankcase pressure will build up even more.
I'm guessing that you have 2 ignition coils, one for each plug, otherwise, with the normal double ended coil, disconnecting one plug would break the TH circuit. The engine then could not run at all. So perhaps you have one weak coil, or, HT leak somewhere.
Regarding the engine, as has been suggested. Removing the engine is probably preferable to cutting the bodywork. The biggest job is disconnecting the exhaust and carb connections After that just 4 bellhousing bolts and front engine mounts.
Probable worth doing to check valve seats and do a decoke etc.
Good luck
Howard