poor running...update

[Terry Horlick]

Improvement!... well just a little. I have checked just about everything suggested here and on e-mails I have received off-list. I sprayed WD40 all around the carbys and the manifolds with no effect on the car's running. I pulled each wire and checked for spark... ok. I regapped the plugs from 25 to 30 thou (my idea)... no improvement. I removed the new from Moss condenser and put the old one on... a little improvement, still pops. I blew air back into the tank... no improvement. I re-drilled the vent in the fuel cap... no improvement. I checked all contacts in distributor (the breaker plate had bad contact when I got the car... it was still ok now) ... no change. I pulled the line from the pump off and made a hose to go on that with a Schrader valve. Put a tire gauge on it and found that the pump can deliver lots of fuel, but it doesn't register on the tire gauge (not sensitive enough). What pressure should I get on that gauge? It seems to me that 1-3 psi is adequate, so I am thinking of getting a digital tire gauge to measure the pressure if I can't find a more sensitive pressure gauge and see what the SU pump is doing. I dumped out the oil in the carby piston dashpots and replaced with thinner oil... no change. Did it again with heavier oil.... a little better. I repeated about 5 more times with progressively more viscous oil. Each time the car ran a little stronger and with less popping. I finaly quit with the thickest oil I have. It is running the best yet, but still pops a bit. I can go faster than before and achieve about 3600 rpm. At last some progress. I now have an oil additive in the dashpots... something calle "PowerPunch". This is a viscosity enhancer and is really a gooey slime the consistancy of congealed/jelled snot. It must have a viscosity or 600-800. The next step would be to clean this stuff out and refill with straight tar. Ok, experts, what does this mean? I can now step on the accelerator and it does pretty well, as it runs at full throuttle for a while it eventually starts popping (no more snorting, just a pop noise and no loss of power), backing off the throttle decreases the noise. I've just about run out of options. I am beginning to wonder if I need to re-do the carby overhaul, or maybe get two new carbys.

[Rick Waters]

Have you considered the possibility of a collapsed fuel delivery line from the pump to the carbs? These lines, as they age, have been known to deteriorate on the inside, creating a blockage and fuel starvation. An excessively lean mixture can cause popping or backfiring, so it's worth a try. How do you check your spark timing? These old engines were statically timed, (originally to TDC), typically by using a small 12volt bulb across the distributor points. The bulb should just light up as the points break. With the timing marks set to TDC (crank pulley) rotate the distributor body against the rotation of the rotor until the light just comes on. All I can think of now. -TC7881 Terry Horlick thorlick@sbcglobal.net> wrote: Improvement!... well just a little. I have checked just about everything suggested here and on e-mails I have received off-list. I sprayed WD40 all around the carbys and the manifolds with no effect on the car's running. I pulled each wire and checked for spark... ok. I regapped the plugs from 25 to 30 thou (my idea)... no improvement. I removed the new from Moss condenser and put the old one on... a little improvement, still pops. I blew air back into the tank... no improvement. I re-drilled the vent in the fuel cap... no improvement. I checked all contacts in distributor (the breaker plate had bad contact when I got the car... it was still ok now) ... no change. I pulled the line from the pump off and made a hose to go on that with a Schrader valve. Put a tire gauge on it and found that the pump can deliver lots of fuel, but it doesn't register on the tire gauge (not sensitive enough). What pressure should I get on that gauge? It seems to me that 1-3 psi is adequate, so I am thinking of getting a digital tire gauge to measure the pressure if I can't find a more sensitive pressure gauge and see what the SU pump is doing. I dumped out the oil in the carby piston dashpots and replaced with thinner oil... no change. Did it again with heavier oil.... a little better. I repeated about 5 more times with progressively more viscous oil. Each time the car ran a little stronger and with less popping. I finaly quit with the thickest oil I have. It is running the best yet, but still pops a bit. I can go faster than before and achieve about 3600 rpm. At last some progress. I now have an oil additive in the dashpots... something calle "PowerPunch". This is a viscosity enhancer and is really a gooey slime the consistancy of congealed/jelled snot. It must have a viscosity or 600-800. The next step would be to clean this stuff out and refill with straight tar. Ok, experts, what does this mean? I can now step on the accelerator and it does pretty well, as it runs at full throuttle for a while it eventually starts popping (no more snorting, just a pop noise and no loss of power), backing off the throttle decreases the noise. I've just about run out of options. I am beginning to wonder if I need to re-do the carby overhaul, or maybe get two new carbys. Yahoo! Groups Links -Rick Waters --------------------------------- Post your free ad now! Yahoo! Canada Personals [Non-text portions of this message have been removed]

[ian thomson]

Just a small point Terry, but in one of your earlier posts did you say that your timimg was at TDC? If so it should be advanced a bit for modern fuel. Start at 5 deg. BTDC and go up to 10 Deg. if needed and if it doesn't pink. If I have misunderstood you just file this in thew bin. Ian Thomson. Send instant messages to your online friends http://uk.messenger.yahoo.com

[tony goodall]

Terry I am not an expert so my analysis of you experimentations is based on not entirely dissimilar problems in the past. It would seem that you have, by thickening the dashpot oil. gradually restricted the airflow, which brings me back to an earlier point about the throttle plates.It could still be that you have to much unwanted airflow into the combustion chamber, and if you are happy that the butterfies are OK and sealing reasonably well, could air be leaking in at the gaskets? You can get distortion of the flanges on the carb bodies and on the inlet manifold and these should be flatted with emery paper on glass before fitting the gaskets, air leaks at the manifold can sometimes be heard, in my case there was a distinct whistle , so easy to spot. I find it difficult to believe that you have fuel starvation since you said earlier that you were getting blow back of fuel which suggests that enough is getting through. I guess, therefore that my thinking is that you are not getting the correct mixture due to air leaks. Incidentally, although it is a pain to do, I would remove the air cleaner manifold until you get this problem sorted - you can run quite happily without the air cleaner unless you are in a seriously dusty atmosphere, and it's much easier to get at things without it in place. I also concur with Ian's point about advancing the static timing - I run at about 7.5 degrees BTDC Good luck Tony TC9825

On 11 Apr 2005, at 04:25, Terry Horlick wrote: > > > Improvement!... well just a little. I have checked just about > everything suggested here and on e-mails I have received off-list. > > I sprayed WD40 all around the carbys and the manifolds with no > effect on the car's running. > > I pulled each wire and checked for spark... ok. > > I regapped the plugs from 25 to 30 thou (my idea)... no improvement. > > I removed the new from Moss condenser and put the old one on... a > little improvement, still pops. > > I blew air back into the tank... no improvement. > > I re-drilled the vent in the fuel cap... no improvement. > > I checked all contacts in distributor (the breaker plate had bad > contact when I got the car... it was still ok now) ... no change. > > I pulled the line from the pump off and made a hose to go on that > with a Schrader valve. Put a tire gauge on it and found that the > pump can deliver lots of fuel, but it doesn't register on the tire > gauge (not sensitive enough). What pressure should I get on that > gauge? It seems to me that 1-3 psi is adequate, so I am thinking of > getting a digital tire gauge to measure the pressure if I can't find > a more sensitive pressure gauge and see what the SU pump is doing. > > I dumped out the oil in the carby piston dashpots and replaced with > thinner oil... no change. > > Did it again with heavier oil.... a little better. > > I repeated about 5 more times with progressively more viscous oil. > Each time the car ran a little stronger and with less popping. I > finaly quit with the thickest oil I have. It is running the best > yet, but still pops a bit. I can go faster than before and achieve > about 3600 rpm. At last some progress. I now have an oil additive > in the dashpots... something calle "PowerPunch". This is a > viscosity enhancer and is really a gooey slime the consistancy of > congealed/jelled snot. It must have a viscosity or 600-800. The > next step would be to clean this stuff out and refill with straight > tar. > > Ok, experts, what does this mean? I can now step on the accelerator > and it does pretty well, as it runs at full throuttle for a while it > eventually starts popping (no more snorting, just a pop noise and no > loss of power), backing off the throttle decreases the noise. > > I've just about run out of options. I am beginning to wonder if I > need to re-do the carby overhaul, or maybe get two new carbys. > > > > > > > Yahoo! Groups Links > > > > > > > >

[joecurto@aol.com]

You will not get a gauge reading on the fuel pump as the gauge is causing the pump to shut off, maybe if you hooked it up with a T fitting in parallel than gauge would register. Joe [Non-text portions of this message have been removed]

[Terry Horlick]

>Have you considered the possibility of a collapsed fuel

delivery line from the pump to the carbs? Yes, I replaced them with new lines from Moss... quite nice metal wrapped tefflon hoses.

>How do you check your spark timing?

I statically time by using a small 12volt bulb across the distributor points. I time it so that the bulb just lights up as the points break. With the timing marks set to TDC (and checked by putting a wire through the spark plug hole to rest on the piston top) I rotated the distributor body against the rotation of the rotor until the light just came on.

>did you say that your timimg was at TDC? If so it should be

advanced a bit for modern fuel I am running at TDC static, but I opened up the distributor plate from 15 degrees to 17.5 degrees to get that little bit of advance you speak about.

>could air be leaking in at the gaskets?

I cut new gaskets and there is no change in running when I spray WD40 around there.

>try removing the canister and cupping your hand thus

restricting the opening I havent done this... will try I think that answers them all. I got an interesting e-Mail which suggested that mynew cork washers on the jets are leaking and that could cause rich at idle and lean at speed. I will have to try his fix of tearing it down and substituting an "O" ring. Thanks, Terry TC2285

[1939mgtb]

Blow back of fuel sounds like cam timing... A little stand off is one thing, but a blow back is another. Was the cam replaced recently? Best regards, Ray "There are no easy answers in this case m'lud."

----- Original Message ----- From: "tony goodall" tonygoodall@blueyonder.co.uk> To: mg-tabc@yahoogroups.com> Sent: Monday, April 11, 2005 4:58 AM Subject: Re: [mg-tabc] poor running...update > > Terry > > I am not an expert so my analysis of you experimentations is based on > not entirely dissimilar problems in the past. > It would seem that you have, by thickening the dashpot oil. gradually > restricted the airflow, which brings me back to an earlier point about > the throttle plates.It could still be that you have to much unwanted > airflow into the combustion chamber, and if you are happy that the > butterfies are OK and sealing reasonably well, could air be leaking in > at the gaskets? You can get distortion of the flanges on the carb > bodies and on the inlet manifold and these should be flatted with emery > paper on glass before fitting the gaskets, air leaks at the manifold > can sometimes be heard, in my case there was a distinct whistle , so > easy to spot. > I find it difficult to believe that you have fuel starvation since you > said earlier that you were getting blow back of fuel which suggests > that enough is getting through. > I guess, therefore that my thinking is that you are not getting the > correct mixture due to air leaks. > Incidentally, although it is a pain to do, I would remove the air > cleaner manifold until you get this problem sorted - you can run quite > happily without the air cleaner unless you are in a seriously dusty > atmosphere, and it's much easier to get at things without it in place. > I also concur with Ian's point about advancing the static timing - I > run at about 7.5 degrees BTDC > > Good luck > > Tony TC9825 > > > > On 11 Apr 2005, at 04:25, Terry Horlick wrote: > >> >> >> Improvement!... well just a little. I have checked just about >> everything suggested here and on e-mails I have received off-list. >> >> I sprayed WD40 all around the carbys and the manifolds with no >> effect on the car's running. >> >> I pulled each wire and checked for spark... ok. >> >> I regapped the plugs from 25 to 30 thou (my idea)... no improvement. >> >> I removed the new from Moss condenser and put the old one on... a >> little improvement, still pops. >> >> I blew air back into the tank... no improvement. >> >> I re-drilled the vent in the fuel cap... no improvement. >> >> I checked all contacts in distributor (the breaker plate had bad >> contact when I got the car... it was still ok now) ... no change. >> >> I pulled the line from the pump off and made a hose to go on that >> with a Schrader valve. Put a tire gauge on it and found that the >> pump can deliver lots of fuel, but it doesn't register on the tire >> gauge (not sensitive enough). What pressure should I get on that >> gauge? It seems to me that 1-3 psi is adequate, so I am thinking of >> getting a digital tire gauge to measure the pressure if I can't find >> a more sensitive pressure gauge and see what the SU pump is doing. >> >> I dumped out the oil in the carby piston dashpots and replaced with >> thinner oil... no change. >> >> Did it again with heavier oil.... a little better. >> >> I repeated about 5 more times with progressively more viscous oil. >> Each time the car ran a little stronger and with less popping. I >> finaly quit with the thickest oil I have. It is running the best >> yet, but still pops a bit. I can go faster than before and achieve >> about 3600 rpm. At last some progress. I now have an oil additive >> in the dashpots... something calle "PowerPunch". This is a >> viscosity enhancer and is really a gooey slime the consistancy of >> congealed/jelled snot. It must have a viscosity or 600-800. The >> next step would be to clean this stuff out and refill with straight >> tar. >> >> Ok, experts, what does this mean? I can now step on the accelerator >> and it does pretty well, as it runs at full throuttle for a while it >> eventually starts popping (no more snorting, just a pop noise and no >> loss of power), backing off the throttle decreases the noise. >> >> I've just about run out of options. I am beginning to wonder if I >> need to re-do the carby overhaul, or maybe get two new carbys. >> >> >> >> >> >> >> Yahoo! Groups Links >> >> >> >> >> >> >> >> > > > > > Yahoo! Groups Links > > > > > > >

[Liz Harris]

...Thanks Ian, I`m glad somebody has bought up the subject of ignition timing....I know all the books say set the static timing to TDC, but I`ve found that 5` or so before has made quite a difference to the running and performance....I have`nt wanted to mention it just in case someone starts quoting the the book....static timing is all very well in theory providing everything is as it should be in regard to wear ....( no roads this time Fed..but I`m promising nothing....I did come home the back way tonight though..) Tweed...not Liz. ian thomson i.thomson@talk21.com> wrote: Just a small point Terry, but in one of your earlier posts did you say that your timimg was at TDC? If so it should be advanced a bit for modern fuel. Start at 5 deg. BTDC and go up to 10 Deg. if needed and if it doesn't pink. If I have misunderstood you just file this in thew bin. Ian Thomson. Send instant messages to your online friends http://uk.messenger.yahoo.com Yahoo! Groups Links Send instant messages to your online friends http://uk.messenger.yahoo.com [Non-text portions of this message have been removed]

[ARTHUR LEWIS]

Terry, I had a similar poor running situation with an early MGB. It about drove me nuts trying, re-trying and re-trying again all of the basic remedies. At wits end, we (John Twist and I) finally discovered that the carb overflow pipes were pinched almost completely. The car would run fine for several miles, but would eventually run warmer than normal and start popping/spitting. New overflow pipes cured it! Check yours to determine if they are pinched or plugged up, maybe you will get lucky....... Art Lewis, TC10010 [Non-text portions of this message have been removed]