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OP
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Re: Still need help
I understood that the thing was supposed to be idling at 12deg btdc on the timing light. The vacuum hose was not plugged in, so it should be 12 deg, no?
For some reason this whole thing has me totally confused...
/ubbthreads/images/graemlins/blush.gif /ubbthreads/images/graemlins/hammer.gif /ubbthreads/images/graemlins/frown.gif
I understood that the thing was supposed to be idling at 12deg btdc on the timing light. The vacuum hose was not plugged in, so it should be 12 deg, no?
For some reason this whole thing has me totally confused...
/ubbthreads/images/graemlins/blush.gif /ubbthreads/images/graemlins/hammer.gif /ubbthreads/images/graemlins/frown.gif
OP
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Re: Still need help
Alan,
The triple carb setup is designed to run centrifugal advance. Mine is set at 8 degrees BTDC at 1000 rpm idle speed. The carbs should balance quite easily, especially since they basically are all tied together rigidly. The vacuums are all blocked off except the large vacuum ports that pull a vacuum on the valve cover. I am still very suspect of your cam setup. Setting up the cam is quite precice and achieving TDC on the piston is critical, as you well know. The car will run if the cam is set up badly, but it will run poorly and often hot. It would be a RPITA to pull the head and check TDC and check the timing chain on the cam but you may have to resort to this. I suppose you could put a dial gauge on each push rod to check lift and set a cam gauge on the crank pulley to see if you are spot on. It just seems to me that the gentleman that set up your engine may have cut a corner or two and "slapped it together". When I set my engine up with the GP2 cam and shaved head, I checked everything at least half a dozen times for accuracy and when I eventually got around to cranking he bad boy, it popped on the first turn over and I have never looked back. Setup, setup, setup.
Not trying to be negative, just have been through some bad mechanic problems in the past and I really have my doubts.
Bill
Alan,
The triple carb setup is designed to run centrifugal advance. Mine is set at 8 degrees BTDC at 1000 rpm idle speed. The carbs should balance quite easily, especially since they basically are all tied together rigidly. The vacuums are all blocked off except the large vacuum ports that pull a vacuum on the valve cover. I am still very suspect of your cam setup. Setting up the cam is quite precice and achieving TDC on the piston is critical, as you well know. The car will run if the cam is set up badly, but it will run poorly and often hot. It would be a RPITA to pull the head and check TDC and check the timing chain on the cam but you may have to resort to this. I suppose you could put a dial gauge on each push rod to check lift and set a cam gauge on the crank pulley to see if you are spot on. It just seems to me that the gentleman that set up your engine may have cut a corner or two and "slapped it together". When I set my engine up with the GP2 cam and shaved head, I checked everything at least half a dozen times for accuracy and when I eventually got around to cranking he bad boy, it popped on the first turn over and I have never looked back. Setup, setup, setup.
Not trying to be negative, just have been through some bad mechanic problems in the past and I really have my doubts.
Bill
jessebogan
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Re: Still need help
Ok, The timing should be 8-10 degrees Before TDC, i.e. advanced. There will be no absolute figure for your car because it has been modified. It is generally best to run the most advance possible without pinging, with probably no more that 30 to 35 degrees total advance . This is checked at whatever speed the centrifical and vacuum advance is all in, but usually 3000, to 3500 rpms. Retarded timing will cause no power, and hot running every time.
To adjust the carbs, disconnect any between the carb linkage and balance the air flow. If you cannot attain a decent idle this way there are a couple of things to check. Remove the carb tops and the pistons. Check that all 3 needles are in about the same relitive position. This may or may not be correct, but at least the carbs should respond about the same. I do not have much luck with lifting the piston on strombergs. They always seem to act lean that way even if checked on an exhaust gas analizer. The other things to check are that the temp compensaters are closed, and that the bypass diaphragms were replaced. They do not come in the commonly available rebuild kits, and must be purchased separately. The other thing is to use the correct gaskets on the bypass valves. The kits come with several choices, as over the years the valves were activated both by external vacuum(Vac. line to valve) and internally. If the wrong gasket is selected mixture will bypass the throttle plate no matter how you adjust it.This seems like a long winded post, but it only starts to scratch the surface on tuning. I hope it helps you to start down the road though. The most important thing to remember is to take a deep breath, and step back when it feels really frustrating. It can take a while to fine tune modified engines, in fact, many books have been written on the subject. Be patient, it will all come together in the end.
Ok, The timing should be 8-10 degrees Before TDC, i.e. advanced. There will be no absolute figure for your car because it has been modified. It is generally best to run the most advance possible without pinging, with probably no more that 30 to 35 degrees total advance . This is checked at whatever speed the centrifical and vacuum advance is all in, but usually 3000, to 3500 rpms. Retarded timing will cause no power, and hot running every time.
To adjust the carbs, disconnect any between the carb linkage and balance the air flow. If you cannot attain a decent idle this way there are a couple of things to check. Remove the carb tops and the pistons. Check that all 3 needles are in about the same relitive position. This may or may not be correct, but at least the carbs should respond about the same. I do not have much luck with lifting the piston on strombergs. They always seem to act lean that way even if checked on an exhaust gas analizer. The other things to check are that the temp compensaters are closed, and that the bypass diaphragms were replaced. They do not come in the commonly available rebuild kits, and must be purchased separately. The other thing is to use the correct gaskets on the bypass valves. The kits come with several choices, as over the years the valves were activated both by external vacuum(Vac. line to valve) and internally. If the wrong gasket is selected mixture will bypass the throttle plate no matter how you adjust it.This seems like a long winded post, but it only starts to scratch the surface on tuning. I hope it helps you to start down the road though. The most important thing to remember is to take a deep breath, and step back when it feels really frustrating. It can take a while to fine tune modified engines, in fact, many books have been written on the subject. Be patient, it will all come together in the end.
OP
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Re: Still need help
OK - its still at 12 deg btdc.
I took off two of the bypass valves and blocked the holes (thanks VTR tech). It runs better, but hunts between 650 and 2000 now. I still can't balance the flow, but the two that were acting up are behaving better now so I'll try the 3rd one as well tomorrow. Can't face doing anything else tonight...
Oh and just for grins, let me tell you how the chap who "rebuilt" the carbs set them up.
1, 2, 3 in order from bulkhead.
1. No damper spring! No adjust on needle. Did I say no damper spring already...
2. Fast idle screw did nothing other than take revs to 3k even fully backed off if you gave it 1/2 a turn.
3. No adjust on needle.
Removed bypass for 2 and 3 and blocked holes. Runs, but hunts now. Will idle back on 2 now at least on adjust of screw. I cant get flow on #1 to drop so I'll try removing the bypass on that also tomorrow. I can adjust flow on 2 and 3 ok though.
If still no joy I have to check the temp compensator. Anyone know how to off the top of their head, just to save me a web search?
Anyone else have ideas as to why I'm finding this so difficult. I'd prefer them not to be "because you are an idiot" though. I already know that...
OK - its still at 12 deg btdc.
I took off two of the bypass valves and blocked the holes (thanks VTR tech). It runs better, but hunts between 650 and 2000 now. I still can't balance the flow, but the two that were acting up are behaving better now so I'll try the 3rd one as well tomorrow. Can't face doing anything else tonight...
Oh and just for grins, let me tell you how the chap who "rebuilt" the carbs set them up.
1, 2, 3 in order from bulkhead.
1. No damper spring! No adjust on needle. Did I say no damper spring already...
2. Fast idle screw did nothing other than take revs to 3k even fully backed off if you gave it 1/2 a turn.
3. No adjust on needle.
Removed bypass for 2 and 3 and blocked holes. Runs, but hunts now. Will idle back on 2 now at least on adjust of screw. I cant get flow on #1 to drop so I'll try removing the bypass on that also tomorrow. I can adjust flow on 2 and 3 ok though.
If still no joy I have to check the temp compensator. Anyone know how to off the top of their head, just to save me a web search?
Anyone else have ideas as to why I'm finding this so difficult. I'd prefer them not to be "because you are an idiot" though. I already know that...
jessebogan
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Re: Still need help
Rythmic hunting like that usually means a pretty good vacuum leak. Did you find a damper spring? And what do you mean "no adjust on needle"? Do you mean that it had 2 non adjustable needles, and 1 adjustable??? WTF? I usually disable the temp compensators by screwing them closed. Firmly.People will likely squawk about that, but it seems that the closer they imitate SUs the better they work. And lastly, "why is this so hard"? Two reasons. 1. It is hard. I have been fooling with LBCs for over 30 years, and I for sure don't begin to know it all. and 2. It seems that your help has been a hinderance. Having to clean up disasters made by others really adds to the difficulties at hand. Hence the term DPO. Or in your case F&^$@#$# Mechanics!
Rythmic hunting like that usually means a pretty good vacuum leak. Did you find a damper spring? And what do you mean "no adjust on needle"? Do you mean that it had 2 non adjustable needles, and 1 adjustable??? WTF? I usually disable the temp compensators by screwing them closed. Firmly.People will likely squawk about that, but it seems that the closer they imitate SUs the better they work. And lastly, "why is this so hard"? Two reasons. 1. It is hard. I have been fooling with LBCs for over 30 years, and I for sure don't begin to know it all. and 2. It seems that your help has been a hinderance. Having to clean up disasters made by others really adds to the difficulties at hand. Hence the term DPO. Or in your case F&^$@#$# Mechanics!
OP
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Re: Still need help
No I mean that the needles were totally outside of the adjusters, which had been screwed all the way down.
We had to take them out and reseat them. I have springs - I have a couple of "spare" carbs out of a bunch I bought on Ebay - they are starting to look like a great buy right now.
I'll see if I can find a leak anywhere. Its not obvious though - I plugged pretty much every hole I could find...
No I mean that the needles were totally outside of the adjusters, which had been screwed all the way down.
We had to take them out and reseat them. I have springs - I have a couple of "spare" carbs out of a bunch I bought on Ebay - they are starting to look like a great buy right now.
I'll see if I can find a leak anywhere. Its not obvious though - I plugged pretty much every hole I could find...
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Re: Still need help
[ QUOTE ]
Or in your case F&^$@#$# Mechanics!
[/ QUOTE ]
Not trying to Bogart your post, but I agree it is difficult or nye-on impossible to find a qualified mechanic that will do the right thing. I certainly don't mind paying the price if the work is sterling, but it seldom is. I personally have been through 3 "certified" mechanics and have had to redo every bit of their work, every bit. I am faced with pulling my tranny again for a bad rear oil seal and would be happy to pay to have it done but know that I cannot find anyone around here that will do it to my specs. That is, correctly.
Good luck Alan, I feel for you.....
Bill
[ QUOTE ]
Or in your case F&^$@#$# Mechanics!
[/ QUOTE ]
Not trying to Bogart your post, but I agree it is difficult or nye-on impossible to find a qualified mechanic that will do the right thing. I certainly don't mind paying the price if the work is sterling, but it seldom is. I personally have been through 3 "certified" mechanics and have had to redo every bit of their work, every bit. I am faced with pulling my tranny again for a bad rear oil seal and would be happy to pay to have it done but know that I cannot find anyone around here that will do it to my specs. That is, correctly.
Good luck Alan, I feel for you.....
Bill
jessebogan
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Re: Still need help
You all need to move here. I have worked on British cars for 30 years. Nowadays, I have to work on some newer "Stuff" but LBCs are where my heart is. The fact is, the mechanics that grew up on Brit cars have either moved on, or are dying out. There are not so many of the cars around anymore, rent and taxes have gone up, and you still need to make a living. Since I was "condoed" out of downtown DC, I am trying to focus back to nothing but English cars, but it is not an easy task. I attend local shows, and try to make sure my customers leave delighted with the work to promote referral business, but it is tough to corner the market. The key, I think is to find a shop/mechanic that still owns and drives LBCs. Then at least you know that they have more than a superficial interest in the cars. English cars are easy enough to fix, but they have their own quirks, and were built when labor was cheap. This means that it is possible that the cost for some repairs can be a little shocking compared with modern cars. On that note, I flat hate fixing Hondas and the like, and will not book appointments for them. I have a saying here, that I do three kinds of work. Good, Fast, and Cheap. The thing is, the customer only gets to pick two. So, Good and Fast won't be Cheap. Cheap and Good won't be Fast, and Cheap and Fast, won't be Good. Good luck, and Happy Motoring
Jesse
You all need to move here. I have worked on British cars for 30 years. Nowadays, I have to work on some newer "Stuff" but LBCs are where my heart is. The fact is, the mechanics that grew up on Brit cars have either moved on, or are dying out. There are not so many of the cars around anymore, rent and taxes have gone up, and you still need to make a living. Since I was "condoed" out of downtown DC, I am trying to focus back to nothing but English cars, but it is not an easy task. I attend local shows, and try to make sure my customers leave delighted with the work to promote referral business, but it is tough to corner the market. The key, I think is to find a shop/mechanic that still owns and drives LBCs. Then at least you know that they have more than a superficial interest in the cars. English cars are easy enough to fix, but they have their own quirks, and were built when labor was cheap. This means that it is possible that the cost for some repairs can be a little shocking compared with modern cars. On that note, I flat hate fixing Hondas and the like, and will not book appointments for them. I have a saying here, that I do three kinds of work. Good, Fast, and Cheap. The thing is, the customer only gets to pick two. So, Good and Fast won't be Cheap. Cheap and Good won't be Fast, and Cheap and Fast, won't be Good. Good luck, and Happy Motoring
Jesse