MG MGB and MGB GT Tech Talk
Here are the instructions, I wasn't sure how to post.
Make sure that your dizzy drive gear is in this location when everything else is at TDC, otherwise your car will do what it's doing. I really don't think it's fuel assuming that the pictures in your last post were all at TDC
Read what it says for then 18G/Ga engine it pertains to all.
As long as the distributor is positioned to match the position of the drive, it doesn't matter which way the drive is in. In other words, if the drive is 90º out, as long as you rotate the distributor the same 90º, it will work. (Assuming of course that the vacuum advance doesn't foul something and prevent you from setting the timing where it needs to be.) Assuming he's set the timing correctly, I think Robert's distributor is a red herring.
Robert, here's a thought. Have you checked the plugs? Perhaps while you've been struggling with this, a plug has fouled out. At least that's a quick, easy check....
Yeah, checked all the plugs... they're burning a nice color. I got the car running again last night, though same scenario. The timing is right, the dwell is right, valves are right. Seems if the timing is right with a light and all, then Rob is correct that as long as the dist. is turned, then the cog wouldn't cause this issue. Also, since Curtis and a couple others have posted that their cars are doing the same thing and they've been driving their cars, then it's not likely they their cogs have jumped or turned to cause the same problem.
I'm going to buy the weber downdraft conversion (want it anyway)... that will at least eliminate the SU's from the equation.
We'll see what happens with that chang.
Thanks for sticking to this topic... I'm sure people are getting a lot of good ideas about what can be gremlins..
Ok -- here's my bias coming out. I don't think a downdraft Weber is as good a carb as a set of good SUs. There are those who prefer them, and I respect their opinions, but I don't share them. Properly set up, SUs are just as reliable, just as economical, and people report that SUs give more low- and mid-range power than a DGV (I can't confirm the last point as I've never owned a DGV.)
I know you're frustrated and want it fixed, but I'd still advise against throwing parts at it until you know what's going on.....
Hang in there!!!
fuel pressure should be 4-6 pounds right? Just checked the level at the carbs and it's at 5. Also, got a little more aggressive with the carb cleaner at the shafts... If I get the tube right at the linkage and blast at it, the idle will drop off... Might be overkill on the testing method... but, well, ya know.
I think if your SU's are working then why spend the cash on a weber. I love webers but I wont take working SU's off for a weber. Just my opinion. SU's are not that complicated.
Well, if I knew for sure that the SU's were working, perhaps I'd keep them. I'm taking them off again today. I think I have some more shaft seals here, I'll swap them out again, recheck the float level, and see what happens with that.
See if you can wiggle the shaft up & down (i.e. radially; perpedicular to it's length) in the carb. There should be no detectable slop. If there is, you need at least new shafts.
I could "barely" feel wiggle in one of mine and lots of wiggle in the other. When I had the folks at John Twist's place examine them during the class, they could see from 2 feet away that BOTH the shafts were bad once they were out and on the table. Btw, It is usually a good idea to replace the bushings when replacing the shafts, but that requires a reamer after intalling the new bushings.
John
Seems to me 4 - 6 pounds of fuel pressure is too high. IIRC it should be 1 1/2 - 3 pounds. Excessive pressure will push the carb needles off their seats and cause an overflow condition.
3 or less on the fuel pressure then? Anyone else care to chime in on that? I could throw a fuel regulator on it and see what happens there.
What's the going rate to ship these to someone "in the know" and have them rebuild the carbs? is there a complete overhaul kit that covers anything that can/will be wrong with these things? shafts, seals, needles, floats... short of buying new SU's??
that's total costs... not just shipping costs ;)
Re: rebuild --- Tom B is the guy to ask...
Sometimes you can get away with replacing just the shaft -- the shafts often seem to wear faster than the bushes. The quick check is to remove the throttle plate, slide the shaft one way or the other so that an unworn portion is in the bush, and try to wiggle it. If it doesn't wiggle, you can replace just the shaft.
I've never rebushed and SU. Rather, I have them reamed for 0.010" oversized shafts. My local MG specialist has the right piloted oversized reamer so it's quick & easy.
So dennis,
You think I need to regulate it down to 2-3 rather than the 5? You think this higher fuel pressure would cause the problems that are going on?
Also, was mentioned... when you take out the mixture jet, then the center cylinder (under the nut, the needle goes through it).. does it have metering holes in it? if so, are there more than one or can it go in more than one way? perhaps there's metering holes in there that are not aligned?
thanks
To Rob Edwards: I agree "IN THEORY" that the distributor can be changed to match the drive dog. But in three places in my Factory manual it clearly states that in order for the engine to operate properly the drive dog must be in that position. It is such AN EASY thing to fix, you just have to remove two bolts. WHy would you not want to put it back to where it should be. Maybe it is slightly off when turned 90 one way or the other.
It just makes sense to me to fix that first, IT IS SOOOOOOO EASY of a fix. Then he's not relying on your word (and don't get me wrong, I'm not meaning to say you're not right) I just remember that when I put my engine together one time that we dropped that drive gear in one tooth off and the car ran terrible. Then we went back to the manual realized what it was. I don't think that I was able to rotate my dist. to match were it was.
Taking 5 minutes to fix that versus sending my SU around the country seems a no-brainer, maybe I'm missing something?
Hey guys, I know that you all think that I'm way out in left field here. I just can't believe it. It all makes perfect sense to me. Maybe I'm just a lunatic, I don't know. But I do know that every manual that I have says that that DRIVE DOG has to be in that position that I mentioned and posted here. That 6 different manuals and one even mentions it 3 times. What makes sense to me is. That yes it will run at idle, because he has obviously moved all of the spark plugs to match where the number one cylinder is firing at TDC. But when he accelerates it stalls ans sputters, that's because the whole plate that the points sit on has now advanced and the spark plugs are firing at the wrong time in relation to the cylinder being aty TDC. I can see from his pictures that the Valves one #1 are at where they should be when one is at TDC and the Harmonic balancer is where it should be but the distributor rotor is off, exactly one grove forward. It is such an easy thing to fix. You guys are talking about taking out fuel tanks and taking off carbs, why not pull the dizzy out and make sure. It will take all of 5 minutes.
I can't believe that every manual says that this is how the engine should be put together and you guys want to overrule that. Maybe I'm just missing something huge here, but I don't think so.
Help me to sleep better tonight and please check that angle of the cog that the dizzy fits into.
Brian
Your #1 plug is now down on the far right, correct? Somewhere in between where my #1 and my #2 plug wires are. You have obviously rotated the dizzy to make the engine idle. But, upon acceleration the car sputters. I think its because, well you know what I think. Your plub wires should be in this location. Because your dizzy in your picture is oriented how it should be, I bet you plug wires don't look like mine do, right?
Please excuse the dirty engine this is not how it looks now, just a pic to help show what I've done in the resto.
Maybe I'm beating a dead horse, I value everyone's opinions here, heck if we weren't different we'd all be the same, and the thought have having to deal with me all the time makes me kinda sick.
Good Luck Robert!
Robert, with the thread going on this I am not sure where to post, but here is a link to fuel pump 101 -- this should answer the pressure question.
What I find interesting is that with high fuel pressure you are not getting flooding or signs of running too rich. As others have said sounds somewhat like fuel starvation at higher speed -- and they have mentioned line blockage. Have you checked your gas tank venting? Might try to run with out the gas cap and see that your vent is not clogged.
I find it best if I just change one thing at a time and slowly rule out issues --you have been receiving a lot of ideas and even conflicting info.
Good luck.
Dennis
<http://custompistols.com/cars/articles/dd_su_fuel_pumps_101.htm>
Brian,
you know... You're SOOOO close to me... just come over and make the thing RUN!! haha.
On your distributor... no vaccum advance? or is it camoflauged..
also, if it makes you feel any better, I picked up the bolt to pull the dizzydogdooflinkydigger
No I have NO vacuum advance on that dizzy. But I did on all the stock ones that I ran. That dizzy in the pic is a Mallory Dual Point Dizzy it has a mechanical advance or centrifugal I can't remember exactly, but the advance in mine is done through the use of weights and springs, I can can the advance very easily with the change of a spring. But it came really close from Moss when I bought it.
I don't mean to be a pain, but it just seems sooooo obvious to me. Read what the manual says, along with the angle of the drive dog it is also out of center so the larger offest should be uppermost. You'll feel the gear slide in and turn at the same time, so you want to start at horizontal and as it slides in it will rotate counterclockwise.
Make sure you are at TDC, the #8 valve will be down. I think that's your problem I really do. And it is really easy to check.
After you put it in the correct way, I think that you'll have to move your spark plug wires to compensate for the change.
I'll keep my fingers crossed.
I really want the MG Wizard Title to be estowed upon me!!!!
LOL
Am I close?? Oh that's right you're in CA now right? or still Arizona, I can never remember anything. If you here close, I will come by, no problem.
Post Edited (03-05-05 15:59)
I watched it done and rebushing is easy to do - with the right tool and a reamer to make sure it is just right. The reason John T. did the rebushing is he uses wider bushes so that the throttle shafts don't wear so easily.
John
well, here's tonight's update.
I pulled the valve cover, carbs, dizzy, dizzy housing, dizzy drive gear, plugs
I regapped the plugs as per the book. took the carbs apart and set them at the book base setting. Swapped out the seals at the throttle shafts, pulled the drive cog for the dizzy and set it like brians book shows, rewired the dizzy cap, checked the points, started it up. Set the timing, adjusted the carbs (which I can now get to go better than LEAN all the time) <-- guessing that was the shaft seals... the others were hard and brittle.
so, it's idling... warmed up... rev... revvv.... revvvvv.... blah blah blah... cough cough, choke choke... rattle rattle rattle... cough cough... idle. So, nothing new. Just the same as before. Sorry Brian, no MG Wizard title as of yet.
And yeah, I'm local.. the CAR is from Arizona... I'm here in HB, REMEMBER? sheesh!!
So, my guess is maybe something engine internal. I'll check the thing again tomorrow with the gascap off. Though the canister doohickey in the trunk isn't connected to anything. I'd think if it was a vapor lock in the tank, it would happen while idling for a long time.
Oh that's right. Hey I can come over tomorrow and bring my weber carb. That will answer all of the carb questions. I totally didn't realize that it was you that is here in HB. I was thinking the other Rob. I'm out in my garage working right now. I can take the carb off tonight and come over tomorrow and I'll be able to get it going, I've been doing this for twenty years.
I'll bring over the manual that I have on disk and you can load onto your computer.
Whatta stupid-a-- I am here I am all getting into your problem and worrying about it, and your right here. God I really have to lay of the crack pipe. Its starting to affect my memory.
If that's what you want to do go ahead and email me, brianmasek@verizon.net and we can exchange phone numbers and work that damn thing out. I'll be up for a while so email away
