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peeeot

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Hello all!

I just picked up a '76 Midget a couple of weeks ago, so I thought it high time to find a forum of British-car-knowledgeable people to help learn the ropes of these cars. I've heard all kinds of things, good and bad, but when I came across this Midget, I figured I'd give it a try.

I'm excited about everything about the car except its engine speeds in the 60-80 mph range (I'm going to be using it as my driver, and though I'm not on the highway often, it doesn't seem as though the Midge will be happy there). I got it from some friends of the family, who went through the trouble to have the engine freshly rebuilt with headers and a Weber DGV carburetor. No air pump, no EGR, no catalytic converter... just PCV. It had been on the road about 2 weeks after dropping the engine in (less than 500 miles) when someone clipped it in the rear. Then it sat for 6 years (!). It can drive, but it is wounded. I have a parts car in quite good shape, either to swap the drivetrain into or to supply donor body panels if I opt to repair the damaged car. Since I've had it, I've just been trying to familiarize myself with it inside and out and to get it tuned up as best I can. It had been in a garage while it sat, and the cylinder walls were clean... I squirted some oil in the cylinders, drained the ancient fuel (gas tank was clean), changed the engine oil, hooked up a new battery, and after some priming with starting fluid to save the battery some effort, it fired right up. As soon as I bled some response out of the brakes (they were pretty much empty), I took it for a brief test drive. FUN!!

There's a lot I don't know, though, and I'm not really pleased with the way the motor is running. It's the 1500 engine, and the emissions label says timing should be set at 2 degrees ATDC; my timing light says that at around 900rpm, it fluctuates between 8 and 10 BEFORE top dead center. The idle is somewhat erratic, varying about 200-300 rpm. Looking down the barrels of the carburetor as the engine runs, the primary looks normal but the secondary will sometimes dribble out a little non-atomized fuel. This increases if the throttle is opened at all. I have premium 93 octane fuel with some lead additive, as this car never had a catalytic converter. Starting with the engine cold, I set the choke fully shut with a light tension and the fast idle screw resting on the cam in the position it was when I got it. Upon starting the engine, it tried to race, so I shut it off, turned the screw out a good deal, and tried again. I set the fast idle around 1600, with the choke partially open. When it opened up more, at a certain point, it began turning close to 2000 rpm. I turned the screw until I had it back down around 1600, although it would sometimes jump a little higher or drop lower. At this point the choke was open, and I opened the throttle just enough to release the fast idle cam. Now it was running at 900 rpm, the desired idle speed, but it was struggling, and very nearly cut out once or twice. I turned it off and disconnected the vacuum advance and plugged the hose. Timing averaged 8 degrees before top dead center. The vacuum pull at the hose was very weak; I even unplugged it and the motor didn't really run any worse. Upon starting the motor again, with the advance hooked up this time, it idled around 1200. I turned the idle screws out until the no longer contacted their cams, and made sure the accelerator cable wasn't stuck, but the engine wouldn't go below 1200 rpm. Timing with vac. advance hooked up at around 1200 rpm was in the 14 degree ballpark.

The only other symptom that is unusual comes around 3200 rpm while driving; I didn't permit the engine to go much higher than that. It was a sound akin to a rattle, but it felt more like the engine being a little off beat or something. I'm really not sure what it was all about.

I'm suspecting vacuum leakage somewhere at this point. Does anyone know how this engine should be timed, or what might be off with it? I think I heard the previous owner mention a non-stock camshaft, but I'm not sure about that. Not sure if it would affect timing. I appreciate any help you can give me, and I'm glad to be aboard! Thanks!
 
Glad to have you on board and it sounds like you have a good handle on the problems at hand. A different cam can make alot of difference in timing and valve adjustment. See if anyone can give yo some spec's. Spray a bit of carb cleaner around your manifold and see if you get a change in idle speed and don't forget the EGR valve down on the exhaust, if it's still there. Wayne
 
Thanks for your response. I found an article about vacuum leaks, and one of the indicators of vacuum leak it mentioned was if adjusting the mixture screw didn't really alter the way the motor runs. Well, I checked it out on my Midget, and it definitely made a difference. The strangest symptom is the refusal to drop below 1050 rpm or so at idle. I visually confirmed that the adjustment screws (fast idle and normal idle) are definitely not resting on their respective cams. I found that I could adjust idle speed a little by altering mixture, but of course the quality of the idle was affected at least as much as the speed. Under moderately aggressive throttle, the midge kinda bogs out. I felt like it was ready to launch off at an alarming pace, but it didn't respond immediately, and I didn't push it (yet). I'm going to contact the PO tonight and see if I can learn more about the cam. As for EGR, that's toast-- this car has headers. PCV is the only emissions device I see that's in use. Also, the only vacuum line I can see coming out of the carb is the vacuum advance line. Would an incorrect float setting result in the fuel dribble I mentioned? It really only occurs when the throttle is opened above idle, and then only in the secondary barrel.

I just went out and looked under the hood(bonnet) again and noted that the pcv line has a t-split between it and the rocker cover. The line coming off the T goes to the charcoal canister, which has some open ports on it. The vapor recycling system isn't hooked up right now. Is that going to affect idle? I thought it might at least affect crankcase ventilation... although the pcv valve just opens up inside of the air filter assembly. It doesn't seem like it would make much difference to me.
 
The previous owner has confirmed that the engine rebuild was to stock specifications; it had a stock camshaft rather than a performance one. Where (ballpark) should the timing be set? Why might the engine bog under aggressive throttle? I appreciate the help, all. /ubbthreads/images/graemlins/smile.gif
 
peeeot, have you checked the fuel pressure, you only need 1 1/2 pounds on the weber,(I think) and it could be blowing by the needle and seat. Where in NC are you? Wayne
 
I haven't checked the fuel pressure because I don't have the gauge for it (at least, not that I'm aware of.). It's a very small amount of fuel that comes out. I'm located in Cary, NC, just outside of Raleigh.
 
Welome Peeeot:

To find vacuum leaks a handy method is to use WD-40.
Start the engine and let it idle at it's lowest RPM. Spray WD-40 (using a "straw nozzle) near areas that you suspect. If there is a vacuum leak, the engine will suck in the WD-40 and slow down a bit (the WD-40 won't hurt anything).
Also, these 1500 engines do not really have clear timing marks for cam installation....I've seen several of them put together with cam timing "off". The correct process is somewhat involved and requires a dial indicator.
By the way, not everyone here is a big fan of the Weber carb conversion...I had one on one car and even after going though a box of various hi/low speed jets and emulsion tubes, I never felt it ran as well as the stock carb.
 
I've gathered that the stock carbs are general favored over the Weber here, which I confess I was a little surprised at, given all I've heard about how hard they are to keep tuned and operating properly. I have the equipment to go back to stock, but for now at least I would prefer to stick with the Weber.

It occurred to me that the change in emissions equipment could also affect idle settings... might this account for the higher-than-expected idle?

As for the cam timing being off, I suppose it's possible, but in general the engine seems to run too nicely for that to be much of an issue. Idle a little over 1000 will remain there pretty steadily. It revs up nicely, too, except when I open up the throttle suddenly. And, as I said, the vacuum at the advance line feels really weak to me (this from holding my finger over the end of the hose) and I know the engine should be stumbling with the hose unplugged and it isn't. So I have some signs pointing at vacuum leak and some not. I'm suspecting the carb mounting gaskets at present. Tightening the carb down didn't really help, but when I had it off, the gaskets beneath were kind of glazed, like they had a lamination on them or something. The only reason I didn't replace was that I didn't have replacements.

I presume 10 degrees BTDC is acceptable timing on an emissions-stripped 1500?
 
peeeot, For everyday use 10 degrees may be too much, try somewhere between 5 and 7 and 1000 rpm's is not that bad for an engine that has all the emissions striped. Don't hook up the valve cover hose to the intake manifold, your carb should have a spot for it or the air filter will work, just not as well, even my old MG had this systen but it also had a breather pipe off a side plate. Wayne
 
The hose from the rocker cover to the air filter of the carb doesn't look like a modification or something jury rigged; it appears as though the Weber kit came with the hole in the lower plate of the filter assembly for the purpose of running the hose to it. There is a white plastic L-shaped fitting that passes through this hole, fitting snugly in it, with a white plastic nut on top to lock it in place on the plate, and the rocker cover hose attaches to it. I have been referring to this white plastic thing as the pcv valve, because I don't know what else it would be, but I do think that if that's what it is, it's placement is rather strange. I don't see any vacuum ports on the carb except the one for the advance. I've read a lot about people having oil coming out their valve cover seals and oil dipsticks due to inadequate crankcase ventilation, and I have not observed either of those symptoms in my car.

I appreciate the timing advice. The car bogs now, except under casual throttle, and when I first looked at the carb when I got it there was definite evidence of a pop (a backfire) through the secondary barrel, and I thought that carb backfire happened when timing was too far retarded. Am I mistaken? That's my only fear about turning the timing back.
 
Peeot, check your vacuum advance on the distributor, either with a vacuum tool or just suck on the hose, I would buy a new one of the right size first. Take the distributor cap off and if the points plate moves, good, now put your finger over the hose connection on the carb and try to feel a little suction. If you don't get the desired results in either this could be the bog down. Please understand that all of us are trying to help, but sight unseen and not knowing what someone else has done makes it very difficult to pinpoint a new start up and with your Weber even more so. Hope we hit on it soon. Wayne
 
I'll try what you suggested at the first available opportunity, which will be this weekend.

I absolutely appreciate the support you all are providing and am aware of the complications with "long distance diagnosis", which is why I've been so wordy, trying to explain things in as much detail as possible. I'm away from the car during the weeks, so I've just been trying to come up with things to try when the weekend rolls around.
Thanks again!
 
So it turns out the main problem I was having had a very simple (albeit unexpected) solution. I took the carburetor off today, and discovered that the throttle pltes weren't working correctly at all. I hadn't looked at the bottom before, and had mistaken the primary barrel for the secondary, because it was opening slower. Someone had overtightened the nut that holds the throttle linkage assembly together, such that both barrels were opening at the same time, and the secondary much faster than the primary. In fact, the primary wouldn't even open all the way, because the secondary would fully open and restrict any further motion at the primary. That dealt with, it now opens progressively as it was intended, and no longer bogs. It will absolutely purr at idle, even as low as 550-600 rpm. Previously, the primary throttle plate was stuck partially open, thus the too-high idle.

The only thing that still needs to be addressed is the fuel dribble, which I now realize is coming from the primary, not the secondary. I don't have compressed air, but I used a hose to blow through some passages in question, and they did not seem to be blocked at all. Why might it be dribbling?
 
peeeot, either needle and seat or to much fuel pressure. I think you said you did the float level, if not, try that. It has to be one of these or something major is wrong. Wayne
 
okay... I looked at the needle and seat today, and they were clean, although I was surprised to find the needle to be solid metal instead of rubber-tipped. Where can I find the float setting for the DGV?

-Peter
 
Okay, I was able to find float settings for the DGV online, and found the float to be off by about 2mm. After adjustment, the dribble disappeared. Thanks for the help, all! The car is running beautifully!
 
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