Okay - I've got a spark

PaulButler

I've set my points , getting a good spark , checked the timing but the old girl (my 1939 112) still won't start. When I pull the plugs out they look a good color but I've noticed that I've got what appears to be slight a petrol leak where the carb sits on the inlet manifold so I'm now wondering if enough petrol is getting through. I've taken the carb off and reseated but still now joy.

Is there any easy way to check that the petrol is gong to where it needs to go?

Thanks,

Paul

Uncle Josh

These old buggies need a squirt of gas down the carb. That way you know it's getting petrol where it's needed.



Also, the choke needs to be all the way closed.



I'd rig up an extra grounded spark plug on the end of a plug wire to make sure you're getting spark thru the distributor, rotor and cap.



Set flywheel at TDC and rotate the distributor until the points just open for initial timing.



If it has furl and spark to the plugs, it has to run unless there are valves stuck open or it's hopelessly flooded in which case towing it in high gear would be in order.

rambos_ride

Would a vacuum leak - perhaps at the base of the carb make one of these old engines not start?

PaulButler

Thanks for the input guys. I've set the flywheel to TDC , set the points , checked the plug leads , had a plug out and made sure I'm getting a spark but still no joy. I pulled the carb off and checked the gasket etc which all looks okay. However when I looked down into the inlet manifold I saw a lake of petrol which I'm guessing shouldn't be there! I'm going to have to wait a couple of weeks for a buddy of mine to get back off of vacation and then try the towing trick.

Dan,

Thanks for the comment. As I said above I've checked thosr bits that I can check - is there are any way of detecting a vacuum leak?

EssexAdv

I don't konw of any way to check for a vac leak without the car running. However, if you put a bit of gas down each of the spark plug holes...it should fire off.... assuming you have any compression and it is timed properly

By putting the gas down the holes you eliminate the worry about the vac leak. BUt it will opnly put for a few revs...

Park_W

Another way to clear a badly flooded engine is to take the spark plugs out and spin the engine over with the starter while the throttle is held wide open. If the plugs are wet or sooty, dry and/or clean them before reinstalling.

Unknown

check the compression with a go on all 6 holes, if no compression, no run, check for stuck valves, S BILL ALBRIGHT

Geoff

I recenlty tried to start a '29 H engine on the test stand. Wouldn't go, apart from the occasionaly chuff. Finally noticed that the condensor was missing! To check for vacuum leak, just put your hand over the carburettor inlet whilst cranking ont he starter, with throttle open - you should feel a strong pull on your hand. if not, you have laeak somewhere, probably a bad inlet gasket.

PaulButler

Thanks for all the input guys. I've done the vacuum leak check and there was certainly a pull as it turned over. I'm going to test the compression over the next couple of days to see where we are with that.

Geoff I'm interested in your comment about the condensor. My troubles started with no spark which I put down to a duff condensor , changed that , got a spark but still no go! I did get the occasional feeling that it was going to start yesterday but it never quite caught.

Jon B

Was this car running okay in the recent past? I'm wondering if the timing is correct. The outer gear portion of those old fiber timing gears can actually separate from the hubs in such a way that they are sometimes in sync, sometimes not. So, if you experienced some rough running in the past, it might have been attributable to the gear separating, and the valves are then out of time with the crankshaft.

RonS

Where is the spark? Pull the coil wire from the dist. cap,hold it next to a ground (head bolt etc.),crank the engine. Is the spark there? If yes,goto the # 1 plug wire .After replacing the coil wire,crank it again.If no spark,its a good bet that you have a broken "pig tail" wire (connects the two dist.plates) or a open condenser. Try these ,A condenser on my 50 Caddy bought the farm one evening and it sounds like the problem you are having.Ron

jtroberg

Try draining the 'lake of fuel' from the intake manifold. Look for a bolt on the bottom of the manifold which can be removed to act as a drain, at least on the '36 models. Your '39 may not have this. Otherwise, I suggest leaving the carb off for a day or so to let the excess fuel evaporate. The engine won't start with that kind of flooding even if you have a decent spark.



John

nick s

since nobody asked this stupid question, I will do it. Is your timing set TDC on the compression stroke? I agree gas + spark should go boom, unless they aren't in the cylinder at the same time. I guess if you did not pull the distributor, this is not likely, retrace anything that was done since the last time it did run.

PaulButler

nick s wrote:

since nobody asked this stupid question, I will do it. Is your timing set TDC on the compression stroke? I agree gas + spark should go boom, unless they aren't in the cylinder at the same time. I guess if you did not pull the distributor, this is not likely, retrace anything that was done since the last time it did run.

Nick,

Not such a dumb question to be honest as this is a question that has been niggling at me today (not a prouctive day at work..) and I'm wondering if I've made a rookie mistake! I'm just getting back into these old cars afterno having owned one for nigh on 25 years and to say I'm rusty is an understatement! What I have done is to line the timing marks up and checked that my No 1 piston is at the top of its stroke by the simple method of putting something down the spark plug opening to ensure that the piston is at the top.

The dumb question that occurred to me today was whether I'd gotten the piston on its compression stroke ad was it enough that it was at the top. I asked a mechanic friend of mine a while ago about this and this was his suggestion - I hope that I understood him.

On another note I'd just like to say thanks to all you guys for the suggestions you've been putting forward for this 50 year old rookie.

Geoff

The t.d.c. pointer is above the starter motor, and the flywheel marks how t.d.c. (the long mark), and the degree marks for checking the distributor and valve timing.

nick s

Paul,
the TDC mark will line up at the top of the compression and the exhaust strokes. It is an extension of the crankshaft. The distributor is gear driven to rotate once for every two crankshaft rotations so yes there is a right and a wrong TDC. As to discerning the two, I guess the correct answer would be to pull the valve cover and be sure both valves are closed when at the TDC mark but you could bump the engine to TDC with #1 plug pulled, you should be able to have a definite puff on the compression stroke, using a compression gauge you could be certain as it should be about zero on the exhaust stroke.

regardless take it easy and don't flood the manifold next time you are trying to get it to fire. you should have a pretty good idea if it wants to try before you over do it.

PaulButler

I've gone through and checked everything that was suggested previously. Nick I made an assumption that if I pulled #1 plug (which I assume to be the one closest the radiator - is that a dumb question?) and cranked the engine over that when I felt compression then I would be on the compression stroke and able to line up as TDC from there. This I did , checked the position of the rotor and put #1 plug lead into there followed by 5,3,6,2,4.

I emptied the lake that was in the bottom of the inlet manifold and cranked her over. Nothing other a slight try. I then cranked her looking into the carb and nearly had my eyebrows removed when she backfired. This suggest to me that I'm still out on timing but I reckon I've done it all right?

I appreciate the help you guys are giving me and am itching to get the old girl going again so any more views?

Thanks,

Paul

rambos_ride

Try the re-wiring exercise again...it's very easy to get the wires only 1 position off...

I don't know what the timing is on these vehicles but for example a GM 350 running at 8 degrees BTDC would mean that when you get #1 on the compression stroke and then look to the rotor to determine #1 on the cap - you actually would look to locate #1 on the electrode the rotor just passed as at true TDC the cylinder would have already fired.

I hope my description makes sense...

Jon B

Let's go back and look at the timing: is the distributor rotated to the correct position? Have you had the distributor out at any point, and possibly replaced it incorrectly? (I believe the gear at the bottom of the shaft, can be replaced in any location; it doesn't 'key in'.) The fact that you are getting a 'cough' indicates you're not quite right on that distributor rotation. You do realize that the advance control arm (with the markings on it) clamps to the distributor in such a way that -- if it were loose -- it would rotate on the distributor? If that has accidentally happened, then even if you're carefully noting the "retard - advance" settings stamped on the arm, you could be waaaay off.

PaulButler

Thanks guys!

Dan - interesting point that one.

Jon - the distributor has been out as this all started with a condensor problem. Before it was removed the relative positions were marked and I have been careful to replace it back where it came from. I hadn't (yet) checked the advance control arm - that'll be the next thing I do.

Relearning lots about the joys of owning an "old 'un" and , fankly , loving every minute of it.

Unknown

Paul be sure the points are adjusted to the correct gap. Set the dist. where the points just open on TDC. compression stroke. Be sure you have the wires in the correct rotation. May have to use a new set of plugs as lots of times once a plug of today has been bad gas fouled they will not fire under compression.

junkcarfann

With all due respect, you may be at the point where you need a qualified mechanic to sort things out and get the car running.

PaulButler

junkcarfann wrote:

With all due respect, you may be at the point where you need a qualified mechanic to sort things out and get the car running.

Whilst I don't disagree with you there one of the major points playing against that is that trying to find someone with even a vague interest in looking at the car - it seems that most of todays mechanics are only interested in looking at cars that can be plugged into a computer.

I also want to be able to do this myself - many years ago I owned a number of these cars and used to able to do this sort of stuff with no real issues. I can't believe that I've lost that much knowledge and a forum like this is a great place to get inspiration from.

junkcarfann

Two things: First, you are right...modern mechanics often do not have the time nor the interest in old cars. Therefore, perhaps you could find amongst the old car hobbyists in your area someone who can help you.



Second, there is the safety issue...you have a pool of gasoline in the intake manifold, and later stick your face into the carburetor, and the engine backfires...yikes!



I also like to do all my own work, but certain things are either beyond me, or unsafe for me to do because of lack of proper equipment. So I do what I can, and I farm the rest out. Just my 2 cents.

PaulButler

I'd cleaned the pool of petrol out of the inlet manifold and I'd added a slight artistic license to my description! I had the choke closed by hand when cranking the car over and there was a slight backfire in the carb.

Dumb I may be - stupid I ain't!

Clutchguy

Sounds like when the distributor was pulled before,the condeser was diagnosed as the problem.I take it the condenser was replaced,but has never ran since?????????? Sounds like it was mis-diagnosed???? You probably need to check the timing gear.As stated here somewhere in this thread,checking compression with a known GOOD,compression gauge will probably tell alot.When the timing gear is worn badly or has broken,it will not have much or any compression.Not having much compression sometimes causes a hard to diagnose problem.Also,how long did it run before this??.It could have ran for a full day on stale gas.Stale gas=VARNISH.This will stick the valves and valve guides as ONE.If the engine is warm or completely warmed up and running,the varnish forms around all the valve stems and valve guides.When the engine cools off,this varnish becomes "GLUE".This applies to all engines new and old.Stale gas is real hard on anything!!!!!,including your lawnmower!! Good Luck