SOS-Engine won’t start..loud combustion

[RPP]

CAR: BMW 2002 1976

 

NEW ENGINE ITEMS:

-Battery

-Points

-Distribution Cap

-Spark Plugs & Wires

-oil filter/ oil change

-fuel pump

-Weber 36/32 DGV restoration kit

-Installed intake manifold new gaskets

-Gas tank completely restores

- Clean and painted alternator/Starter

- Fix radiator and replace hoses

 

PROBLEM:  After several weeks of restoration work, today was the day I was going to attempt to turn the engine on. The lights beams worked, a 12 V wire was attached to the coil, Coil to distributor, firing properly arranged 1-3-4-2, fuel pump was pumping gas and everything seems ready. I cranked it several times and it cranked with good strength but it did not start nor did it try to start. Suddenly, a strong combustion. A dry “boom”  from the carburetor. I had put some gas in in before cranking. I am puzzle as to what can be causing the problem. I had to redo some of the existing wiring for the heating system was eliminated (I live in the Caribbean), the original fuel pump relay was removed when the pump was replaced with an universal pump. Carburator? Electrical? Where do I begin?

 

footnote: When I acquire the car, the owner turned it on without difficulty. He drop a few drops of gas in the carb and it turned on. The pump was disconnected and the car needed a lot of repairs.

 

I appreciate your thoughts on what to do next.

[Hans]

I'd start with timing. Are you sure you have tdc for #1 cylinder? Do you know how to set initial timing?

[RPP]

Thanks. I did not touch the ignition nor I made any timing adjustment. That is beyond my DIY skills.  Tell me more.

[dlacey]

but you say you changed the points -> so theres a good chance that the ignition timing has changed.... and a boom back thru the carb would suggest its too far advanced.  You need to do static ignition timing.

Or quick & dirty: Mark the position of the distributor body against its clamp housing (scratch with a screwdriver so you've got a line on the dizzy body and a line on the clamping casting. Loosen the clamp bolt so that the distributor body will turn...line up your marks.... get a decent glove to avoid electric shocks, get a friend to crank it over while you twist the dizzy body 5-10% clockwise.... if it fires and runs then fine twist the dizzy to maximise revs...then clamp it there.... that will get you moving....but you gotta learn to time it properly later...

[ray_]

 

1342 clockwise or counter?

 

I'll bet the spark plug cables are not in the correct order and/or orientation. 

[RPP]

Thanks for the all comments. When I changed the points, I turned the engine manually until the cylinder inside the distributor marked the highest point of the cam. Then I used a calibration tool and used 0.016 in gap to set the points.  I also changed the condenser. I did not moved the distributor from where it was originally. The firing sequence was set at  1-3-4-2 clockwise, 1 being the lowest point from the locking bracket. I will double check everything.

[ray_]

How did you determine where to place #1 spark plug cable?

[dlacey]

44 minutes ago, RPP said:

Thanks for the all comments. When I changed the points, I turned the engine manually until the cylinder inside the distributor marked the highest point of the cam. Then I used a calibration tool and used 0.016 in gap to set the points.  I also changed the condenser. I did not moved the distributor from where it was originally. The firing sequence was set at  1-3-4-2 clockwise, 1 being the lowest point from the locking bracket. I will double check everything.

Yes thats all good, but your old points and your new points may not be mechanically identical....so your settings so far are all good, but ignition timing is not guaranteed to be exactly same as before....you need to check it after changing points.

Also beware new condensors....the quality is not good....if after you've checked the timing it still wont start then consider reverting to old condensor...it might just save the day...

[KFunk]

I would rotate the distributor a little by little until you can get it to fire and run rough, then check the dwell with a dwell meter. Adjust points accordingly (setting it just by measuring gap is crap, you want proper dwell)l. Then, when dwell is correct, you set the ignition timing properly with a light.

if you don’t have a dwell meter or timing light, get them!  If you don’t understand how to adjust them, then learn!  It’s easy, and you’ll need to do this stuff if you ever want to mess with this car much.

Oh, and if rotating dizzy a lot doesn’t get it to fire at all, then worry about fuel supply.  If fuel supply is good, and timing is way off, it’ll at least fire some occasionally. If it’s never fires without putting fuel directly in carb, then you got a fuel problem.

Edited April 17, 2020 by KFunk

[willys]

did you replace the ignition wires one at a time to avoid confusion?  If not, perhaps you have misplaced wires or a counter-clockwise distributor

 

good luck

 

Geez just realized this was covered above - blame it on isolation or alcohol - both apply - 

Edited April 17, 2020 by willys
isolation

[Hans]

Do you have a 12V test light?

[RPP]

Gents, Thank you for your replies. I will try to answer the best I can the inquiries above:

 

1. I started the placement of the spark wires 1-3-4-2 beginning 1 at the notch that locks the distributor cap in place. From there, clockwise, I place 3-4-2;

2. When I replaced the spark wires, I removed them all simultaneously because I thought I had a pretty good understanding of the ZÜNDFOLGE 1-3-4-2, and was able to install them in the right order. (So I think)

3. When installing the point and condenser I ordered from Pelican Parts (BMW originals/Bosch), I rotated the engine manually until placing the cam inside the distributor to the highest point. (It appeared that there are two identical highest points). I used a gauge measure and calibrated the point to 0.016 in.

4. I do have a digital voltimeter and installed a 12 v wire into the + side of the coil. From the - side of the coil, I connected a wire to the new condenser outside the distributor.

 

I am re-checking everything again. What do I do once I find the TDC on cylinder one? I do not have a timing light, nor a dwell meter. Hard to find one as we are still in complete lockdown in San Juan and all commerce is close. Trying to work with what I had.  Many thanks to all.

 

Roberto

[Hans]

Check that both #1 valves are closed at tdc. 

[RPP]

Here is how the spark firing sequence looks.

[RPP]

Hans, I have never check TDC before. By doing some research on it, looks like I will have to use my finger because I do not have a piston stop. Once I check TDC, what next? If is not in TDC, what do I need to do? Thanks.