1.5 JB Misfiring in high revs since rebuild

Guys,i rebuild the engine 1 year ago and changed everything electrical,coils,points,spark plugs,cap,rotor,and the timing is on the spot,when driving normally the car is fine as soon as i get on it around 4500-5000rpms the car starts bogging.Half the mechanics i took the car in told me its a carb issue(Pierburg)i tuned it and still the issue remains.Tried different type of spark plugs and coils,same thing.What do you think?Anyone with the same problem?

Have you checked for air leaks around the carb flange - can cause uneven running at high revs?

typ_53b said

Have you checked for air leaks around the carb flange - can cause uneven running at high revs?

 How do I test this?I can see the carb flange but I don't see anything wrong with it,I put a piece of toilet paper near it and revved it but it didn't seem to suck it

I'm not familiar with the exact flange on the JB engine, but it is likely made of flexible rubber sandwiched between two steel plates, one attached to the manifold and one attached to the carb. This is to allow movement between the two parts to minimise vibration of the carb.

Failure is usually in the rubber joint. If you apply some sideways force to the carb/filter box each way, and you detect more than very slight movement, it is quite likely the rubber joint in the flange has split

typ_53b said

I'm not familiar with the exact flange on the JB engine, but it is likely made of flexible rubber sandwiched between two steel plates, one attached to the manifold and one attached to the carb. This is to allow movement between the two parts to minimise vibration of the carb.

Failure is usually in the rubber joint. If you apply some sideways force to the carb/filter box each way, and you detect more than very slight movement, it is quite likely the rubber joint in the flange has split

Well I just tested it and the carb seems rock solid doesn't move one bit.All these bits had been replaced by a carb expert near me six months ago,but this issue has been going off since the rebuild.By the way sometimes when I get on it and it bogs if I keep doing it for a while it seems to be getting better,but that's not a solution.

I have had similar problems and the solution was to earth the coil bracket to a rocker cover stud with a wire. This is standard on later golfs with electronic ignition.

zod said

I have had similar problems and the solution was to earth the coil bracket to a rocker cover stud with a wire. This is standard on later golfs with electronic ignition.

well believe it or not I changed the breaker points and the thing is revving up to 6000rpms no problem 😃
It's Aliiiiive

zod said

I have had similar problems and the solution was to earth the coil bracket to a rocker cover stud with a wire. This is standard on later golfs with electronic ignition.

Well maybe I am going to test this,because today the stutteding returned and I barely made it home.The car started cutting around 3000-3500rpms and within 10-15 minutes it was breaking up and cutting really aggressive above 2000rpms.Honestly,what you guys think could be?Its been one year now the same problem

OK. please keep us posted. Revving it while stationary is different to driving under load/at speed.

Also are you sure it's not a fuel supply issue? Are your fuel lines clear? Have you changed your fuel filter and is your fuel pump OK

zod said

OK. please keep us posted. Revving it while stationary is different to driving under load/at speed.

Also are you sure it's not a fuel supply issue? Are your fuel lines clear? Have you changed your fuel filter and is your fuel pump OK

So I solved it,fuel pump was new,I took the distributor cap off and the rotor and I noticed a slight movement on the distributor axle(the one the rotor plugs in).Had a spare distributor and switched it set up my carb again from the beginning and set the timing and guys WOW.Car is running better than ever and pulls hard without hesitation.So apparently a slight movement on that part messes up the points every time and throws the timing off as well!