Engine miss when hot

[John Alves]

Hi all
I have a new addition to the family, a 1968 1500sp beetle which I am slowly sorting out.
The latest issue is a slight engine miss when cold, after the motor is warmed up, she runs like a bomb,
Any ideas on trouble shooting this?

[73type2]

Perhaps electric choke is not set correctly?

[fig]

Check your manifold heat risers. They are probably blocked.

[Tony Z]

Check your manifold heat risers. They are probably blocked.

aftermarket exhausts sometimes have ports for the heat risers, but they are usually designed wrong and dont allow flow, so they block with carbon

also, check for vacuum leaks

[John Alves]

choke is working, heat risers are blocked off, my other two air cooled cars don't have heat risers and have no issue ????
I have checked for vacuum leaks, will check again
did all the usual when I bought the car, points gap, valve gaps new plugs, set timing, replaced dizzy cap with one I had lying about.

could it be a sticking valve which loosens up with heat?

[Tony Z]

try advancing your timing 2-3 degrees

[John Alves]

thanks Tony that did the trick

[John Alves]

Worked for a while and them came back with vengeance, I replaced the dizzy and coil from my other ride and all is 100% now.
Could it be a faulty Chinese condenser? I don't have a spare condenser as all my other rides have been converted to electronic pick up

[retrovan]

Bash the sides of the condenser with the flat side of a spanner, and it will work again,

Till you can get a Bosch condenser from Diesel Electric.

Herman

[John Alves]

The saga continues, I now have a minor miss when cold, runs ok for about 20min and then miss comes back when engine is warm, It feels like a total loss of power but for such a short time and not steady, I connected a multi meter to the coil positive and ground and as the miss happens so the voltage drops to about 10v then back up again,
Is this an indication of a intermittent short on the coil power wire or could the voltage drop also be caused by something else?

[retrovan]

Still sounds like a condenser.

Or bash the bottom of the condenser with the round edge of a 19 spanner to dent it.

But to be sure, fit a blue Bosch coil

Herman

[John Alves]

not using a condensor I switched to a working dizzy with igniter system

[Tony Z]

ignitor system isnt reliable

[John Alves]

I know, but this one was taken from my ghia and is working

[retrovan]

May be incorrect coil for the ignition, try moving the coil from the Ghia with the unit and try again.

Herman