Series IIA engine problem

[btm]

G'Day all, I'm having trouble locating a problem with my 2.25ltr petrol engine. I am hoping that someone can identify the problem from the following symptoms...

a) The vehicle is a 1968 ex-army LWB series IIA, all original 2.25ltr petrol engine.

b) Engine starts first time every time, and idles beautifully and will rev freely when the engine is stationary.

c) However when I take it for a drive it starts to spit and fart in the upper rev range??

d) I have recently replaced all HT leads, points, dizzy cap, and rotor. I have also just re-kitted the carby (only non-original part on the vehicle - stromberg).

It sort of feels like something is restricting the engine when I put my foot down. If I only press slightly on the loud pedal it will let me slowly accelerate, but if I put my foot down it starts to fart and backfire???

Just not sure where to check...? Does it sound like a fuel problem or electrical?

Hope someone can help explain, I have owned the vehicle for 18 years now and have been able to fix every other problem, but htis has me stumped!!!!

thanks tim
Darwin NT.

[dobbo]

Sounds like a fuel delivery problem, who rekitted the carbie and was it tuned to the vehicle. Or opposite has the rekitted carby found a tuning problem on your car.

[Phoenix]

Fuel pump or vacume advance would be worth looking at.

[101RRS]

Sounds like a timing issue caused by either dodgey vacuum advance or spring weights (have they seized) or both in the distributor.

Gazzz

[BigJon]

Possibly running too lean, suffering lean burn miss / backfire.

[nobbydoldrums]

It does sound like an ignition issue to me. Stupic question but did you replace all the plugs along with the other ignition components?

[LandyAndy]

Im with Big John
Running lean.
Possible that the carby gasket is leaking,or even the nuts on the carby come loose(MY BET!!!!!).Been there done that with the same carby conversion!!!!
A good way to check for leaky gaskets is get a can of CRC type stuff with that little tube they supply.With the engine ideling spray along the gaskets,if the revs pick up youve located the leak.
Let us know what you find.
Goodluck
Andrew

[JDNSW]

I see three possibilities:-

1. (Most likely) Fuel restriction, either a fuel pump fault, a partial blockage on the suction line such as the screen in the tank, or an air leak somewhere in the suction line.

2. Ignition - in view of what you have done, have you rechecked the points gap - I have seen this when the points close up, possibly also wear on the shaft bearings. Could also be incorrect timing due to the vacuum advance not working or the centrifugal advance seized or otherwise not working. Could also be a sick coil, or bad connection somewhere, a prime candidate being the internal earth wire between the contact breaker and the distributor body - if it is broken but making contact until the vacuum advance is in a certain position, this could account for the symptoms.

3. Air leak somewhere into the inlet manifold as suggested.

[btm]

G'Day Guys,
Thanks for all the good advice, will start working my way through the things people have suggested this weekend. One other thing I wanted to mention was that when I was replacing the 'points', I took out the base plate of the dizzy because the whole inside of the dizzy was covered in 38 years of crap. When I put it back in I noticed the there was a small pin on the underside of the base plate that was supposed to fit in an eyelet (which is attached to the vacuum advance shaft thingy???) and I reckon I didn't get the pin back into the eyelet... Could this prevent the vacuum advance from working and therefore retard the engine??

timbo

[JDNSW]

G'Day Guys,
..... Could this prevent the vacuum advance from working and therefore retard the engine??

timbo

Yes. The exact effect will depend on whether you set the timing static as in the book or used a timing light with the engine running, but it will disable the vacuum advance - so the timing will be incorrect except at one throttle opening.

John

[UncleHo]

G'day btm :)

I posted a reply to your quiery on the REMLR site, but I didn't note that when setting the timing with a timing light, it is done with the Vacc Advance disconnected, and the timing to be set at 6deg BTDC;) then re-connect the Vacc Advance to the Carby:)


cheers

[Michael2]

This one sounds bizarre, but I've seen it 2 or 3 times.

Look inside the distributor. Find the wire that earths the mounting plate for the points to the body. If this wire is loose or cracked, it will break contact when vacuum advances the most and pulls the wire apart. When the motor stalls, the car starts and runs fine again. Easy to fix, and easy to find, but only if you look for it.