Weird Engine Stutter

[CamBiscuit]

Help Please!

When I'm driving the car and just maintaining a constant speed or using very low throttle pressure the car stutters and hiccups quite badly, no problem once you start to apply enough throttle to make the car accelerate.

I've recently replaced the leads with Magnecors, had the distributor rebuilt and recurved and added a Pertronix, had the Webers apart, cleaned & rebuilt, replaced the coil.

The car is a '71T running a 2.4 S motor with 2.2 S pistons & Webers. The problem seemed to start a while after the Webers were rebuilt but not right after....

Any ideas what the cause could be?

Thanks

[Eric911S]

Cam: We have to stop meeting like this. I think you have plugged idle jets. These are the ones near the top of the carbs. Remove the idle jets from there holders and hold them up to the light. Look through them to see if you have some crud blocking the holes. If you do see some crud then blow them out and reinstall. Remember the idle jets work at idle and the mid range at constant throttle. If you increase throttle you activate the accelerator pump and the engine revs. Hope this helps. Note: you may have to clean the jets out alot if you have crud in the petrol tank. I had one car that I had to clean the jets out once a week for a whole month till all the jets stayed clean. That was also using using good fuel filters as well. Good luck. Thanks Eric

[CamBiscuit]

Eric,

Yes I think I owe you a beer or two if you ever make it Down Under or vice versa

I did take the idle jets out yesterday and blow tem out with compressed air. The tank has also been out this year for a flush out (nothing to bad came out) and I have one fuel filter per carb.

Do you think there could be a blockage in another part of the idle circuit?

Cheers

[Eric911S]

Cam: I'm a Canadian and can drink my share of beer maybe not as much as you Aussies. Another thing you may try is to see if the distributor advance is working correctly with a timing light. You have to look through the idle jets to see if they are clear. Also what size of idle jets do you have. Have a cold one for me since that is what I'm doing right now. Thanks Eric

[Steve@Rennsport]

Cam:

Eric is right; your idle jets and likely, idle passages too, have some gak in them.

This is a common problem with Webers until the tank is spotlessly clean, effective 5 micron fuel filtering is used, and any water in the gas gets removed (the tiniest drop of water can block a jet passage).

I clean the carbs by pulling the idle jets and main jets so I can blow air back & forth through the idle fuel wells and progression passages that loosens any tiny piece of dirt. Simply pulling the idle jets to blow those out still leaves small impurities in the passages that will obstruct the idle jets as soon as the engine is restarted.

I machined a small tube that threads into the main jet receptacle to allow the introduction of compressed air into the jet wells. This prevents the floats from being banged around while you blow air back & forth between the idle jet holes and the main jet wells.

As long as you have good fuel filters, that should do it,.....

[CamBiscuit]

Thanks Guys

Eric I had a beer for you last night..! I have some relatives in Vancouver but have yet to make it there. Always good beer weather here in Darwin, the average daily temp is about 30C all year round...!

I pulled the carbs off yesterday and will start to strip them today and blow some air through the passages as described. I'll be taking off the top cover so that I can hold the floats when I blow air through.

I also have some new venturis, emulsion tubes etc etc coming soon from PMO which should suit the engine configuration much better and give the car a bit more at the top end. Can't wait to get it all together

[Eric911S]

Cam; Good deal! I now live in South Texas and it is about 36 here today. Spent the day cutting grass and fixiing the lawn tractor then a swim in the tank. Vancouver is a great city. I'm originally from Toronto. Good luck with your clean out and be carefull not to crush the floats with the air pressure. Take the carbs totally apart then clean them. Thanks Eric