Engine not idling cleanly with Dizzy to Carb vacuum connected?
#1
Engine not idling cleanly with Dizzy to Carb vacuum connected?
Good Evening Ladies and Gents,
I've just installed an S3 4.2 XK Engine to my S1 to get the old girl back on the road. I've pulled the EFI off and retro fitted the S1 Carb setup.
I disconnected the Coil and Fuel Pump, pulled the Spark Plugs and cranked the engine to 'prime' with some oil pressure. All good.
Hooked all the above back up and cranked the engine. It took a couple of attempts after some gentle Dizzy adjustments. The engine fired up, but died shortly after. It also didn't want to rev and would intermittently backfire through the Carbs.
I disconnected the Vacuum Pipe between the Dizzy and the Carb and the engine idled cleanly? Some gentle revving and still all good?
I can only think that the fault lies with the Dizzy? The vacuum advance is sticking or shorting to earth during movement? he Dizzy is the original off the old S1 engine too.
Any advice appreciated.
Woz
I've just installed an S3 4.2 XK Engine to my S1 to get the old girl back on the road. I've pulled the EFI off and retro fitted the S1 Carb setup.
I disconnected the Coil and Fuel Pump, pulled the Spark Plugs and cranked the engine to 'prime' with some oil pressure. All good.
Hooked all the above back up and cranked the engine. It took a couple of attempts after some gentle Dizzy adjustments. The engine fired up, but died shortly after. It also didn't want to rev and would intermittently backfire through the Carbs.
I disconnected the Vacuum Pipe between the Dizzy and the Carb and the engine idled cleanly? Some gentle revving and still all good?
I can only think that the fault lies with the Dizzy? The vacuum advance is sticking or shorting to earth during movement? he Dizzy is the original off the old S1 engine too.
Any advice appreciated.
Woz
#2
Join Date: Jul 2012
Location: Walnut Creek, California
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I suspect:
1. The source of vacuum. At throttle on one and manifold on the other. matched on one mismatch on the other.
Back off static timing a tad and see if things come into alignment.
Or match vacuum source. present to former.
Plug the vacuum add a tad more static and go with it. there is a life sans vacuum advance, albeit a bit imperfect.
Carl
1. The source of vacuum. At throttle on one and manifold on the other. matched on one mismatch on the other.
Back off static timing a tad and see if things come into alignment.
Or match vacuum source. present to former.
Plug the vacuum add a tad more static and go with it. there is a life sans vacuum advance, albeit a bit imperfect.
Carl
#3
Thanks Carl, I understand your comments about the static timing and I did try playing around with it, with no real improvement.
I will do the Dynamic timing over the weekend and see if things improve.
Looking to get shot of the points sometime soon, so this might be the excuse I'm after!?
I will do the Dynamic timing over the weekend and see if things improve.
Looking to get shot of the points sometime soon, so this might be the excuse I'm after!?
#4
I completed the dynamic timing today and the engine is running a lot better, but there is definitely something not quite right.
The Tacho starts jumping all over the shop as soon as the ignition is turned on. The car started reluctantly after a a few back fires through the Carbs. Once started and a bit a temperature was in the engine, the idle settled. It still sounded like there was the odd misfire and the Tacho was a a little unstable.
I think I'll have a good look at the Dizzy and maybe trace the wiring back to the relay to ensure there's no insulation breakdown anywhere?
The Tacho starts jumping all over the shop as soon as the ignition is turned on. The car started reluctantly after a a few back fires through the Carbs. Once started and a bit a temperature was in the engine, the idle settled. It still sounded like there was the odd misfire and the Tacho was a a little unstable.
I think I'll have a good look at the Dizzy and maybe trace the wiring back to the relay to ensure there's no insulation breakdown anywhere?
#5
Join Date: Jul 2012
Location: Walnut Creek, California
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Woz:
As the tach is driven by the Distributor _ , wiggles indicate issues in trhe distributor or the wires from it to the coil.
Wild card: A reliable and steady supply of 12v + from the ignition switch is needed. a failure there would do the same thing, a jumpy tach.
A bum ignition switch in my car caused a lot of travail. A replacement made worlds of difference.
Carl
As the tach is driven by the Distributor _ , wiggles indicate issues in trhe distributor or the wires from it to the coil.
Wild card: A reliable and steady supply of 12v + from the ignition switch is needed. a failure there would do the same thing, a jumpy tach.
A bum ignition switch in my car caused a lot of travail. A replacement made worlds of difference.
Carl
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