The vacuum lines and the thermal vacuum switch and cold starts. Upon first start after the engine is stone cold, I get misfire, black smoke until the engine runs for awhile. I found the mechanical advance frozen in the advanced position and got it operating again.
1978 Chev Nova 250 1bbl. completly stock. Does the thermal vacuum switch make the egr work when the engine is warm? or cold? right now I am bypassing the tvs. could this be it? How do I check the hei module? How do I set the electrick choke to stock specs Thanks the help.This thing is driving me crazy, can you tell? 196kmiles 160 compression all cylinders!
2007-01-01 04:35:42 · 4 answers · asked by cadet 2 in Cars & Transportation ➔ Maintenance & Repairs
The thermal switch turns on the EGR when it is cold. It has to do with the timing and air fuel ratio. Because an engine takes in more fuel and air when it is cold you can advance the timing with out detination. You also need more fuel to keep a proper air/fuel ratio since cold air is denser. If you can get rid of the thermal switch, vacuum advance, the TVS and the EGR and get a non-advancing distrbutor for it and set the timing and air/fuel ratios right from the beginning then your problems should go away. You can get an A/F.R gauge at say Advance Auto Parts to set the ratio. Set your timing first then keep switchig between them until your stoic AFR is 12.5:1 or so and you have no pre-detination or delayed knock.
2007-01-01 05:05:04 · answer #1 · answered by Anonymous · 0⤊ 0⤋
The thermal vacuum switch only routes vacuum to the EGR when the engine is hot i.e. over about 140F. This allows some hot gas into the cylinders to lower combustion temp. to reduce NOX production. If the engines has a good spark, i.e over 40K volts and runs then the hei is OK. Sounds like you need to concentrate on the choke. Check the adjustment on the side and lean it a bit so you get a good start with less smoke, aka unburned fuel.
2007-01-01 10:50:57 · answer #2 · answered by gary o 7 · 0⤊ 0⤋
You shouldn't bypass the TVS. But it really sounds like a choke problem. You should have a decent Chilton guide for it, right? That should tell you about the settings. But it sounds like it's too tight. Back it off a bit. The HEI usually works until it dies. If you're getting anything out of it, it's probably not the problem.
2007-01-01 05:01:18 · answer #3 · answered by Anonymous · 0⤊ 0⤋
saya dikasih bintang 5 aja udah cukup lah.
2016-05-23 03:09:36 · answer #4 · answered by Patricia 3 · 0⤊ 0⤋