4.3 idle change when fogging?

[cliffblue]

When I fogged my 2001 4.3 mercarb, the right barrel would drop the idle a little bit and the left barrel would increase the idle a little bit. I switched back and forth 3-4 times and it responded the same every time. Any ideas anyone? A vacuum leak is all that comes to mind, but that intake has no vacuum lines.

 

[Walt T]

Re: 4.3 idle change when fogging?

One venturi is probably running a little leaner at idle than the other. It's not uncommon but it's not ideal either. Sometimes a simple adjustment can help, but I'm not sure you can adjust mixture on those. I'm sure others will chime in. It isn't necessarily a problem.

 

[cliffblue]

Re: 4.3 idle change when fogging?

Yeah, maybe. Crap! I can't remember if there is only 1 mixture screw or 2. I'm thinking there is just one, but I'll have to look later to be sure. Thanks

 

[Bondo]

Re: 4.3 idle change when fogging?

When I fogged my 2001 4.3 mercarb, the right barrel would drop the idle a little bit and the left barrel would increase the idle a little bit. I switched back and forth 3-4 times and it responded the same every time. Any ideas anyone? A vacuum leak is all that comes to mind, but that intake has no vacuum lines.

Ayuh,.... Generally speakin',... dumpin'/ sprayin' Oil into the carb causes all sortsa things to act weird, 'n usually, the motor finally Stalls,...

Which is what Foggin' is all 'bout,...

 

[Capt Ken]

Re: 4.3 idle change when fogging?

2001 is a Mercarb so it has one mixture screw.

 

[cliffblue]

Re: 4.3 idle change when fogging?

Yes sir Bondo. This was my first time fogging. Next time I'll have two cans so I can pour it down both sides at the same time.

 

[NHGuy]

Re: 4.3 idle change when fogging?

Spray it, don't pour it. Or if you want to pour it, do it very slowly. You want to gradually make it stumble with the oil, then shut it off. All the fogging oil does is keep the valves and cylinder walls from getting rusty. The reason I say don't pour it too aggressively is that too much oil can hydro lock a cylinder which breaks things like connecting rods.
So fog the motor, but don't fill it with liquid.

 

[Bondo]

Re: 4.3 idle change when fogging?

Spray it, don't pour it. Or if you want to pour it, do it very slowly. You want to gradually make it stumble with the oil, then shut it off. All the fogging oil does is keep the valves and cylinder walls from getting rusty. The reason I say don't pour it too aggressively is that too much oil can hydro lock a cylinder which breaks things like connecting rods.
So fog the motor, but don't fill it with liquid.

Ayuh,.... Or Don't fog it at All,... I don't,... waste of oil, 'n time on a simple 6 month lay-up,...

6 Years would be different,....

 

[haulnazz15]

Re: 4.3 idle change when fogging?

Ayuh,.... Or Don't fog it at All,... I don't,... waste of oil, 'n time on a simple 6 month lay-up,...

6 Years would be different,....

I tend to agree. Besides that, I can keep a constant stream of fogging oil spray going down the carb at idle, and while it will stumble/chug, I can't ever get it to stall out. I eventually just cut the fuel off while spraying the oil and it will finally run out of go-juice.

 

[cliffblue]

Re: 4.3 idle change when fogging?

Hey NHG, thanks but I was just being a little dramatic. I meant spray. Bondo, appreciate the point of view. Here in NW Louisiana, it's probably 4-5 months. You are probably correct. But heck, I had already bought the fogging oil.

 

[Walt T]

Re: 4.3 idle change when fogging?

I agree with Bondo. It doesn't hurt to fog but like filling the engine with antifreeze it's not really necessary for a few months layup

 

[cliffblue]

Re: 4.3 idle change when fogging?

Well, the temps finally are hitting 60-70 degrees plus for the next week. I've started the top side tear down to try and find where the moisture is getting in the oil and upgrade the one-piece exhaust manifolds while I'm at it. My first question is will the new OEM manifolds have the attachment points for the gear shift-throttle-shift switch bracket and PCM? My next discovery was that the head and intake gaskets looked great. No evidence of leakage. The combustion chambers, ports and cylinders where all rust free. Everything looked normal. This was probably a waste of time and money! The only possible thing I've found was the crappy plastic spacer under the Mercarb. It had deformed enough that it wasn't sealing the gasket to the intake. I've ordered a new one, but it is probably plastic too. Is there an aluminum alternative?

 

[Bondo]

Re: 4.3 idle change when fogging?

Well, the temps finally are hitting 60-70 degrees plus for the next week. I've started the top side tear down to try and find where the moisture is getting in the oil and upgrade the one-piece exhaust manifolds while I'm at it. My first question is will the new OEM manifolds have the attachment points for the gear shift-throttle-shift switch bracket and PCM? My next discovery was that the head and intake gaskets looked great. No evidence of leakage. The combustion chambers, ports and cylinders where all rust free. Everything looked normal. This was probably a waste of time and money! The only possible thing I've found was the crappy plastic spacer under the Mercarb. It had deformed enough that it wasn't sealing the gasket to the intake. I've ordered a new one, but it is probably plastic too. Is there an aluminum alternative?

Ayuh,.... The Merc manifolds, 'n most any aftermarket manifolds, built for a Merc, will have the holes to hang yer accessories,...

The block under the carb is plastic, because it's a heat block, not just a spacer,...
Aluminum would conduct the heat into the carb,..

 

[cliffblue]

Re: 4.3 idle change when fogging?

That makes sense, but it should be made from something more sturdy.