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Exhaust manifold heat control valve question
https://slantsix.org/forum/viewtopic.php?t=57268		 Page 1 of 2
Author:  spacecommander [ Wed Mar 11, 2015 9:07 pm ]
Post subject:  Exhaust manifold heat control valve question
My carter 400CFM 4bbl on the Offy manifold seems to develop a fuel boil in stop and go driving after i stop and turn it off - I'll remove the air cleaner cover and watch the carb and every now and then a geyser like jet of fuel will squirt out of a air bleed about 3" up. :-( A carb spacer/insulator will be installed but the exhaust heat control valve does not seem to be fully closed when the engine is turned off hot. It appears that at idle the valve is still somewhat open - it is free to turn more to full closed - I marked the round counterweight for full open and full closed. It's as if the thermostatic spring was wrapped one turn too many? Is this at all possible? Should the valve be fully closed when the engine is fully warm? Again, the valve turns freely with no binding, it just stays at about 3/4 - 7/8 closed position, not fully closed, when hot. It moves around from full this position to full closed - bouncing back and forth - when the engine is running at idle and fully warm.
Author:  '67 Dart 270 [ Wed Mar 11, 2015 10:11 pm ]
Post subject:  heat issue
Others feel free to chime in, but I don't think mine fully closes either, 7/8 is pretty close to being closed. As you know, the valve is supposed to deflect heat to the manifold and then close when warm enough to direct hot gases away from the intake heat box. But I don't think it has to be a perfect closure, it's not a super high tech mechanism. Though it could be you have a weak spring.

Did you have the heat build up issue before or is this a new issue? If it's new, I tend to think it is not closing enough, but if you've always had a heat soak issue, then I tend to think it's not enough airflow in the engine bay. Did you recently switch to electric fans by chance? I had heat buildup issues as well, I had my dutra duals ceramic coated black and I think that increased the heat load due to black having a higher emissivity. So I used a heat shield between my offy intake and my carbs, solved the problem. But, I later switched to electric fans, it kept my engine easily at operating temperature, but the engine bay would get too hot due to not enough air exchange. I went back to belt driven high volume fan and no issues.

brian
Author:  spacecommander [ Wed Mar 11, 2015 10:18 pm ]
Post subject:  Re: heat issue
Quote:
. . . Did you have the heat build up issue before or is this a new issue?
brian
The intake manifold and carb were just installed - it had a nasty welded aluminum 1bbl and a totally played out 1bbl on it. Underhood temps are an issue as there is a diesel truck hood heat shield installed to help not bake the new paint job sprayed on last Fall - and the sun is HOT here in New Mexico. Installed a fresh air intake air cleaner setup with the duct running to the front to try and help, but in stop and go . . . .

Again, will get a thin insulator/spacer and install it. Have a big 1" or 1 1/2" spacer kicking around but it will monkey with the throttle linkage too badly.
Author:  '67 Dart 270 [ Thu Mar 12, 2015 9:10 am ]
Post subject:  heat shield and high volume fan
I would recommend trying a fan that moves more air than the stock fan, I use the one in the link below, it really moves a lot of air (I also built a shroud from aluminum (bolted it to my radiator):

see: http://www.summitracing.com/parts/flx-1080/overview/

NOTE: Summit sells the identical fan with aluminum blades, the one above has SS blades, I like that better (same price).

Also, I fabricated a heat shield out of sheet aluminum used to shield the carbs from heat. Just cut holes for the carb/studs and any linkage that must past through the plane of the shield, it really keeps the carbs cool. I used double phenolic spacers and put the heat shield between them (I don't think you need that extra bit but I wanted it). In the pic below you can see under the carb is a black phenolic spacer about 1/4 thick, there is another one under the shield, between the shield and the offy manifold. You could simply use thin gaskets on both sides; you need to make sure there's a good seal between the carb/shield and the shield/manifold.

see: http://s785.photobucket.com/user/67dart ... ort=3&o=17
Author:  SlantSixDan [ Thu Mar 12, 2015 6:13 pm ]
Post subject: 
Carb spacer: Yes.
Carb heat shield made out of an insulating material (not sheetmetal): Yes.
Fuel line mod & vapour-return filter: Yes, read this.
Better radiator fan: Yes, read this and pick carefully.
Sensible thermostat temperature: Yes, read this.
Messing with the manifold heat control valve: No. It's not broken or faulty.
Author:  spacecommander [ Thu Mar 12, 2015 7:32 pm ]
Post subject: 
Monkeyed with the throttle linkage/bracketry and was able to install the 1" spacer / insulator. Fit just fine. ;-)
The car has a 190 degree thermostat, I think. Had a 160 when I got it - I don't like too cool thermostats - usually they are an attempt to solve an overheating issue that is a result of a plugged radiator, faulty water pump, timing or mixture or such.
Have the Mopar thermal clutch fan, think it works fine at idle and I need every single horsepower or even squirrel power at 5500 feet with a slant six pushing a W150 4WD truck up rather steep hills.

Thanks for the info SlantSixDan - I read your fuel line mod post and discovered that I did basically those same mods already myself - the FI line and such. I ditched the 3 nipple fuel filter hoping that the fuel in the line wouldn't drain from the fuel line to the tank.
While doing these mods a rather large exhaust leak was discovered as the rear bolt on the exhaust manifold - tail pipe was very loose. Tightened that up.

Tomorrow is the test as I'll be going in the city again. Do have some insulating materials to use as heat shields - very efficient in insulation capabilities but no longer available new. Stiff and about 1/8" thick, perfect for building a insulating barrier.

Oh, did take the truck for a decent drive today and noticed the carb seemed much cooler to the touch.
Author:  SlantSixDan [ Thu Mar 12, 2015 7:39 pm ]
Post subject: 
Quote:
Have the Mopar thermal clutch fan
Which one? If you mean the Mopar Performance item or another 5-blade type, you can do (much) better.
Quote:
I ditched the 3 nipple fuel filter
Put it back. It's good for preventing symptoms such as you describe. Especially at high altitude.
Quote:
Do have some insulating materials to use as heat shields - very efficient in insulation capabilities but no longer available new. Stiff and about 1/8" thick, perfect for building a insulating barrier.
Details on this mystery material?
Author:  spacecommander [ Thu Mar 12, 2015 7:40 pm ]
Post subject:  Re: heat shield and high volume fan
Quote:
. . . Also, I fabricated a heat shield out of sheet aluminum used to shield the carbs from heat. Just cut holes for the carb/studs and any linkage that must past through the plane of the shield, it really keeps the carbs cool. I used double phenolic spacers and put the heat shield between them (I don't think you need that extra bit but I wanted it). In the pic below you can see under the carb is a black phenolic spacer about 1/4 thick, there is another one under the shield, between the shield and the offy manifold. You could simply use thin gaskets on both sides; you need to make sure there's a good seal between the carb/shield and the shield/manifold.
Thanks, a heat shield will go in this weekend.
Author:  spacecommander [ Thu Mar 12, 2015 7:51 pm ]
Post subject: 
Quote:
Quote:
Have the Mopar thermal clutch fan
Which one? If you mean the Mopar Performance item or another 5-blade type, you can do (much) better.
Quote:
I ditched the 3 nipple fuel filter
Put it back. It's good for preventing symptoms such as you describe. Especially at high altitude.
Quote:
Do have some insulating materials to use as heat shields - very efficient in insulation capabilities but no longer available new. Stiff and about 1/8" thick, perfect for building a insulating barrier.
Details on this mystery material?
The fan is the traditional Mopar thermal clutch 5 bladed fan - it seems to pull quite a bit of air at idle. I do have the fan shroud installed. The car originally had AC but no longer does. I couldn't imagine how slow it would be at 5500' and a big AC compressor sucking gobs of power . . . .

I was worried the fuel would drain out of the fuel line over time through the tiny orfice in the 3 nipple fuel filter and would have to be filled again vai the fuel pump and cranking the engine for a while. That used to be the issue. Ditching the 3 nipple fuel filter seemed to make a big difference in initial starting - this was even back when it had the 1 bbl on it - I'd crank it and it would start right up - with the old 3 nipple it would cough then crank a few times (2-3 sec) then start. I can put it back and see if it helps.

Very old clothes iron insulating pads. Yes, I know. Have some hi-temp epoxy paint they would be covered in when formed.
Author:  matv91 [ Sun Mar 15, 2015 2:53 pm ]
Post subject:  Tsb FUEL RETURN CHECK VALVE
Image
Author:  matv91 [ Sun Mar 15, 2015 2:56 pm ]
Post subject: 
Image
Author:  matv91 [ Sun Mar 15, 2015 2:59 pm ]
Post subject: 
Image
Author:  matv91 [ Sun Mar 15, 2015 3:18 pm ]
Post subject:  TSB fuel Return check valve
The part number 4185363 is put into the third nipple fuel return line down near fuel pump. Pump pressure holds the valve open while running. After shut down pressure will bleed off to closing point,half a pound or so and then valve will close not allowing drain back. Both my slants have these ,seem to work
Author:  spacecommander [ Sun Mar 15, 2015 3:21 pm ]
Post subject: 
Awesome! Thanks! I have to get a new canister - it's all plugged I bet.
Author:  matv91 [ Sun Mar 15, 2015 3:23 pm ]
Post subject: 
Heres one http://www.ebay.com/itm/Mopar-OEM-Carbu ... =Motors_Ca
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