Slant Six / Carter BBS Heat Soak

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66DartConvert

66DartConvert

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Hello all. I'm having heat soak issues with my Carter BBS on my 225 slant six (the fuel in my carb and stock metal fuel line is boiling from heat build up about 10 minutes after engine shut off when the hood is closed). I plan to do the following to resolve it...

1 - Reroute the fuel line straight up from the fuel pump and over the value cover with rubber fuel line (to keep it as far away from the hot exhaust manifold as possible).

2 - Install a phenolic spacer between the carb and the intake manifold to minimize heat transfer from manifold to carb.

3 - Install a heat shield between the carb and intake manifold to minimize heat transfer from manifold to carb.

A few questions...
The spacer...Where can I find the correct phenolic spacer? I have been coming up empty in some internet searches to find one. What thickness is suggested for the spacer (I saw one post that used a 3/8" spacer with good results). I'm assuming the spacer will need to have the same shape, notches and holes as the carb/intake manifold gasket - good assumption?

Heat shield...I am assuming I will need to fabricate my own. I've seen some diagrams/plans for making one of these. I am assuming I will need to duplicate the openings and notches of the carb/intake manifold gasket in the area of the shield that will be sandwiched between the carb and intake manifold - good assumption?

And one final question...Has anyone installed an electric fan to exhaust hot air out of the engine compartment after engine shut down? If so what type and where did you mount it. I would only do this if the changes mentioned above don't solve all of the heat soak.

Thanks all!!
 
Fuel line mod: http://www.slantsix.org/forum/viewtopic.php?t=15778

By far the best mod for warm weather startups, and as a daily driver. Follow the directions to the "T" and slip a heat shield over the fuel injection line, and hot start problems are non-existent.

Just reroute the fuel line over the valve cover in a wide arc (no kinks) and install your metal (plastic is OK) fuel filter.

All-in-all, this fuel line mod was very simple to do, and is very cheap.
 
Is the heat riser butterfly working or stuck open all the time???

....Taking the line up over th valve cover? Routing in front of the engine puts it closer to the air flow of the fan. (Assuming the original fixed balde fan....) And higher up is hotter, especially when the engine is off..
 
So far here is what I have done to solve the heat soak...

1) Since I couldn't find a spacer for my 1 barrel carter carb I made my own thermal carburetor spacer out of 1/4 " plywood by tracing the existing gasket onto the plywood to duplicate the gasket shape including all holes and notches. I cut the linear cuts and the (large) bore hole with a hand held jigsaw and made the small holes with a hand held drill. Cleaned it up with files and sandpaper and then installed it on the manifold so now between the carb and manifold is...standard gasket, 1/4 " plywood spacer, standard gasket.

2) I insulated the portion of the fuel line that was heating up which was right near the exhaust manifold (the main source of the heat soak heat). Thought I'd try this before re-routing the fuel line.

The results so for...The car now runs and starts MUCH better. Also as a visual sign of the improvement I now have mostly gasoline in my transparent plastic fuel filter where before I had mostly vapor and very little gas. Also the carb stays much cooler than before. So far so good! I may still install an electric fan to remove the hot air from the engine compartment after engine shut down. Still looking for the right fan and fan controller for this.
 
nm9stheham said:
Is the heat riser butterfly working or stuck open all the time???

....Taking the line up over th valve cover? Routing in front of the engine puts it closer to the air flow of the fan. (Assuming the original fixed balde fan....) And higher up is hotter, especially when the engine is off..
Click to expand...

For now I insulated a portion the line instead of rerouting it.

Right now the butterfly is wired open to minimize manifold heat (i.e. let it escape out the exhaust pipe).
 
Ditch that plastic fire bomb filter and get a metal filter with a return line to vent the vapors back to the fuel tank. You will have to run a return line and get it back into the tank. Depending on your sending unit, you may already be set up for it. You do that and your problems should end.

[ame="http://www.ebay.com/itm/MOPAR-Chrysler-Motors-Fuel-Filter-package-4046224-5-91-dodge-ram-/321447664906?pt=Motors_Car_Truck_Parts_Accessories&hash=item4ad7c61d0a&vxp=mtr"]Mopar Chrysler Motors Fuel Filter Package 4046224 5 91 Dodge RAM | eBay[/ame]
 
Sounds good. The next owner will wonder why he is digging toothpicks out of the cylinders at rebuild time...! LOL I am sitting here thinking how you could impregnate the plywood with something to keep it from falling apart.....drawing a blank right now.
 
momoparman said:
Ditch that plastic fire bomb filter and get a metal filter with a return line to vent the vapors back to the fuel tank. You will have to run a return line and get it back into the tank. Depending on your sending unit, you may already be set up for it. You do that and your problems should end.

http://www.ebay.com/itm/MOPAR-Chrys...Parts_Accessories&hash=item4ad7c61d0a&vxp=mtr
Click to expand...

Thanks...I'll check out the sending unit to see if I'm set up for a return line...i've read that that can help. That would also help keep the fuel line cool while the engine is running since fuel would be flowing through it pretty much constantly ... when the carb bowl is full and the carb needle is seated the fuel pump pressure would send the fuel back to the tank via the return line. May not help much with heat soak after the engine is shut off though.
 
Vapor will still be able to get through the line back to the tank and you wont have heat soak.

Trust me we have fixed several cars in the last year this way.

The new gas is formulated to vaporize quickly as that is better for EFI. That is a major reason for heat soak and vapor lock these days......well that and hot weather. The return line will solve your problem. I would stay away from plywood.

Good luck.
 
back in the '70's when i was about 12 my grandmom got a new dodge demon :D
slant 6

it never had problems starting when it was warmed up. of course the gas is supposedly bad nowadays, but i hardly think it would cause this bad of a problem.

i also dont think a hack mod is necessary.

tell me the history of your carb. start to finish. where did the carb come from. what has been done to it. etc.
 
moparlover said:
back in the '70's when i was about 12 my grandmom got a new dodge demon :D
slant 6

it never had problems starting when it was warmed up. of course the gas is supposedly bad nowadays, but i hardly think it would cause this bad of a problem.

i also dont think a hack mod is necessary.

tell me the history of your carb. start to finish. where did the carb come from. what has been done to it. etc.
Click to expand...

...but it was a big enough problem for Chrysler to add this heat shield to newer slant sixes....I think I found it on a late 70's truck
 

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I wasn't sure what material to use for a spacer. I chose phenolic plastic sheet. Grainger has 3/8" by 12" squares for $32-$40 each. Use the method used to make the plywood spacer and it is good to go. A little toxic, practice safe dust control when milling/cutting.
 
Did you use the really thick carb base gasket that most of the time does NOT come with a carter 2 bbl rebuild kit? Every Super Six deal I ever pulled from the boneyard that that really thick 2 bbl base gasket and the extra space on the 2 carb studs is there for that purpose. And now that I think about it, even my 1 bbl six bangers come with a really thick base gasket too.
 
New gas is **** for old cars.

Why do you think they want them gone for good.

Remember the early 80's when they had all the bone yards crush every thing they had so nothing could be rebuilt?

All the new cars run EFI....all the gas is formulated for EFI not NA.

Nuff said....quit playing and do whats needed. you can ask all the questions you want but till you do something to try to figure it out nothing will resolve your problems.

Dump the vapor and your problems are gone.

Last post.

PO
 
Thanks everyone for your input. I will look into making a spacer out of the phenolic sheet material. By the way...I didn't come up with the wood spacer idea on my own. I read about it on this and other sites. Many reputable companies sell manufactured wooden spacers (see for example... http://www.summitracing.com/search/?keyword=wood carb spacer&dds=1 ). And according to internet posts by others many folks have successfully used wood for spacers and many have specifically used plywood as the spacer material. I'm not saying it's the best approach but it is getting me by for now until a more permanent fix can be applied. The car started and ran poorly when under the influence of heat soak and I'm sure cranking the starter for long periods with the pedal to the floor, starting the engine at full throttle, and then sputtering down the road for a bit is not good for the drive train.
 
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