Cooler Carbs

Dave-R · Post by **Dave-R** » Sat Aug 20, 05 5:49 pm

I have noticed over the last couple of years that the heat of the engine tends to evaporate the fuel from the pump shots so sometimes we get a bog if the secondaries have not been opened for a little while. If they boil dry it is the third stab on the throttle that produces the good "squirt" and the first two blips are poor.

Watch the pump shot on the front carb and listen to the engine in this clip. You can see what I mean about the third shot being the good one.

http://challenger.mpoli.fi/hauki-on-kala/ourchally.wmv

Dave-R · Post by **Dave-R** » Sat Aug 20, 05 5:57 pm

So I decided I need to keep the fuel bowls on the carb cooler. Usually the carbs are too hot to touch!

I have seen a few cars using an ally plate as a heat shield between the carb and the intake. I thought I might make one for the six pack.

But how effective are they?

I did a test on an old slide projector at work.
These have a 1mm thick ally plate over the 250w lamp to stop the casing above the lamp from getting too hot to touch.

With the little plate in place the casing above the lamp was a warm 43 degrees. Without it the casing soon rose to 56 degrees. So it might work quite well under a carb.

Dave-R · Post by **Dave-R** » Sat Aug 20, 05 6:02 pm

Also while at the Nats I was talking to Neil (Wil) and he sold me a one-peice six pack carb-to-intake gasket that is 2mm thick and is designed to act as an insulator for the carbs.

The original six pack gaskets are just thin paper. I currently use a 1mm thick set of gaskets that are better but nowhere near as this gasket Neil got for me. Thanks Neil!

I used my 1mm gaskets between the intake and the plate.

Dave-R · Post by **Dave-R** » Sat Aug 20, 05 6:05 pm

The only thing I found with Neil's gasket was it was pressing on the pump shot lever. The fix is to cut out a notch to clear it.

Dave-R · Post by **Dave-R** » Sat Aug 20, 05 6:09 pm

Here is how it looks complete. I will do some temp measurements when the engine is running next year. Then I will know how many degrees C i have lowered the carb temp.

The lip on the front of the plate is to shield from the heat thrown by the radiator fan.

Ashley · Post by **Ashley** » Sat Aug 20, 05 6:10 pm

Dave that sounds like a good idea.
Thats the only thing i haven't tried.
Remeber our little chat at the Nats

Dave-R · Post by **Dave-R** » Sat Aug 20, 05 6:11 pm

You can't really see it with the air filter base in place.

Dave-R · Post by **Dave-R** » Sat Aug 20, 05 6:12 pm

Ashley wrote:Dave that sounds like a good idea.
Thats the only thing i haven't tried.
Remeber our little chat at the Nats

Oh yes Ash. I had forgotten about that.

Alex · Post by **Alex** » Sat Aug 20, 05 7:11 pm

Thats a nice bit of work there Dave, really nice.

TrevD · Post by **TrevD** » Sat Aug 20, 05 7:18 pm

that looks good dave , my only thought is would it be better to put the thicker gasket between the manifold and plate to insulate the plate to keep it cooler.

Anonymous · Post by **Anonymous** » Sat Aug 20, 05 7:25 pm

Dave if there's no clearance issues ya could always put a gasket either side of the plate

Cometic also do an ally spacer properly machined for the 6 pack, my guess would be it would raise the carbs approx 1" when used with 2 gaskets, also the higher they go with the correct sized holes the more torque you make.

Same with a 4 barrel the higher with 4 holes the more torque, higher with an open spacer the more top end power you gain, sorry Dave i'm nicking your thread

Dave-R · Post by **Dave-R** » Sat Aug 20, 05 7:32 pm

TrevD wrote:that looks good dave , my only thought is would it be better to put the thicker gasket between the manifold and plate to insulate the plate to keep it cooler.

I thought about that Trev and considered it. But after much thought I decided it was better to insulate the carb from the plate rather than the plate from the intake. Because the plate will get hot no matter what from radiated heat. But the plate itself will not radiate heat very well although it conducts heat very very well.

Dave-R · Post by **Dave-R** » Sat Aug 20, 05 7:33 pm

Alex wrote:Thats a nice bit of work there Dave, really nice.

To be honest Alex I was bored with decorating and fancied doing a bit of metalwork.

Alex · Post by **Alex** » Sat Aug 20, 05 7:48 pm

LOL ! still, great work mate, rare to see stuff turned out like that these days, too easy to buy things instead.

Anonymous · Post by **Anonymous** » Sun Aug 21, 05 11:11 am

Dave, if you market these plates, I will have one from you! What a great idea! Re the lip on the front, wouldnt it be better without so to catch the cooling air off the fan?
also like that gasket Wil, do you stock them and the plate?
Not sure how much my carbs can lift before the rubber filter lip crushes too much against the hood though