TR2/3/3A SU 1 3/4 Carb to Manifold Insulating Block; '59 TR3A

[Frank_D]

I am experiencing quite a bit of heat transfer from the manifold to the SU Carb body through the insulating block. It may be contributing to engine run on after a long run. Carbs are hot to the touch. I am told that there may be more effective insulating blocks out there. Has anyone had any experience with this or have a lead on better quality insulating blocks? Thanks folks.

Frank D........

 

[TR3driver]

I assume you're talking about the stock insulators, which only help block heat conducted from the intake manifold. The carbs pick up a huge amount of heat radiated from the exhaust manifold as well.

Adding a simple sheet metal heat shield between the carbs and exhaust manifold made a big difference on my TR3.

Adding some sort of high temp insulation on the carb side might help a bit more, but I haven't tried that yet.

PS, I got my heat shield from Joe A at http://gasketinnovations.com/product/ss-carburetor-heat-shield-tr3-tr4/

 

[Frank_D]

Thanks Randall. The advice provided from you is always sound so I will pursue that. When I had the engine re-built a couple of years ago I had the exhaust manifold ceramic coated to help wth heat but I think I need to add the shield you have suggested. I will let you know how it goes when I get one and install it. Looks a little tight around the bell crank. Did you have to drill the hole for the vacuum line or did it come that way? Thanks for the link too.
Frank D..........

 

[Snowkilts]

Adding a simple sheet metal heat shield between the carbs and exhaust manifold made a big difference on my TR3.

Just curious, what did this do for the car?

 

[TR3driver]

It came with the hole for the vacuum line, but I did have to enlarge it just a bit with a Dremel tool. I think the original hole was just large enough for the nut to pass through, but it got distorted a bit when the bend was made.

I'm pretty sure I told Joe about it though, so that may not be a problem with new ones.

The carb mounting studs were a little bit short too, so I used thin distorted thread locknuts on them instead of the original nut & washer. Longer studs would probably be better, but I had the nuts on hand and they've worked well so far.

 

[TR3driver]

Just curious, what did this do for the car?

My main goal was to eliminate difficult starting when hot. Before installing the shield, it wouldn't want to start for half an hour or so after shutting it off on a hot day. The stuff they sell us for gasoline around here seems to boil a lot easier than it did back in the 50s (note that we can only use E10 or higher here in CA) and it seemed the fuel was actually boiling in the carb jets, pushing both vapor and liquid fuel out into the carb throats. (Called percolation, like an old coffee pot.)

Not just my car either. My local club does several runs through the mountains each year, and one year we stopped partway up to Mt Wilson for a "biology break". 20 or 30 cars, and every one of them had trouble getting started and blew black smoke when they did get going.

But I also saw evidence that heat from the exhaust was shortening the life of the rubber carb bowl mounts. These were less than a year old (I had the carb off for other reasons)

So far, so good. I was only getting a year or two out of those seals before I installed the shield; haven't had to replace them since then. Of course, I've also retired in the meantime, so now I rarely get stuck in rush hour traffic on hot days. Might have something to do with it

 

[STeve 1958]

I made a heat shield that looks just like the one in Randalls photo but mine only has 2 bolt holes and it mounts over the carburetor flange.
That way I can take it off by just removing 2 nuts and not removing the carburetor. I seems to work well as its main goal is to shield the float bowls.