I have a problem with my 1970 E-type Jaguar. It seems to warm up normally and runs fine but then it starts to overheat and the idle seems to increase and it starts to misfire and stall. I have been told that my problem may be an intake manifold leak so I purchased a new original equipment metal gasket. My problem is I can't find any torque specifications in my repair manuals. Also I'm not sure if I should use any additional gasket material. Some people have recommended a high temperature paint to coat the gasket before I install it.

Submitted by jklein@genphys… on Fri, 07/09/2004 - 15:28

While I agree with 90% of what Steve said, I beg to differ on the secondary butterflies. If you go to trip SUs you should get rid of them. But, I found with the stock Stroms that they add significantly to the transition smoothness and idle if working and set up properly. Jag didn't add them to spend extra money and complexity, they are there to serve a purpose. I imagine quite a few of the ill tuned twin Stromberg cars out there are due to the fact that someone did disconnect or "wire open" the secondaries and then "mistuned" the carbs to compenssate.

Do you have the crossover pipe hooked up and does the vacuum actuated heat sensing positioner for the air horn versus "off the exhaust" paths work? Could be that you are continuing to pull air off the exhaust after the car heats up versus through the cold intake?

Jeff Klein
1970 OTS, BRG

Submitted by NE52-32043 on Fri, 07/09/2004 - 11:30

Have you ruled out the carbs? I assume you have the dual Zenith Stromberg carbs, not the triple-SU's. They have a secondary set of butterflies behind the carbs that are supposedly part of the "warm-up" system. Those are totally useless (IMHO and others I've talked to). Try wiring them open and see if that effects your idle/running at all. Also, have you checked to make sure that the mixture is correct. Running lean can cause the car to overheat as well. Check to make sure that the choke wire is adjusted properly and that it is fully releasing when "off."

Before you go and pull the manifold, check other obvious things. Pull the plugs and check for evidence of either running too lean or too rich, or water infiltration. Check for vacuum leaks in and around the carbs. Make sure that your thermostat is working properly, that the radiator is clean inside and out, and that you're water pump belt is still there and properly tensioned. Make sure the fans are coming on when the car gets up to temperature. Check the vacuum module on the distributor, make sure the line to it is okay and not leaking. Check your plugs, wires, distributor cap, rotor, etc. Check the timing as well.

Replacing the manifold gasket is the last thing to do unless you have hard evidence that it is actually the cause of your problem. I'm not an expert on the metal gaskets, but would assume that a THIN coating of a high-temperature silicone sealant like blue or copper RTV would be appropriate. Don't "goop" it up because you don't want any of that stuff being forced into the water or oil passages.

I could not find a torque number for the manifold nuts either. When I installed the manifold for the triple-SU's this winter, I tightened them hand tight snug. Don't force them, just good and snug should do it. Make sure you start in the middle and work your way out, alternating sides, snugging them progressively tighter, making several passes.

Steve Weinstein, JTC-NJ
'72 E-type 2+2
'70 XKE FHC