under bonnet heat

stagman · Post by **stagman** » Sun Jun 07, 2009 10:52 am

hi guys ,i have a rover 3.5 in my stag, fitted with a edelbrock carburetor,manifolds wrapped with heat tape, new rad with a header tank and 16" fan at the front blowing air towards the engine. i have no problem with the engine /rad temperature, but i have with the under bonnet heat,with the bonnet closed, the heat after a while vopourises the petrol ,{ carb floods and taking the pipe off a hiss is heard}. my question is how can i get over this problem??. will wrapping the rubber pipes or changing to steels ones help??.or placing a other fan under the bonnet blowing over the engine as the engine fan would have done.{the engine fan is removed as no room for it }or placing slots in the bonnet??. any help please before i kill myself. paul

topcatcustom · Post by **topcatcustom** » Sun Jun 07, 2009 11:15 am

If you don't mind putting louvres in the bonnet or raising the rear slightly to let heat out then either of those would help, rubber is a pretty poor insulator anyway but braided hoses may help a little. Trying the insulate the carb from the heat would be the best bet, do you have a heat insulator spacer between the carb and manifold? It is just like a thick gasket and could solve your problem!

TC

stagman · Post by **stagman** » Sun Jun 07, 2009 11:31 am

topcatproduction wrote:If you don't mind putting louvres in the bonnet or raising the rear slightly to let heat out then either of those would help, rubber is a pretty poor insulator anyway but braided hoses may help a little. Trying the insulate the carb from the heat would be the best bet, do you have a heat insulator spacer between the carb and manifold? It is just like a thick gasket and could solve your problem!

TC

hi tc ,thanks for your reply, i just fitted a spacer yesterday, made no differents, i could try braided pipes. this job must have been done in a stag before given the stag engine problems. paul

bones · Post by **bones** » Sun Jun 07, 2009 11:40 am

the plate fitted is it a thermo plastic one,

rich

stagman · Post by **stagman** » Sun Jun 07, 2009 11:47 am

bones wrote:the plate fitted is it a thermo plastic one, rich

hi rich, yes its a 1" phenolic spacer, only problem its moved the carb nearer the bonnet. paul

RoverP6B · Post by **RoverP6B** » Sun Jun 07, 2009 11:55 am

Hello Paul,

Is your engine fitted with an AC mechanical fuel pump or are you running an electric one?

What temperature thermostat are you running?

Is your engine fitted with tubular manifolds?

You could wrap the metal fuel lines along with the rubber fuel hose with heat resistant fibre glass cloth. It is a woven material, about 6" wide and you can buy it by the roll or in the length of your choice. It is an excellent product.

Ron.

r2d2hp · Post by **r2d2hp** » Sun Jun 07, 2009 11:56 am

Have a similar problem on a mates car. Plan is to fit a return pipe back to the tank. The return pipe is very restricted with a piece of metal in it that has a small 1mm hole through the middle.

Think Ford did something similar on old Zephyr’s back in the 60's

Obviously fuel pressure will then need to be adjusted to take account of the return flow.

stagman · Post by **stagman** » Sun Jun 07, 2009 12:03 pm

RoverP6B wrote:Hello Paul,

Is your engine fitted with an AC mechanical fuel pump or are you running an electric one?

Ron.

hi p6b, it has the stag electric pump,the stat is a 74, yes i have the tube manifolds, where do i get this product to wrap around the pipes paul.

stagman · Post by **stagman** » Sun Jun 07, 2009 12:09 pm

r2d2hp wrote:Have a similar problem on a mates car. Plan is to fit a return pipe back to the tank. The return pipe is very restricted with a piece of metal in it that has a small 1mm hole through the middle.

Think Ford did something similar on old Zephyr’s back in the 60's

Obviously fuel pressure will then need to be adjusted to take account of the return flow.

hi r2d2hp, how would this help ?. paul

bones · Post by **bones** » Sun Jun 07, 2009 12:17 pm

have you got the manifolds wrapped, you can get a thermo sleeving for the fuel line pipe from merlin motorsport and other places,

rich

stagman · Post by **stagman** » Sun Jun 07, 2009 12:22 pm

bones wrote:have you got the manifolds wrapped, you can get a thermo sleeving for the fuel line pipe from merlin motorsport and other places, rich

hi yes they are wrapped, thanks i will enquire about some sleeving. paul

r2d2hp · Post by **r2d2hp** » Sun Jun 07, 2009 2:22 pm

It helps as fuel is always flowing through the system and any air is expelled into the tank, vapour has a way of escaping from the fuel pipes.

Later 3.0 Capris had this done as well

CastleMGBV8 · Post by **CastleMGBV8** » Sun Jun 07, 2009 2:45 pm

Paul,

I find it a little confusing that you are suggesting fuel vapouristion but the carb is actually flooding.

Before you do any thing else i would check that you have correct float levels, both height and drop need properly setting as they rarely leave the factory properly set.

If you don't have the carb handbook you can download it online from the Edelbrock website.

Good luck,

Kevin.

stagman · Post by **stagman** » Sun Jun 07, 2009 3:08 pm

r2d2hp wrote:It helps as fuel is always flowing through the system and any air is expelled into the tank, vapour has a way of escaping from the fuel pipes.

Later 3.0 Capris had this done as well

i see, so what would you have to do, put a tee peice near the carb so the fuel would pass back to the tank or to the carb. but like you said the pressure might not be enought to work ok . paul

Ian Anderson · Post by **Ian Anderson** » Sun Jun 07, 2009 4:37 pm

Or the Zimbabwe Method

Wrap your fuel hose with cloth
Unplug your windscreen washer hose
Attach said hose to the cloth and when the fuel vapourises press you windscreen squirt button

Gives a cool water squirt and evaporation does the rest!

Worked with Ethenol Blended petrol in 40 degree outside temp

But I would also check your floats as the carb should not flood but be lean if the fuel is evaporating. It could be that once the whole carb heats up the float needle or hinge "pinches" tight

Ian