Hard starting with Weber Carb

ghce

ghce

Well-Known Member
Hi I have some problems with hard starting (wont start for a couple of hours after) once the engine is hot but its not petrol evaporation in the fuel lines, I suspect that the Carb is getting too hot once the engine has been turned off and the resultant rising heat is affecting the carb. Do any other p6B owners have a similar problem? I have been thinking to put a heat isolating Gasket between the carb and inlet manifold as currently it is just a plain standard paper gasket.
If you have a Weber does yours have the phenolic/ resin/ plastic gasket on your setup?

Graeme
 
I had a similar problem, there had been 2 factors that contributed.

1st the fuel pump none return valves had stopped working properly so there was some fuel starvation

2nd which I think was the real cause was the coil, once this was replaced the car always started OK.

The other item you could check is the capacitor as these also tend to work when cold but not when hot when they are on the way out, best to swap to electronic ignition.
 
Hello Graeme,

I am pretty sure that you have hit the nail on the head....too much heat. The phenolic spacer would be just the ticket.

Ron.
 
I had this problem when I first bought Sparky, but no longer get it.

I changed the dizzy from a mallory to an SD1 contactless system, and had the carb tuned.

Seemed ok after that.

I did have other problems which may have contributed to it including wiring issues.

My weber does have an angled spacer but just the normal gaskets.
 

Attachments

  • 100_5478.JPG
    100_5478.JPG
    191.3 KB · Views: 681
Initially I went down the path of changing the Capacitor and Points then Coil to nil effect. When driving it's OK but when you sit at an intersection or lights for a while on idle then take off it wants to miss and fart about then stall (can be a red face moment). This also lends to my heat getting to the carb theory as there is less cold air rushing into the engine bay to cool the carb. Looks like I will have to find a supplier for the phenolic spacer, priced to have one made, luckerly there was a seat near by ofr when I fainted at the price!.
What is the best thermostat temp to go with in the interests of reducing block temperatures?

Graeme
 
Have you got an electric fuel pump yet? Certainly overcomes fuel vaporisation problems when standing, your problem sounds somewhat similar so might succombe to the same solution.

Also what arrangements does your inlet manifold have for coolant? Some have the heater supply going through the manifold (as the SU manifold) some do not. If yours does have cooling, make sure the heater matrix is clear so that you have good coolant flow through the manifold (a bit of back flushing should do the trick).

Chris
 
Got all those bases covered, I put in an electric fuel pump when NZ went to unleaded fuel, and recored the heater matrix when I got a pin prick leak that caused my windscreen to steam. The old mechanical pump which was in fine condition till they changed fuel started engine starving due to vapourisation at about 25 MPH on a hot day, got to be a little embarrasing in the middle of peak traffic on a hot summers day lol.

Graeme
 
How about a Kenlowe fan wired so it can run with the ignition off to deal with any heat build up after switching off ?
 
Yes thats a good suggestion and one project that I would love to do if just to gain the 1 or 2 horse power lost by the gianormous factory direct drive fan and the added benifit of off ignition cooling would be a big plus as well.
In the short term I have been getting prices from the US for an Edelbrock part number 9266 which is a heat gasket kit which consists of a 0.320 inch synthetich heat isolating gasket approx US$15.00 works out at about US$35.00 shipped to my door, that and a lower temp thermostat will I hope resolve the issue. The electric fan issue I will have to investigate also.

Graeme
 
1 or 2 HP lost to the engine driven fan? And the rest!! That's the figure near idle - at the top of the rev range you might expect to lose between 5 and 15 HP depending on the precise fan arrangement. On my MGC, which in standard form has an engine that is notoriously strained and apparently asthmatic at top revs, eliminating the engine driven fan (by shedding the blades through over-revving!!!) absolutely transformed the engine into the true big Healey inheritor it always should have been. And of course there is a commensurate improvement in economy.

Chris
 
Havent had a chance to research it yet but I am certainly keen to get an electric fan in there, had looked at those viscous systems but gave them away as a bad idea. Is there a specific kit or procedure that people have been using to get lecky fans in there P6B's?

Graeme
 
You must log in or register to reply here.
Back
Top