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Hard to start when hot!

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don62

don62

Senior Member
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My MGB 76 run great and start great when cold but when the engine is hot and I stop the car for 10 min and more, it won't start. She's reacting like having too much fuel. It does start great though within 5 min. I checked the float levels and they were as specs. There was a lot of fuel pressure though in the chamber and there was a fuel jet.
Is this normal(the engine was hot). I do have SU HS4 carbs and the jet heads are adjusted at 7 flats. Sometine though the idle will vary from 800 to 1500.

Thganks

Don
 
Air leak is causing th idle varation.

Might also do something for the hot starting.
 
and 7 flats would seem to me to be kinda lean. Fuel pump delivery pressure should be around 2.5 to 4 psi, no more than 5 (and that may be a bit too much for float needle/seat). Have you got the heat shield in place?
 
In my experience a "hard to start when hot" problem is often a bad spark coil. You may want to check your spark quality when hot or just replace it to try.
Bill
 
I experienced this problem when the heat shield lost most of its shielding material. I did a homegrown replacement using some high-temp shield and wrap on the back of the metal shield. It has has helped alot.

Also, check your ignition timing. My car's timing had become retarded, which seems to lead to harder starting.
 
Thank you all for your help.

I re-adjusted the jet heads to 9 1/2 turns instead of 7 and everything is fine now.
Starts great when hot and the idle is stable.
She's even more powerfull.
This forum is "the place" to get help.

Cheers

Don
 
That's what needs to be disseminated. We're here to keep 'em running! /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif

We ain't just a bunch o' pretty faces, y'know! /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif
 
We knew that Doc. Preaty face indeed, at our age we are lucky to have a face.
 
...mine's a transplant...
 
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