Dellorto weird issue [did a search]

[dubdubz]

ok so Fredster popped over todayto assist in the fine tuning of my 1745 with 36 Dells.

It was popping and not running right. Appears to have been a mixture thing as it now runs better thx Fred

BUT here's the rub

Engine started and idle set to 850 all good - runs fine no issues, however Rev beyond the idle revs and anything upto 3000 [that's as hight as we tried btw] and release the throttle the revs do die BUT down to 1100 ish and then it takes a further 10secs or so to drop back to the set 850..........

I know what the first thoughts are going to be linkage - Yep exactly what we thought - but it's not that, whilst the idle revs are high, we pressed hard against the stops and the revs still stayed high and dropped seemingly of their own accord??? pushing on the throttle stop/lever made no immediate change or in fact any change?

I sprayed wd40 to see if there was an air leak, but this test also didn't highlight anything?

The jets are 122 mains , 60 idles and 35 pumps - so could it be overfuelling and this is taking a while to get through the carb hence the hesitation to drop?

I [and Fred] are confused....I have a filter king fitted and the gauge was reading 3 or 4 [I can check]

Any pointers or suggestions?

 

[petegee56]

Hi,

Mine have started to do this as well, it started after the mixture screw was adjusted to improve the idle, but i have not had chance to look at why it is doing it yet, but i think it will either be a case of adjusting the mixture screw slightly or that my carbs are not fully closing and the increased fuel mixture is causing it to overfuel at idle.

Not alot of help to you i know but hey thought i would respond anyway :roll:

Pete

 

[dubdubz]

thanks for the reply - it's good to know it's not a weird 'me' only one! LOL

I think it may be the overfueling thing - I've added the bakelite gaskets which I didn't have before so perhaps the fuel which was getting vapourised through heat...now isn't. So I can perhaps drop down on my idles and pump jets.

I really need to get a rolling road session done - when I can...my only concern is running lean and therefore killing a piston or 2....but I'm pretty sure I'm running a bit rich currently.

I have read that a sticky dizzy shaft can cause similar symptoms or dodgy vac can [or the internals not returning to idle position]

for me the carbs have not been run on an engine for awhile and they have been covered so - I think it possibly something else and not the carbs and the engine that they ran lovely on is the same bar the heads...

ran good...engine stored for 6months covered up in shed
added new heads DRD G03, and the bakelite gaskets, added servo takeoff [yes I'm going to check this again!]...
put back on engine...runs rubbish

so in an attempt to see what I did perhaps to cause the problem is not visible to me at this moment....it won't be anything major thankfully I'm sure! just annoying as when it was running sweet it was super nice!

 

[Slammed]

Yes min e does this when its warmed up, but it stays on high revs, I know its running rich as I'm running it in but I'm not sure of the cure.

 

[67panel]

have u got vac advance diz ,have known advance to hold timing up and then slowly decay or hold on,to test just take of pipe

 

[dubdubz]

yes I have a vac adv dizzy - I'll try that - so simply take off the pipe and leave open ?

cheers

 

[six]

id second vac adv dizzy issue first . take the pipe off and see. Also seen incorrect float setting [height] casuing simular problem, reset float height to min and max settings cured that. reason i found out cos the carbs were off another engine and float height was set to get more fuel in

 

[dubdubz]

ok - pulling the vac pipe off made no difference at all??

I think that I need to strip them down and give them a clean - reset the float [or at least recheck] reinstall the 33 pumps and 57 idles

found I've also got endfloat on my alternator :lol: see new thread......[well after I've searched!]

 

[Slammed]

Cured it - my mains were loose! :lol:

 

[dubdubz]

not had a chance as yet to get any further on - Monday in between decorating :lol:

D

:lol: :shock: @ my mains were loose !!