twin 34ict's

[bac2ba6]

Not so much a problem just wondering ? on start up from cold when revving a bit the carbs seem to sort of pop/cracking sound almost a slight hesitation from idle a small pop and then fine ! does this a few times until either a good few stamps on the throttle or a good blast up the rd for a few hundred yards ? is this just the fuel getting to them or a fueling/timing/ balanceing issue ?

once normal tickover is achieved all is fine ?

Also once warm when dropping down a gear or just takeing foot off the throttle the exhaust pops a bit on the overrun dunno if its because its a fairly large back box with 4 into 1 header or again timing/fueling issue ?

valves,plugs,points are all good

vac advance dizzy (svda) timing reaches about 36 degrees full adavance and 6 degrees on tickover .

Have read that the svda dizzy can reach as much as 40 degrees advance ( dunno how true this is )

like i said no major problems just your thoughts if you please

 

[froggy]

SVDA timing at idle is usually 7.5 deg BTDC with the vac pipe disconnected and blocked.
I would try setting the timing to this 1st before trying anything else

 

[bac2ba6]

Hi froggy thanks for the reply i know typically idle is set at 7.5 but always thought the advance timming was more important ?
and have read that you should set this and the idle timming falls where it falls and can be anywhere between 5-7 degrees ?

just followed the steps on vw-resource ? to quote "Check the static timing -- it should come in at around 5-7 degrees BTDC. The exact amount doesn't matter, so long as the maximum advance is okay."

timming always seems to confuse me :lol:
Any more views welcome

 

[cyberdyne systems]

Hi froggy thanks for the reply i know typically idle is set at 7.5 but always thought the advance timming was more important ?
and have read that you should set this and the idle timming falls where it falls and can be anywhere between 5-7 degrees ?

just followed the steps on vw-resource ? to quote "Check the static timing -- it should come in at around 5-7 degrees BTDC. The exact amount doesn't matter, so long as the maximum advance is okay."

timming always seems to confuse me :lol:
Any more views welcome

The reason they say this is because they are talking about 009's, which apparantly can have varying amounts of total advance due to different quality etc (the copy ones). So they made sure the total advance was around 30 degrees and let the idle fall wherever it wants to be, the problem is as you say the idle timing could be out at idle - so really if this is the case that distributor is junk in my opinion.

So assuming you have a genuine svda then your really only checking total advance doesnt exceed the 30 degrees area, and if it does there must be a problem with it. This is with the vacuum plugged - they can advance more with the vacuum connected but its only momentary not constant as with centrifugal advance. So set it at 7.5 at idle then just confirm the total advance (with vacuum blocked off) and it should be within the correct range and run as best as possible.

The other thing is, the carbs and manifolds might be cold at first causing the fuel not to properly atomise, which resolves after the engine is warmed up a bit.

 

[bac2ba6]

cheers dude thought it may be because the manifolds are cold for 30 secs or so !

will have another play around with the advance and idle and see where it gets me .

the only other thing is im not running an anti pulse valve on the dizzy as yet again
conflicting issues some say need one and others say not that important .

could this be a possible reason for the slightly strange readings ?

 

[cyberdyne systems]

im not running an anti pulse valve on the dizzy as yet again
conflicting issues some say need one and others say not that important .

could this be a possible reason for the slightly strange readings ?

Not sure what this is? Can you enlighten me?

 

[bac2ba6]

im not running an anti pulse valve on the dizzy as yet again
conflicting issues some say need one and others say not that important .

could this be a possible reason for the slightly strange readings ?

Not sure what this is? Can you enlighten me?

its a valve that you put between the carb and the vac advance dizzy on the vacumm port and its supposed to smooth out the vacumm and stop you getting pulses therefore a smoother advance ! hence "anti pulse valve " .

some people recon there essential when running a svda dizzy and other say there not that important .
eurocarb sell them for about £16 odd