bike carbs and vac advance

i have a beautifully made bike carb manifold with a single vac take off on cyl4 for the servo, but im a little confused as to what to do about vac advance for the dizzy? i understand that running from that single take off will mean the vac unit will see a pulsing vac which breaks it, so what to do? should  drill all 4 runners and dasiy chain them together or will this create running probs as i will have effectively created a leak between each cylinder?
excuse my confusion as ive been doing alot of reading up and as of yet not found one good answer to my question. i understand bogg bros just dont bother with vac advance, but vac advance is vital for correct running at idle and cruising speed.

Sorry I can't help mate, but I'm in the same boat as you, I have had mine running and driving but at the top end it stutters and then won't idle properly for a little while, I think it's the lack of vac advance that causes that.

Good luck either way, it may be worth a quick call to Bogg Bros to get the lowdown, I had my last car tuned up there and they're super knowledgeable chaps and happy to share what they know.

I only ever had one vac take off for both brake servo and vac advance (I.e. shared between the two) and I never had a single issue.

No pulsing brake pedal, no dodgy ignition timing. I really wouldn't read too much into it.  Get the carbs set up by someone proper, like Bogg Bros and you'll never have any problems either

cheers phataz… cool i will try a t piece. how long have you been running bike carbs, and what are they like, economy etc?
 i hear lots people just ditch vac advance but thats wrong! its vital for road use. have a read of this pretty good explanation.
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i wish i could get boggs to set it up, but i live in cornwall!

I hear you about the distance to Bogg Bros I'm in the north west and its still a good 250 miles from me!


Was the best thing I did going up there though, £80 to get your car running perfectly is a bargain IMO. The second best thing was converting my setup to use the proper carb mounting rubbers :wink:


I ran my carbs for about 3 years.  I ditched them in the end because I kept having to change engines, each one different, and the carbs were still set up for my first engine so it never ran perfect afterwards.  And I couldn't be arsed with another trip to Bogg Bros :redfaced:

Boggs did blank off my vac advance during the rolling road session, but I refitted it later on.  

Economy after being set up was better than my standard carb'd clipper cab is now! I really rate them to be honest, it's just most people do it half arsed or attempt to set needles/jets them themselves and they never have them running right.

Phataz is it you that makes manifolds? I had my mk1 with AFH on bike carbs set up at bogg bros and it was a total rocket - just had some problems with the head and never got it running right again! Hopefully be back over to bogg bros sometime in the next few weeks, only 40 miles from me thankfully!

georgeyv said

Phataz is it you that makes manifolds? I had my mk1 with AFH on bike carbs set up at bogg bros and it was a total rocket - just had some problems with the head and never got it running right again! Hopefully be back over to bogg bros sometime in the next few weeks, only 40 miles from me thankfully!

Yeah I've made a good few!

AFHs on bike carbs are very impressive! My mate had his set up about 4 years ago, a couple of years off the road and it still runs as it did when he had it set up.  He ran a 14.7 quarter mile time too 8O You won't find 20vt converted mk1s hitting those times!

Its a shame when things happen to your engine after having it set up :cry: Almost makes that initial setting up a total waste of money Thats why I never went back to Boggs, I was waiting until I found an engine which would be consistantly reliable before I had it set up again

You don't fancy doing another do you? Mine is a real bodge job and I've got a feeling that's the cause of a few of the problems I'm having!

A friend of mine (who coincidentally is on his way over to have a crack at my golf now) has a mk2 polo saloon with an AFH on bike carbs, it's absolutely wild, but he's sunk some serious cash and time into that engine- Just stuck a quaife diff in it too and was running low 15's at Bugjam! Sure he could knock a fair bit off that with better tyre choice and more practice.