Timing & twin carb tuning help please

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65southafricanbus
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Timing & twin carb tuning help please

Post by 65southafricanbus »

I've just fitted twin carbs & a Turbo Thomas exhaust to my rebuilt 1641 (brand new Weber 34s) - I haven't a clue how to tune them or what setting on the pulley wheel I should be timing them to. Engine starts but is phutting and spluttering & backfiring - noise seems to be coming back up through the carbs. The distributor is an 009. The engine code is AB which I think is a 1300 block.

I'd be grateful for any help - have spent two months rebuilding back end & am desparate to get bus on the road for hols next week
bought a 65 South African bus & doing it up slowly

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Post by Gnarly »

Get it down to Stef in Manchester and get it set up right :wink:
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65southafricanbus
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Post by 65southafricanbus »

would do if I could get it running - tried running up the road with it & it had no power & was getting very hot - that was before I set the valve clearances though
bought a 65 South African bus & doing it up slowly

sidewinder
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Post by sidewinder »

Set the ignition timing at 30 deg BTDC at 3500 RPM for starters.
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65southafricanbus
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Post by 65southafricanbus »

can't even get it running beyond idle speed before it cuts out - can anyone tell me a starting point for mixture screws - plugs are sooting up even with mixture screws nearly fully in
bought a 65 South African bus & doing it up slowly

flatbeat
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Post by flatbeat »

Do you have a carb balancer? If not, you could take 'em off and set the butterflies with a feeler gauge(between the butterfly and carb body) try 4 thou, that will get em sucking the same. Wind the mixture screws in GENTLY until they stop, don't force them, and then wind 'em back out maybe 3 to 4 full turns. See if that gets you up and running. If it starts, let it run until the manifolds have warmed up a bit. Once warm start on one carb at a time and slowly wind the mixture screw in. the revs should pick up and then start to drop off. Wind 'em back out to where it sounds best, then the same on the other carb. The snapping and popping usually means weak mixture. The fact that the plugs are sooty could be because it's just not warmed up enough.
Carbs deffinately fitted OK and not sucking air thru' poor sealing? Are you using a mechanical pump ''cos some of them put out 7+ lbs of pressure and webers don't like more than 3 or 4. Fuel pressure regulator?
Rewarding when you get there :wink:
Packed a few belongings and headed out to Pirates Cove. In my buddy’s old grey Kombi we rolled until the gas got low.....

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65southafricanbus
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Post by 65southafricanbus »

Thanks for suggestions

Was desparately trying to sort it today before working evening shift - in the end wife called out mobile tuner - turned out he'd served his apprenticeship at a VW place - he got it running & I drove it straight to MOT place - passed! so now have got 12 month ticket - I'm well chuffed. Still needs some tweaking but at the mo it's pulling as strong as the old stock setup w 1641 engine
bought a 65 South African bus & doing it up slowly

flatbeat
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Post by flatbeat »

All the way there and back with a big :D
Congratulations. Time to enjoy :wink: 8)
Packed a few belongings and headed out to Pirates Cove. In my buddy’s old grey Kombi we rolled until the gas got low.....

1965 11 Window aka 'Rustina'.
1961 Beetle.

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Telboyofpeckham
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Post by Telboyofpeckham »

I'm a bit late on this but for future reference, this website seems to be full of good advice.

http://www.aircooledtech.com/

Here's the link to the intial 34 ict set up.

http://www.aircooledtech.com/weber_ict/

BTW 65southafricanbus I'm setting up virtually the same engine. Any clever tips from your recent experience?

Cheers

65southafricanbus
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Post by 65southafricanbus »

Thanks again chaps - I'll have a look at the on set up the carbs.

Seems to be pulling OK but as yet lacks some acceleration. I'm hoping that the extra oomph from the twin carbs & exhaust will compensate for the higher gearing

As far as building it back up it was fairly straightforward. The carb linkage goes over the standard coil mountings - I got round this by using the top coil mount and fitting the coil horizontally above the coil linkage, then putting a self tapper & washer to hold the top coil mount. Also fitted some little brackets w self tappers to fan housing to keep fuel pipes tidy & out of the way

I've added the Allen keys needed for the linkage to my bus toolkit.

Whilst I was at it, and had the whole back end out, I fitted a horizontal bar roughly in line with the top of the petrol tank with seatbelt bolts through to the inside in the correct positions for fitting 3 rear recoil seatbelts at a later date. I also bought a brake pipe flaring tool from Frosts & replaced most of the rear steel brake pipes with copper nickel ones

Also replaced the swing arm rubber bushes & the handling seems to a bit tighter. Oil needs changing more or less straight away once it's fired up & run a while

Turbo Thomas exhaust was a bit tricky to fit but fine once it's on

I've set the timing to 7.5 deg BTDC statically but will experiment w tachometer & strobe
bought a 65 South African bus & doing it up slowly

65southafricanbus
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Post by 65southafricanbus »

Just started from scratch & got it all set up following advice above & it's running beautifully - only took me 30 mins - cruises quietly, then flies when foot down. Just spent about an hour writing a how to & it disappeared when I tried to post it!
bought a 65 South African bus & doing it up slowly

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