Dual weber 34 icts

[vw_bud]

Ok so just rebuilt my 75 westy dual weber 34 ict carbs....its an 1800cc engine and now when I try to check timing the mark won't consistently match the timing degree and then it idles fast I had it running pretty good this morning but it had no power couldn't leave 1st gear

[vw_bud]

I also have a dual vacuum dizzy and when I had the single weber the retard side of the vacuum can was plugged and the other side went to the front of the carb is there a diagram to hook it up to the ict? There's only 1 vacuum port on each carb

[Zed999]

Hook up advance to one carb, block port on other carb. No expert of retard, but if blocked I imagine it prevents the advance working?

Over in the uk ICT's come with F87 emulsions which flood the engine and make it undriveable in a bus. I believe they are for single carb applications In a car people seem to manage to drive with them but I don't think they're right for dual carbs. They are routinely changed for F6. Hopefully your suppliers over the pond do better but could be worth a look.

[vw_bud]

The advance side is hooked up to the left carb the retard side is blocked if I hook a hose up to each carbs vacuum port do you think it may work?

[Spike0180]

[vw_bud]

Dang what a headache lol I just want my bus to run again lol that single weber ran great but the bus was seriously underpowered and this dual set ugh, I'll try blocking them both off I do have the old petronix dizzy still that I had before the single when I had dual dellortos i removed after the engine fore and rebuild for the single weber the petronix acted as if it didn't work anymore

[vw_bud]

Now the timing won't go to 7.5 bdtc but it will set at 5atdc if I try to set it with the strobe light at idle to 7.5 it starts to idle very high and will not smooth out to be able to read where the mark is at

[coolerthanelvis]

In a regular vacuum advance can, the other side is vented to atmosphere. Would blocking the retard side of the dual vacuum can create "vapor lock" and prevent the diaphragm inside from moving?
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[telford dorr]

Blocking the retard port will seal gas inside the can. This will make it hard / impossible for the advance diaphragm to move. Better to leave the retard port open.
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[TomWesty]

Since you don’t have stock induction, timing it at idle may be folly. You want to be somewhere around 28 degrees at 3500 rpm. Can’t remember what you do about vacuum hoses. I think you block them. Let the idle fall where it may.
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[wcfvw69]

A couple of things here.

You're describing a DVDA distributor. The vacuum canister requires 180MM hg of vacuum to start pulling the advance arm to advance the timing. Have you measured what kind of "ported" vacuum you're getting out of the carb/s? I'm not familiar with those carbs. Some aftermarket dual carbs are drilled correctly under the throttle plate to provide enough vacuum while others are not.

The retard side of the vacuum can works off "manifold" vacuum pressure. So, you need find or drill and tap a tube/nipple into the carb intake manifold.

Your best bet is to go buy a cheap vacuum gauge. "T" it into the vacuum hose from the carb to the advance side of the vacuum canister. Rev the engine and see what kind of vacuum your getting from one of the carbs.

If you don't use the retard side of the canister, cap it off. There's two different chambers inside the vacuum canister. Blocking one off won't affect the other side and will keep moisture and other crap out of it. It you want to run the distributor with only the advance side hooked up, provided your carbs produce enough vacuum, set your initial timing at 7.5BTDC to achieve a good idle. Remove the vacuum line from the distributor and cap it off. Then, rev the engine up to say 3800 RPM and make sure the timing doesn't advance more than 30* BTDC.
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