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Sun Aug 13, 2006 6:17 am

I just purchased a '72 Bay, with twin carbs. After quite a bit of coaxing it will start, but has tremendous flat spots. There is no backfiring, but a serious amount of flooding. Even with gentle acceleration it only managed 45mph in 3rd gear. A shift to fourth caused it to bog down. There is no trouble in starting and stopping the bus, it will settle into a rather fast idle, but as soon as your press on the gas, it begins to bog down, and only gentle feathering builds up any sort of speed.
Any ideas?

Sun Aug 13, 2006 6:24 am

I would check to see if your vacuum lines going to your distributor are connected properly. If they are not, then your advance and retard mechanisms are out of wack making your timing off.

I would also get a Bentley manual and go through the carb and tune up specs to make sure everything is as it should be.

I have a 73' transporter with the same carb setup. They are complicated at first, but you'll get the hang of it after you read how they work.

Sun Aug 13, 2006 8:32 am

CHB1 wrote: I just purchased a '72 Bay, with twin carbs. After quite a bit of coaxing it will start, but has tremendous flat spots.
Usually a timing problem but sometimes due to the carbs.

Quote: There is no backfiring, but a serious amount of flooding.
You can smell the fuel?

Quote: Even with gentle acceleration it only managed 45mph in 3rd gear.
That's a little low for a bus but not too far off. Check that the accelerator cable isn't too slack preventing you from opening the throttle all the way.

Quote: A shift to fourth caused it to bog down. There is no trouble in starting and stopping the bus, it will settle into a rather fast idle, but as soon as your press on the gas, it begins to bog down, and only gentle feathering builds up any sort of speed.
Do you have a vacuum gauge? You need to see if the vacuum hoses are making a good seal.

You need to check the dwell and timing of the distributor like 86 syncro said. You also need to check that the vacuum can (if you have one still) can hold vacuum otherwise the leaks are going to shift the timing around.

There is a small gold can to the left of the booster fan:

http://homepage.mac.com/ratwell/.Pictures/Parts72Bus/13-CharcoalCanister.jpg

http://homepage.mac.com/ratwell/.Pictures/Parts72Bus/37-VacAdvCutoff.jpg

It serves to cut off the vacuum to the distributor advance in gears 1-3 (there is a switch on the transmission) which may explain the big change when you shift into 4th. I recommend people disconnect it after they verify the timing is normal and the vacuum can is functional.

Sun Aug 13, 2006 10:42 am

[quote="86syncro"]I would check to see if your vacuum lines going to your distributor are connected properly. If they are not, then your advance and retard mechanisms are out of wack making your timing off.

I would also get a Bentley manual and go through the carb and tune up specs to make sure everything is as it should be.

I have a 73' transporter with the same carb setup. They are complicated at first, but you'll get the hang of it after you read how they work.[/quote]

unfortunately someone has switched to the dreaded 009 dizzy. have heard a lot of bad things about them, maybe this is why

Sun Aug 13, 2006 11:21 am

CHB1 wrote: unfortunately someone has switched to the dreaded 009 dizzy. have heard a lot of bad things about them, maybe this is why
What is the timing set to at idle then?