What’s your altitude?
Zero vacuum at idle. Need help.
- Thread starter misterpepper
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- Thread starter
- #22
Getting vacuum off of this port. Looks original. Somebody earlier suggested there might be some wadding in there that can be removed but I haven't touched anything. Seems to provide vacuum just fine.
The T fitting is to also be able to have my vacuum gauge connected.
So for tuning purposes should I leave the distributor unhooked from vacuum? It seems like if I did that my timing at idle would be way off when I plugged it back in. As is, to tune things seems like it takes a lot more back and forth between the carb and the timing right now, but again I haven't put a lot of effort into tuning it until I get some fresh gas. I'll have parts to rig up a gravity feed system tomorrow.
My altitude is 2700'. I'm not 100% sure how this carb is jetted because the jets weren't numbered. I have a trollhole carb that I can swap jets with but it runs the same as this one...crappy. If fresh gas isn't the miracle cure I'll swap the trollhole back on, but it's a bit of a process because I have to swap some brackets between carbs.
The T fitting is to also be able to have my vacuum gauge connected.
So for tuning purposes should I leave the distributor unhooked from vacuum? It seems like if I did that my timing at idle would be way off when I plugged it back in. As is, to tune things seems like it takes a lot more back and forth between the carb and the timing right now, but again I haven't put a lot of effort into tuning it until I get some fresh gas. I'll have parts to rig up a gravity feed system tomorrow.
My altitude is 2700'. I'm not 100% sure how this carb is jetted because the jets weren't numbered. I have a trollhole carb that I can swap jets with but it runs the same as this one...crappy. If fresh gas isn't the miracle cure I'll swap the trollhole back on, but it's a bit of a process because I have to swap some brackets between carbs.
Yes I suggested it… you’re not getting full vacuum … it has “wadding” in there 
“Seems to provide vacuum just fine” yes it shows vacuum … but not full vacuum
“Seems to provide vacuum just fine” yes it shows vacuum … but not full vacuum
- Thread starter
- #25
Has anybody tested to verify that? I can understand that the wadding could slow the response of the vacuum port, but I doubt that under relatively steady state it would affect the actual vacuum reading.
When balancing carbs on my BMW motorcycle I use a differential vacuum gauge and had to really restrict the flow in the vacuum hose to be able to read the gauge clearly. Even then, things went from the needle bouncing wildly back and forth with each intake stroke to a much steadier and more readable needle, but the number it pointed to didn't change, it just went from a blur to a stable needle. And it required me to really restrict the flow, down to not much more than a pinhole.
This truck is a bit of a bastard child with parts from a lot of years, but the 1F engine is period correct for the chassis. I believe the distributor should be period correct as well. There are not a lot of places to connect vacuum within the engine bay. It's possible that a PO has plugged everything and removed the correct vacuum port for the distributor, but the port I have it connected to now was only capped and not replaced with a threaded plug. Where is the correct place to connect the vacuum operated distributor on a 1F? The only 3 vacuum ports I can find within the engine bay are on the distributor itself, at the base of the carb and this muffled port on the intake. Currently the port on the base of the carb is capped and I have the intake manifold port connected directly to the distributor (albeit with a T fitting temporarily for a vacuum gauge).
When balancing carbs on my BMW motorcycle I use a differential vacuum gauge and had to really restrict the flow in the vacuum hose to be able to read the gauge clearly. Even then, things went from the needle bouncing wildly back and forth with each intake stroke to a much steadier and more readable needle, but the number it pointed to didn't change, it just went from a blur to a stable needle. And it required me to really restrict the flow, down to not much more than a pinhole.
This truck is a bit of a bastard child with parts from a lot of years, but the 1F engine is period correct for the chassis. I believe the distributor should be period correct as well. There are not a lot of places to connect vacuum within the engine bay. It's possible that a PO has plugged everything and removed the correct vacuum port for the distributor, but the port I have it connected to now was only capped and not replaced with a threaded plug. Where is the correct place to connect the vacuum operated distributor on a 1F? The only 3 vacuum ports I can find within the engine bay are on the distributor itself, at the base of the carb and this muffled port on the intake. Currently the port on the base of the carb is capped and I have the intake manifold port connected directly to the distributor (albeit with a T fitting temporarily for a vacuum gauge).
My vacuum port in the intake is straight across from cylinder #5. Its has like a 6mm hole inside. I run my vacuum gauge on this port. Have straight mechanical distributor.
Toyota calls that a gas filter. They still sell various versions of them with one, two or three ports. The idea behind it is so that gas vapors don't get sucked into whatever you're connecting to that vacuum source. I would leave it alone, or if you're concerned about it being clogged, get a new one.
At 2700ft ASL your vacuum reading will be almost 3in (2.7 by general rule of thumb) lower than at sea level. So that puts you around 16-17in which isn’t terrible.
I would hope that a '69 FJ40 might have the '69 & earlier vacuum advance dizzy. The one with the octane adjuster and little oiler on the outside. It's one of my favorites and I ran one for many years. That dizzy you should connect to the port at the base of the carb.
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- #30
The distributor on there now is vacuum retard, as verified by the fact that the vacuum actuator pulls the plate clockwise. The sticker is mostly gone so I can't read the part number on it.
It turns out I have a Toyota vacuum advance distributor as well. That one was missing the cap and rotor so I refurb's the vacuum retard one. I didn't notice at the time that they were different. I'll get that one cleaned up and ready to swap in, since that's another thing that I can test.
It turns out I have a Toyota vacuum advance distributor as well. That one was missing the cap and rotor so I refurb's the vacuum retard one. I didn't notice at the time that they were different. I'll get that one cleaned up and ready to swap in, since that's another thing that I can test.
- Thread starter
- #31
@Pighead, is this the distributor you are talking about? Mine cleaned up nice. Thank goodness for buying up all the boxes of FJ40 parts I could find for sale for a while years ago. Unfortunately it looks like my dizzy is missing a couple of parts, namely the vacuum nipple and a cover for what I think you are calling the octane adjuster. Do you know how to adjust that?
Skreddy
SILVER Star
If you can, pull the plug circled in blue and run a nipple there to get vacuum from for vac readings. I also use this for full manifold vacuum to my advance distributor (same one it looks like you’ve got now).
On a side note, I see your Amazon carb is a Kipa brand. Of the knockoffs, those are the best I’ve seen. As in, needing the least work out of the box. Was still some mismatching in the vacuum secondary diaphragm housing and ports; needed surfacing and a slightly bigger o ring to seal. But, with some stumbling, etc., the secondaries shouldn’t be your current issue, but if leaking there, it could contribute.
On a side note, I see your Amazon carb is a Kipa brand. Of the knockoffs, those are the best I’ve seen. As in, needing the least work out of the box. Was still some mismatching in the vacuum secondary diaphragm housing and ports; needed surfacing and a slightly bigger o ring to seal. But, with some stumbling, etc., the secondaries shouldn’t be your current issue, but if leaking there, it could contribute.
Skreddy
SILVER Star
Unrelated to your 40 issue: is your BMW an Airhead?
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- #36
Yes, it's an R65LS but I've cut it up a bit to make kind of a cross between a cafe racer and a scrambler.
Here's a better picture of the landcruiser I'm trying to get running, and the "parts" cruiser I keep stealing pieces off of to try different things.
I got that carb on a warehouse deal from Amazon in "used, like new" condition for pretty cheap. I was worried that it had been installed already and was maybe a bad carb. Looking inside all the mating surfaces looked well machined so I didn't do anything to it. I'm curious which o-ring might need to be swapped out, though, and what else I should check.
Here's a better picture of the landcruiser I'm trying to get running, and the "parts" cruiser I keep stealing pieces off of to try different things.
I got that carb on a warehouse deal from Amazon in "used, like new" condition for pretty cheap. I was worried that it had been installed already and was maybe a bad carb. Looking inside all the mating surfaces looked well machined so I didn't do anything to it. I'm curious which o-ring might need to be swapped out, though, and what else I should check.
Skreddy
SILVER Star
I’m building an R100RS right now into a “cafe” bike. My vision is “what would a super bike of that era look like?”
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- #38
Whelp, fresh gas wasn't the miracle cure. No real difference at all, actually. I did manage to tune it a little better using the vacuum gauge to about 14.5" which still isn't that great, actually. I wasn't able to stab in the vacuum advance distributor yet. Unfortunately with no exhaust and a fair amount of backfiring I have to stop my tinkering early out of respect for my neighbors. I did get the distributor tuned up and ready to stab in, though.
With the fresh gas being gravity fed to the carb the level was about 1/8" lower in the sight window. Close to the bottom of the window but still visible.
One positive is that I was able to verify that the fuel pump is working well by using it to pump out all the old fuel that was in the tank.
With the fresh gas being gravity fed to the carb the level was about 1/8" lower in the sight window. Close to the bottom of the window but still visible.
One positive is that I was able to verify that the fuel pump is working well by using it to pump out all the old fuel that was in the tank.
Sounds like either too rich, or considerable vacuum leak post carb.
Have you ruled out leaks at the base of the carb and intake to head? Short blasts of starter fluid at those places while running, wait a few seconds, and listen for idle quality improvements.
Where is the idle mix screw relative to fully closed (never screw it in hard; just till you can feel it touch the seat, then count screws out… typically based line this at 2-6 turns out, then do a lean drop set).
I just swapped a carb I rebuilt on mine, and I feel it is idling rich. Mostly because I know my throttle plate is not open too far, and if I pull a plug on my 3 port vacuum filter on the intake to plug in a gauge, the idle quality vastly improves until the loop is sealed again by the gauge. Could be a bad idle solenoid o ring, or I’m just way too far out on the mix screw. An overly rich engine will idle poorly and suck less air. How does yours run with a small intentional vacuum leak?
Have you ruled out leaks at the base of the carb and intake to head? Short blasts of starter fluid at those places while running, wait a few seconds, and listen for idle quality improvements.
Where is the idle mix screw relative to fully closed (never screw it in hard; just till you can feel it touch the seat, then count screws out… typically based line this at 2-6 turns out, then do a lean drop set).
I just swapped a carb I rebuilt on mine, and I feel it is idling rich. Mostly because I know my throttle plate is not open too far, and if I pull a plug on my 3 port vacuum filter on the intake to plug in a gauge, the idle quality vastly improves until the loop is sealed again by the gauge. Could be a bad idle solenoid o ring, or I’m just way too far out on the mix screw. An overly rich engine will idle poorly and suck less air. How does yours run with a small intentional vacuum leak?