Vacuum Leak? Vacuum gauge showing 12 mercury from intake. (1 Viewer)

[BigHighBlue]

Just do all the things

 

[WILLD420]

If it revs when you spray flammable liquid under the carb, make sure it's not evaporating and getting sucked up into the carb entry. I always test with soapy water. If it sucks the water in, it is sucking in air. Yes, driving it with a vacuum leak is bad. If you go too lean, you can burn a valve and it will cause all kinds of drivability issues.

If you have the valves too tight, that will definitely cause the issue. Doesn't take much, a couple thousandths of an inch too tight and it will suck air, then eventually burn the valve. A tell tale sign of vacuum leak is the inability to get the idle screw to make sense. Normally there is a narrow range where they run good, maybe a turn or two at the most from lean stumble, to too rich. IF you can open it all the way out and it doesn't cause an issue, you probably have a vacuum leak. If you have it most of the way out and barely turn it toward lean and it starts stumbling, you probably have a vacuum leak.

 

[cps432]

are these any different than standard feeler gauges? i've got some old school ones here they look like this

View attachment 3436124

The go no go gauges have a step on the end. For example the .016mm will step up to .017mm so you can feel the resistance. If you can get the .016mm into the gap but not the .017mm part then the gap is measuring at .016mm.

If the .017mm part fits in the gap then the gap is at least .017mm. Then you would move to the gauge that has .017mm on the end and steps up to .018mm. If the .018mm part won’t fit into the gap then you know the gap is in fact .017mm

Having that hard line helps you with the “feeler” part of the measuring. It helps you adjust things correctly without going too tight or too lose.

 

[ToyotaMatt]

Hi all,
Trying to tune the 60 but its proving difficult doing the lean drop with this aftermarket chinese carb I'm running with. Using a line from the intake I get 12 mercury, but i know the ideal range is 15-20. will this increase as I get closer in tuning this, or do I have vacuum leak?

Im leaning towards vacuum leak because If I hook up any of my other vac lines to this gauge it shows 0 mercury (no pressure, obviously). All vac lines should have roughly equal vacuum running through them, right?


I ran desmg, and there's a chance I hooked up something incorrectly, but I assure you all vac lines are plugged in, so not sure why a misplaced line would create a leak if its plugged.

Thanks,
Beehanger

12 inHg vacuum is very low. - unless you’re above 6000 ft elevation
Not all the vacuum hoses carry full vacuum all the time.
Connect the vacuum gauge to the small pipe jutting off of the brake booster manifold fitting.

Most of the well tuned cruisers around here pull around 15-16. I’m at 6k in Colorado. 12 seems low.

Some of those Chinese carbs are hit or miss. Some people have dropped them straight into the truck and they work perfectly. Others seem to have better luck replacing all the gaskets and seals with Japanese components.

Further more, some of the mating surfaces could be uneven and not making a seal internally. You could have a leak inside the carb. There could be gunk from the manufacturing process left inside. You might need to adjust the float to keep the correct amount of fuel in the bowl.

I was just chasing what I thought was a vacuum leak and it turned out to be out of adjustment valves, worth the check before you start pulling a bunch of stuff apart...

Have you checked your timing yet? Faulty timing, bad wires, misfires, too low rpm etc will do that. Try pinching off the vacuum booster hose, see if that fixes it. Same can be done with all the other hoses that you see coming off the intake. Otherwise, suspect the gasket under the carb. I got bit by that one a few years back.

Might be an unpopular opinion but I run gaskets even with the ones on the insulator. If nothing else it makes me feel better about not having leaks. There are two, one that goes between the carb and the insulator with 2 holes for the primary/secondary and a second that goes between the insulator and the intake manifold with one oval hole. I think City Racer may have them and I know Spector has them.

- i only know of 1 single live TECH Video in existence , that clearly shows the 2F Engine Valve Adjustment Procedure per the FSM step by steps

- it is the MAJOR part of a W.W.N ( Project Wrongway ) Episode podcast and Everyone's SOLID MUD buddy , mr. Ben

- the actual valve adjustments are skillfully done by the Iconic @orangefj45 Georg from Valley Hybrids / Cruiser Brothers ...


- i WILL hunt for it right now and post it here as soon as i determine what exact episode it was ?

- it's being done on a STOCK FJ60 exactly like Dan has .....

LINK BELOW :



.






@HemiAlex

 

[Beehanger]

Circling back on this thread....!
My mission from September until late feb was getting the damn header/intake situation figured out, fixing an oil leak at timing cover, ordering a new carburetor, fixing big coolant leak and getting showered multiple times, installing gauges, and making the insulator plate fit to my headers.

It's been a long 4 months and my progress got a lot more complex and stagnated. This thread is helping. The last part is by far the hardest and its requiring me to get better at the mental aspect, focus and prepardness aspect, not losing tools etc. Been a humble awakening as I knew I was close, which I was am am, but the truck required a whole nother level and period of fortitude, skill development, and patience I didn't see coming.

Trying the things mentioned on this thread, still running at 11-12 mercury but I haven't given up, even though its been slow I have steady progress. A smoke machine test last week especially showed that I had 3 small/mediumish vacuum leaks on the city racer carubator. Going to try to tigthen that up first to start. will move onto readjusting valves etc. after that. (im now recalling there was a crack in one of the "supports" on the rocker assembly and wonderingif that's creating play in the valves.)

@ToyotaMatt thanks for your kind words never caught that comment. Means a lot right now!

If you guys have input on this gauge reading that would be awesome. It's "wobbly" and I don't have expereince knowing what that means. Google wasn't that big of a help either>
Attached files. (Guage, and leaks on): Google Drive: Sign-in - https://drive.google.com/drive/folders/1--9Tf9jCK_SQslaNem0DYpByLka3yXxy?usp=drive_link

Still Fighting,
Dan