AMC360 Vacuum help

[MReno]

It has all new plugs, distributor rotor and cap. The real issue I have it it's really hard to get it running to a point where it idles without stalling. It takes a lot of cranking, choke, starting fluid then accel pedal. Once warmed, it seems to settle into an idle.

I tried adjusting the carb screws, and have it where it seems to run best. But I don't have much carb experience, so what do I know!

[letank]

It has all new plugs, distributor rotor and cap. The real issue I have it it's really hard to get it running to a point where it idles without stalling. It takes a lot of cranking, choke, starting fluid then accel pedal. Once warmed, it seems to settle into an idle.

I tried adjusting the carb screws, and have it where it seems to run best. But I don't have much carb experience, so what do I know!

Could be a little lean, I had the same flutter years ago, and gave it a 1/4 turn and the needle was steady... as you are saying that it takes starting fluid... also the timing could be a little low, loosen the distributor a give it a slight nudge counterclockwise to increase timing, the idle will go up but it is a good start...

As for spark plug I am running the Jeep recommended Champion RN12YC or # 404

Here is the 85
[youtube]https://youtu.be/pe3xgInq65U[/youtube]

[MReno]

So I loosened the distributor and slightly turned it both counterclockwise and clockwise, and fluttering of vacuum gauge needle only got worse. I have been able to get the idle down now to stock (@500rpm) now that I have the throttle cable connected properly to the carb linkage. Now I just need to resolve the hard start issue and then determine if the vacuum issue is a result of rings, valves, etc.

Thanks for everyone's help. I actually feel really good about my ability to work on an old carb engine, with all you guys as resources.

[letank]

Thinking that you may not have the OEM camshaft, that could explain the loopy idle.

Even with bad parts, with a good tune it will start. For example, my 86 project with fubar 3 lobes on the camshaft started very well hot or cold a bit of a shake, decent vacuum. After the camshaft and lifter replacements, it started well when cold -high idle allowed to curtail some deficiencies- but would stall after a slight warm up, but restart without a problem... then would barely hold idle on it inaugural trip when in gear... I discovered that it was leaned out for the idle and the jets were high altitude, enriched the mix and changed jets...

I saw your post about the transmission bushings... same here I need some...

[MReno]

Still having issues. Here's latest video https://youtu.be/LzaljVpO6e4

[MReno]

And one other thing....https://youtu.be/EGQFjsJrEoQ

[sirrus]

And one other thing....https://youtu.be/EGQFjsJrEoQ

Water is probably just condensation that accumulated in the exhaust and is forced out when engine is running


Sent from my iPhone using Tapatalk

[letank]

water is normal, it is a byproduct of combustion = 2C8H18 + 25O2 = 16CO2 + 18H20

If you take it for a spin... do you have power... ?

As for not being able to see the timing mark on the balancer... , do you have a timing light with an dial to visualize the timing advance on the dial ?

If you snap the throttle rapidly open and close, what is the vacuum gauge reading?

[MReno]

letank,
So I have not been able to take if for a spin yet (not registered), but where I live, I could probably get away with a short drive, but not getting her above say 20 mph. I do have a timing light that has a dial on the back, but not exactly sure how to use it.... If I snap throttle, there is a instant of hesitation, then the gauge hits 0, then rebounds to like 25, then settles back to about 11 (border line between red and yellow on gauge).

[MReno]

letank, BTW, I found some bushings that fit and hole the linkage in place. I found them at my local TrueValue. They are similar to stock, but snap in and when I press in the linkage rod, they seem to grab and hold if fine, while also allowing the linkage to twist as needed.

[letank]

letank,
So I have not been able to take if for a spin yet (not registered), but where I live, I could probably get away with a short drive, but not getting her above say 20 mph. I do have a timing light that has a dial on the back, but not exactly sure how to use it.... If I snap throttle, there is a instant of hesitation, then the gauge hits 0, then rebounds to like 25, then settles back to about 11 (border line between red and yellow on gauge).

online diagnostic is tricky, especially if you cannot take it for a spin... the leo's are probably not patrolling too much lately... with the Shelter In Place. May be you can it insured for test purposes if you live in a busy neighborhood... you don't want to go over anything while watching your vacuum gauge!

Either luck or not, we drove with a 6 months expired tag for 40 miles last year, we had forgotten to put the new one... it was in the glove box... especially after the ignition was failing and we had to stop every 5 miles to let the electronic cool.

Snap throttle test to 0 , then over to 25 and lower to 11... it all depends on your cam at this point, back to the engine history... may be the cam is not the OEM cam and a slightly flutter is not something to try to control. Or worn rings according to dr Bob link on page 1, but anything else can happen such as nothing, how many miles on that rig?

[MReno]

The Odom shows 180k. When I snap the throttle, there is a slight hesitation, then revs, and returns to idle. I'll be putting the seats back in this week after painting the interior floors, so I hope to try and take it for a spin this weekend and will report then. Thanks again for the reply.

[MReno]

What would cause a back pressure burst through the manifold when trying to start the engine? On my capped manifold port, when I try starting the wagon, it takes several attempts with hard cranking to get her running and while doing so, on failed attempts to start, back pressure is experienced that blows a cap off a port. Its like an internal backfire.

[REDONE]

This usually happens when the plug wires are mixed up so the wrong spark plug fires while that cylinder's intake valve is still open. Sometimes it's because of raw liquid fuel in the intake plenum but that's almost always after someone "primes the carb" with a gas can. Less common is something physically broken, like a cracked valve or cylinder head or something.

[MReno]

I actually got it started fairly quick this evening and it seemed to run smoother. What I did was cap the return line from the fuel filter that leads back to the tank as suggested. That may have helped.

[will e]

I actually got it started fairly quick this evening and it seemed to run smoother. What I did was cap the return line from the fuel filter that leads back to the tank as suggested. That may have helped.

That's good to hear.

[MReno]

Also increased idle to about 800rpm when in park.