304 Engine Ring Question (right bank smoking).

Agreed-I just got excited

 

OK, did a compression test (WOT) on Jr's 304 and we need some help here w/the results.

Results Drivers Side Front to Back (no smoke from this side):
122-clean plug
122-clean plug
125-plug a little fouled
105-clean plug

Results Passenger Side front to Back (big time smoke from this side):
116-clean plug
125-clean plug
115-plug fouled big time
125-clean plug

Seems like the passenger side cylinder is the one that's doing all the smoking.

He is running a Autolite 65 plug and we want to try a hotter plug but not sure what number to run. I called O'Reilly and the guy suggested a Autolite 866.

We would like to try the hotter plug so he can drive it to the pressure wash station before we do a valve job.

Any thoughts?

Thanks,
Jim

 

I assume this was a cranking compression test? Dry no oil squirted in cylinder? did you have all the plugs out and the carb butterflys wide open? Last did you turn over each cylinder the same amount of turns?

The numbers are obviously low as I believe a new motor was around 150 lbs cranking........the 304 only had 8.4-1 compression so don't hold me to that 150 lbs........... the good news is they are all worn and the variance between all is not that great............not great enough to say that one side or the other is bad...............which may point to valves or valve guides.
Do you have the ability to do a leak down test? That's a different set of gauges that will tell you a little more about the condition of each cylinder. Basically you would put the cylinder you are testing on TDC and blow in compressed air through the test gauges........one gauge tells the amount of static air coming in the second gauge tells the percentage of leak.............by listening at the exhaust or the carb you may be able to hear leaking air at either point which would point to either the intake or exhaust valves.........if you hear air leaking in the pan or the crankcase or at the valve cover breather that would normally mean Rings............you could also have issues with your valve guides or there seals........a common problem.............not saying it does not need help but perhaps a valve job and some head work may get you through another year or so..............

 

Here is the WET test on those two cylinders.

All plugs in while testing the cylinder in question.

WOT.

Results Drivers Side Front to Back (no smoke from this side):
122-clean plug
122-clean plug
125-plug a little fouled
105-clean plug - Added some WD-40 and the cylinder went up to 110lbs.

Results Passenger Side front to Back (big time smoke from this side):
116-clean plug
125-clean plug
115-plug fouled big time - Added some WD-40 and the cylinder went up to 124lbs.
125-clean plug

 

The plugs should be all out..............those cylinders don't seem to be that bad.............do a leak down. Whatever cylinder with the fouled plug on the right side , I would look there at the valve seals & guide.

 

Terry, why do all the plugs need to be out? Never heard that before.

Can I go a hotter plug (if so what-he runs a Autolite 65) for a few days so he can drive it to pressure wash the motor?

Thanks,
Jim

 

I would have to see if AZone has a leak down tester.

 

Some have said if the lbs go up after a wet application then it is rings-confused but really appreaciate the time you all are helping me/my son out.

I have a 401 and a 360 & SBC350 waiting on me if I want them 400.00 total Jeep-both running/401 & the 360 ran when parked a few yrs ago.

 

The idea is to keep the cranking speed up and consistent for consistent readings. With the plugs installed you are creating compression. This in turn creates resistance that effects cranking speed and excessive loads on the starter and battery which can ultimately affect the accuracy of the compression readings. The throttle plates and choke plates should also be blocked in the wide open position and ignition system disabled.


Sent from my iPhone

 

Jim,

Nick M. is correct and answered your first question......................and if you did not do the test that way you should retest and keep track of how many revolutions your turning the motor over.........keep the test constant on all cylinders. The key here is not so much how high the compression goes because we already know the motor is old as opposed to how consistent the readings are across all cylinders......
Hotter plug may or may not help or do nothing at all............again hard to diagnose via the computer.
Not sure where you are in Nevada but places like Harbor Freight sell leak down gauges cheap or ask your friends if they have one to borrow you will need an air compressor for an air source...............go on line and read the proper way to do that test..........it can be very informational. Does it smoke under acceleration or de-acceleration? I'm still thinking valve guides.........but the testing will help determine that.

 

Wow-all these years and I have never taken all the plugs out, I can always learn something new

I don't count revolutions, what I do is count the pumps-meaning, the compression upon the gauge whereas it bumps the needle up. I do three bumps of the needle.

I will look on HFreight.

Upon acceleration it is big time smoke but only when hot. Deceleration not to much but it is there.

Back to testing.


Thanks again,
Jim

 

Jim, The good news is that hopefully everyone learns something me included.........that's what these Forums are all about.

Revolutions and pumps can be construed as one in the same as this is a 4 stroke engine: Intake, Compression, Ignition & Exhaust............three bumps of the needle would be 6 revolutions.

Make sure the motor is warm, Do everything we have previously mentioned, I would give it 4 bumps or 8 revolutions...........a 15-20 lbs variance between cylinders on a used motor is fine. It is important to keep the test consistent with cranking speed and number of cycles............some mechanics even put a Jumper Battery on the system to keep the voltage up and cranking speed constant. Don't know what altitude you live at but that will also effect compression.....
Get the test results doing the test correctly and post them..............There are numerous things that can cause smoking.......Rings, a broken ring, excessive cylinder to piston ring & skirt clearance, a broken piston. Smog valves and crankcase ventilation. Valves and valve guides and seals..............leaking intake manifold gasket........Nothing were doing here will solve the smoking issue unless it is smog related or a leaking intake.
Most likely its internal but by doing the testing one should be able to at least know going in where the issue is.........that's where the leak down gauge is important.

 

Thank you.
Here is the plug on the passenger side-doesn''t look fired so I think I will replace the wires/plugs as well.







Heading to AZone then back to testing as you say.

Thanks again,
Jim

 

Is that a plug that came in the Jeep? Or did you install new when you bought it?

Plug wires are usually neglected, so a new set is probably needed.

Anti-foulers are available, that will move the plugs away from the combustion chamber and prevent fouling. Won't cure your oil control problem though.

 

OLD NUMBERS

That plug came w/the Jeep.

I installed new plug wires and Autolite 65 plugs.

Still smokes out of the right bank.

I let it idle for a while to maybe burn the oil oil out of the cylinder (maybe 10min). Then I drove it around the 3 acres and it kept smoking.

I then stopped and help the throttle @ about 1500 rpm and punched it a few times. Big time smoke and also when I took my foor off the accellerator pedal I did see some smoke (not much but visible in the daylight) coming out.

Here are the new compression numbers with ALL the plugs out/WOT/engine cold.

NEW NUMBERS
Drivers side front to rear:
118
125
126
105

Passenger side front to rear:
119/120
122
100
130

 

Jr's Jeep is a 3spd/304 and I have a question.

Question, if he pulls a 360 that has a auto behind it, can he take the pressure plate (where the clutch rides/motor turns the tranny) off the 304 and bolt it to the 360 or does he have to get one for a 360?

Question, will the same work for a 401?

Also, will his bell housing will bolt up to the 360 and the 401?

Thanks,
Jim

 

The 304 clutch (disk & pressure plate) is smaller in diameter than the 360/401 clutch (ca 10.5" vs. 11"), so he might not want to use it ... even though he can.

360 and 401 clutch parts are the same. The clutch parts do not affect the balance.

Bellhousing is the same, 232/258/304/360/401 - what I call the "unified" AMC pattern. Yes, ALL the external dimensions of the 360 and 401 are the same as the 304. The 360 or 401 engine bolts right in. But the V8s are externally balanced engines (aka "Detroit balance") - the balance is different for each of them. The external components are part of the balance of the rotating assembly.

 

So he would need a new clutch, throwout bearing (might as well) as well as a Flexplate/PPlate?

 

So what do you think about the new compression numbers etc?

 

Huh. These look tired to me. Not dog tired, but tired. I would expect up around 150-160. Variation is not terrible, 118 +/- 15 roughly. About +/- 10%.

These are wet or dry?

You have any idea how many miles this engine has?