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It is advancing with centrifugal. I don't know enough yet to say if the two advances are fully independent.
Benton
They are.
The weights control centrifugal. The Vac can moves a plate, that can get stuck. The vac can doesn't make a lot of power. The plate must be able to move fairly easily.
Thank you Mike- I will try it that way (compression check, which is reverse of the inflating from my compressor)
I think you really want to do a leak down test.
But I don't think either a leak down or compression test will tell you anything about the valve guide seals- only the condition of the valves themselves and rings.
Benton,
If I'm understanding correctly what you're attempting to do you may be a bit confused. A compression check is done by removing individual spark plugs and inserting the compression gauge fitting into the spark plug hole and cranking over the engine several times (remove the coil wire so that the engine doesn't start) and reading the gauge for compression.
Replacing the valve seals entails filling an individual cylinder with constant compressed air which forces the piston down and the compressed air holds the valves up so that you can remove the valve spring retainers and springs so that you can slide off/on the valve seals. Key here is constant compressed air typically via a air compressor. No need to mark your harmonic balancer or anything else for this procedure.
I believe the second scenario is what you're attempting to accomplish
Last edited by leif.anderson93; 04-26-2016 at 01:31 PM.
Benton,
If I'm understanding correctly what you're attempting to do you may be a bit confused. A compression check is done by removing individual spark plugs and inserting the compression gauge fitting into the spark plug hole and cranking over the engine several times (remove the coil wire so that the engine doesn't start) and reading the gauge for compression.
Replacing the valve seals entails filling an individual cylinder with constant compressed air which forces the piston down and the compressed air holds the valves up so that you can remove the valve spring retainers and springs so that you can slide off/on the valve seals. I believe the second scenario is what you're attempting to accomplish
I read that he was putting a momentary blast into the cylinders and then shutting off the air pressure and the air bled off as expected.
But if he had a cylinder with way low compression, that could give him a sensation of an engine misfire at high load.
We've already found a problem with the carb. Don't know about the plugs yet or even what heat range they are. I'd go there first as previously stated.
Benton,
If I'm understanding correctly what you're attempting to do you may be a bit confused. A compression check is done by removing individual spark plugs and inserting the compression gauge fitting into the spark plug hole and cranking over the engine several times (remove the coil wire so that the engine doesn't start) and reading the gauge for compression.
Replacing the valve seals entails filling an individual cylinder with constant compressed air which forces the piston down and the compressed air holds the valves up so that you can remove the valve spring retainers and springs so that you can slide off/on the valve seals. Key here is constant compressed air typically via a air compressor. No need to mark your harmonic balancer or anything else for this procedure.
I believe the second scenario is what you're attempting to accomplish
In essence I was not planning on a compression check until I found that the compressed air would not hold any time in my cylinders. I do realize I don't need to mark the balancer for a compression check- but the topic of checking compression arose out of my attempt to install the valve guide seals- which I do need to do in sequence if I understand the article correctly.
this I assume is just to make sure that each pushed/rocker is adjusted while they are at absolutely rest.
The saga continues.
A mentor of mine suggests that tapping on the head of each valve with a hard rubber mallet may allow the older valves to seat and allow me to then get compressed air to hold long enough for each cylinders new seals and retainers to go on.
In essence I was not planning on a compression check until I found that the compressed air would not hold any time in my cylinders. I do realize I don't need to mark the balancer for a compression check- but the topic of checking compression arose out of my attempt to install the valve guide seals- which I do need to do in sequence if I understand the article correctly.
this I assume is just to make sure that each pushed/rocker is adjusted while they are at absolutely rest.
The saga continues.
A mentor of mine suggests that tapping on the head of each valve with a hard rubber mallet may allow the older valves to seat and allow me to then get compressed air to hold long enough for each cylinders new seals and retainers to go on.
Benton,
If all you're doing is putting a blast of compressed air into the cylinder and hoping the cylinder will hold pressure, you're chasing your tail. You must have a constant and continuous flow of compressed air in the cylinder to hold the valves up and in place so that you can remove the retainers and springs. Once the cylinder is full of the constant flow of compressed air, tapping the top of each valve may make the removal of the retainer easier, as sometimes over time they get stuck. Do you have a spring compressing tool? If not, they are inexpensive and you may be able to borrow one from the local auto parts store.
Benton,
If all you're doing is putting a blast of compressed air into the cylinder and hoping the cylinder will hold pressure, you're chasing your tail. You must have a constant and continuous flow of compressed air in the cylinder to hold the valves up and in place so that you can remove the retainers and springs. Once the cylinder is full of the constant flow of compressed air, tapping the top of each valve may make the removal of the retainer easier, as sometimes over time they get stuck. Do you have a spring compressing tool? If not, they are inexpensive and you may be able to borrow one from the local auto parts store.
I do have a spring compressor. The lever type I bought will not work on the #1 exhaust spring with the radiator hose in place. Figures.
I can supply continuous air to the cylinder - yes. Several locals have told me they do it with the compression gauge hooked up this way, so I've been trying to make that work- not trying to go against your advice here.
The leak down has made me wonder what a cranking test would show. I have a video of anyone wants to receive it via text showing the 90 psi max going in, and rushing out anything more. 120 psi at the regulator will NOT enter the cylinder and you can see the gauge falling off immediately on removal.
This car is obviously way out of tune and may have been so for decades. I do wonder if all my fouled plugs with 4k miles on them are indicative of years of washed cylinders.
I simply don't have the benefit of knowing what one of these "can" run like when fresh and in tune. I'm too young and the car is also relatively new to me.
I'm not discouraged at all- I wouldn't trade her for anything! But I do have thoughts creeping in about years of poor running.
All I can say it that it starts easily, idles, runs down the road, and can be barely induced to grab a little second gear rubber.
I will report the compression check findings in a bit. Off to get my son from school.
I lied. I went out and adjusted the rockers back on - cranking compression around the Lowe number on a short burst. Maxed out on a longer crank at the second reading (maybe 7 revolutions for the first and 10-12 for the second. Engine turns fast with no plugs, hard to count)
Longer cranking. <br ><br >
Short crank. <br ><br >
I agree -- that is OUTSTANDING compression on a well-used SBC...
Those plugs are sooty as all hell. I run NGK-XR4 in both my C1 and C2 and they burn a light tan all the time. These are AC-R45S plugs that have burned ethanol 87 octane pump gas for 10,000 miles - NGK plugs burn even better.
This pic are plugs out of my dual quad '61...a setup that is notorious for running too rich in most cases
I still say this needs attention before you run off optimizing advance curves..
Last edited by Frankie the Fink; 04-26-2016 at 04:03 PM.
As Mike mentioned you have good compression, far more than you need to avoid a miss at idle, at least in this cylinder you tested.
Your idle vacuum of 18.5 also indicates good compression. Vac at idle falls off when you have low compression or a burned valve, worn rings etc.
If the vac gauge reading is bouncing up and down at idle it usually means at least one leaking valve in the engine.
Any leak down test would involve testing one cylinder at a time and each cylinder would need to be rotated to top dead center on the compression stroke.
If not at TDC compression stroke you will blow air out the exhaust or Intake and never learn anything.
Study your eight removed plugs, they should be kept in order by cylinder. You can learn a lot about what cylinders have been working well and which are not by studying your old plugs.
EDIT: I guess I was typing my note as the pictures in order of your plugs were posted. They are dark and certainly indicate you need some carb work.
Last edited by Westlotorn; 04-26-2016 at 09:47 PM.
Forget the valve seals for now and fix the carburetor. Those plugs are very crappy looking.
I do hope I show myself to be at least "teachable." I'm going to button up the valve covers at least for now and sort out the rich condition. I will go on and install the vacuum advance and new ignition parts.
I've got a "working man's" willingness to work on my carb, I have had another carter on a 340 mopar, a q-jet on my 69 Corvette, and a couple of autolites on the big Fords. I'm sure with some reading and a good soak in my gallon of cleaner I can lick this!
I recall it is a 3721- correct. Bubba may well have metered it to fuel a Saturday V. I will have to search out how to baseline it with a selection of rods and jets it seems.
Frankie- those NGK plugs did come with your stamp of approval a way back when
I appreciate the notion my compression may be great - hopefully I've painted an accurate picture of the cranking interval that produced those two readings (emphasis on the shorter one)
If you're doing a cranking compression test, tie the carb wide open, and hook up a battery charger that will restore the battery to a top charge between cylinder tests. Also remove all the plugs, and leave them all out until all cylinders have been tested.
This will eliminate some of the variables that can lead to fluctuating or decreasing results.
Benton, your plugs are fuel-fouled, not oil-fouled. Fix your over-rich condition before doing anything else. Could be a high float level, etc.....but it is waaay too rich. Rich enough to wash your cylinders and wear out your engine in a hurry.....
Benton, your plugs are fuel-fouled, not oil-fouled. Fix your over-rich condition before doing anything else. Could be a high float level, etc.....but it is waaay too rich. Rich enough to wash your cylinders and wear out your engine in a hurry.....
Yes my friend. You and a couple others have pointed to this and I know the rich condition does show fouling all
Over.
SO:
Today I buttoned the valve covers back on after setting the timing to #1 ten degrees before TDC (easy with the valve cover off right?)
I put a new set of basic R45 plugs in it gapped at .035.
New vacuum advance went on (I will have the number of the old one as requested when I get home). New points- admit I set them with a feeler gauge to .019- no dwell meter yet. Sorry.
New condenser. New cap rotor and wires.
Took off my AFB- could not find a carb kit in stock today so I took a chance blowing cleaner easily through the mixture screw holes. Took off the metering rods. One seemed a little sticky. The rods were "16 199."
One thing I notice was even though I have only hand turned the engine (several dozen times in total) the last 30 hours or so, I had A huge spray of fuel at the carb inlet! I have a flaps 4657 or similar replacement pump. More on that later.
Anyway, I put the carb back on after the ignition work and tried running the car - just idling a while as I checked things and a lap of the neighborhood until it was up to temp.
Idle quality was obviously improved with new plugs and a working vacuum advance and the car seemed to respond well to the timing being pulled in -a noticeable seat of the pants kind of improvement. Not "stroker motor" but "hey, that's dandy!"
When I got home and it was warm I set the idle to 700/650. Then I tried turning the mixture screws in (I had set them baseline at 1.5 turns out, each).
Running the screws in actually added 300 rpm to the ideal- nothing we didn't know, the carb is way rich, turning the mixture lean just "helped" the problem.
Obviously I'm rebuilding it next but I needed to get the ignition and valve train buttoned up. I have previously lowered the floats a bit to help with hot start issues. I'm wondering if my fuel pump is one like I've read about where it's putting out abnormally high pressure (in the teens is what I hear sometimes). I suppose I need to get a tester for that as well.
It would seem to be at least one possible solution to this "pig-rich" situation- that my fuel pump is overcoming the needle and seat.
This is a lengthy post but I've received so much help I hate to stop now!
Last edited by ChattanoogaJSB; 04-27-2016 at 04:20 PM.
04-26-2016, 12:45 PM
