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Curious if these photos tell you anything about my car.

matmire

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I had the carbs off the other day, and thought I'd take some photos inside the inlet ports while they were exposed. I'm not really looking for problems or anything. I just thought I'd see if everything looks ok to the more experienced folks here on the forum, since I don't always know what to look for. :eek:

https://i.imgur.com/nzqAJ66.jpg
https://i.imgur.com/16kRMQM.jpg
 

Rut

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Looks like a normal head to me...just a little carbon build up. More experienced people might see something I don't.
Rut
 
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matmire

matmire

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I'm not really trying to diagnose any problem. Just throwing up the photos from a curiosity stand point. It is a little more glisteny in there than I expected. Does oil ever enter the inlet from around the valve stems? Or maybe that comes from the crankcase ventilation. Sorry if this is stupid, I'm learning.
 
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matmire

matmire

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the engine does run, and I don't get blue smoke. I do get a fair amount of carbon soot out the tail on cold starts, but I attributed that to a rich running weber (I'm converting back to SUs soon, hence the removed carb). I did a compression test a while back, and though I didn't have large variances the numbers seemed a bit low to me (about 102-109 if I remember right. don't have the numbers in front of me). Maybe that's normal for this motor. It is the 12v/587z low compression spec 1275.

I was planning on doing a valve adjustment and compression test this weekend. Maybe I should pick up a leak-down tester too.
 

Boink

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Are the plugs oily?
 
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matmire

matmire

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I'll check the plugs again this weekend. Last time I checked them, some months ago, they were all fine. Maybe there's just enough oil coming through the valve guides to give it a nice sheen, but not enough to get pulled into the combustion chamber.

Currently the oil separator is connected to the sidedraft weber via a hose piped into the front of the air cleaner. Maybe there's some fine oil mist coming in through there?
 

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It's surprising, too, that the condition of the engine shut-off process itself can have a significant effect on plugs, valve appearances, etc. Sometimes looks don't mean a lot. I'd be most curious about compression, timing, and any oil-consumption. I've also used the Gunason Color-tune for a good sense of combustion.
Oil from the separator shouldn't add up to much (or if it does you'll really notice it).
My, admitted weak, take. :wink-new:
 

zabond

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with that low comps & wet black inlet ports it could be inlet valves not seating properly and or worn rings, valve guides, check your valve clearances then do a comp test, first do a dry test then add a squirt of oil in each cyl then do the test again, if you comps rise you have worn rings if the same valves need grinding
 

SaxMan

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Those compression numbers seem low for a 1275. I'm running around 140 - 155 psi on a '69 Sprite IV with worn rings. I'm blowing oil out the tailpipe. Between the leaking main seal and pan gasket as well as the burning oil blowing past the rings, I'm putting in a quart every 250 miles. I believe normal compression is up around 165 psi

As I learned when I was diagnosing a blown head gasket, running a leakdown test will give you a much better idea of the condition of your rings and valve seats than a standard compression test. My #1 and #4 cylinders are on the green / yellow border of moderate loss, the #2 & #3 cylinders are well into the yellow of moderate loss. All engines will show some degree of loss during leakdown testing, but it's how much loss which is a good indicator of your engine's condition. The leakdown and compression tests together will give you a pretty solid picture of what is going on.
 
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matmire

matmire

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Ok, I've got my first batch of results... I haven't done the leak-down test yet.

-all the valve/rocker clearances were too small, by about 1-3 thousandths. I opened them all up to .012

-took some pics of the rocker area for the heck of it, see them here: https://imgur.com/RIRaA

-Pulled the plugs, which you can see here: https://imgur.com/pg2EB

-also stuck a USB endoscope into each cylinder for the heck of it, watch that chaotic video here: https://youtu.be/oEnXq_HC1yI?t=49s

-did a dry followed by a wet compression test, with the engine cold.
Dry: 152, 149, 145, 144
wet: 170, 166, 165, 158

Got much better numbers this time around. I figure the low numbers I had before came from one of two things: The valve clearances weren't allowing the valves to properly seat, OR the fact that I did the old test with a crappy Harbor Freight tester that could have been giving me bad readings.


Thoughts so far?
 
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matmire

matmire

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question... is it necessary to re-adjust the ignition timing after a valve adjustment? since I opened up my valve lash a little, is that change in duration going to affect ignition timing or is proper ignition timing more tied to piston position?
 
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Ok, I've got my first batch of results... I haven't done the leak-down test yet.

-all the valve/rocker clearances were too small, by about 1-3 thousandths. I opened them all up to .012

-took some pics of the rocker area for the heck of it, see them here: https://imgur.com/RIRaA

-Pulled the plugs, which you can see here: https://imgur.com/pg2EB

-also stuck a USB endoscope into each cylinder for the heck of it, watch that chaotic video here: https://youtu.be/oEnXq_HC1yI?t=49s

-did a dry followed by a wet compression test, with the engine cold.
Dry: 152, 149, 145, 144
wet: 170, 166, 165, 158

Got much better numbers this time around. I figure the low numbers I had before came from one of two things: The valve clearances weren't allowing the valves to properly seat, OR the fact that I did the old test with a crappy Harbor Freight tester that could have been giving me bad readings.


Thoughts so far?

Rings are shot. Of course, depends on how much oil you put into the bores. Squirt or two max. Knew a guy once who put a WHOLE lot into a decent engine and got a BIG jump on wet...but that's because he half filled the cylinders.
Oil temporarily seals worn rings to bore.
Next, there is no place I have ever found that will calibrate your compression tester.
One thing you can fairly well count on (excluding bad Schrader valves) is consistency. Different gauge will give you different numerical, but the spread should be that same (oh, like 5% across the board, or whatever it is).
As far as re-adjusting timing...well, usually when you do maintenance, like valve lash, you check point dwell and timing...and carb adjustment.
As your timing chain wears and slacks, the camshaft slightly changes position to crank, which changes timing slightly.

It's all part of the procedure. Valves first, then dwell, then timing, last carbs (or that's how I do it...because you set the cabs up, then adjust valves and timing, you'll be back to the carbs anyway when you're done).
 
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matmire

matmire

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really? Everything I've read says a 10% or so rise from dry test to wet test is acceptable. I used 3 shots from an oil can. Also, I did the tests with the engine cold, so wouldn't the difference between wet and dry test be exaggerated by the lack of heat expansion of the rings?


...and just to clarify. The old test was done with the harbor freight tester (the one that gave me results around 105). I bought a new one to do the new tests because I read so many bad reviews of the HF model.
 
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Depending on the oiler, in 40+ years of hands on, three pumps is too much. The more oil, the less available area, and you're readings will come up.
It's 10% variation from bore to bore. NOT wet/dry. If is was, you failed that anyway (#1, 152/170)
Never seen any exaggeration hot/cold on wet/dry.
You expect it to get better when warm?
Try it and see.
And this time, one to 1-1/2 pumps, all plugs out, spin the engine with starting motor a couple of seconds, to distribute the sealing oil, and do the test wet.
 
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matmire

matmire

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I'll try the test again warm and with less oil.

I really appreciate your input, and I don't want to be difficult... but I guess I am going to be :smile: Respectfully difficult, I hope.

I am aware that you want less than 10% variation between cylinders. But also, with a quick google search I found dozens of articles that say wet testing raising the reading 10% (some say 15%) is normal. Even when you read about leak-down testing, they say some ring leakage is expected. The oil filling in just the ring gaps would account for some rise in compression pressure, wouldn't it? And everyone seems to say rings seal better as the engine warms up.

the car doesn't use much oil to speak of (probably more from drips onto the garage floor than out the exhaust, anyway). Has no blue smoke. Plugs look fine to my eyes, not oily at least. The manual states compression pressure should be 120psi and I'm getting 144-152 (and it's the lower 8:1 compression engine). The only symptom of anything out of sorts is somewhat oily inlet ports. You'd think if enough oil was leaking through the rings to enter the intlets, I'd be getting LOTS of blue smoke, no? To me, that all sounds like leaky valve guides or seals. Or too much crankcase vacuum through the weber, sucking in oil mist.
 
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Oily inlet ports can only be attributed to rigs if:
The rings are shot, and the inlet valves are in dire need of facing.
Oil in the inlet ports is generally attributed to worn out valve guides.
If I had a dollar for every LBC guide I have had to replace, and rings I have had to replace, I would be living quite comfortably now.
You can read anything on the algore.
There will be a small increase in compression, as, yes, there is a small amount of wear that will seal with oil.
I would be quite unhappy with a 10% variance, and would be yanking the engine for work at 15%.
Now....if your crankcase pressure is far too high (worn rings or broken), and the inlet valve guides are shot, you could conceivably be blowing more oil into the inlet port than would normally just drip with a worn condition.
The readings you have given for wet/dry is not good.
Your #3 reading of 145/165 is close enough to 15% variation that given the worst case da google gives you, it's shot. (166.75)
If you do a cylinder head refurbishment on a worn out engine, you will have lower end issues....smoke, for one.
Right now you are leaking, due to miles and wear, out of both ends, valve faces and rings. Seal one up, all the pressure now goes to the lower end and you will have issues.
But, if you know that in advance, and are prepared for it, go ahead, yank the head, have the guides replaced and valves faced...and look carefully for scoring and ridge in the cylinder bores, and if that looks okay (you can feel .002") put it together and run it.
If you take shortcuts, you will not be happy, and folks will generally know with the WWII Destroyer Smoke Screen.
 
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matmire

matmire

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.
If I had a dollar for every LBC guide I have had to replace, and rings I have had to replace, I would be living quite comfortably now.

I'll happily give you a $1 each to replace my guides and rings! Shoot... I'll give you $2 each!! :friendly_wink: Sorry, I couldn't resist
 
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