The Stovebolt Site Forums The Shop Area Engine Shop Multiple Questions!!!

Hi guys-

3 Questions...

1. Finally getting around to doing the oil change on my truck. The Shop Manual recommends 20 weight oil

http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0002.html

I've looked around to different FLAPS and the closest I can find is 20W-50. The engine has 120K on it and I don't think it's ever been rebuilt. Should I use the 20W-50?? Would it hurt to use a high detergent 30 weight in it?? I don't plan on dirving it too much once it get really cold out. Also... I have an old remote filter on it

2. I pulled the valve cover to make sure that it was getting oil to the top end, and after running the engine for less than a minute I started to see oil slowly drizzle out of the small holes on top of the rocker arms. Is this OK??? should it be coming out faster then that??

3. What is the correct Dwell reading? I've heard that if it's near 30 it OK. is that correct ?? does that correspond with the .016" points gap? When I tested it the other day it was around 42...

Sorry for the multi-part post!

Thanks guys,

1: I run 15/40 in my 38. If you want to run straight 20 try a farm store. Also look at the API rating. SM oil has been know to cause wear problems in flat tappet engines. Our local farm store carries some SL oils which still has zinc in it.
2: You're fine with the top end oiling. The feed line is small and there's no anti drain back valve so getting full rockers in a minute is pretty good.

Bryan,
SAE 20 or 30 are monograde oils (20 weight, 30 weight, etc.). They are for warm weather only applications. The 5W, 10W, 20W are referring to muti-viscosity (cold temperature) capabilities, not the actual viscosity. As it shows in the manual a 5W-30 oil will flow sufficiently at -30 degrees and still hold its viscosity (30) at 90 degrees. The actual kinematic viscosity is classified at 100 degrees C.

Depending on how cold it gets where you are, a 5W or 10W-30 or even a 10W-40 would be sufficient. A 20W-50 might be a little too high of viscosity unless most of your driving is during very hot summer days. As Tiny said, just make sure that the oil you use has sufficient ZDDP levels. Most newer oils have reduced zinc and phosphate which are needed for proper lubrication of the older engines.

I have used a 20W-50 with no apparent problems. Any of the multi-grade oils should work fine.

At present, I'm using a 15W-40.

Here is a Chevrolet Service News sent out at the end of 1954

If you drive in the winter, use the 5W-20 that my wife had to use all year in her VW Turbo.

On a 120K mile 235, no need to worry about the zinc level in the oil. You can run any oil you like. Stick with a 10W40 or 10W30 and change it every 3000 miles or once a year.

The missing zinc is hurting the newer engines with way more valve spring pressure then you have. Plus, its the modern fast ramp high energy cams that are taking a beating along with the new start up (break in) engines. Once the cam and lifters are polished from the break in or from 120K miles, there is very little chance of cam damage.
Oils from the '60 & '70 had less zinc in them then the oils today even after it was reduced. Its the cam and valves spring makers who asked for it to be added due to the extreme pressures and ramp angles. I just read this in the newest edition of Hotrod & Restoration (http://www.hotrodandrestoration.com/)

Something to think about,
A stock 1937 216 engine had 42 to 48 lbs of valve spring pressure with the valve closed and 94 to 100 lbs of pressure open. A stock 1954 235 has 52 to 58 lbs closed and 155 to 165 lbs open spring pressure.

A new set of Crower brand SBC race springs can have over 400 to 600 lbs of pressure when open!

There is a enough lead and zinc in your oil pan sludge to last your engine for life time.

Points information, (http://chevy.oldcarmanualproject.com/chevyresto/54154.htm)


Joe

Straight 30 weight will be alright as well. I run mine on straight 30 all year round, and have never had a problem with it in the winter.
Don't put too much stock in the whole "don't use SM oil" thing, either. All motor oils are required to beckwards compatible. While there have been failures recently with the reduced ZDDP levels, but most of those can be traced back to poor workmanship on the rebuild, improper break in, or mismatched valvetrain parts. I put SM grade oil in flat tappet engines all the time, have yet to see one fail.

Bryan,

Dwell for your engine typically would be 32°-35°, but 30° is alright. I don't know how the dwell angle relates to your point gap of .016"; the dwell angle/point gap relationship is a function of the contour of the distributor cam, and I don't know that anyone has published that information, mostly because no one really cares- if you set the gap properly, the dwell will be satisfactory, and vice-versa. But a 6-cyl distributor at .016-.019 point gap will get you in the range of 30-35 degrees of dwell. Your dwell of 42° is a little high, indicating that the point gap is a little close. A rule of thumb for dwell is 55% of the lobe angle (which is the angle between cam lobe apexes). For a 6-cyl distributor, the lobe angle is 60°; 55% of that is 33°. Allowing ± 2-3 degrees of dwell gives a range of 30-36 degrees. Some manufacturers go up to 38° dwell (6-cyl), but the reality of it is for low-speed engines, even 25-28 degrees is sufficient for reliable ignition system operation. What is important is that you set the timing after any point adjustment: a degree of dwell change gives a degree of timing change: increasing dwell retards timing; reducing dwell advances timing.

The risk with high dwell angle is that the point gap will be lower that optimum, which can lead to excessive arcing and reduced life. The points might also run hotter because of the longer duration of current flow. For longer point life, lower dwell is better. And set the timing after the dwell adjustment.

Harvester

Thanks guys,

I figured these old engines wouldn't be too picky. I'll probably end up running a high detergent 10W-30.

Yesterday I attempted to adjust the point gap and get it timed properly. I shouldn't have messed with it since it was running OK. Before I messed with it, it was at about 42 degrees of dwell. and the point gap was probably around .022"

After dropping the gap down to the proper .016" and timing it so that the steel ball is in line with the pointer in the clutch housing, it would barely stay running, it would miss and generally idle very low... The dwell stayed roughly the same during this process aroung 40ish.

So...trying to get the dwell down to aroung 30 I increased the point gap up to .020 so that it was running at about 35 degrees of dwelland re-timed... I still don't think it was running as well as it was running before.. What did I do wrong???

The rotor and distributor points looked a little burnt/corroded, could that make the point gap/dwell figures not coinscide??

I thought that a point gap of .016 was supposed to coinscide with a dwell of about 30 degrees...

I think harvester submitted his comments as I was still writing my last post.

Thanks Harvester....

Which do you think should hold precedence? point gap or dwell??

let me explain...should I make the dwell 30-35 deg. and forget about what it was gapped it at in order to get there, or just the reverse...


And does someone have a picture of points/rotor/distributer cap that are burnt far enough that they need to be replaced... This is my frist time doing this process

Thanks!!

I think your assumption of .016" gap and 30° dwell probably is pretty close, although probably you would find a little higher dwell. Yes, rough/pitted points will cause a wider gap when set with a feeler gauge, and will result in a higher dwell angle.

I don't have any pictures of good/bad parts as you asked about, but maybe I can find some. Absent pictures, look for the following:

Irregular or black, fuzzy lines on any bakelite/alkyd/plastic parts are a bad sign. Usually those indicate cracks, but they may be surface carbon-tracking. Replace the part.

Rotor: no cracks or carbon tracks in/on the bakelite/alkyd/plastic part; center contact should be smooth and shiney; rotor should be tight/snug on the distributor shaft; "finger" tip may have some roughness and carbon, but if it is not loose, roughness is not a problem. Make sure the bottom of the rotor below the rivet is not discolored. Discoloration indicates insulation failure.

Distributor cap: same as the rotor; also, the center carbon button should be smooth and shiney- a little flatening is not a problem if the carbon is not worn down to the metal sleeve. If the button is dull black and 'fuzzy' looking, the rotor contact has been arcing and the cap and rotor both must be replaced. The wire terminal sockets should be clean and tight, but corrosion can be removed. Don't try to remove roughness from the rotor end of the wire terminal- the roughness is caused by the arc there when the spark plug fires. The roughness will only return after a while, so save your time and energy on that one.

Points: the contact surfaces should be smooth, preferably shiney, but used points will have a frosty look. A bluish color, like hot metal is just that- the points have been overheated, maybe high dwell, but also high ignition current. Pitting and metal transfer indicates a condensor matter, and/or maybe incorrect dwell, depending on which way the metal transfer goes. Look at the spring- should be shiney- any discoloration indicates high ignition current or high dwell combined with extended low-speed engine operation- idling a lot of the time. Usually, discoloration of the spring is the result of high coil current. That can be caused by shorted primary windings or high primary voltage- voltage regulator setting, or no ballast resistor or shorted coil if you have a 12-volt system.

Hope this helps.

Harvester

very old, very original 6-volt system...just to clarify.

the cap terminal sockets look like there has been material steadily removed from it through the arcing process...not black and burnt, but slighty white/powdery.

very much the same goes for the "finger" on the rotor, except I think (after looking at replacement rotors on NAPA's website) that material has been transferred from the cap terminals ONTO the rotor....can that be right???

didn't get a good enough look at the surfaces of the points...

I think I might need a new condenser... Is there supposed to be a condensor on the coil AND in the distributor??

What does the octane selector do? Slightly advance and retard the timing??


I'll try to put up pics if I can

Bryan,

The powdery residue is oxidation. You probably can clean it off. Are those contacts aluminum? If so, you can probably clean them satisfactorily, but eventually the cap will have to be replaced.

What you are seeing on the rotor tip is probably just the effect of the spark jumping the gap- the current flow is from the rotor tip to the cap, in case you are curious. Those contacts are not known for metal transfer, but if there is, I would suspect build-up on the cap terminals, rather than on the rotor, because the rotor tip is negative with respect to ground during the spark, although only about 1000-1500 volts negative during the spark. But that idea of metal transfer is only a guess.

If there is a condensor on the coil, it is for radio noise supression if the truck has/had a radio. It should be connected to the positive terminal. The radio condensor is not the same capacity as the ignition condensor.

The octane selector permits easy adjustment to timing, advance or retard, according to the scale on the bracket and a mark on the distributor pad. The original purpose was to permit quick timing adjustment to accomodate variation in fuel octane rating, which varied quite a bit in past years (distant past years). You shouldn't need to use that adjustment after setting the timing properly, but you can change it if you like, to see what happens. Probably, you won't notice much change, except detonation/spark knock if you go too far advanced.

From your earlier post, use the dwell setting as your reference, rather than trying to get the points precisely set with a feeler gauge. And don't worry about being off a couple of degrees of dwell. Lower dwell is better than higher dwell anyway, unless you are planning to race the truck. But set the timing after all the point adjustments.

With your distributor, you should not see any dwell change beyond a degree or two when you increase engine speed from idle. Lower is better, no change is ideal.

Harvester

Harvester-

Thanks for all your help, I'm still trying to learn how all this old technology works.

I can't remember how much the dwell needle moved when I revved it up, but it may have been more than "a few degrees"... How do you prevent that from happening??

I think I'm going to replace many of the system components...Cap, Rotor, Points, Condenser, Plug wires, and Plugs.

I'm slowly eliminating my truck's excuses for not running correctly!!

Bryan,

With your distributor, dwell variation with engine speed is most likely caused by shaft bushing wear inside the distributor housing. The bushings can be replaced if you can find them, and can find someone to install them. An electrical rebuilder maybe can help, and I think others have posted information here on that topic.

A couple of degrees of dwell change as you raise the engine speed to 1500-1800 RPM is not of concern, but if you get more than 3 or 4 degrees change, you should look into rebuilding the distributor- bushings and drive gear. Four degrees change for your distributor is getting pretty high, bearing in mind that a degree of dwell change results in a degree of spark timing change. That amount of timing change can cause light throttle hesitation, roughness, poor throttle response, and detonation, depending on how much the timing changes and whether it advances or retards.

Before you get too far involved with dwell change, disconnect the vacuum advance and see if the change (if any) is consistant with, and without the vacuum advance movement- it should be, since your breaker plate does not move with vacuum advance; the whole distributor turns. Also, make sure your vacuum advance bracket is tight on the engine, the clamp on the distributor is tight and the whole mechanism is not worn and loose. The vacuum advance mechanism should not affect dwell change in your distributor, but check those items anyway. Some distributors have a natural dwell change when the vacuum advance operates, but yours does not.

A couple of points not related to dwell change, but may be helpful:

When the engine is stopped, you should be able to turn the rotor a small distance, a quarter inch or a little more, against spring tension. It should return to the original position when you release it. That movement gives important information:

1)The direction of movement indicates the direction of shaft rotation when the engine is running, which normally you don't need to know, but you should know.

2)The movement against spring tension tells you that the mechanical advance springs are functioning, and the weights are moving. Or at least one of the springs is functioning. If you don't feel movement and spring tension, either the mechanism is stuck, or the springs are weak or broken. The breaker cam should not be loose and floppy when it moves.

Hope this helps.

Harvester

I've turned the dist. by hand and could feel good spring tension, and it sprung back into position fairly quickly....

I have heard to disconnect the vacuum line from the dist, and turn it to it's limit, then place your finger over the hole on the advance mechanism, and release the dist. the dist shouldn't rebound, or else you have a bad advance mechanism.

I have been having a problem with the engine dying out when I punched the throttle. I had attributed it to the accelerator pump, but I suppose it might be the distributor... Most likely a little of A and a little of B

This is more involved than I thought!!!

Bryan,

My first thought on your hesitation is that the accelerator pump is at fault. You should see a good stream of gasoline from the discharge jet when you work the throttle with the engine stopped. If you see only a dribble or a delayed discharge, the pump is not working as it should. You should see the pump discharge for nearly the full throttle travel. Pump check valves are often the cause of that trouble. Vacuum leaks are a possibility, also, but vacuum advance and distributor causes are low on the list.

Harvester