The Stovebolt Site Forums The Shop Area Engine Shop A few tune up questions

1.I have done a search about dwell for a 216 (47) A lot of talk about setting points and dwell but not what the actual dwell reading should be. What is the actual dwell reading? 2. A lot of posts say to disconnect the vacuum line to set the timing but my manual and operators guide does not mention anything about disconnecting the vacuum. What's the correct way? 3. What's the 3/4 inch knob under the distributor for? 4. How do you check the coil using a multimeter? Thanks.

1. Dwell setting.

2. The vacuum advance in the earlier years was usually a steel line with fittings at the carb or intake manifold. The year specific manual would be useful in determining if it should be disconnected for the timing setting.

3. the knob was for changing the timing based on the grade of fuel you were running. again the manual would explain this feature and the proper use of it. With todays gas you should not have to mess with it once you have the truck running good.

Thanks for the info. My manual doesn't say anything about disconnecting the vacuum so I guess it doesn't have to be done. The manual shows a picture of the distributor with the knob in view and a hold down nut on top of a pointer pointing to a scale with zero in the middle and marks on either side of it. It just says to change the octane selector without much in the way of instructions. The knob appears to free wheel in either direction.

You may be thinking about the grease lube cap.

If the dist vacuum advance does not advance at idle you don't need to disconnect it. These are hooked to ported vacuum & will not advance till the throttle is opened a little. If a dist. Is hooked to full manifold vacuum it will advance at idle & would give an incorrect reading of the initial advance. After you set the timing you can taylor it a bit with the octane selector. You can run more advance then called for because today's gas has more octane then they had back then.

You can set your points for 28-33 degrees of dwell. Lower is better for point life; the higher dwell angle will allow a potentially higher engine speed before ignition misfire begins, but for your engine, that is not a factor- the engine won't go fast enough to outrun the ignition system at 33° dwell. Set the timing after you set the points.

A general guide for dwell angle is 55% of the lobe angle: .55x60° for a 6-cyl distributor = 33°. Lobe angle = 360°/Number of lobes on the distributor cam, except for the odd-fire V-6 engine that GM used for a while- but that one is a different story.

I don't recall ever seeing a single-point, 6-cyl distributor with the OEM specification of 38-45 degrees of dwell- I think that specification is incorrect in the link provided by FriedGreenTmater. But I've been wrong before.

Harvester

you know i love this place. Battling with a misfire for a couple weeks. 46 Stylemaster that is not driven much. Changed the points about 5 years ago. Read this and thought keep it simple stupid. Dig out the dwell/points meter. Sure enough excessive resistance in the points. Complete tune-up coming!

just a thank you and hopefully Rusty figures out his issues.

You have been mis-informed, FriedGreenTmater. The knob is on a grease cup. The cup is filled with grease and the knob is turned a dab every so often to lube the distributor shaft.

OK, I must have been thinking of the old Model T or something.

FGT,

Your memory is not that bad. Early Stovebolt distributors had the Octane Selector adjustment knob just as you described. I do not know which years had that type Octane selector but I am fairly certain it was before 1941. However, as Cletis posted, Rusty is probably referring to the distributor-shaft lubrication "cup".

My dwell was too high and I didn't know how old the points were so I replaced the points and condensor,(I taught my son (it's his truck) how to do this as he had never seen points and condensor before) set the dwell at about 31 degrees, checked the timing and the truck runs quite nicely now. Had previous problems with hesitation, popping, bucking, and lack of power. Now about this grease cup. Does it pull off, screw off or...? Thanks

I thought the choke cable was broken and that the truck was running fine with no choke. It was smelling a bit rich so I took off the air cleaner to have a look and the choke was on. (The cable will pull the choke on but won't open it up when the knob is pushed back in.I have a replacement for the cable) When I manually unchoked the carb, the idle went down and I was back to the stumbling, popping and dieing. I thought I had it licked but now will have to trouble shoot. I will spray with fluid to try to find a vacuum leak and I'll check the plugs. I'm reluctant to adjust the idle screw because it was set by a mechanic in order to pass emissions testing. Is it possible that the idle mixture needs to be changed because the dwell and timing have been changed? It was running so nice before my 'discovery'. If an engine is running lean, does using the choke even things out? Any suggestions? (It's a 47 but the carb is a Chevs of the 40's rebuild from a 49)Thanks.

The 216 in my 38 Master has one of those funny looking octane timing adjusters with the big knob. It is rather large and complicated looking.

Another question: When I look for a vacuum leak, does it make a difference if the choke is opened or closed?