The Stovebolt Site Forums The Shop Area Engine Shop Is the distributor my problem?

62, 235 always ran great. Then,……… one day, she would start and idle fine. As RPMs increased, she falls on her face. No backfire or anything like that. Acting like She’s drowning. Replaced points 2x, with two different point part numbers. Same effect. Vacuum advance does work. Condenser and 6v coil also have been replaced. Timing is at 6-BTDC and point gap is .018. Distributor is a newer aftermarket replacement that operated perfectly before this issue. It’s a Wai- DST1609. Correct for the engine. Vacuum at venture is 20” or so. At the wiper port, 50”. I can drive it as long as RPMs stay low, and no real load. I’m leaning towards distributor advance springs. Suggestions?
Thanks,
Jim

One of those chinesium distributors huh? I can’t say whether it’s “correct” or not. I have never seen one up close but I will presume it’s built similarly to the delco remy 2304 which is correct for a 62 motor. The other thing is are you using an 62 flywheel of something else, because if the weights and springs look good, the only real way to tell is to plot the advance.


So first, take the point plate off and look at the advance weights, springs. Make sure it’s all lubricated and not rusted solid. If it looks complete and is free moving, you will have to plot the advance to see what it’s doing.

For that you will need to know tdc. That is the reason I ask what flywheel you are using.

Assuming a 62 flywheel, you will need a dial back timing light and a tachometer. The specifications I can give you if you decide to tackle this. Disconnect and plug the vacuum advance. Start motor, adjust idle to factory specification, check that the timing is set at tdc on the flywheel.

Mechanical advance starts at about 300 rpm, so 0-1 degree of advance at 300 distributor rpm, which you double to get the figure at engine rpm. So 2 degrees at 600 engine rpm, 8-12 at 1400 engine rpm, 18-22 at 2700 engine rpm, and 24-28 at 3500 rpm. Bring the motor to 600 and use the dial back light to determine whether you are getting advance at 600 rpm and what that advance is. Then go up to 1400 rpm, same drill, until you have plotted out the advance, so many degrees advance at so many rpm’s.

Otherwise, you will need to take the distributor to someone with a Sun Distributor Machine and have them put it on the machine and see what it looks like.

Once you get tired of tinkering with the distributor, find the exhaust restriction and fix it.
Jerry

Mike,
The flywheel is off of my 216. I did check my TDC per one of Jerry’s prior posts, and it’s right on. I will perform your recommended advance test tomorrow.
Jerry,
That’s another good thought. Now that I think about it, I was coming home from Winchester with my daughters car and the cat got clogged. Almost the same scenario. I will check that first since it’s easier.
Thanks for your responses!
Jim

A quick check for exhaust problems is a vacuum gauge, connected to the windshield wiper port, not the distributor vacuum. If the vacuum drops to virtually nothing even with slight throttle opening, there's most likely exhaust problems. Loosen the exhaust pipe at the manifold and see if the performance improves.
Jerry
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Just because I am curious, what process did you use to find tdc for the engine?

Mike,
This way,
Take all the spark plugs out so you're not fighting compression, and turn the engine clockwise from the front by turning the fan blades. Watch the last two valve springs back by the firewall. You'll see the last valve start to open (compressing the spring), then it will begin closing again. Just as that spring reaches its full-closed position, the second spring from the back will begin to compress. At this point, #6 cylinder has just finished its exhaust stroke. The #1 cylinder will be at the top of the compression stroke, ready to fire the spark plug. Install the distributor with the rotor pointing toward the #1 plug wire and turn the distributor housing clockwise until the points are closed, then rotate the housing CCW until the points just barely open, and lock the dizzy down at that point. The spark timing will be set close enough to start the engine. Even if the flywheel happens to be installed wrong, this method works. The only possible way to have problems is if the camshaft timing is incorrect, with the timing marks for the crank and cam gears out of alignment. Once it's warmed up, minor spark timing adjustments can be made to get it running smoothly. No oil, no mess, and it works every time. Just be sure the tang at the bottom of the distributor shaft is fully seated in the oil pump drive as you install the dizzy.

If the exhaust checks out fine, I would be looking at a fuel issue. Sounds like it's starving for fuel with any load on it.

Ok, That will get you close. Not exact but close enough. Let’s see what you find when you take the distributor point plate off.

Mike,
With the help of some fellow bolter’s, we were able with your help, diagnose the issue. We used your timing advance post to find the distributor was my source of the problem. At 2500 RPM’s the advance went to 50+.
I have a original distributor for that era of engine that is being rebuilt. I will follow up when that is installed.
Thanks,
Jim

Any chance you took the point plate off? I would be curious to see what the issue was.

Yes, I did take the point plate off. From what I could see, nothing was out of place. I’m guessing that the spings are weak????? From my eyes anyway.

Springs only control the rate of advance- - - -the distance the weights travel control how much advance there can be. Every degree of advance at the distributor cam translates to two crankshaft degrees, since the camshaft and distributor turn at half crankshaft speed. 15 degrees of distributor cam rotation would translate to 30 crankshaft degrees. Most engines (even modern V8s) run best with around 36 or 37 degrees of centrifugal advance at the crankshaft, with about another 10 added when the vacuum advance is maxed out. That vacuum advance goes away almost instantly when a load is applied to the engine, such as hill climbing, passing, or pulling a trailer.
Jerry

Advance curves are printed in some of the GM heritage kit documents. In the 1960 Chevy Truck doc it has 5 degrees initial, 24 to 28 degrees centrifugal (3500 RPM) and 22 degrees vacuum.

Hmmm. Even weak springs would not give you 50 degrees all in at 2500 rpm. The 2403 distributors provide between 12-14 degrees of mechanical distributor advance, so 24-28 total at the motor. The total advance is limited by the shape of the weight and the internal mechanism itself. So it may be that the design of the distributor is bad from the get go, or any chance you forgot to disconnect the vacuum advance?

Mike,
Yes, the vacuum advance was disconnected. Also, new plugs,wires,points, basically anything to do with ignition. We even switched carburetors with one for a 261 and checked compression. Fuel pressure is also good. Engine still breaks up at higher RPMs. This weekend, I will swap out the distributor with the rebuilt one.
Jim

Check this as I had a similar running truck and was caused by the spring on the points as some now come in two pieces.I had put a set in mine thinking the other piece was for a different application and now know the extra piece is required to be assembled . Th picture is of one set with the spring assembled and another set how it came in the box .Could be easily missing from a new set .

Good point- - - -some of the higher priced point sets such as "Blue StreaK" had a copper conductor instead of relying on the spring to carry the primary current. Leaving the spring off would cause point float and stuttering at any speed much above a fast idle.
Jerry

I trouble shot a GMC 6 (same distributor) on the phone to a guy in Kansas a few years back that was missing the steel spring and depended on the brass "spring" (actually it was just there to conduct electricity) on a brand new set of points. Wouldn't run faster than 1500 RPM even in neutral. The guy had never messed with a set of points before, so he didn't know what to look for and I couldn't see the missing spring in the pictures he sent. Eventually I sent him my spare tach/dwell meter. Dwell was right on at idle, but by 800 RPM it was starting to move towards zero. Point float just like Jerry said above. By the time the engine got to 1500 RPM the dwell was around 10 degrees.

#1---------------------- Throw factory wiggly waggley in trash can
#2 --------------------- Turn off shoulder on 250 I6 HEI 3/8"
#3 --------------------- Buy hold down clamp # 91044030 from Speedway
#4 --------------------- Wire up and run AT LEAST 100k miles without touching

LOL. “Factory wiggly waggley.” I have added to my automotive lexicon today.

-I did try two different set of points. Neither came with auxiliary spring metal.
-Evan, In layman's terms, what do you mean in your #2 list? Ima guessing a new HEI distributor? Or Petronics?
- Now I'm really curious. what other than distributor issue would cause my timing to so far out at high RPM's?
Sincerly,
Dazed and confused!
AKA,Jim

Have you looked at exhaust restrictions like Jerry suggested? Based on the posts above, you appear have to decided that this is an ignition problem but it is not clear (to me) why.

Evan is suggesting putting a later model HEI distributor on. A bit of machine work on the shaft is needed to make it fit, but once you do that you can use off the shelf wear parts on it.

I'm in the process of adapting the old "wiggly" distributor housing to run the General Motors HEI reluctor and pickup coil instead of points. Modern electronics in an original-looking housing, with the module mounted on a heat sink and hidden on the firewall or under the dash, even. Best of both worlds- - - -looks original, and runs modern electronic parts available at the local FLAPS.

What about a simpler version of Coilover’s suggestion?

Speedway sells a large cap GM HEI for the 235/261 for $100-ish. Machine work is already done. Yes, it’s chinesium. But unless you’re pulling an OEM out of a wrecking yard or paying dearly for NOS on eBay…the HEI dizzy for your SBC is probably Chinesium, too.

Perhaps swap some better internals into the Speedway dizzy and have the best (or less bad) of both worlds?

(FWIW - I have no intention of trying this. I don’t much care for the look of the large cap HEI on a Stovebolt. Old wiggly and my “clap-trap” generator seems to keep doing their thing).

The most efficient way to diagnose any advance issues with the chineseium distributor is to pull it, and run it up on a distributor machine. That is where I would have gone with this after doing the timing light test. Confirm, confirm, confirm.

- Fibonachu. There is no exhaust restriction. That was tested
- JW, I like you, prefer original.
- Mike, unfortunately nobody around here has a distributor test machine ( that I know of) The distributor that was recently rebuilt to replace the Chineseium is from an older 235.

Jim

Good advice. I will add, "replace all of the female spade connectors". The alloy used in them are too soft and do not remain tight and in place. Tight connections are crucial to avoid electricity flying around to where it does not belong.

I had Cardone rebuild an original dizzy for me over 10 years ago for the Galaxie. Excellent job and it's still going strong. Only had to change the points once since it was rebuilt.

Here is one issue with using an older distributor in a later 235. Depending on the distributor, it may have a cam gear for a steel camshaft and will not be all that workable on a cast camshaft like the 62 has. Also, depending on the year, it uses a different rotor and point set, and may have a different timing curve. I have a Delco Remy book at home that lays out the curves for various series of distributors. The distributor you want to use ends in 2403. this was the part number used from 56-63, and according to my Delco book, was the designated replacement distributor, even for the early units.

Thanks Mike! I will verify all of that prior to install.
Jim