The distributor gear is 13 teeth so each one is 27.7 degrees. The cap has eight terminals so their spacing is 45 degrees. What happens if you start changing the indexing of #1 is that at most positions the rotor tip is far enough away from the cap terminal that the spark doesn't jump or dissipates enough energy that it won't jump the spark plug gap, and you get misfires. Guys who don't index the wires IAW the shop manual I call bubba. As I've previously said I've been bailing guys out of these screwed up distributor assembly and installation screwups for 60 f...ing years!

Did you find an read the two threads I recommended? I know what I'm doing!

There is another part number in my tuning seminar (search threads starting by me) that has a shim kit from another vendor in addition to Moroso.

I have grown to dislike sitting in front of a screen and banging on a keyboard for somewhat complex subjects, which this is. I would prefer continuing on the phone, but I understand you are in Belgium and international calls are expensive, but if you can give me a call, USA pacific time

310
372
5527

In the meantime can everyone else just lay back, observe, and LEARN?

BTW, Lars and I are on the same page,

Duke

 

Hello,

I had not enough time today to complete all the work today but got pretty close:-)

• Removed the distributor and checked the dimple compared to the rotor - they are aligned, assuming that the dimple on the picture is the right one
• Measured the shaft end play (see picture) and measured .060" (1.5 millimeter) - I found the info back in the articles regarding the available kits.
• The shop manual mentions to install the distributor in a "v"-block and measure, but so far I've not found any info an what exactly needs to be measured.
• Placed the timing mark on 10 degrees BTDC on the power stroke of number 1 cylinder
• Installed the distributor using the 'walk the distributor' method. Works pretty well but takes some practice:-)

Challenge I have now is that with the rotor placed towards the number #1 cap tower I don't have enough room between the coil and the manifold (the B28 can is larger than the previous can) to follow the ohm-meter procedure as described in Lars' document. The can hits the coil before the point are opening. Only when the can is against the coil and I nudge the centrifugal advance the point will open but I'm currently stuck at this point. Moving the rotor to the 'before' or 'after' position doesn't work as the jump is large.

I ran out of time but checking here whether it's fine if I start the same process but now at 8 or 6 degrees BTDC? This should probably give enough room between the can and the coil to complete the ohm-meter setting.

See also the picture where on the base plate of the distributor there is a mark, which may be by coincidence, is in the same line as the rotor and my mark on the can (to indicate the number 1 position wire cap tower).

Will continue to work on it over the weekend and will report back.

Thanks for the telephone number Duke and will take the offer if it doesn't work out.

Ides

 

These two blades combined to measure the shaft play

 

Hello,

quick question: when ordering the shim kit is it advised to order new bushings and other washers to blueprint the distributor?

Thanks,

Ides

 

 

Thanks Duke.

With reference to my posting #42, am I in the situation where the camshaft gear is not indexed according to the factory spec and will require the dimple to be rotated 180 degrees in respect to the rotor?

See also https://www.corvetteforum.com/forums...post1603428190

I went already a few times through the distributor blueprint. Posted it here to keep the info together: https://www.corvetteforum.com/forums...-overhaul.html

Thanks and enjoy the weekend,

Ides

 

Did you reindex the wires on the cap to be IAW the shop manual?

Some afternarket cams need to have the dimple pointing opposite the rotor tip, so if you have the wires properly indexed you may need to rotate the gear 180 degrees.

Duke

 

Hello Duke,

I tried most of the settings on the BTDC (between 12 degrees and 6 degrees) but none of them result in a satisfactory position of the distributor versus the rotor and the possibility to fine tune as there is simply not enough space between the coil and the manifold to get it right. Or I'm at +/-12 BTDC and just a few millimeters between the can and the coil or I'm at close to 0 TBDC and hitting the manifold with the can.

Are we talking here about a really bad valve cam or a valve cam which is good but not indexed the right way??

What is the story about the alignment of the dimple on the distributor? It's not mentioned in the shop manual but the threads are full of it that it should be aligned with the rotor. How many timing degrees are we talking about when the dimple is rotated 180 degrees WRT the rotor?

The shaft shims are ordered and while at it I'll rotate the dimple 180 degrees. So far I have not indexed the cap tower wires as I cannot get to the right timing. The car is down. I start to understand why the previous 'whatever' changed the index of the wires as the current setting was the one where he/she could get it (almost) right.

Thanks again for staying with me. I received more tips/expert knowledge (and motivation - important) in the last 3 weeks from this community than in the last 30 years tinkering with mostly single cylinder 2-stroke and 4-stroke dirt bike engines.

I'm confident that we'll bring it to the right end. It just needs time to get stuff through customs into Europe:-)

Thanks,

Ides

 

The first thing you HAVE TO DO is index the wires on the cap per the shop manual. Nothing will ever work properly if the wires are not indexed per the shop manual, PERIOD!!!

Have you disassembled the distributor for inspection and cleaning? Now is the time to do it while it is out.

If the shaft has no or barely perceptible side play, then the housing bushings are okay.

The procedure to disassemble/assemble the distributor is in the '63 shop manual, along with an an exploded parts view, however, as you found there is nothing about the dimple. I found out about the dimple in 1965 when I was 19 years old, myself, because the dealer and small block "experts" were clueless, and I've been fixing guys' screwed up distributor assembly and installations ever since, the last time being a few months ago on the '65 L-78 that I documented in a thread I referred you to.

There is a note about dimple indexing in the distributor assembly drawings, but AFAIK there is NOTHING in any service literature about it. The gear has 13 teeth so depending on how the dimple is indexed affects the radial position of the housing by about 14 degrees, which is why the VAC hits the manifold or coil bracket before you get sufficient initial timing.

So one or two steps at a time. FIRST GET THE PLUG WIRES PROPERLY INDEXED ON THE CAP.

Then do the overhaul. Use dental curettes to remove the tiny wavy c-clip that retains the breaker plate (see the exploded parts view in the shop manual) to the dist. housing. Be sure to carefully inspect the breaker plate wire for broken stands and secure attachment to the breaker plate. Use the dental curette to carefully remove the upper bushing grease well seal and reuse it.

Us a high quality full synthetic grease for the tach drive gears and upper bushing grease well.

I'm on the west coast, USA, Pacific Daylight Time. I usually look at the forum between about 5 and 7 AM my time and I'll try to look at it again every day in the afternoon. I figure you're about 8 or 9 hours ahead of me.

Duke

 

I am not reading all of this, but make sure you have a dial back timing light. You want to ensure that distributor is doing its thing (weights and springs) at the right rpms.

 

Hello,

still waiting for the shaft shims to be delivered but I went already ahead by removing the distributor and mounting the gear (dimple) 180 degrees from its original position. Re-indexed the HT-wires on the cap according to the shop manual and did the initial timing using an ohm-meter. This time there was enough space between the manifold and the coil for the distributor to move.

The engine fired-up easily but noticed backfires through the carburetor indicating timing is not optimal yet. Ran out of time today to get the timing light on it and further investigate but will get back to it tomorrow.

Thanks,

Ides

 

Verify that the choke system is working properly. It should completely close on a cold engine when you push the throttle to the floor to give the venturis a pump shot. Upon firing up the choke valve should partially open (choke vacuum break) and initial fast idle should be about 1500. The service manual has all the carb adjustment data.

Duke

 

Hello,

I had the time today to hook up the timing light and it was clear immediately that the static TBDC timing was way off causing the backfires through the carb. Only when getting the engine starting up and revving it up to +1500 RPM provided a stable regime ( no wonder as the vacuum can is a full advance at that time). Everything below that RPM resulted in carb backfires and engine stalls.

The timing light showed that even when the static timing was done at 10 BTDC it was approximately at 8 ATDC. Maxing out the travel of the can against the manifold brought the static timing (can detached and carb vacuum plugged) to 2 - 4 degrees ATDC. Problem is that when I move the rotor with one more tooth clockwise it won't work either although the dimple was rotated 180 degrees.Circumference distributor: +/-304.7 mm

1 Degree = 304.7mm/360 = +/-0.84mm

Between manifold and coil with the B28-can there is +/-10mm travel (measured on the distributor circumference) = 10mm/0.84mm= +/-11.9 degrees max change.
Distri has 13 teeth giving 27.7 degrees per tooth change.
Moving distri one step clockwise will yield 27.7 - 3 degrees = 24.7 degrees but with 11.9 degrees max change on the distri this would still give 12.8 degrees advance which is too much and won't help in setting the timing.

Question is: how come that when the static timing is set at 10 BTDC, the timing light shows a discrepancy of many timing degrees moving towards ATDC? I don't believe the balancer is off as the timing mark (at the bottom of the timing plate) lines up very well with the TDC of the #1 cylinder at the compression stroke.

The dwell angle is at 28 degrees.

Is it the rotor which is not inline with the cap? The distri-cam not in line with to rotor? Points go open at the right time but rotor or cap or a few degrees offset? The distributor plate is not what it is supposed to be? This would really be strange....

I'll move the rotor/distri with one more step clockwise and will get back to you all. Numbers will need to add up at the end. This is not fuzzy logic going on:-)

Thanks,

Ides

 

I recall that after you properly indexed the wires you installed the distributor, but I have no idea how you did that. I've written this countless times, but here it it again.

1. set the balancer notch at 10 on the timing tab.

2. hold the distributor housing above the hole with the VAC about 30 degrees toward the passenger side.

3. Position the rotor about 20 degrees to the right of engine centerline.

4. Rotate the bottom of the distributor about 90 degrees up so it is horizontal and note the radial position of the flat machined at the bottom of the shaft.

5. Place the dist. asside and look at the slot on the oil pump drive shaft. Use a paint mixing stick or similar tool to align it so the shaft flat will slide into it as the distributor is installed.

6. Place the dist. above the hole with the rotor pointing straight ahead.
'
7. Drop it down and as the gears engage the rotor will rotate CW.

8. If it doesn't seat you need to tweak the oil pump drive shaft.

The above procedure takes some practice to get good at, so be patient.

9. Once the dist. fully seats on the manifold rotate the housing CW to the limit and then rotate CCW while observing the breaker points. The instant they open will be 10 degrees initial. This is called static timing the engine. If you have never done it before do it a few times to get a feel for it. You can also use an ohmmeter.

Once set slightly snug the dist tie down bolt, but only enough so you can still rotate the housing by hand.

Start engine and set intial timing (VAC hose removed and plugged) once idle speed is BELOW the start point of centrifugal or rev to above the point of max centrifugal and set as high in the range of 36-40 as the engine will tolerate without detonation.

Connect VAC hose and test drive.

Duke

 

Hello and good morning Duke,

As I couldn't make that much from my own findings after rotating the gear dimple (see #53) I used that data to come to the following conclusion:

• After rotating the gear 180 degrees (opposite rotor position) and using the above procedure (see #54), the vacuum can hit the manifold at 2-4 degrees ATDC (without the vacuum connected)
• As rotating the dimple 180 degrees provides 14 degrees timing difference and with max travel of 12 degrees timing of the can between the coil and the manifold, rotating the dimple once again 180 degrees should give me enough advance with the rotor 14 degrees advanced in CW direction.
• Now the timing is 38 degrees advance at +/-3000 RPM with the vacuum can disconnected, Moroso silver springs on the centrifugal advance, static timing at idle is 9 degrees advance at 850 RPM and the dwell angle is 29 degrees. Vacuum can is B28. Spark wiring index is now according to the '63 shop manual

Happy that this work is done now and thanks for hanging in there with tips and advise.

I'm still waiting for the shims to be delivered so the end play of the shaft can be set to the shop manual value. While at it I'll replace some of the distributor parts too.

Thanks again,

Ides

 

 

Road test will be for a bit later as I have an issue with the parking brake and the wheels need to get off.

Thanks,

Ides

 

Ides:

When you static time an engine with a points distributor, there are TWO places for each cylinder where the points change position (open - close)........either side of the distributor cam high point. You need to make sure that you are on the correct OPENING side for that cylinder and not on the CLOSING side. If you get this wrong, you will get the results that you obtained. So be careful and check rotor rotation and get on the correct side of the distributor cam high point.

I have used static timing for both cars and motorcycles over 50 years and it works without any issues if you take your time and do it correctly. I can get within +/- 1 degree of spark advance from the correct setting using the static timing technique.

FWIW.

Larry

 

Rotating the dist. base CCW from it's CW interference point while watching for the points to open is the same as the base fixed and the shaft rotating CW.

If one explicitly follows the instructions in post 53, especially number 9, there's no way to screw it up.

Duke

 

Key points to remember about this thread. First, remember the old adage that 90 percent of fuel injection (and I'll add carburetor) problems are the ignition system. If faced with poor engine operation always check the ignition system before condemning the fuel system.

1. Make sure the #1 plug wire is indexed IAW Chevrolet service literature (C1 and C2 engines), and this is in the cap terminal immediately to the right (pass. side) of the cap window.

2. The dimple on the side of the dist. gear should be pointing in the same direction as the rotor tip. (Some aftermarket cams may require it 180 degrees opposite, and some aftermarket gears have no dimple, so trial and error.)

And if you follow the distributor installation instructions (post 54) with proper static timing (in the range of 6 to 16 degrees), the plane of the cap window should end up approximately normal to engine centerline as in the photo attached to post 56. If it's noticeably skewed either direction there's likely a problem with distributor assembly and/or installation.

Duke