Ignition Issues, Crab distributor

[BIG KEV]

Took the advance apart. This looks a bit rough but I don’t have a lot to go off of on experience on these advances. Shaft kinda binds a smidge going in and out of the weight plate.

[petehoovie]

Originally Posted by BIG KEV

Took the advance apart. This looks a bit rough but I don’t have a lot to go off of on experience on these advances. Shaft kinda binds a smidge going in and out of the weight plate.

[ford38v8]

Big Kev, I think, after reading your story, that you may have multiple issues, but one main issue I am having is to understand exactly what you are working with. In various places in your narrative, you speak of 12 volts, 4 barrel carbs, multiple carbs, single carbs, internally resisted coils, vaccuum brake distributor, brand new carburetors, hopped up 59A, who know what incompatible parts. Tell us exactly what you have to give us a fighting chance at helping you.

[BIG KEV]

Originally Posted by ford38v8

Big Kev, I think, after reading your story, that you may have multiple issues, but one main issue I am having is to understand exactly what you are working with. In various places in your narrative, you speak of 12 volts, 4 barrel carbs, multiple carbs, single carbs, internally resisted coils, vaccuum brake distributor, brand new carburetors, hopped up 59A, who know what incompatible parts. Tell us exactly what you have to give us a fighting chance at helping you.

Thanks for the reply. Here is the list...

59ab, factory relieved block bored .125 over bore.
Isky 1007b camshaft with real Johnson adjustable lifters.
Aluminum timing gear
Late model 1 piece valve guides with chevy style valves.
Offenhauser heads .400 clearance for valves.
Offenhauser 2x2 intake setback style for generator clearance.
Normally runs two large logo Stromberg 97s on top, 46 jets inside both carbs-4 hole style emulsion tubes.
5/16 copper fuel line supplied to both carbs off the fuel pump.
New fuel pump rod, measured out 100% to spec. single gasket on the fuel pump stand as well. Verified with gauge I am 2.5 psi running fuel pressure with both pumps on as well as the mechanical pump only running.
Fuel is rebuilt factory pump pulling through a bosh pump on the frame rail as a fail safe, prime pump, pulls through just fine. Barely use it unless super hot outside or priming for cold start.
Both carbs sit on phenolic spacers 1/4" tall.
Crab Distributor, vacuum brake hooked up to manifold vacuum. Points gapped to .014 on both.
Dwell is 34 degrees on the tester.
Bosch 00012 12v internally regulated coil no ballast resistors at all now.
Spark plugs are NGK b7hs
Nobel speed solid core plug wires, Rajo ends on the plug side.
12v Superstart battery, 4 gauge battery cables, ground to transmission, and jumper ground from there to the chassis as well. All terminals are clean as the day they were new. All grounds cleaned with Scotchbrite for 0.0 ohm of resistance from battery to the engine block, trans and chassis.
Powermaster gear reduction starter.
Powermaster Power gen alternator.
Power from the battery comes inside the car 10 gauge wire to a 4 fuse block, glass fuses, from there goes to each respective load. The ignition switch on the column is used for the ignition, so the path from the fuse block goes 10 gauge to the switch, out of switch 16 gauge to the coil and 16 gauge to the gauges in the car.
The other loads are electric fuel pump and cowl lights on circuit, brake light switch on its own circuit and headlights on the last.


The only recent change is the removal of the Stromberg 97s and installation of a single Edelbrock 94 carburetor. All are 2 barrel units. When running on only 1 carb I have a 1/2" thick plate to bolt in place of the carb that is removed.

https://youtu.be/va8kw1Y0si4?si=ZmktifaYq0mDgueY

[35fordtn]

How was your 34 degrees of dwell determined? KRW or sun machine?

Also Check the spring tension on the terminal stud on the distributor (should be stiff). be sure the tip of it and the brass contact on the breaker plate are clean. When it dies are the plugs wet? If not, does any starting fluid down the carb make it start? Are you running Dennis Carpenter brand points? if so replace them. Is your fuel cap or sending unit depending on your tank set up venting properly? (This one kicked my butt one time)

[scooder]

Sponsored Links (Register now to hide all advertisements)

With high compression and that 1007B cam your engine will like more initial timing than a stock engine.
Also what rpm are you idling at? Your combination will require a higher idle to stop it cutting out under braking or cornering.
I know it's nice to hear the slow lope at idle, but with a track cam you need a bit more idle speed.
This is from experience.
Martin.

[Terry,OH]

Thought you were using NGK B8HS10 ?? If so they come from the factory with 0.040" gap which is a bit too wide suggest 28 to 32.

[ford38v8]

Kev, I'm no expert at these issues, not by a long shot, but I do thank you for the detailed list of what you have to work with that the real experts can go with. I have, however, picked up on a couple things that may be worth investigating:
1 - you mentioned the vacuum brake and piston, but had nothing to say about it's leather seal atop that piston and it's rub on the advance disc. That seal does double duty, one to seal the vaccum, and two to dampen the disc. Back in the day with low octane fuel, adjustment of that damper was critical to prevent ping, but with today's fuel, its main purpose is to prevent wild bouncing of the advance disc. Adjustment to provide that dampening effect may be fruitful: A leather softened with oil, turned to a fresh rub spot, and cranked in enough to stabilize but not immobilize is good.
2 - The shaft binding on the disc is a no brainer, I assume you've gotten that issue taken care of.
3- You may have done this already, but try running the Bosch pump continuously for a test run, but only if you have a proper pressure regulator in the system. your stated 2 ½ lbs is perfect, but is it consistent? A related issue can be checked if when it suddenly dies with apparent fuel loss, immediately remove the air horn to check the fuel level at engine shut-down. I say immediately because a hot engine will rapidly evaporate the fuel from the bowl. There was a neat KRW visual bulb external to the bowl, but I believe it proved unreliable due to strong under-hood air currents.
Again, just the village idiot here, so what do I know?

[glennpm]

Originally Posted by BIG KEV

Well, You hit something I think, did a second stress test today, started surging a bit, few hundred rpm, then started this light clattering from the front of the motor. Then it died, I did find when you block the vacuum to the distributor it dies.

Originally Posted by ford38v8

1 - you mentioned the vacuum brake and piston, but had nothing to say about it's leather seal atop that piston and it's rub on the advance disc. That seal does double duty, one to seal the vacuum, and two to dampen the disc. Back in the day with low octane fuel, adjustment of that damper was critical to prevent ping, but with today's fuel, its main purpose is to prevent wild bouncing of the advance disc. Adjustment to provide that dampening effect may be fruitful: A leather softened with oil, turned to a fresh rub spot, and cranked in enough to stabilize but not immobilize is good.

I too think this is an ignition problem, condensor first and the vacuum brake second.

I just went through an adjustment of my Crab's vacuum brake this week. I was lead to do it since I was getting misses at WOT, otherwise fine. I suspected that my crab was not advancing enough at high RPM. My initial advance is set at 7°.

I had rebuilt my distributor last winter so I knew that I had freedom of movement but decided to take another look at the damper. I disassembled it, cleaned the piston bore and then lubed it with some break-in oil with Teflon. I made a gasket for the large nut to disy body.

I read an old article that suggested checking the vacuum brake function with a vacuum pump saying that the piston should lift at about 5 " of vacuum. I modified an air pump red nozzle so that it was tight in the disy vacuum port hole and would stay in place with light hand pressure while I pumped with the other hand.



I backed the vacuums bolt out all the way to the top and then turned it back in 1-1/2 turns and then checked with the vacuum pump. It lifted off at ~ 5". I then screwed the bolt out to the top again and applied some thread sealer to the bolt threads, screwed it back in again 1-1/2 turns, tightened the nut and checked it again. All was good.

Then for the road test. WOT to just under 4K RPM plus and it is now perfect and the distributor is fully advancing as it should!

[glennpm]

I neglected to mention that during my earlier rebuild, I made a new leather puck for the brake, oiled it then and also this last week. I had screwed the the brake in too far and it was limiting the advance. 1-1/2 turns I think is best, at least for me it is :-)

[BIG KEV]

Originally Posted by ford38v8

Kev, I'm no expert at these issues, not by a long shot, but I do thank you for the detailed list of what you have to work with that the real experts can go with. I have, however, picked up on a couple things that may be worth investigating:
1 - you mentioned the vacuum brake and piston, but had nothing to say about it's leather seal atop that piston and it's rub on the advance disc. That seal does double duty, one to seal the vaccum, and two to dampen the disc. Back in the day with low octane fuel, adjustment of that damper was critical to prevent ping, but with today's fuel, its main purpose is to prevent wild bouncing of the advance disc. Adjustment to provide that dampening effect may be fruitful: A leather softened with oil, turned to a fresh rub spot, and cranked in enough to stabilize but not immobilize is good.
2 - The shaft binding on the disc is a no brainer, I assume you've gotten that issue taken care of.
3- You may have done this already, but try running the Bosch pump continuously for a test run, but only if you have a proper pressure regulator in the system. your stated 2 ½ lbs is perfect, but is it consistent? A related issue can be checked if when it suddenly dies with apparent fuel loss, immediately remove the air horn to check the fuel level at engine shut-down. I say immediately because a hot engine will rapidly evaporate the fuel from the bowl. There was a neat KRW visual bulb external to the bowl, but I believe it proved unreliable due to strong under-hood air currents.
Again, just the village idiot here, so what do I know?

Thanks Ford38v8.
1. yes its a good leather turned 90 degrees, the piston I am using in the new distributor is working good, no more clattering at low rpm. So I think that fixed the advance dropping down and killing the motor.
2. Yep, I took 3 distributors to make 1.
3. Did that yesterday, I really BEAT on the old gal HARD like she owed me rent money. Fuel pump running the entire time, hard stops, hard starts, corners, all of the beans. I have driven it with fuel pressure gauge inside and I am not seeing any flutter from 2.5. Thanks for the tip on the KR wilson bulbs, I always wondered about those, glad I never got one.

Side note, when I first fired her up, she had a miss, BAD miss. Figured the plugs were just a little dirty from all the BS I have had going on. Cleaned em and put em back in, idle was good. Took off down the street, she had a miss still. Weird..... once she got to the end of the block the miss went away and she cleared out and the beating commenced once we got to 140 degrees on the temp. The carbs wanted more and more fuel from the mixture screws the hotter the motor got. But no dying out this time. I had wet set the floats this time to 1/2" fuel level and this seems to have helped the issues somewhat. I think you did hit a nail on the head with multiple issues. I have a good one for ya... Fired her up today, BAD miss again, shorted a few plug terminals out and found 2 that were not getting any change in rpm. Ok, pulled the plugs. Clean but a little wet. hooked up the wire and ran the motor with the plug out of the cylinder, the dang thing was firing from the porcelain to the edge of the threads. Pulled plug 2 and same thing. Going tomorrow to get some champion plugs or Autolites. In doing this today, one of the Rajah terminals broke at the 90 where its riveted on. I am going to change the wires out since these were made for the 90s and not straight boots. Hot, I did pull a plug wire to test spark, she is jumping blue 1/2" so I'm pretty sure were getting somewhere. Or I am closer to checking into Shady Oaks Asylum.

Originally Posted by glennpm

I neglected to mention that during my earlier rebuild, I made a new leather puck for the brake, oiled it then and also this last week. I had screwed the the brake in too far and it was limiting the advance. 1-1/2 turns I think is best, at least for me it is :-)

I really need to do the thread sealant on the adjuster once I get the brake dialed in, I am running it a bit too tight I think, but once I get it, I'll do your method, I like that idea, any little bit to help it can't hurt. Thanks Glennpm

[ford38v8]

Kev, A small correction here that may give you an insight on your adjustments: The "mixture screws" are merely IDLE mixture screws, not to be adjusted for anything but idle. Since you do have a lumpy cam and need a higher idle speed, they will need to provide more fuel. Locate instruction for adjusting them correctly with your cam and that should help.

EDIT: This might be the first ChatGTP advice on the Fordbarn:.

Step-by-Step Idle Adjustment (Holley 94, Lumpy Cam)

Warm it up

Run the engine until it’s at full operating temperature.

Make sure choke is fully open.

Baseline settings

Gently seat both idle mixture screws (don’t force).

Back each screw out 2 full turns.

Set the idle speed screw so the engine will just stay running (probably around 650–750 rpm for a lumpy cam).

Hook up a vacuum gauge (if you have one)

Plug it into a full-manifold vacuum port.

If not, just go by ear and feel.

Adjust one side

Pick one idle screw.

Turn it in slowly until the engine just starts to stumble or rpm drops.

Now turn it out slowly until rpm peaks (or vacuum is strongest).

Leave it there.

Adjust the other side

Do the same with the second idle screw: in until stumble, then out to the sweet spot.

Re-check idle speed

If rpm is too high or too low, use the idle speed screw (on the throttle arm) to bring it back to a steady idle.

Expect around 700 rpm as a realistic goal with a lumpy cam (stock would be lower).

Final tweak

Go back and make a small touch-up on each idle screw (⅛ turn either way) to get the best compromise: highest steady rpm, strongest vacuum, and smoothest response when you crack the throttle.

[glennpm]

Originally Posted by ford38v8

Final tweak

Go back and make a small touch-up on each idle screw (⅛ turn either way) to get the best compromise: highest steady rpm, strongest vacuum, and smoothest response when you crack the throttle.

After this final tweak, I would check the numbers of turns in for both sides and then set them out to an average position. For example:

- Left side turns in = 1-3/8
- Right side turns in = 1-1/4

Finally set both out 1-5/16 turns

[BIG KEV]

Thanks Ford38v8. Yeah may be the first time ever I have seen AI quoted in this stuff, but hey it really goes through the normal process I use honestly word for work. Glad to know the old timers taught me something that the computers figured out.

I bumped up to 600 idle speed, she seems to like that, I can see 500 and she shakes and sounds fun but Ill take a little more idle speed to keep her happy honestly.

I put a new set of NGK I had bought a while back for something else. I didn't want to go to the store and buy another set of plugs just to be disappointed and throwing money at issues.

NGK BR6hs plugs.
These have a resistor core to them. Honestly it's been months since she fired on less than a full revolution and once ran, she fires under 1/4 revolution. These are a hotter resistor plug, so we will see how this all pans out. I have heard alot of folks say not to use resistor plugs with points etc. I normally don't run them as well just purely off what the old timers told me back when. Kinda like suppression core wires is only if you want a radio to work.

[ford38v8]

Originally Posted by glennpm

After this final tweak, I would check the numbers of turns in for both sides and then set them out to an average position. For example:

- Left side turns in = 1-3/8
- Right side turns in = 1-1/4

Finally set both out 1-5/16 turns

Glenn, that sounds perfectly reasonable, but in practice, dunno if even possible to get that degree of rotational accuracy on those screws while bent over into the hot engine compartment! At that point I’d be reluctant to disturb what’s already a good thing!

[hueyhoolihan]

too bad they aren't thumb screws..would facilitate accuracy. if i had all the time in the world and a lot more ambition i'd have someone braze a couple of dimes on the ends.

[Ziggster]

I just went through this entire thread. Lots of good info. I’m in the process of resurrecting one of my crab distributors to test on my Allen Syncrograph machine. I can say the following:

1. No play or “grabbiing” on my advance plate.
2. Both the pistons I have for the vacuum brake fit nicely with no slop.
3. Cleaned up ALL electrical contact points with 600 grit paper. Thus includes condenser tabs, main ground stud nuts, distributor hsg where condenser mounts. Contact area on main plate for spring loaded ground stud. Of course breaker points cleaned, rotor and contact points cleaned.

Questions for you:

1. I’m running the same cam in my C59A. What is your advance setting on the distributor?
2. What conditions are the csm lobes in?
3. Did you lub all the contact surfaces for the moving parts?
4. What condition are the rotor contacts points in?

I watched this vid to help me. He says folks run no vacuum brake without issues.
https://youtu.be/US6Gg7hhFRI?si=Cm8-TN4p3t_M2UdD

[BIG KEV]

Originally Posted by Ziggster

Questions for you:

1. I’m running the same cam in my C59A. What is your advance setting on the distributor?
2. What conditions are the csm lobes in?
3. Did you lub all the contact surfaces for the moving parts?
4. What condition are the rotor contacts points in?

I watched this vid to help me. He says folks run no vacuum brake without issues.
https://youtu.be/US6Gg7hhFRI?si=Cm8-TN4p3t_M2UdD

Thanks and I’ll do my best to answer.

My initial setup is timing it using the bolt factory method. My timing tab on the distributor shows dead in the middle.
Yes I used synthetic grease for those parts and used 30w motor oil for the hard bushings in rear and point plate.
Rotor contact points are good. A minor variance on the micrometer of .0002 think was worst I had. I run a very thin coat of synthetic grease on this where the point arms contact. Found it to stay in place.

One find I did notice when pulling the old distributor down was a sheen of oil inside the distributor. Not thick. Just looks like aluminum with a little oil in its pores. Makes me wonder if the point plate was floating ground with that as added resistance when hot. It’s plausible. The vac brake was deff an issue though.

Sounds like you’re on the way to making a good distributor as well.

If ya try with no brake let me know how it goes.

[Ziggster]

Sounds good. If my machine ends up working, I’ll test the heck out of it and post up the results. Got a thread going on the HAMB.

https://www.jalopyjournal.com/forum/...1217704/page-2

[Ziggster]

By some miracle, as I’m playing around with the machine, and with the crab distributor mounted, I got the strobe lights and tach to work. If anyone knows how to use this thing, please PM as the manual I purchased for it is almost useless.