Harmon Collins build thread ...

[alchemy]

I found a website for Chief Aircraft Parts and they don't show anything with that part number. Can you let us know the application or another part number?

What do you think about hand grinding the "extra" cam bumps off by hand? If I could finish the surface nicely, does it need to be a perfect profile, or would "gone" be good enough?

I've got two complete units, but another spare inner cap and rotor that could possibly be turned into a third distributor.

And, thanks for the hint that the cap clips are off a loadamatic. I'll have to strip them off before I toss the next one of those in the recycle bucket.

 

[37Ford]

I have used Bendix aircraft contacts (# 10-357174) in my HC.

 

[TerryOH]

You can grind off every other lobe of the cam but where do you start, what lobe? So be careful. You may have to modify the points slightly to get the wires to attach with the lock washers and nuts. The Bendix 10-357174 has to be slightly modified or 10-52344W is original.

 

[v8fordman]

Does anyone make the bracket or have a drawing with the dimensions for the condenser bracket? What condensers will work or does anyone have any originals for sale?

 

[KiWinUS]

Jay I can get measurements & take pics of one of my brackets if that helps you. Cheers. Tony

 

[tubman]

Just about any good condensers will work. If it's looks you're after, original Mallory "Trash Cans" are available and pop up on eBay occasionally. However, almost all of these (even those NOS "in the box") usually have split cases. If you find a couple test them before use, including "heat cycling" them. I got discouraged by the used units, so I made my own. A lot of guys used them, so I make and sell them on a limited basis. $50.00 to forum members plus $8.00 shipping.

 

[BUBBAS IGNITION]

Does anyone make the bracket or have a drawing with the dimensions for the condenser bracket? What condensers will work or does anyone have any originals for sale?

Here ya go from the bench today ........

 

[BUBBAS IGNITION]

Some condesnor work today , bracket dimentions in previous post answer ..
The Collins is a very good example of two 4 cylinder systems , we are using the 3.0 ohms Bosch blue coils and two Vertex Magneto condensors ( these are the very best condensor available today ) My friend owns a very serious racing magneto business and has these made ( high quality) to service his customers . They test at .36 mfd and use a soldered end ground which makes them bullett proof !!
Note the connectors are NOT soldered , he claims a crimped connection is better than soldered one as solder will vibrate and break !!!

 

[BUBBAS IGNITION]

condensor pics collins

 

[BUBBAS IGNITION]

Some more assembly for today .......
The shaft appears to be the stock crab unit , the cam has been ground off slightly on one side ( detailed pic to help if ya need the index to grind your own ) On assembly i use a new clearance washer as most are kinda ground up after some use , ( my friend Mike Baker made me some of these a few years back , hes a diehard early Ford guy that owned a machine shop) and i use a smaller snap ring ( From 3rd Generation Mike Driscal) , makes assembly easier and adds a little bit of clearance . ( shaft must spin easy by hand , if it dont ya did something wrong )
Spark retard ring is also pretty standard ring .....
I use spray lube on all these parts and mobil one red grease on bushings etc .
There is a couple mods to the actual case i will address later in the build .
Install the point plate and snap ring and its looking pretty good ........

A note on the peanut butter crackers on the bench , my helper Terry hides them all over the shop and its my job to eat them , dont really like them (not) but it hurts his feelings if i dont keep them ate up ???

 

[BUBBAS IGNITION]

Ok back on it this monday morning .
Assemble the shaft etc , adjust contacts to .015 before testing can begin . Both set at .015 mount on tester and use "house" Vertex" test lead will mount both condensors later.
Each wire is 4 cylinders adjust on dwell meter to be perfect ( 015 is 70 degrees of dwell) and each degree of dwell is 2 degrees of engine timing !!
Both sets MUST be synced ( cant imagine this ever being correct with out a machine !!!!???
Note that after adjusting one set and checking the sync of the other side it is 4 degrees ( 8 degrees of engine timing ) and must be readjusted , not hard to do on a distributor machine .
If left alone one gang of four cylinders would run out of time ( sync) with the other gang !!!!!!! This is true with all the dual coil sytems .
Now we have the primary ( section one) ignition adjusted and timed so we can move on to part two ( the hard part ) checking the high voltage part of the dual coil using higher voltage for the secondary ignition firing the spark plugs .
Stay tuned we are geting there .
Something we take for granite here is the BUZZ of the distributor . After a while everyone can tell if its wrong just bu sound , this one has a very smooth BUZZ at 3000 rpm !!!!!!!! yea !!!!!!

 

[STAN WHITE]

Bubba I have a question on the vacuum brake. I was told by a Flathead engine builder that I did not need to use the vacuum brake. he said that I needed to back it off by a couple of turns. This was on a highly modified 59AB Engine. It ran great is this correct? Stan

 

[BUBBAS IGNITION]

Wow , the engine builder was running on a myth !!!! I disagree , the vacuum brake is needed at the very least to prevent spark scatter . With no tension on the retard ring the spark will jump back and forth ( I call it spark scatter as that’s what it looks like on a distributor )
I will illustrate as time allows ..,

 

[KiWinUS]

Great thread Bubba. Are there any significant differences (other than the obvious) from the Crab H&C to the 8BA style H&C.
Thanks
Tony

 

[BUBBAS IGNITION]

Great thread Bubba. Are there any significant differences (other than the obvious) from the Crab H&C to the 8BA style H&C.
Thanks
Tony

I have done some loadamatic collins units as far as i can tell they are pretty close to being the same set ups .

 

[BUBBAS IGNITION]

Some more discussion today :

The Harmon Collins uses a standard set of advance weights and spark ring .
( I have three in the building a each one has the advance slot modified ) So i think the orginal units have a stock advance adjustment and the hot rodders have made the slot wider etc .
This example is comparing the one i have here to a stock alum and cast iron unit on the bench..
Tuners almost want more of everything and the Ford crab doesnt leave much for adjustment with two bolt hold own and very little adjustment .
This one has 22 degrees of adjustment (measured on dist tester ) stock is 12 or 6 either direction compared to 11 either retard or advance .
My dyno time has shown that a 4 degrees change was a ton on the dyno.!!!!!

I use a ton of mobil one grease on piston leather to help seal the piston and provide lube for movement !!

Note : You are somewhat limited to timing advance as too far will cause rotor index to be way off and cause a misfire either low or high rpm !!!!!!!!!!!!!!

 

[BUBBAS IGNITION]

SOME more for this afternoon :

New nuts ( bras) and screws for the primary connections. Pay attention to the seondary ring the cap , rotor and connections to the condensors .
Make sure the rotor adapter is pushed ALL the way down if not rotor damage will occur !!!

Something new i have been thinking about for some time is a secondary test with live 12 volt battery and all plugs hooked up...
We have the primary synced and adjusted but havent loaded the secondary , my friend Ed at Mag Tech made me this bar for 8 and 12 cylinder secondary testing .
This will allow me to actually test the spark to each plug and test ( with a scope ) if i want to........
Remember i have a couple here that will only fire 4 cylinders ....

 

[spendingtheirinheritance]

You have one H-C unit there that fires 7 cylinders like magic. However #1 cylinder gets zero spark. You can take #1 wire off the plug and put it to your tongue and get nothing--it's a very accurate test. I've changed caps and wires, cleaned everything and still #1 finds an alternative ground. Perhaps hooking up your sparkplug bar will help find the answer.

You began this thread asking if we really need this H-C dual coil set up. Practically no. The car runs great with the crab. However the car itself needs the set up.

It's a 32 roadster, Merc crank, ported and relieved, pre-war slingshot manifold, cheater heads, 37 LaSalle transmission, Culver City Halibrand quickie, Ed Stewart dropped axle, Lincolns on all four corners, and a killer set Of Halibrand six-pin knock-off smoothies to ride on.

 

[BUBBAS IGNITION]

You have one H-C unit there that fires 7 cylinders like magic. However #1 cylinder gets zero spark. You can take #1 wire off the plug and put it to your tongue and get nothing--it's a very accurate test. I've changed caps and wires, cleaned everything and still #1 finds an alternative ground. Perhaps hooking up your sparkplug bar will help find the answer.

You began this thread asking if we really need this H-C dual coil set up. Practically no. The car runs great with the crab. However the car itself needs the set up.

It's a 32 roadster, Merc crank, ported and relieved, pre-war slingshot manifold, cheater heads, 37 LaSalle transmission, Culver City Halibrand quickie, Ed Stewart dropped axle, Lincolns on all four corners, and a killer set Of Halibrand six-pin knock-off smoothies to ride on.

Good example of when ya gotta have a Harmon Collins , i agree !!!

 

[KiWinUS]

Now that’s what you call “a hot rod”