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Old 03-17-2019, 07:11 AM   #1
Paul Howes
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Default model B engine

After talking with others and seeing some of the responses from this forum, I have yet another question. On my B engine the timing pin is located about 3/4" lower than the pin on an A engine I have.
When I insert the pin, finding the dimple on the gear, the rotor is pointing at #1 with the points just starting to open. A model B block with what appears to be a B cover and pin location lower AND everything timed like an A engine. How can this be? Paul
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Old 03-17-2019, 08:34 AM   #2
jhowes
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Default Re: model B engine

I have been rethinking this and it seems to me that everything is as it should be. The pin location is like a B engine and the engine is a B engine therefore it should time out as it does. I have never had a B block so I am just guessing at this point. Jack
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Old 03-17-2019, 10:45 AM   #3
Bob C
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Default Re: model B engine

Quote:
Originally Posted by Paul Howes View Post
After talking with others and seeing some of the responses from this forum, I have yet another question. On my B engine the timing pin is located about 3/4" lower than the pin on an A engine I have.
When I insert the pin, finding the dimple on the gear, the rotor is pointing at #1 with the points just starting to open. A model B block with what appears to be a B cover and pin location lower AND everything timed like an A engine. How can this be? Paul

The hole on the B timing cover should be higher than the A cover.


Bob
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Old 03-17-2019, 12:54 PM   #4
Phil Brown
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Default Re: model B engine

The timing cover (and pin location) is more relevant to the distributor that's being used in the motor than the block
"B" distributor use the "B" cover
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Old 03-17-2019, 01:45 PM   #5
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Default Re: model B engine

Could the B cam be different too?
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Old 03-17-2019, 02:03 PM   #6
Purdy Swoft
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Default Re: model B engine

The model B distributor cam has more dwell than the original model A distributor cam . The extra dwell is said to double the spark when used in the model A distributor . I think all of the distributor cams that are now offered have the model B profile .
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Old 03-17-2019, 04:06 PM   #7
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Default Re: model B engine

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Originally Posted by Purdy Swoft View Post
The model B distributor cam has more dwell than the original model A distributor cam . The extra dwell is said to double the spark when used in the model A distributor . I think all of the distributor cams that are now offered have the model B profile .

good day Purdy. what advantage in a Model A distributor cam? thanks, gary
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Old 03-17-2019, 04:52 PM   #8
Purdy Swoft
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Default Re: model B engine

Hello Gary .The advantage in the model A points cam is it is easier to know when you are on high cam when setting the points . The model B distributor cam has an ocean wave profile and high cam isn't as well defined . There is a fairly new tool that slips over the cam and allows for the points to be adjusted without rotating the engine and finding high cam . The model A distributor cam has less dwell and the spark is not as hot . There are other ways to increase the spark .

Last edited by Purdy Swoft; 03-17-2019 at 04:59 PM.
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Old 03-17-2019, 05:13 PM   #9
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Default Re: model B engine

In 32 the timing gear cover was cast so it could be drilled and used as a replacement on the A engine. There is an oval pad that was big enough to drill for the B or A engine. So you could have the replacement cover made in 32 drilled for the A engine/dist.

If it is a B cover and you are using an A dist., it is going to be way advanced (BTDC) from the get go.

In 33 and 34 it was a round boss for the B engine, but the gen mount was different.
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Old 03-17-2019, 05:51 PM   #10
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Default Re: model B engine

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Originally Posted by vernon View Post
Could the B cam be different too?
yes,in a most positive way..about .040 higher in measured lift if you find the right one.lobe design and duration different too.The B mechanical advance distributor is best served by timing with a timing light,pin timing gets you close,but to truly dial it in you need use a light,that way you can check timing at different rpms using a tach dwell meter and the light.

Combine a B flywheel (10 lbs lighter than an A) B cam,B distributor high compression head and a B carb and you'll be quite pleased with the improvement in performance,and still look correct.
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Old 03-17-2019, 06:55 PM   #11
Ray in La Mesa
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Default Re: model B engine

I think the timing covers on your A & B engines have been reversed.
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Old 03-18-2019, 08:06 AM   #12
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Default Re: model B engine

I'm going to try and make sense of this one more time. Why was the timing pin location changed for the b engine? The cam comments above do not address the valve cam or its' position, instead the comments talk about the dizzy cam. Is the camshaft different than the a in position? I know that the profile is different in several of the camshafts available. Jack
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Old 03-18-2019, 10:18 AM   #13
Joe K
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Default Re: model B engine

I think Mr. Brown said it

Quote:
The timing cover (and pin location) is more relevant to the distributor that's being used in the motor than the block
"B" distributor use the "B" cover
The B distributor is a completely different animal from the A distributor.

Differences in internal plates, positioning of the points relative to the driving shaft. Aside from a change in location of the condenser.

https://fordbarn.com/forum/showthread.php?t=132187

A previous discussion of the similarities and differences between the two components - including a link to Vince Falter's valuable FordGarage.com site (if it still works!)

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Old 03-18-2019, 10:26 AM   #14
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Default Re: model B engine

The B (1932-34) timing was set 19 degrees before top dead center instead of after top dead center like the A
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Old 03-18-2019, 10:43 AM   #15
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Default Re: model B engine

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Originally Posted by vernon View Post
Could the B cam be different too?
Which cam are you referring to? The Camshaft? or the distributor cam?

If anyone is replacing an A distributor cam with a new replacement B distributor cam, I suggest that you check the finish on the new cam to ensure that it's as smooth as it needs to be.
Don't ask how I know.
I will say that rough distributor cams rear down the points rubbing block fairly rapidly.
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Old 03-18-2019, 11:11 AM   #16
Bob C
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Default Re: model B engine

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Originally Posted by jhowes View Post
I'm going to try and make sense of this one more time. Why was the timing pin location changed for the b engine? The cam comments above do not address the valve cam or its' position, instead the comments talk about the dizzy cam. Is the camshaft different than the a in position? I know that the profile is different in several of the camshafts available. Jack

No, the timing gear is in the same position if that is what your asking.


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Old 03-20-2019, 05:49 PM   #17
Chuck Sea/Tac
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Default Re: model B engine

The B distributor has a auto advance. The timing on an A engine is set closer to 0 or retarded. My understanding is that’s to protect you from kickback while hand cranking.???
Or at least that’s another myth floating around.
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Old 03-20-2019, 08:28 PM   #18
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Default Re: model B engine



Take a look at the 12170 assembly.The B distributor uses flyweights to advance the spark,its timing curve is perfect for a model a as well it advances 1 degree per 100 rpm..the timing corrects either during increase or decrease of rpm perfectly.Modified top plate for modern points and open the oil passages and your good to go,perfect spot on timing at any speed.
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Old 03-20-2019, 09:34 PM   #19
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Default Re: model B engine

Quote:
Originally Posted by jhowes View Post
I'm going to try and make sense of this one more time. Why was the timing pin location changed for the b engine? The cam comments above do not address the valve cam or its' position, instead the comments talk about the dizzy cam. Is the camshaft different than the a in position? I know that the profile is different in several of the camshafts available. Jack
Try this for an explanation of the CAMSHAFT. The CAMSHAFT gear position is in a different location on a B from an A obviously because of the distributor. The timing pin location has nothing to do with TDC or anything like that. Plain and simple the timing pin location is only for the distributor.

http://www.fordgarage.com/pages/camshaftspecs.htm
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Old 03-21-2019, 06:13 PM   #20
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Default Re: model B engine

Re B engine with B cover and dist; The starter will//might power thru the engine firing BTDC, hand cranking not so much. Try miss timing a Model T with 1/2 the HP and see how much damage can be done when it backfires while cranking by hand.
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