No 1 Piston relation to timing marks

[Don]

I assume engine ran a long time ago ,think I have enough info to figure it out,will take I pad to shop in morning and go over everything,
Tonite is 58 yr anniversary ,,got other things on my mind!!!!!!!!!

[Brian]

58 years ago you'd have had something else on your mind!! Congratulations on making 58 years.

[Bubsyouruncle]

At least all this is mechanical. And can be observed with the naked eye.

Modern stuff? Good luck and an open checkbook!

[Mart]

Do a simple sanity check.

As no1 (or any other cylinder, for that matter) piston goes past tdc, on every 2nd stroke, the valves will be overlapping. The exhaust will have been open and will be almost closed, the inlet will be just starting to open.

This is a good a method as any to see if you have the cam timing correct.

In this case it will either be correct or way off.

Obviously for a race motor setting things calls for more accuracy.

Please report back after doing the above.

Mart.

[Don]

Will report back after I do some of the checks mentioned ,some one else might be here sometime,I thought I knew all about this,,

[JSeery]

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The timing gear on the camshaft has nothing to do with piston position in the cylinder. If a pressed on timing gear slipped (or a keyed one was miss marked) the valve timing would be off, but it would not have any effect on the crank timing gear position or it's relationship to TDC. The crank timing gear uses a key to establish it's position on the crankshaft. Now, I'm not sure that the crank is at TDC when the crank timing gear dot is straight up. I would have to check that to see. But, the timing gear marks are not there to establish TDC, they are to establish the correct relationship between the crank and the camshaft (cam timing).

[flatjack9]

Originally Posted by JSeery

The timing gear on the camshaft has nothing to do with piston position in the cylinder. If a pressed on timing gear slipped (or a keyed one was miss marked) the valve timing would be off, but it would not have any effect on the crank timing gear position or it's relationship to TDC. The crank timing gear uses a key to establish it's position on the crankshaft. Now, I'm not sure that the crank is at TDC when the crank timing gear dot is straight up. I would have to check that to see. But, the timing gear marks are not there to establish TDC, they are to establish the correct relationship between the crank and the camshaft (cam timing).

The crank is at TDC #1 when the dot is up. Sometimes the dot is hard to see with the slinger in place. Not all are marked in the same location.

[rotorwrench]

Many manufacturers make the marks just to time the cam to the crankshaft. They don't always have a relationship with TDC on #1 cylinder. The procedure for the 8BA engines doesn't mention anything about TDC when installing the camshaft. A person just makes sure the dots are aligned. There is a cam/valve timing check procedure for the 8BA series to insure things are as they should be. The 1946 Service Manual procedure for cam gear replacement is pretty much the same. No reference to the TDC at all. There is no cam/valve timing check in that manual. The cam gear generally has offset bolt holes so that it will only go on one way on the 8BA and likely on earlier models too. The gear bolt pattern can be checked to make sure it will only go on one way. If the gears were on wrong way around, there would be no dot visible.

[George/Maine]

The basics intake opens at top dead center #1
The early engines had press on cam gears that's how they were checked.
Now with Bolton types they should be correct with marks lined up.
Now what did the engine sound like? People like hot cams with the retarded sound.
The cam in engine may not be stock. It should still be close TDC intake opens. That's not the firing TDC

[Don]

Hope I have found the problem! Don't think anyone ever said positively that cam dot and crank dot should line up with #1 at tdc,well for a fact I am say they do if the correct crank dot is used,look at crank dots and tell me which one you would use , A or B. Well I tried B #1 at tdc turned cam ,put gear on and dots lined up,and 4 bolts lined up ,put dist on and rotor was firing # 1 plug,,,turn engine # 1 goes down Back up as ex valve opens. Goes back down intake opens. Back and both valves close and dist fires # 1.
With 1 tdc # 6 also tdc and 2 & 3 are even from top,,,..the crank gear was marked wrong,does all this sound correct,,hope the pic comes thru,,thanks for all the help,,,good discussion

[George/Maine]

The keyway looks to be at 12 o'clock and B

[Mart]

Don, do you have all 4 bolts in on the cam gear? I think one is offset slightly so you can't put the gear on in the wrong position. (or did I dream this??)

Mart.

[Don]

Mart check post above,all bolts lined up .crank key way is 31/2 teeth from center,have did a search and keywAy was same as mine think I ok to put togeather??????

[Jack E/NJ]

Don---As I recall, the crank gear dot on my early 38 21-studder looked like the A dot on your crank gear tooth. The cam gear had 2 similarly placed dots on side-by-side teeth. I simply lined up and meshed the crank dotted tooth in between the cam dotted teeth. Didn't pay much attention to Ford #1 piston position at the time until I put the helmet back on to make sure the rotor was pointing at Ford #1 at TDC with valves closed. Jack E/NJ PS: Your crank B mark looks more like a chip or imperfection to me. PPS: What does the other side of the cam gear look like? Any dots on side-by-side teeth?

[flatjack9]

Originally Posted by Don

Hope I have found the problem! Don't think anyone ever said positively that cam dot and crank dot should line up with #1 at tdc,well for a fact I am say they do if the correct crank dot is used,look at crank dots and tell me which one you would use , A or B. Well I tried B #1 at tdc turned cam ,put gear on and dots lined up,and 4 bolts lined up ,put dist on and rotor was firing # 1 plug,,,turn engine # 1 goes down Back up as ex valve opens. Goes back down intake opens. Back and both valves close and dist fires # 1.
With 1 tdc # 6 also tdc and 2 & 3 are even from top,,,..the crank gear was marked wrong,does all this sound correct,,hope the pic comes thru,,thanks for all the help,,,good discussion

Definetly B. I believe in post #3 I said the dots have to line up. That other mark just looks like a little defect in that part of the gear.

[rotorwrench]

The keyway on the 8BA crank is at about the 10:30 location when the tooth with the dot is at 12:00. The dots usually look like someone started to drill with a 1/8" bit but just stop before the outer flutes break the surface. I can see why that would be deceiving. That other mark looks like a center punch mark. Whom ever did that didn't do anybody any favors.

That might have been some grabastic fool jacking with the next mechanic that puts it together.

[Jack E/NJ]

flatjack>>>Definetly B. >>>

Are we looking at the same photo? Looks like A to me. Jack E/NJ

[Don]

I did remove the crank gear and check back side first thing this morn,no markings,I know the B mark is not the best I've seen but everything works as it should with B Mark,so have to go with it,I'll blank out the A punch mark someway and make a better B dot

[Jack E/NJ]

The white marked dot in the valley of the cam gear, may be the correct one to mesh with the crank dotted tooth but I'd still like to see the other side of the cam gear. Jack E/NJ

Don, you beat me to looking on the other side. 8^)

[Jack E/NJ]

I dunno Don. Your looking at it in person. And I'm looking at enlarged pictures on a small screen. I guess as long as the rotor is pointed at Ford#1 when at TDC and valves closed, it's good to go. Jack E/NJ