Timing gear question

Ron_r1959

Ron_r1959

Senior Member
What is the difference between the timing gear set on a 59AB and an 8BA, I assume the camshaft is the same. is the bottom gear the same and just the cam gear different?
 
My reason for asking this is I built a big bore 59AB block and it seems to be firing a little bit advanced while idling you can hear it spitting just a little through the carb. I have checked my timing and the valve lash and they are correct. it is better if I retard the timing as much as possible but still not right and does not want to wind up . My compression is even on all cylinders. So I was wondering if I could have any possibility of incorrect parts between a 59a and an 8ba style? I have tried a known distributer from another good motor I have, but I have same issue if i put it on this motor. I am running out of ideas. thoughts??
 
Timing gears are cut at an angle, this direct the thrust created by the anglr. For the early engines the thrust is towards the back (block) ont the late 8ba engines it's torwart the front (cover). I prefer to use the early gears. However if you have the late gears it mau effect to distributor. Interesting problem, have to think about it for awhile, little slow on thinking these dayd/
Gramps
 
So that means my gears are a matched set then at least as far as the engine family is concerned. I ordered the crank gear new for the early style block, so I am wondering about the cam grind. I feel like I have a shaft that isn't ground quite right.
 
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Ron_r1959 said:
So that means my gears are a matched set then at least as far as the engine family is concerned. I ordered the crank gear new for the early style block, so I am wondering about the cam grind. I feel like I have a shaft that isn't ground quite right.
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The style of gears your using will not effect the timing so there's a few possibility's on what may be taking place. You write about wondering if the cam shaft is not ground right. Question what cam are you running? Each aftermarket flathead cam comes with a cam timing card the purpose is to check the cam timing to determine if its installed correctly. Some grinders suggest advancing the cam 4 degrees.
Checking cam timing on a flathead is not a big deal once you understand how to do it. The big deal deal comes into play if you discover the cam timing is not as advertised on the cam timing card.
You mentioned checking a different distributer on the the engine which made no improvement. Question is the distributer the front mounted pancake style? If yes have you adjusted the static timing be moving the adjusting screw on the side of the housing? Ignition timing may be the issue but it all depends on the style of the distributer. And if your running 6 or 12 volts. Example an ignition problem using suppression spark plug wires with a 6 volt system that's not a good idea.
If you can write other details about what your using then others may be able to hopefully point you in the right direction.
Ronnieroadster
 
Like Ron says... it wouldn't go together if you mixed 8ba cam gear and 59 crank gear. Angle of teeth is reversed. As for cams being the same... not really, as 8ba has the distributor drive gear on it, and 59 does not. So, what distributor do you run? up top, 8ba? or down front, crab type?
 
You did a compression check. What were the readings? Too high a compression will produce the same symptom.
What octane gas are you using?
Do you have a timing mark on the crank pulley?
 
I am running the original front mount style distributer, I checked my timing gear timing and it is at the 0 degree mark, but I have not checked the cam itself to see if its correct, that might be worth looking at. I am using the max 1 cam shaft. I am running 115 octane gas and the compression is probably too high, compared to my other motors. I didn't plan it to be that high, but I bought the cast heads at an auction and I am guessing they have been decked more then normal, the actual compression checked at 190. I intend to cc these heads and see what they check at but I haven't done that yet. I have played with the timing slide on the side and at the moment it is fully retarded. I have not functionally checked the timing with a light yet, not sure if it has a mark or not, I will have to check that. Does anyone have a link on how to check the actual cam timing on the cam to match the card, I have never done that.
 
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Since you have a set of cast heads that were decked a lot and the 190 is high for compression the 115 octane gas is helping to keep the tops of the pistons from being pounded to death from detonation. Your lucky the piston domes are not touching the heads and the valves are not bent. Or maybe they are. Did you check the heads for clearance?

Here's a great video on cam timing how its done and why.

https://www.youtube.com/watch?v=57gfBu8uc6k
 
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That was pretty helpful, I am going to get a degrees wheel kit and check that out.
I did grind heads for clearance around the valve and checked for clearance on them, I haven’t checked for pistons clearance, but it doesn’t want to wind enough to get into stretch issues. I do have a scat crank kit
So I suppose keyway issues are possible, I am thinking my compression should be around 9.5-1 but I won’t know for sure until I cc the chamber

From what I could read, that would be about the max I could expect to run but I believe that octane should make it possible unless the flathead doesn’t like that? I know I couldn’t do that with pump gas

Sent from my iPhone using Tapatalk
 
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Since there's only one keyway involved {the crank gear} I would be surprised if that was the issue. With any resurfaced heads the dome area can become so small there's now a flat surface around the outer diameter where the dome was once located. This flat area on the head will create problems. The poor flame travel design of the flathead combustion chamber can use all the help possible including a higher octane gas so that's a good thing for sure.

What's the Scat crank stroke and piston size your running ?

There's a delicate balance between compression and timing in a situation like yours. Sounds like the stock pancake distributer is not very good for what your doing.
Ronnieroadster
 
Ron_r1959 said:
Real curious what kind of gearing you have to run at 200 mph lol
Click to expand...

The gearing depends on the length of the coarse and if were running at sea level here on the East Coast or at high elevations like Bonneville.
Having a quick change rear axle allows us to adjust the ratios depending on a number of factors. So we always have a selection of gears from a high of 220 to a low of 280. Gearing is usually set so we pull 6500 in high gear at the timing point. The distance we run is always between 1 -1/2 to a max of 4 miles.
To get to 200 with a vintage engine under 300 cubes burning gasoline all it takes is horsepower and torque. :D

Ronnieroadster
 
Don't think I've ever seen a flathead with that high of a compression reading. especially with a Max#1 cam the chamber must be quite small.
Gramps
 
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