Question on cam gear marks
- Thread starter Russ/40
- Start date
Ive been thinking , what kind of cranking noise does it make with no spark ( removing coil wire ) is it the same strange cranking ? If not check for cap problems , carbon tracking offset internal posts , etc . If it does still crank strange, remove one plug at a time and with no spark , crank . Replace that plug and crank until you hopefully find one that stops the strange cranking . If one plug improves it but doesn’t eliminate it , mark that cyl and see if any others also improve it but doesn’t completely eliminate it . Then remove all the plugs that improved the cranking . Hopefully theres only one maybe 2 . Then its at least narrowed down .
Good luck , i hope this testing process makes sense ,
Gary
Russ/40
Well-known member
Gary, with all plugs removed it cranks like any other flat v8. When running, I have removed ignition from each plug and checked how it reacted and with throttle. All seemed to respond in a similar manner. Thanks for thinking about my problem. I'm putting it aside for a few days to put my thoughts together.
Brian
Well-known member
Russ, I've been following this thread. A bit hard to diagnose over the computer. However, the first thought I had, I haven't seen it mentioned, but a very useful diagnostic tool is a vacuum gauge. Such a device can be handy for pinpointing late valve timing, sticking valves, ign timing, etc....Can you possibly run it with a vac gauge hooked up?
My other thought; a blown out heat riser in the inlet manifold.
Good luck, Brian
My other thought; a blown out heat riser in the inlet manifold.
Good luck, Brian
Russ/40
Well-known member
Hi Brian, the engine is partially torn down for visual inspection. I'm considering pulling the heads so i can check the rings for broken. When putting some of the pistons in, i had a problem with the multi-piece oil rings catching the upper detent left from pulling the original sleeves. I ended up using a thin wall steel sleeve as my ring compressor after putting a knife edge on the sleeve to get past that ridge at the cylinder top. This has been the "Engine from hell" since the very beginning. It was originally built by a shop, and I found a lot wrong with it, including a cylinder crack they missed. I put a low mileage 8ba crank in this '41 block at 3 3/16ths with std bearings with the intent of makeing a decent backup motor.
I really am interested in your blown heat riser suggestion. I will check that!
I really am interested in your blown heat riser suggestion. I will check that!
Automotive Stud
Well-known member
I think you may have made an obvious mistake that nobody has caught yet. The timing marks on the cam and crank gears line up when the piston is at the top of the cylinder and the cam is at the beginning of the cycle, before the intake valve opens. The spark plug firing at TDC occurs at the end of the second stroke of the piston, so TDC for firing purposes occurs when the crank mark is straight up and the cam mark is straight up also. Look at this illustration and note that the colored wheel represents the camshaft. I don't think your cam is in wrong, I think your firing order is way out.
Edit: I was hoping this gif would be animated. You can see it move here: https://www.google.com/url?sa=i&url...ved=0CA0QjhxqFwoTCIi2jrrG8OsCFQAAAAAdAAAAABAD
Attachments
Last edited:
Ronnie
Well-known member
This a cut and paste from Gofast 2017 Works well one turn of the cam and done.
R
Easiest method we've found is follow the firing order, set both valves on that cylinder that would be firing!
Two complete turns of the engine, you're done. Doesn't get any easier!
Thanks, Gary in N.Y.
P.S. This method will allow you to double-check the valves already set by spot-checking all the previously set valves. If any change is felt on any already adjusted simply re-set it at that point! __________________
R
Easiest method we've found is follow the firing order, set both valves on that cylinder that would be firing!
Two complete turns of the engine, you're done. Doesn't get any easier!
Thanks, Gary in N.Y.
P.S. This method will allow you to double-check the valves already set by spot-checking all the previously set valves. If any change is felt on any already adjusted simply re-set it at that point! __________________
v8nut
Senior Member
I have posted a pic of the cam and cam gear marks on my 1935 21 stud.. I took this picture after a very bad experience with this engine. As you can see the mark on the cam is very small and hard to see if you don't know what you are looking for. Earlier my engine rebuilder had an apprentice assemble the engine. He didn't know what he was doing and assembled (pressed on) the cam to cam gear miles off the the correct spot. Of course the engine did not run and it didn't take too long to figure what the problem was. As you probably can imagine it was a lot of work to fix it. I was not pleased. At some point later the design of the cam to cam gear assembly was changed to preclude the ability to make this mistake. Jim in San Jose
Attachments
Bored&Stroked
Well-known member
Checking the cam timing with a degree wheel is never a bad idea - I always do this. BUT, unless the cam is manufactured incorrectly (or you want to alter the timing), and both gears are correctly manufactured, then all you do is put the crank in first, with the crank gear timing mark straight up, then put the cam in so the mark on it's gear aligns to the crank gear. Assuming you have a bolt-on cam gear, there is really nothing to think about as far as where the valves are located . . . just align the dang marks. As the cam gear is indexed to the cam bolts, it can't be installed incorrectly - so if the cam/crank gear marks are aligned, then you're good to go.
Validation: You can then install both valves on #1 cylinder, figure out where TDC is (you'll need a way to create a timing pointer and mark the crank pulley), then you can use a degree wheel and validate the cam timing. It is NOT uncommon to find that some of the aftermarket performance cams grinders - do not deliver cams that correctly match their timing tags. Even worse, in some cases you can't even advance/retard the cam to get them to a correct timing - as the lobes themselves are "off".
Validation: You can then install both valves on #1 cylinder, figure out where TDC is (you'll need a way to create a timing pointer and mark the crank pulley), then you can use a degree wheel and validate the cam timing. It is NOT uncommon to find that some of the aftermarket performance cams grinders - do not deliver cams that correctly match their timing tags. Even worse, in some cases you can't even advance/retard the cam to get them to a correct timing - as the lobes themselves are "off".
Automotive Stud
Well-known member
Right, but if he also set the distributor at #1 TDC at this point, that's wrong. Both timing marks should be straight up, not facing each other, at the firing point.
Bored&Stroked
Well-known member
Not to be a pain, but have you worked on one of these early flathead engines?
The end of the cam has a t-slot in it, that is offset, so the distributor can only go on in one direction, it cannot be 180 degrees out of time, unless you incorrectly force it into the slot, which will break the casting when you turn it over. Ford made this stuff really simple -- if you aligned the timing marks on the gears, then you should be good to go - as the distributor can be taken on/off the vehicle and the timing does not change - due to the indexed/offset t-slot. Hope this helps!
B&S
Automotive Stud
Well-known member
Not to be a pain, but have you worked on one of these early flathead engines?
Ford made this stuff really simple -- if you aligned the timing marks on the gears, then you should be good to go - as the distributor can be taken on/off the vehicle and the timing does not change - due to the indexed/offset t-slot. Hope this helps!
B&S
I read too quickly, I saw 8ba rotating assembly in his initial post and assumed 8ba type distributor also.
Yes that is correct, same as anything else.
Ronnie
Well-known member
Automotive Stud You are thinking the flathead tdc when cam is first in that it the same as what happens with a small block chevy. They are not the same. When marks are set up with a small bloc that is at tdc #1 cyl is at tdc exhaust and tdc #6 is at tdc compression. In a flathead when marks are at 6 cam and 12 crank the engine is at tdc compression # 1 no need to do anything.. In a small block some turn as you say to put it at #1 tdc compression that is up to the builder. That isn't really required if the dizzy is installed with the rotor pointing at #6 as the engine is already at compression on 6.You can wire starting with 6 and carry on from there or turn engine till rotor lines up with #1 and start plug wires from there.
R
R