Powerplants > 301
My 301 NA Refresh Build
Nexus:
Not too much happening, as life interrupted, and I need to research the timing end of things before I put more of the engine together.
As is always in my life, something else more important always comes up and this gets shoved to the back of the line.
Something I followed, and not sure at this point if it's correct, is that I brought the #1 cylinder to TDC, pointed the timing dots toward each other, then rotated the crank so that the #6 cylinder was TDC, making it roughly 180 degrees (if I remember correctly) from where it was, and then added the timing chain.
I need to verify if this was the correct procedure, for my 301 and I need to find out If I really need a cam degree tool.
5th T/A:
It's been many years since I have done a Pontiac timing chain. Because of a disintegrating plastic coating on the cam gear, they would fail far more often than other makes. I did a lot of these on Pontiac V-8 and also the four cylinders on the early Tempest.
Bring the number one piston to TDC (front piston on drivers' side). The gear on the crank should have the dot at the top (12 o'clock) position. The dot on the cam gear should be at the 6 o'clock position. When you slide the gears on, both dots will be pointing at each other. When you are ready to install the distributor, you will have to rotate the crank until the number 1 cylinder is on TDC of the (compression stroke). When number 1 cylinder is at TDC of the compression stroke the dot on the cam gear will be at the 12 o'clock position.
Since these were street driven cars we never bothered with a degree wheel and never had any problems.
I'll see if I can find a written procedure in a shop manual or at least a picture of the gears properly installed.
tajoe:
Welcome back, Charlie. We can feel for ya with life's unexpected challenges.
I've heard many concerns about the proper way to install the chain and gears. One question I hear is "do I put both dots at 12 o'clock, or the crank gear at 12, and the cam at 6"? Which doesn't matter cause once the crank spins 1 revolution, the cam dot will be at 6 anyway, seeing the cam gear spins 1/2 speed of the crank.
Because of the keyways, you can only put the gears on one way. If you 1st install the crank gear onto the crank, then line it's dot up to 12, then drape the chain over the cam gear, with it's dot at 6 o'clock, you can begin installing the cam gear and chain, by rotating, and aligning the cam snout keyway, to the cam gear. Fortunately with the Pontiac V8, the crank gear is a slip fit, so once I have the cam key in the right position, and the crank gear also, I'll slide on the 3 assembled pieces, ensuring the dots are aligned once in place. It sounds more complicated than it is. Keep at it, when you can.
As far as degreeing a street motor, it just depends what your application is. The minor error in the aftermarket components won't be felt, seat of the pants. And degreeing is always a compromise. More advanced valve timing helps the bottom end, and just the opposite the other way. I've at times advanced my cams maybe 3°, to help with holeshots. Not that I've ever been able to tell. Mostly phycological.
Nexus:
--- Quote from: 5th T/A on July 04, 2023, 02:53:47 PM ---It's been many years since I have done a Pontiac timing chain. Because of a disintegrating plastic coating on the cam gear, they would fail far more often than other makes. I did a lot of these on Pontiac V-8 and also the four cylinders on the early Tempest.
Bring the number one piston to TDC (front piston on drivers' side). The gear on the crank should have the dot at the top (12 o'clock) position. The dot on the cam gear should be at the 6 o'clock position. When you slide the gears on, both dots will be pointing at each other. When you are ready to install the distributor, you will have to rotate the crank until the number 1 cylinder is on TDC of the (compression stroke). When number 1 cylinder is at TDC of the compression stroke the dot on the cam gear will be at the 12 o'clock position.
Since these were street driven cars we never bothered with a degree wheel and never had any problems.
I'll see if I can find a written procedure in a shop manual or at least a picture of the gears properly installed.
--- End quote ---
This is very helpful
Thank you!
Nexus:
--- Quote from: tajoe on July 04, 2023, 06:57:05 PM ---Welcome back, Charlie. We can feel for ya with life's unexpected challenges.
I've heard many concerns about the proper way to install the chain and gears. One question I hear is "do I put both dots at 12 o'clock, or the crank gear at 12, and the cam at 6"? Which doesn't matter cause once the crank spins 1 revolution, the cam dot will be at 6 anyway, seeing the cam gear spins 1/2 speed of the crank.
Because of the keyways, you can only put the gears on one way. If you 1st install the crank gear onto the crank, then line it's dot up to 12, then drape the chain over the cam gear, with it's dot at 6 o'clock, you can begin installing the cam gear and chain, by rotating, and aligning the cam snout keyway, to the cam gear. Fortunately with the Pontiac V8, the crank gear is a slip fit, so once I have the cam key in the right position, and the crank gear also, I'll slide on the 3 assembled pieces, ensuring the dots are aligned once in place. It sounds more complicated than it is. Keep at it, when you can.
As far as degreeing a street motor, it just depends what your application is. The minor error in the aftermarket components won't be felt, seat of the pants. And degreeing is always a compromise. More advanced valve timing helps the bottom end, and just the opposite the other way. I've at times advanced my cams maybe 3°, to help with holeshots. Not that I've ever been able to tell. Mostly phycological.
--- End quote ---
Also very helpful!!
thank you
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