Due to a lobe issue, I am replacing the cam shaft in my 1970 Buick GS 455 from a Comp Cam 218/218 with a TA performance 284-88H cam. Upon removing the old cam I was very careful to leave number 1 cyl on TDC with the rotor pointing to the number 1 slot of the distributor before removing the timing cover. Here is a 'before' picture of the timing chain showing the horizontal lineup of the bolt(note, this picture is really not clear enough to show the timing mark on the crank shaft, but the cam sprocket mark is pointing a little to the right of 6 oclock ) Here is another 'before' picture that is better in showing the timing marks circled in red. Here is the last 'before' picture showing the sprocket removed with what I call a half moon on the top side. (I had to rotate the cam slightly to get the sprocket off the cam shaft and did not realign it horizontally like the first picture shows) Here is a picture of the new cam shaft installed prior to putting on the sprocket The last picture is with the cam sprocket installed and timing marks are lined up at 6 and 12. For the most part the cam sprocket bolts are 'almost' horizontal. My observation was it seemed the 'half moon' straight part of the cam shaft was horizontal and on the top of the cam when I looked at the old one to compare this when installing the new cam. I've looked thru many forum appends discussing cam shaft replacement and haven't seen anything about this 'half moon' observation. I need some help if my observations are correct or wrong in this cam replacement before I go much further. Does this look ok?
Short version is you cant compare the old cam and position to the new one.. it has to be degreed. Many aftermarket cams arent indexed to a factory (or any other cam grinder's) spec , and just kinda land where they feel like it.
The exact location of the flat on the camshaft is not relevant to cam position, as was previously mentioned. It is normal that if the cam was indexed properly, the attachment bolts to the timing chain would be straight across from each other, and perpendicular to to the cam/crank centerline. You either degree the cam, or hope someone ground the cam correctly. I would put your timing chain on 4* advance, if we are going to assume it's ground correctly. I would like to take a nice hefty 54MM Tomahawk camshaft, find the person that started the "run it straight up" lore when it comes to camshaft timing, and beat them about the head and neck area. More guys have suffered from that advice that probably just about anything else. Once in a great while I will find a wilder race motor that runs better up high with the cam at zero, or maybe retarded a degree or two, but even that is not common.. NO street setup, using that timing chain, wants to be in "at zero".. Remember, the factory timing set has 4* advance built into it.. the rollmaster set does not, so you ARE NOT duplicating how it was set at the factory, by "lining up the dots". That lower gear has 9 keyways, the best odds of correct timing are the 4 or 6* A positions, speaking as someone who has installed and degreed well over 100 of them, in this engine, using this chain, from this cam provider. That said, degree it, instructions are on the board here. JW
Thanks for the comments so far. I appreciate them as I have a lot to learn. I looked at the Camshaft degreeing 101 and have a few observations. It appears the best way to do the degreeing is with the 'heads off'. Has anyone done a camshaft degreeing with the 'heads on' technique by using a piston stop to find TDC? Can anyone recommend a specific camshaft degree kit for a Buick 455 that they have purchased? I see this one: COMP Cams Camshaft Degree Kits 4936 https://www.summitracing.com/parts/cca-4936 However, in the comments it had: Crank socket will not work on Buick 430 and 455 engine.... So, you need to find a different crank turning socket..I see this that might fit: Summit Racing™ Crank-Turning Sockets SUM-G1062 https://www.summitracing.com/parts/SUM-G1062 thoughts?
I would think the crank/balancer bolt and a suitable breaker bar would be all you need to turn the crank. It doesn't have to be tight as it will only tighten until the crank starts to turn. Heck, use the balancer and bolt a piece of drilled flat steel to it where the crank pulley goes.
there are no crank sockets for Buick cranks, I had to modify a pontiac unit. But the crank bolt method works just fine.
