I'm getting ready to assemble my 464 and have a question about degreeing the cam. Here is a run down of the cam card: EX CLOSES 30* A TDC EX OPENS 70* BBDC IN OPENS 28* BTDC IN CLOSES 52* ABDC Lobe Separation 106* The card says the Centerline is 102* it says "The above center line will make this cam 4* advanced. 260-280 @ .050, .604-.603 lift Should I put the cam in "straight up (0)? This is a 12.2-1 464 with aluminum Stage II heads (no porting til end of season), TA SP1, 1090 Dominator, 3900 stall, 4:10 gear, 3900 lb GS. Thanks! Tom Jenkins
Tom, I'd put it in at the 102 center. Like the card said, this will give you 4 degrees advance. Now... what you have to do to get it in at the 102 center is a different story. If the cam already has 4 degrees ground into it then I'd start by putting it in at zero and adjust from there. If the cam doesn't have any advance ground into it, then you'll have put it in 4 degrees advanced and adjust from there. If you wanted to try the cam 2 degrees advanced then you would going for a 104 center. The motor may or may not even know the difference. I have my 308s (lobe sep. is 106) at 2 degrees advanced. Someday I'll try 4 degrees and see which way works better. Sounds like our cams are pretty similar. Just be very careful with your setup and try and be as accurate as possible. If you using a smaller wheel then make sure your head is in the same place when you take you readings. I've known people that would take a reading several degrees off just by moving their head. I like to take a reading .020 on each side of the intake lobe center and then split the difference for the centerline. Give me a call if you need to (937)431-3916. Good luck
Since I designed the cam Tom is using, I know a little about it. It is ground 4 degrees advanced with the intake lobe centerline at 102. This puts the lobe centerline at 106, obviously. My suggestion is to install the cam straight up, but degree it in. Every 9 way adjustable timing chain I have seen are off. It's not unheard of to have to skip a tooth to get a cam to degree in properely. 3900 stall needs to go up to around 4400-4600 which you can get with a good nine inch. Perry Carlini
Perry, I like your cam choice for this combination. I think most of the camshafts run by our Buick friends are a bit on the large side therefore down on cylinder pressure. From what your saying it sounds like this cam has a lobe seperation angle of 106 degrees. And if put in straight up (eventhough there is 4 degrees advance built in) would still have the intake centerline of 106 degrees ATDC and the exhaust centerline of 106 degrees BTDC. Eventhough the cam has 4 degree advance built in it can still be degreed in at this point. Or Are you suggesting to Tom to put the camshaft in at the suggested 102 degree intake centerline which would be an intake centerline of 102 degrees ATDC and the exhaust at 110 degrees BTDC centerline? I think I know where you want the cam but just trying to clarify what your asking Tom to do. Tom, It will be interesting to see what kind of cranking compression this engine will squeeze. My guess is right around 215 to 225 psi per cylinder. If you get a chance after the engine is broken in could you check the cranking compression? Your gonna make some nice power with this combo. Then when you get those heads ported.... LOOOOK OUT!!! Good Luck
Sorry....I should have said to install it with the intake lobe centerline at 102 and the exhaust at 110. With 4 degrees advance built in and lobe sep at 106. I had the same cam in my car for a few years, although I originally designed it for my good Stage 1 heads (note the duration spread). Even though this cam was not designed for Stage 2 head flow, and in a last ditch effort to get to the Nationals a few years ago, I put my old motor together with this cam and my new AM&P Stage 2 heads. Knowing it wasn't the "right" cam for my new combination, I didn't expect too much. Still went a best of 10.16. I would suggest to Tom that when he gets his heads ported, a better cam can be made. Perry Carlini
Perry, I am certainly no camshaft expert but I am finding that more and more of the camshaft experts are suggesting to run larger duration splits eventhough you have a 75% to 80% exhaust to intake flow. I have always heard to keep the durations close to even in this situation but lately this trend seems to be changing. You do more work with cams than I do Perry so have seen this trend? If yes, what are the real advantages? Take Care John
Thanks Guys! I'm going to have to put it together with the iron heads for now. The aluminum heads wont be ready to ship from TA until late July or early August. I'm still trying decide between Stage 1 or Stage 2's Tom Jenkins
What should I do? I finally got around to working on this thing again. I ended up with 101 on the intake and also checked the exhaust and came up with 109.5 Should I leave it alone or advance it 2*? If so, how do I do this with the 9 way set? If I put the crank gear at 2* advanced where should the cam gear dot be? I put the crank gear at 2* advanced and lined up the dot from the cam gear and #1 was not at TDC. Should I advance 2* or just leave it alone. Thanks! Tom Jenkins
I'm getting 2 different results. If I go to highest lift, rotate engine counterclockwise (backwards) to .100 then go to .050 (to get slack out of chain) to get 1st reading and go to .050 after highest lift for 2nd reading I get 101* (suppose to be 102*) If I only turn engine in clockwise direction and take my readings at .050 before highest lift and .050 after highest lift I get 104* (suppose to be 102*) Help! Which should I trust? Why are my results different? Which is the proper procedure to degreeing a cam? Should I leave it alone because my results are close to the 102* I should have? Thanks! Tom Jenkins
I would only rotate the engine in the direction of normal rotation. That is how it will normally operate. I think by turning it back and forth, you introduce error due to the slack in the chain.
