69318satellite
Member
Hi there,
First I think it's important to mention that the FBO plate option worked for me, however I encountered a couple of issues along the way and thought it might help someone to know what I learned in the process. I also came across a thread that mentioned the FBO plate over advancing so here is my experience.
What I started with:
An angled slot cam like my 18 (x2) would advance far too much and too quickly to be used with the FBO plate, the numbers indicated on the plate are then way off but it sort of makes sense, they must be measured for straight slot cams. So I got a straight slotted cam from Halifaxhops whom I thank again for his help by the way.
Due to limitations with my throttle cable, I managed to get a satisfactory idle speed with 17 degrees of initial timing advance. I wish I could have advanced it a little more (maybe up to 20) but my bracket setup would not let me lower the idle speed any more and the car runs very well at 17 so that'll do.
With that done and the "new" 9 (x2) rated and unmodified distributor cam installed, I decided to give it a try with the 18 FBO plate slot for an expected total of 35 mechanical advance. I got actually 39 degrees total so the FBO was actually advancing 22 degrees instead of 18. I tried with the 14 slot of the FBO plate and got a total of 35 degrees total, pretty much what I was aiming for, so 14 on the FBO plate is actually 18 in my case. I would explain it by the diameter of the pins in my distributor being slightly smaller than some, even a tiny difference could throw it off.
Anyway, I then proceeded to verify that by measuring the pin diameter and thus the amount of travel allowed by each slot on the FBO plate and got the following results:
So that's it, I certainly don't blame FBO since I ended up getting what my engine feels good at (17 + 18 and a lighter spring) without having to do any welding on my cam.
I hope this can help anyone who encounters a similar situation.
First I think it's important to mention that the FBO plate option worked for me, however I encountered a couple of issues along the way and thought it might help someone to know what I learned in the process. I also came across a thread that mentioned the FBO plate over advancing so here is my experience.
What I started with:
- 318 bored .030 over
- Comp cams XE256H-10
- original single point Chrysler distributor
- initial timing set at zero, total mechanical at 36 degrees thanks to some crazy angled slot distributor cam
- no vacuum advance canister
An angled slot cam like my 18 (x2) would advance far too much and too quickly to be used with the FBO plate, the numbers indicated on the plate are then way off but it sort of makes sense, they must be measured for straight slot cams. So I got a straight slotted cam from Halifaxhops whom I thank again for his help by the way.
Due to limitations with my throttle cable, I managed to get a satisfactory idle speed with 17 degrees of initial timing advance. I wish I could have advanced it a little more (maybe up to 20) but my bracket setup would not let me lower the idle speed any more and the car runs very well at 17 so that'll do.
With that done and the "new" 9 (x2) rated and unmodified distributor cam installed, I decided to give it a try with the 18 FBO plate slot for an expected total of 35 mechanical advance. I got actually 39 degrees total so the FBO was actually advancing 22 degrees instead of 18. I tried with the 14 slot of the FBO plate and got a total of 35 degrees total, pretty much what I was aiming for, so 14 on the FBO plate is actually 18 in my case. I would explain it by the diameter of the pins in my distributor being slightly smaller than some, even a tiny difference could throw it off.
Anyway, I then proceeded to verify that by measuring the pin diameter and thus the amount of travel allowed by each slot on the FBO plate and got the following results:
- slot number 10 on the FBO plate = .334" travel = 14 degrees
- slot number 12 on the FBO plate = .354" travel = 16 degrees
- slot number 14 on the FBO plate = .374" travel = 18 degrees
- slot number 18 on the FBO plate = .414" travel = 22 degrees
So that's it, I certainly don't blame FBO since I ended up getting what my engine feels good at (17 + 18 and a lighter spring) without having to do any welding on my cam.
I hope this can help anyone who encounters a similar situation.
