I understand power timing my 462 motor. And just for your info, there's an awesome article on this site by Mr. Larry Hymowitz about power timing the big block. I'm running a stock points distributor so I'll be using the Crane vacuum canister/ spring kit in my distributor. My problem is that I only want to run a max of 8 degrees of vacuum advance timing. with the Crane canister, they tell you to bottom out the set screw and run the car and adjust it two turns at a time until the motor stops pinging! I'm not gonna do that! Surely, one of you guys knows how many turns it takes with the 3/32 allen wrench get the canister to limit the total timing to 8 degrees. Please help me out on this! Thanks, Jim
I would assume that since you are instructed to turn the set screw all the way in (clockwise), that would be the setting for the largest amount of additional timing. I would also assume that turning it all the way out would decrease the amount of additional timing. How many turns can you back the set screw off (turn counterclockwise)? And...will the set screw actually fall out if you turn it too much? Thanks, Jim
The setscrew doesn't set the amount of timing from the canister, it set the vacuum level at which the timing comes in. There should have been a small black plate with notches on it that comes with the kit. The plate goes under a screw holding the vacuum advance to the dist. at the rear. Different notches hold the vacuum advance arm at various positions and limit the amount of advance it can kick in. Your best bet is to go to a GOOD NAPA and have them look up a '60 HiPo 396, Vette or Chevelle. That will be a good one with only 8 degrees total. VC680 may be the number but don't quote me.
Mike is correct, the vacuum nipple adjustment sets the "vacuum rate" There is a spring inside the canister that opposes vacuum pull. What you are doing is adjusting the pre load on that spring. The stronger the spring tension, the faster the vacuum advance will pull out when you jump on it. This allows you to adjust out part throttle ping. It also allows you to adjust for different cams (vacuum advance starting point) The cam they supply limits the amount of advance in the canister. The instructions call for attaching the cam to the forward mounting screw. The notches in the cam contact the link as you turn the cam. This pushes the link further into the canister, so you are starting from a different point in the link travel. As you push the link further into the canister, there is less travel left, and less total vacuum advance. There are 2 disadvantages to this. One, every time you rotate the cam 1 notch, it advances your base timing 2*, and that adds 2* to your total timing. Two, it also tightens the spring pre load at the same time. A better way is to mount the cam ahead of the link, so that it restricts the amount the link can move into the canister. This entails drilling and tapping a screw hole. This allows you to adjust amount of advance, and rate independently. Pictures courtesy of Dave Ray (The Ignitionman)
Mike and Larry, Thank you both. You both gave me valuable information. I think I'm gonna try to find the hipo Chevy cannister and give that a try. Once again...thank you both, Jim
Looked on www.rockauto.com, and did a google search. Came up with these numbers for the vacuum advance Mike suggested. B28 High Perf. 3-5 8 @ 5.75-8 NAPA/Echlin VC-1810 Niehoff DR-305 Borg-Warner V329 Standard Motor Products VC-177 This might be the next closest option: B20 High Perf 5-7 8 @ 11-13 (same as B26 VC1808) NAPA/Echlin VC-1765 Niehoff DR320 Borg-Warner V375 Standard Motor Products VC-181 AutoZone,#DV1810. AC Delco #D1312C, GM part #88924985. http://www.autosupplyco.com/searchitem.epc http://www.autosupplyco.com/item.wws?sku=VC-181&itempk=1836968&mfr=STANDARD MOTOR PRODUCTS&weight=5
For everyones info, I went online and coincidentally found a web site www.chevelles.com with an OUTSTANDING ARTICLE about vacuum advance canisters, there part numbers, applications, and detailed explanation. The article was written by 69SSRAT(Tech Team) and was under that sites "performance" section. Basically, what it says is that the most applied canister for performance applications by Chevrolet was the "B1" can or NAPA part# VC-680. That canisters specs are 8 - 11 8 @ 16 - 18 The second canister for lower idle vacuum performance applications was the "B28" or NAPA part# VC-1810. That canisters specs are 3 - 5 8 @ 5.75 - 8 For those that might be interested, you need to look this article up and read/copy it as I did! ITS A MUST READ FOR YOU TRUE MOTOR HEADS!!!!
