|10-19-2012 12:28 AM|
I believe you are right on the way the Accel unit works.
Time will tell whether it works.
My main interest is getting the idle leaner and adding at least 10 deg timing right in the idle range. This will bring back the mpg I have lost as this is how it originally worked before I blew out the vac diaphram.
Additionally I need to look at a way to bleedoff boost to the vac adv unit.
I have to check again how much vac there is under the carbs at full boost and in the 5000-5500 range. If it is less than 5 in I can just hook the vac adv to the carbs as the vac adv does not start until after this.. I have a cheezy check valve that is supposed to go to the vac modulator but I have not used it. The thing is just a tee with a ball check in the vertical leg. Pressure lifts it up and there is no pressure on the diaphram.
|10-18-2012 09:32 PM|
I have done the same bench test with a crane unit. Used a pump to see what the start of travel was in "hg and then what the end point was in "hg compared to turns out on the screw.
The crane unit always has the same length of travel on the actuation rod so the amount of vacuum advance added is the same for the entire adjustment range. Crane uses the limiter plate for a way to limit the amount added, accell uses a "one screw fits all" method and must have an end stop in there that is changed via the set screw, the screw must change the spring zero or start point at the same time it changes the limit of travel.
Two ways to skin a cat I suppose.
The advantage to the accell unit would be on an HEI application (if it does what they say it does). The crane limiter plate adjusts both the base timing (moves the reluctor static position) and the actuator rod starting vacuum in " hg (shifts the spring range up) as well as the limit when the plate is adjusted, it is mounted on the back side of the rod. When you adjust the limit on the accell HEI unit with the screw you are not changing the initial timing as it increases the allowable limit without moving the reluctor becuase the limit is on the front side or end of travel on the rod.
|10-18-2012 08:54 PM|
Looking at the Accel instructions...
1 turn out vac adv starts about 8in all in by 9in. about 3 crank deg.
9 turns out vac adv starts about 4 in all in by 11 in about 29 crank deg.
It seems to be pretty linear in terms of turns , deg, start point and end point.
Poor resolution on the instructin page.
The adjustment seems to be for motors with quite low vac at idle. It looks like you put this thing on and you will get most of the vac adv travel below 10 in except for the very long adv adjustment. This is all in by by about 11 in.
More than likely going from no vac adv to active vac adv will pick up vac and it simply will give full dialed adv when you plug it in.
I have a hand vac pump and gage so I'll give it a test before I install it tomorrow night. Assuming I don't do something stupid like I did the last time I installed the vac adv. haha
|10-18-2012 08:18 PM|
|10-18-2012 07:26 PM|
Thanks. I think I will get one of these too.
Why does it take an auto enthusiast to weasle a part number out of auto parts stores??
|10-18-2012 02:58 PM|
|10-18-2012 09:40 AM|
|10-17-2012 08:27 PM|
Got the adj vac adv today.
Quality leaves a lot to be desired. I spent about 20 min trying to get the allen wrench to engage the internal hex. Finally I tweeked the mounting bracket and gently forced the allen wrench into the socket. The internal guts seemed to be loose in that turning the allen wrench ccw as instructed only met with limited resistance then a "click." I wiggled the actuator rod a little and the internal guts seemed to take a seat.
From here I can adjust it as per the instructions. Sure hope this thing stays adjusted as it will be very difficult to reach once installed.
Made in the USA I think.
|10-16-2012 11:31 PM|
Well hitting AZ, NAPA, and O'reiley I came up with a blank. they could not find the unit I requested.
Gave up and ordered an adjustable vac advance unit. I did find the specs for it on the Accell web site. It is pretty fast acting in that it starts advancing at pretty low vac and is all in by 12-13 in at max deg of advance. About 1/2 way should work for my blower motor. I'm thinking about 10 crank deg to start and maybe work up to 15. I'm sure hoping to pick up the mpg I've lost since busting the original vac adv.
I won't get to try it untill the week end however. I have senior baseball practice both days so I'm going to be pretty worn out.
|10-09-2012 09:43 PM|
Thanks. Very informative article.
I think I found what I need in the list.
Since my vac at idle is relatively low, the B28 or VC 1810 is the one to use.
It's not recommended except for application with low vac and radical cams.
I'll order one this week and give it a try. Can't be any worse than what I have.
|10-09-2012 11:33 AM|
|10-09-2012 10:05 AM|
|10-09-2012 01:11 AM|
|bentwings||Cobalt....the units in the thread are for HEI...is there something similar for point style?? My MSD pro billet uses the point style.|
|10-06-2012 01:27 AM|
|cobalt327||Some applications are listed in the following thread: http://www.hotrodders.com/forum/cent...ce-177478.html|
|10-05-2012 11:04 PM|
What cars are these used on???
I just installed a new one from a high performance model and it doesn't even start to operate untill 10-12 inches of vac. at about 15 inches it is all in using a vac pump.
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