How do I take the center plate off? Do I pull it off the top like the weights? If that's the case it seems pretty stuck on there. Any advice would be great, thanks.
On an hei dizzy you just remove the springs from the advance weights, and then remove a couple of tiny c-clips from the posts that the springs connected to. Then the plate just pops off. If you look at this pic you can see how the shape of the center plate is different on one edge vs the other edge. When the advance weights hit the center plate they stop advancing. This change in shape is how rotating the plate can change the advance limit. From memory the advance weights and center plate work the same way on the points style too.
Flip it over. Which ever side is facing up should face down. Feel free to put a dab of white out or something on it to make it easier to remember where you started incase you want to change it back. Think of it like a baseball card. If the picture is face up than flip it over so the stats are face up. And here's another pic to show the clips Go down to pic 22 http://www.chevelles.com/techref/techref5.html Again this is on an hei distributor. If you want info on the points type than I'll have to dig up pics of the chevy dizzy I have kicking around. Or stop being lazy and dig it out and pull it apart again
For some reason I don't have any clips on my center plate, seems to just be stuck on there with the two pegs sticking out. It doesn't even budge. I've gotten my total timing down to 36* though, which might still be a bit high with 8* vacuum advance. I don't know, I couldn't tell if it was pinging or not.
While you can remove the center plate on a GM HEI, I do not believe that is the case with the points distributor. I think it is braised to the shaft.
I was actually wondering that myself. I haven't looked at the one I have very closely to find out. I did remember that the advance kits for the points dizzy didn't have a center plate included.
Larry, I am just getting around to the engine, a stock 455. I have changed points and plugs, but it still seemed to lack power. I hooked up a vacuum gauge, set the idle screws out 2 1/2 turns, started it and dialed it in. Steady 18.5 at 1,000 msl on a hot day. I put on a set of gold springs from the Mr Gasket set I already had. (dist. is 1972 with 12-16 total mech adv.) Smooth idle and the car runs like a bat out of tire smokn, second gear scratchn hell (3.55 gears, TC, and trans go help) Two problems. The car is a little hard to start (turn over), but just a little. I am also running out of "steam" at higher rpm (3800 ish) at wot. No ping or knock, but feels on the verge. Without hooking it to a timing light ...do I have too much initial timing or too much vacuum advance or both? Also..the car will die if the vacuum advance is on manfold vacuum,but runs great on ported. Just trying to understand this without just setting it. (Crane adj. Vacuum is ordered.) I have pondered it, and think it is both..a little too much initial and too much total. Oh..bye the way..thanks for the thread!!
If you set the total timing at 32*, your initial timing might end up somewhere between 16 and 20*, and that is fine, but if the engine is hot, it may crank harder at that higher initial timing. It gets worse the hotter the engine runs. The only thing you can do is make sure all of your connections at the battery and starter motor are clean and tight, and use as thick a battery cable as possible. I like 2 gauge minimum. I also use one of Jamie's mini starters. It cranks the engine much better than the stock starter. sometimes with very light springs, there can be some mechanical advance in at idle speeds. When you throw it in gear, that timing can go away, which drops the RPM enough to stall the engine. The same thing can happen with vacuum advance. Hooking the vacuum advance up to manifold vacuum gives you as much as 18* of timing at idle. That requires backing off the idle screw to lower idle speed. Throw it in gear, you lose mechanical timing, and some vacuum timing, which lowers RPM, and the engine stalls. Once you set the total timing with light springs, replace those springs so all your timing is all in by 2500-3000 RPM. Make sure that there is no timing being added at idle speeds. You don't want the mechanical timing to start below 1000 RPM. That may take some mixing and matching of springs. Limit your vacuum advance canister to 8-10* maximum. You can try manifold vacuum or use ported vacuum, but limit the canister to no more than 8-10*. Use what feels best to you. With that distributor, you will end up with a lot of initial timing. The engine will like it. It can crank hard when hot though unless everything is fresh. If you want to use the stock starter, make sure you have the high torque 455 starter. The 350 starter will bolt up, and it has less torque. Or use a Mini starter.
Thanks, Larry! I will hook it up to a timing light next week when the Crane Vacuum kit gets here and then I will know for sure. Today I was guessing and playing with the vacuum guage. Just having fun and trying to understand it.
Larry, I have read this thread many times over the years. (It even has it's own bookmark) Sometimes it all seems clear as day to me, but then get overloaded with information. But, overall think I got it. For my '70 Riviera, I purchased an Accel adjustable vacuum advance canister #31034, and the Mr Gasket 928G spring kit that includes the bushing to limit mechanical advance. 2 questions. Even with the adjustable vacuum canister, I will still need to make up a limiter for it correct? I was under the impression that the adjustment you make using the allen wrench was adjusting the total amount of vacuum advance, but now gather it only adjusts the amount of engine vacuum needed to bring the vacuum advance into play. (earlier / later) Correct? Accel says to begin with the adjustment turned all the way counter clockwise, then adjust it by 2 turn increments clockwise until the engine pings, then back off. Do you have a feel from your experience as to how many turns clockwise I should use as a starting point? 4-6 turns clockwise? Also, the Mr Gasket spring kit does not include any instructions or info at all. I want to confirm that the black springs are the stiffest, gold medium, and silver lightest?
Dale, First, the Acell adjustable vacuum advance is NOT the same as the Crane unit. The Crane unit adjusts the amount of advance and rate of advance with two independent adjustments. The Acell unit adjusts both through the vacuum opening. When they tell you to start with the maximum counterclockwise adjustment, you are at the minimum amount of advance, about 7* I think, and the rate is the slowest. As you turn the adjustment clockwise, you add advance and quicken the rate at the same time. As far as the Mr Gasket spring set, I'm not sure which are the lightest springs, but you can certainly tell with a timing light, and tachometer by watching how quickly the total advance comes in. I remember years back that they did provide a chart that showed the difference in spring rate. I searched around and found the attached. If you notice, even the lightest springs don't get all the advance in until 4000 RPM. That's late for what we want. That is why I recommend the Crane kit, better springs. In any case, what you should do is leave the vacuum advance disconnected. Decide what total advance you want to run. Then set it, and get it all in by 2500-3000 RPM. Play with the total, and rate You can mix and match the springs). Test drive the car from stop, and at various speeds at full throttle. Determine what total works best, and feels best with no ping. Once you are satisfied, then connect the vacuum advance, and test for part throttle ping. Drive on the highway at 50 MPH, and apply moderate to full throttle. Adjust the amount/rate of vacuum advance to eliminate any ping. That's it.
Thanks Larry! I think I'll approach it in this manner to begin with. I should probably make up a limiter for that vacuum advance though.
For what it's worth, I'm also using the Mr.Gasket advance kit, and the chart they supply is worthless in terms of when the advance is all in. I ended up with one light and one medium spring, advance all in by 2200-2300rpms. Using both medium springs, full advance wasn't all in until well over 3k rpms. Just my two cents, good luck! :beers2:
Great question - I've got the same kit. My distributor is set up with two silver springs and is all in just over 3000 rpm. I'd like to swap in a light spring on one side and try to be all in by 2500. From what I've read, the black springs are supposed to be heaviest, yet they have the fewest number of coils...the gold are supposed to be the lightest, yet have the most number of coils Anybody have any clue which are the heavy springs?
A good article on various kits and how the springs affect RPM http://www.arkansaspontiacs.org/techstories/Recurvekits/recurve.html
I've emailed the company to try and get a solid answer on which color spring is what with the Mr Gasket kit because there is so much conflicting info I am reading online. Yesterday, I removed my vacuum advance canister, and made a limiter similar to the one Larry pictured in post #153. I set my initial at 12*BTDC. Seems real happy there. Installed the silver springs, which seem the lightest to me by feel. o No: With the vacuum advance disconnected, and using a dial back light, at 2500 rpm I have 22* total advance. Revving didn't take it any further. For the heck of it, I removed the mechanical advance limit bushing I installed earlier. No change. At this point I took it for a quick drive, and it ran ok. Hooked up my vacuum advance and it is adding 10* of advance. Went for another drive and it runs well enough for now, and pulls like a freight train. From a dead stop it frys the tires with no brake assist through 1st and 2nd. (Not necessary, but I just had to try it!) :Brow: I was going to see what the gold springs did, but was getting late in the afternoon and wifey was telling me there was beer with my name on it waiting. :beers2:
You should be able to tell the difference in spring rate, with a light, by simply observing how fast the advance builds.
Yeah, I know Larry. I will experiment more with it, but wanted a definitive answer from the mfg. Here is the response from Prestolite Performance regarding the springs in the Mr Gasket advance kit. "Black is the lightest (will advance the soonest), Silver is the medium and gold is the heaviest (will advance the latest)."
Which is the exact opposite of the Moroso kit - no wonder there's so much confusion! You think there'd be some standardization?
