Has anyone used the Moroso HEI mechanical advance kit? The center plate shape and new weights are supposed to limit the total mechanical advance to 23 Deg. It seems like this kit would be a better option than welding up slots. Apologies if this has been covered. I didn't go back and re-read all of the posts. A search of the thread for "Moroso" only turned up one post that wasn't related to this question.
Mike, If it does in fact limit the mechanical advance to 23*, that would be great. I can't find anything on it that definitively says that though. http://performanceparts.com/part.php?partID=4581
Hey guys, I'm a new member here and happen to have a distributor machine and I'm an ex-machinist. I would be interested in helping members of this site out by recurving their distributors. I can set/modify/limit total advance and adjust curve rates on non-HEI distributors and should be able to HEI's soon. Any interest? Dave :beers2:
Dave, I'm sure there will be interest. A lot of stock distributors have entirely too much mechanical advance built into them, especially the HEI's. The 1969 distributors have 30-34* in them for TDC initial timing. I figure 20* is optimal. Maybe you can advertise your services in the Vendors Forum.
Here's the chart from the Rev "A" instruction sheet for the 72300 kit. At least for the one I have, the chart on the back of the package is a little different with a max of 23 deg, and it didn't have a separate instruction sheet. I just noticed that the back of the package has a disclaimer that the instruction sheet doesn't. "**Note: THIS CHART IS FOR REFERENCE ONLY: Actual advance can vary greatly due to differences between the location of the weight pins, the weight's drag, magnetic pickup, ignition module and other variables." I've got this kit in the distributor of my 3.8L and I'm getting the advertised 23 Deg at ~2400 RPM. I don't have any mechanical in at 800 RPM even with the lightest springs. Looks like YMMV though. Chart 2 is what was on the back of the package.
Yes, I've seen that before. All I can say is to make sure it stops advancing beyond that 2400 RPM. If it does, you're good, if not, you'll have problems.
I'm not a vendor I would do it for free just as long as the owner paid shipping. It's easy to limit total so you can run more initial. But I will also post in Vendors as your suggestion points out. Dave
thanks larry. you are helping a lot anthousiast hobby mechanics al over the globe,:Smarty: greetings from belgium, i will use your verry nice explaned info on this. :beers2: :beers2: :beers2: :beers2: :beers2: :beers2: :beers2:
Some great information about the mechanical advance in an HEI. Posted by Dave Ray on Buick Thunder: http://buickthunderforum.com/viewtopic.php?t=881
A big thankyou to Larry for this thread :TU: I run my 72 Riv on LPG (Liquid Petrolium Gas) which is a dry fuel and burns very differently to petrol (US gas) which is a wet fuel. LPG needs more initial timing, and less total, and most people who convert just turn the distributor to get the initial right and tell you how great it runs, but only a few admit that it all goes pear shaped when they go above 2500rpm, so us guys running LPG probably need this thread more than most. ( LPG timing details here ) As thanks for all the good info and to hopefully contribute something usefull myself, I have made a PDF of the timing marks for the balancer based on the details given in this thread, print it on a sticker and put it on your balancer. Just remember to print it with NO scaling Again, a big thanks to everyone. OzBro
Eppoh (Stefan) sent me these photos of his vacuum limiter. Just another way to accomplish the same thing. Limit the pull pin distance to limit the amount of degrees. Stefan used the links from a bicycle chain.
I agree. The new mallory 75 series HEI distributor has fully adjustable Vacuum and mechanical advance with built in under the cap mallory hifire with rev limiter. i will update on another post http://v8buick.com/showthread.php?t=153968 when i get some results at the track but it is real easy to work with.
ok, my turn I have a 72 century 350 motor in my full sized jeep, its been running horrible for some time now but I mostly drive it in the winter and it really likes the cold air, not so much in the heat. I bought a small little boat yesterday and towed it about 120 miles home in the heat of the afternoon, and in the end it was touch and go if I would get home. The detonation and overheating climbing into the hills out of the central valley was horrible. Thats one tough little motor, got me home and died in the driveway due to wickedly hot intake boiling the gas out of the carb and vapor locking the motor. Pour a bit of water on the intake and it quickly boils and evaporates away. temp gauge saw sustained 230* and bouts with 250+. not good. So I went down and bought a fancy new Equus 5568 dialback timing light today and am committed to getting this sorted out into an enjoyable driving truck. Currently the large cap HEI has the Crane adjustable vacuum advance kit in it with silver springs (not sure if they are the ones that came with the crane kit or not, I dug the other springs out of the back shelf and there were silver ones in with the blue and gold as well). IIRC I installed some new weights, the ones in there are marked 105 and 105 (could be 103 on one of them, the edge of the # stamping is cutoff) on a 482 center post. can't recall why I did that. I have a 30* mark that I put on the harmonic. did my reading on the site prior to going out today, hooked the timing light and a vacuum gauge up, disconnected and blocked the distributor vacuum and started the truck. these days the truck requires a squirt of ether to start cold, but once warm it starts fine. today was no different even thought its an even 100* out. drove it around the block to get it warmed to its normal 190* (180* thermostat, a 160* is on the bench seat waiting to go in 'soon') initial numbers: 12-14* @ 720 rpm, 16" steady vacuum adjusted the dizzy to get 2* @ 670 rpm, 16" steady (no jumping around at all) and locked it down Then I started screwing the idle adjustment screw in and learned to use the dial back feature - btw the combo tach/dial back degrees readout on this light is money, a great feature. recorded these numbers as I went along: 1k rpm +8* dial back to get to the original 2*, 16" rock solid vacuum 1260, +10*, 18" 1530, +12*, 18.2" 1780, +16*, 18.6" 2060, +16*, 18.8" pleased that vacuum needle was so solid thru out, but it seems that my total advance is lacking and I'm all in (fwiw) at or before 1780. If I'm understanding the info on the site that I've been pouring over all day I have 2* initial advance, 16* centrifugal advance for a total of 18* advance - I'm well away from my target of ~32*. I'm not sure where to go next - all suggestions very very appreciated. Let me know if I should open a new thread with this info or if this is ok to tag on to this one
continuing to try things, installed the yellow springs and picked up 2*at 2050 rpm. according to the crane docs the yellow should have 100% of the advance available in by 1600 rpm at this point my thought is that its either a blocked plate preventing the advance from fully coming in, or a problem with the weights. not sure what the full range of movement of the plate should look like but that's where I'm off to next
First, when you dial back, you dial back to 0 on the tab, not 2*. At any RPM, dialing the mark back to 0 will enable you to read your advance off the dial. If you want 32* total, all you need to do is turn the dial to 32* With the distributor just loose enough to turn, aim the light at the timing tab. You should see the balancer mark (NOT THE 30* MARK) just below the timing tab. With the yellow springs installed, rev the engine to 2000 RPM, or until the mark stops moving up. Have someone hold the engine at 2000 RPM. Turn the distributor until the balancer mark lines up with the 0 on the tab. Tighten the distributor down and let the engine return to idle. Recheck the timing. As you rev the engine, the mark should move up from below the tab, to the 0 on the tab and stop. You now have 32* total timing. Your initial timing is whatever it needs to be for that distributor and 32* total. If you want to know what the initial is, put the heavy springs back in, run the engine at a normal 700 RPM idle. Point the light at the car, and dial the balancer mark back to 0. Look at the dial and read your initial timing. The yellow springs are very light and will allow some mechanical advance in at idle speeds. They are great for setting your total, but they are too light for everyday driving. I suggest 2 silver, or a silver and blue, or a blue and yellow. See what you like best. Now, limit the vacuum advance to 8-10* maximum. Until you do that, leave it disconnected. If you run it, the motor will over advance at part throttle. The engine will surge and ping at part throttle. You must limit the cannister. Look at the pictures in the first post. That is the correct way to do it. Forget what it says in the Crane instructions. You need to drill and tap a hole in the advance cannister arm, and mount the limiter cam ahead of the pull pin. Hope that helps. Any other questions, don't hesitate to ask. The 30* mark is for use with a plain timing light, not a dial back light like you have. Use the original balancer mark for timing adjustments with your new dial back light. BTW, you are running either retarded, or over advanced, which will make the engine run very hot. When you get the timing staightened out, it should cool down quite a bit.
I thought that you dialed back to get to the initial timing value, but ok, makes sense. Won't that negatively affect my initial timing? Guess I'm confused then, I thought what I was doing was setting initial at 2* and then using the springs to adjusting what rpm all the advance came in at. If I want set the timing mark to 0 @2000rpm with 32* in the light by spinning the distributor to the factory mark on the balancer then I've also changed the initial timing haven't I? ok, I'll do this as the next step I have had the limiter plate installed, I pulled it out yesterday to get thru these tests. once I get through this initial setup I'll reinstall it. i added the 30* mark long ago before I had the dial back light, I'm using the original mark as the reference. off to set 32* and see where I go, thanks for the reply
Mike, Dialing back to 0 enables you to read your timing at any RPM. You shouldn't worry about your initial timing at all right now. Your engine doesn't run at the initial timing while your driving down the road. Yes, you in all likely hood will change the initial timing. Hopefully, it will be quite a bit more, because 2* is not where you want to be. 12*+ will make the engine idle better, and run cooler at idle and low speed. Different distributors have different amounts of mechanical advance built in to them. THEY ARE NOT ALL THE SAME. The amount in yours determines where your initial timing will be with the amount of total advance you wish to run. We don't know that right now. All the springs do is change the rate of advance, not the amount. Once you set the total up with the yellow springs, then put the heavy springs in and see where your initial is. Then subtract the initial from the total, and you will know how much mechanical advance is in YOUR distributor. Higher initial timing is desirable UP TO THE POINT WHERE THE ENGINE BECOMES HARD TO CRANK WHEN HOT. (forgive the caps, I'm not yelling but using them for emphasis:TU: ) The center plate and weights in an HEI change the amount of advance. See what you have. About 20* of mechanical is about perfect. Then with 12* of initial, you'll have 32* of total advance. If you bump the initial up to 14*, you'll have 34*, 16 and 36*. You may have more or less mechanical advance. It is very important to use heavier springs to see where your initial advance truly is, the light yellow springs will allow the weights to swing out even at idle speeds. Hope that helps. After you get the total sorted out, limit the vacuum advance cannister to 8*-10*. Then run it to a manifold vacuum source. It will give you extra advance at idle and low speed and allow the engine to run cooler in that desert heat.
k, here are the results of this mornings battle: put in yellow springs to make sure that all the mechanical advance was in by the time I hit 2krpm. set light to 32*, cranking the idle screw up to 2.2k rpm, timing line was way below, had to turn dizzy counter to bring it up, got it set at 0*, turned motor off, clamped dizzy down, started back up to recheck, still at 0* shut down and installed blue springs to check initial, turns out initial is 17* so reading your info above my total mechanical advance available is 32-17 = 15*. is that enough?? no prob on caps, taking it in the spirit offered! so do I want to proceed on to the limit plate, or figure out how to get more mechanical available?
