"Just using 2 very different spring tensions will have this effect somewhat". That's what I've been told too Larry.
I see. Devon my car is laid out right now with no rear end Im swapping out the the stock gears and peg leg and rebuilding my rear end with a posi unit and 3.73 yukons that I got from monzaz:TU: .So i figured that since this is going to be a major change to my car from the 2.73's that I would need to fine tune it all over again and I want to try and dial it in just right. Like I said in my earlier post I thought timing was just stab it get it to where it sounds just right and plug in the vacumn andvance. Larry I was looking at the unilite distributor instructions online it says that most off them come with 24 degrees of mechanical advance between 3000-3200 rpm. So if im understanding everything right I want to adjust it and try and get it so I get all of the total mechanical advance at about 2500rpms?o No: Im so lost lol:shock: I did not know that timing affected everything so much. Oh and I also have the hyfire ignition box is there anything I need to do to the box with doing the adjustments to the dizzy? Thanks guys for helpin me learn this Russ:beer
Russ, I attached a PDF of the Mallory advance kit instructions to a prior post of mine. I linked that post a few responses back. If you don't have that kit, it is well worth getting it. The instructions are very explicit, and the mechanical advance is easily adjusted. Changing the RPM is easy, you just change springs. Adjusting the amount of mechanical advance depends on which style of Distributor you have YH, or YT. If you read the instructions, you will be able to tell by looking at the pictures which style you have.
Larry, I want to re-curve my distributor. I think I read your first post about 5 times until I was sure to understand exactly what I have to do. I got me a timing light today. Does it depend on the application to know which springs to put in? For example: Is the weight of the car important? I have a Centurion. The short block is untouched. Just a K&N filter, Performer intake, ported exhaust manifolds, dual exhaust..... Normal street mods. I rebuilt the distributor a few days ago. Does the use of a Mallory 6A ignition effect the choice of springs? And I´m not sure about what kit to buy. I couldn´t find the crane springs anywhere. What do you think about the Moroso Kit? http://www.jegs.com/i/Moroso/710/72310/10002/-1 Here´s a link to the Moroso instructions. Just scrol down, there you find a chart about the springs: http://www.moroso.com/catalog/images/72300_inst.pdf And what do you think about this: http://store.summitracing.com/partdetail.asp?autofilter=1&part=CRN%2D99619%2D1&N=700+4294925143+4294839065+4294845846+4294908256+4294925079+115&autoview=sku What total timing should I go for? 32 degr. ? More, less?
Peter, There is no recipe for a specific car weight, engine, modifications etc. Every combination is different. You have to experiment and find what your engine wants. Being that Crane is now out of business, I'm not surprised that you can't find the adjustable vacuum advance kit. Just buy another kit with springs. Use the lightest springs to set up your total advance. You can start with 30 or 32*. See what feels best with no detonation. Leave the vacuum advance unhooked and blocked off. Work with the total advance. Put in springs that get it in at 2500 RPM or before. Again, you need to experiment with how fast the advance comes in. 2500 RPM is a good figure, but it depends on a lot of things. Some cars need it in slower, some will take it fast. Find out what the engine will take. Make full throttle runs from a stop and various speeds and listen for detonation. After you have determined what total advance you need, then you can play with the vacuum advance. Before you do any of this, the engine must be running correctly. It sounds to me (from your other thread) that you have other problems. Unless the timing is really far off, I think you have other things going on.
Good Page from MSD, Thanks to Doug Gorton (Sailbrd) for finding this:TU: http://www.setyourtiming.com/index.html
Whats the general experience regarding the need to adjust the carb (leaner/richer/no change) after doing the Power timing? I was replacing the spark plugs the other day when I came to think of it. From a quick look I think Im pretty ok, maybe could go a little leaner oro No: ?
Per, When you adjust the carburetor mixture needles, what you are doing is adjusting the volume of mixture, not the mixture itself. The actual fuel air idle mixture is dictated by the the idle restrictions and air bleeds and for all intents and purposes, it is non adjustable. You can always check it with a vacuum gauge after timing adjustments, but normally, it shouldn't require any attention after you set it up initially.
Thanks for that clarification Larry, <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com<o></o> Think I need to study what settings the Q-jet offers and how to check it with a vacuum gauge. <o></o> Is there a super-thread like this one that could be recommended?<o></o>
No, but if you search "idle mixture adjustment", you should find what you need. BTW, none of that will affect the appearance of your plugs. Overall jetting would be the biggest contributor to that. Light gray to light tan is what you are after. With unleaded gas, it takes quite a bit of miles to get some color.
Think I’m with you now, this is due to the emission demands right? On European cars from the same years you typically could adjust the fuel-air mixture but you guys were ahead of us on emissions and limited possibilities to adjust the carb was maybe a consequence of that? I have one of those legal inspection coming up in about 10 days where they will measure the carbon monoxide (CO). Last time I was up 5-6 % so I’m a bit excited if all the new ignition components and mods will get me any lower this time .
No, not necessarily. There are fixed idle bleeds and orifices that determine idle mixture. It is possible to modify them ,but you better know exactly what you are doing, because you can't undo them.
After installing new spark plugs and a set of Taylor Spiro 8mm ignition wires I suddenly get pinging hm Guess I should have done this before playing with the timing but I didnt expect new wires to make THAT much difference. Ive retreated with the advance now to 12* at idle (vacuum unplugged), the pining is gone and the car still performs well or even better than before! Seems like those 8mm Spiro ignition wires delivers a lot stronger spark. My old ones didnt really look bad at all, theyre just the standard type of wires.
It had dropped to 3.7 :beer I havent touched the carb other than adjusting the idle since the last time I had it measured, so this should be due to the ignition upgrade, unless whatever leftovers there may be of the dry gas additive I poured in the tank a few tanks of gas ago did that much effect Guess I may have a better combustion now....
I just thought that I would record my ignition findings here, so I don't forget where I started. Car is a 1970 Buick GS 350 (hi-compression) with the original Q-jet (rebuilt by me) and 146k original miles. Car seemed pretty slow to me after picking it up last year, so I decided to play with the timing. 1. Pulled the dizzy and installed a modified vacuum canister with 10* of advance 2. Installed Moroso weights and lightest springs (gold) Now I've got 8* of initial timing + 25* mech adv = 33* in before 3000 RPM. Car feels much better now, especially since before I don't think I was even getting 10* of mech adv with the stock spring and weight setup. Still have to do some more playing around with the carb and timing, but it runs pretty well considering it's the original engine! Thanks to Larry for the excellent thread
Hey Larry, Great thread. I have a 1973 455 with an HEI distributor installed. The car ran fine before I pulled the distributor but it always loaded up the plugs at idle. Anyways, I pulled the distributor, performed the advance mod like Andy said earlier with a screw in the factory hole and limited my vacumn advance to 10 degrees. I installed the distributor and adjusted everything to spec but my engine wont start and I am not getting any spark from my plugs. I have a new coil, module and wires. I even swapped back in my old module and col but still nothing. I have 12.6V coming to the distributor in Run, and 11V while cranking. I am unable to figure why there is no spark. Any help or similar cases you can think of would be great. It is 105* outside and I am losing my patience with this car after a hot day at work. Help please o No: Thanks, Steve
Pole piece (magnetic pick up) is bad. To change it requires distributor removal. Try moving the wires from the pole piece to the module around. I've seen them go bad before.
Thanks Larry, I am going to run some ohm tests on it tomorrow and see. I picked up the last AC Delco pickup XL parts was stocking in Houston. They said it is now discontinued. Thanks GM. I also found the receipt for the distributor from Advance Auto and will try to get it warrantied first. If not, I will replace the pickup coil. I'll keep you posted and will probably have more questions soon. Steven
I think you will find that there are plenty of aftermarket suppliers for them. Thew last one I used was made by Niehoff. Here's the listing from www.rockauto.com AIRTEX Part # 4P1208 More Info Part Image $30.79 $0.00 $30.79 Add to Cart STANDARD MOTOR PRODUCTS Part # LX303 More Info Part Image $45.79 $0.00 $45.79 Add to Cart ACDELCO Part # D1999D More Info {#89057326} COIL,DISTR PICK UP * Non-stock item--shipping delayed up to 5 business days Part Image $38.79 $0.00 $38.79 Add to Cart Distributor O-Ring
