famous bob
mopar misfit
What are you guys w/ 500" wedge engines running for timing on them ? I have 21 initial, 34 total, all in at 3200 (91 lawnmower gas), w/ max vacuum set at 42. Any body ?
advance
- Thread starter famous bob
- Start date
-
vitamindart
Well-Known Member
locked mine out, no advance 32-36 depending on what swill I was running.
famous bob
mopar misfit
Thanks but not what I`m after. We used to run mech only on the hemi`s at 36 all in at 2800. This is a streetcar, and really likes gasoline, trying to help it a bit.
Bamalam
Member
With very limited info on the engine /car combo. I would say that is a really good starting point. If you have alum heads and static compression around 10:1 you could safely go 37/38* with 91 octane. That would give you a little more initial timing which the engine will really like if you have some healthy duration on the cam.
Rapid Robert
Well-Known Member
I would set the initial with the "vacuum gauge method" then shorten the slots to get 36 total (initial+slots) and the FBO $22 plate is by far the best bang for the buck way to change your mech adv amt, then toss the heavy spring with the elongated loop on one end & sub in a mr gasket/MP/transdapt/OE, one of the three, light springs in its place along with the OE light spring for a start & mix & match from there staying just under the pinging point at WOT up thru the gears on your hottest/driest (most likely to ping) day and there is silent ping & peoples' hearing varies so give yourself a cushion then plug in the can (if used) & adj it with a 3/32 allen wrench so you are under the same pinging point in everyday driving conditions under varying load/RPM. CCW slows the curve. do these 4 in order & on the spring selection you do not want the adv to start any less than 1-200 RPM above your hot in gear (auto) idle speed (or neutral) which is what you are at from stoplight to stoplight.
moper
Well-Known Member
Timing curves will depend on the package, but for most of the ones I've built, you're about right if not a little too much, too late. These engines don't need a lot of timing to make up for anything so you can run 18-20 initial, and if it's a smaller chamber and quench dish run with tight quench, the total will be closer to 30-32. That leaves some room for the vacuum advance amount, which I will always advise be run on a street car. You should also be able to bring it in a little faster because depending on what your gearing is (most big strokers have mild gearing) you want to have the advance "in" right around your typical cruise-at-50mph rpm. If it's built properly it should be fine with that. If it's a wider quench, or cam too small, you may not be able to do that with 91 from a local pump.
famous bob
mopar misfit
Engine is a r/b 440/505" wedge, alum heads, .628 lift solid street roller, 254/260 @ .50), 10.3 c.r./ dished pistons, .039 quench, 727, loose 3500 convertor, dana 60/3:73 Detroit locker. 68 fastback form S car, subframes tied, 6 point roll cage ( just to stiffen it up, I really didn`t want a bar----but figured it needed it. 295 65 15 drag radials for the street.) All timing can be set w/ my hand held for the fast 2.0 f.inj.,(1200 cfm throttle body) so changing it is a lot easier than screwing w/ the old style dist. and springs. -- 21 initial , 34 total all in at 3200, max of 44 vacuum advance. engine only has 7-9 " , which is more than I figured, probly due to the gapless rings........ Thanks and , comments welcome ------Bob. ---- Oh, thinking the car weighs around 3000.
moper
Well-Known Member
I would keep it at 20* initial, set for 32* total, all in at 2500, plus another 12-14* as vacuum. So total with vacuum would be 44-46*. You can bring it in a lot faster, and richen it as you need to but honestly with that convertor I don't think you'll need to do much. Light car, loose convertor, big engine.
famous bob
mopar misfit
^^^^^^^^^^^^^^^^^^^^^^^
Have been wondering most about the all in rpm, w/ the 91 no lead, non ethanol, lawnmower gas we have here .
Have the total at 44 now.
moper
Well-Known Member
The quench should be helping you. A huge part of the equation is the mass the engine has to move. You're making it easier: light weight, with gear, and with convertor. So bring it. Watch the plug porcelain with a lit magnifier for any signs of piston material. Also be aware of carb tuning each time you make a timing change. You don't always hear a problem. But we run 91 crap with 10% ethanol in the ground here.
famous bob
mopar misfit
Thanks for all the replies ! A little update, I weighed it at the dragstrip last SAT., it weighed 3278 w/ 1/2 tank of lawnmower gas. Didn`t get around to running it, want to put some miles on it first. It seems to like 21 initial, think I might try bringing the total in a little sooner . Thanks again , bob
You have a fairly big cam for a street engine so your engine will probably want a lot of initial advance. Once you get enough advance in the engine to make it happy then you have to walk a tightrope on the advance curve to keep the engine happy on the street without having it ping when you jump on it hard.
I don't think I've ever had one that came out perfect! Sometimes I just run extra advance for street driving and then twist it back a little bit if I'm going to the track.
I don't think I've ever had one that came out perfect! Sometimes I just run extra advance for street driving and then twist it back a little bit if I'm going to the track.
famous bob
mopar misfit
I haven`t had any pinging so far. It tried to not start when I had 22 in it initially, it even balked at 21 Saturday, on a quick hot restart. thanks, bob.
Amazing what 1 or 2 degrees will do.
Is your distributor easy to adjust for advance? Most distributors are hard to adjust as are most vacuum advance cams. That is one reason people just give up on this stuff. If you can adjust everything then I'd put as much initial in it as it will take and then work around the other issues with the springs and slots.
This is a good example of why I'm switching over to EFI. Then the whole pile of parts goes in the trash and I can set my timing curve on the computer just how I want it. No more messing around with springs and slots and vacuum ans and all of that analog crap that is so hard to set up and keep adjusted.
This is a good example of why I'm switching over to EFI. Then the whole pile of parts goes in the trash and I can set my timing curve on the computer just how I want it. No more messing around with springs and slots and vacuum ans and all of that analog crap that is so hard to set up and keep adjusted.
famous bob
mopar misfit
u musta missed it. LOL . I`m messing w/ a fast 2.0 set up, all done on the handheld. Sho nice !
I had to disconnect my vacuum advance because it was surging a bit on the highway. At first I thought it was a lean surge issue, but a buddy told me to try bringing the RPMs up slowly in neutral and see if it started to misfire, and it did. I disconnected the vacuum advance and problem solved. I didn't want to mess around trying to limit the vacuum advance so I just left it disconnected. The point I am trying to make is it may be as simple as setting your initial and total mechanical, and then just keep adding vacuum advance until you detect any misfire? I don't have fuel injection, but I bought an MSD pro billet distributor, and an MSD dial back controller where I can dial in (out)up to 15 degrees of advance. I am planning on using that to dial in extra advance on the highway instead of the vacuum advance (whenever I get around to installing it).
does the FAST set up not have seperate base timing and idle timing like the FiTech?
Ahh, I did miss that part. In that case tweak away until you get it perfect. The good EFI systems allow total control over the ignition. Does FAST have a start retard function? The Holley setup has another screen for starting. I think with FAST you just put less timing in if the RPM is less than 500 rpm. That way you can run 20+ degrees of initial timing but only have 12 or 15 while starting. See if you have that option in your software.
I wouldn't worry about putting a lot of total advance in for cruise conditions. If the manifold pressure is low (high vacuum) then you can run more than 50 degrees of total advance. When the manifold vacuum gets close to atmosphere (WOT) then you need to pull the timing back to the low 30 range. But that is easy to do with EFI, just fill out those top rows in the low 30's and then put 45 or 50 in the bottom rows and then just smooth it out. Put 10 or 15 in the left column for starting and you should be really close to done.
famous bob
mopar misfit
Initial, mid, all in, and total. HAS 8 DEGREES BUILT INTO IT FOR AUTOMATIC PRESET. WERE GETTING OVER MY HEAD W/ SOME OF THIS. lol But so far so good . Think I might try to bring the total in a hair sooner. The engine likes to idle about 1050, also helps control my hot oil pressure.
-
