At least part of the lopiness of your engine is the unstable timing at idle. If it were me, I would try to get the timing to sit still at idle. That is probably not killing things, but it is annoying, and not helping the picture any. What kind of vacuum are you pulling at idle? You might get a more stable idle if you backed the initial timing back a couple of degrees, and opened the throttle blades a bit, and readjusted the idle circuit. You will get a better smelling exhaust too.
Just a thought.
Sam

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It idles at 1000-1050rpm. It will idle lower at 900rpm and timing will remain stable at 10 degrees, but I was told not to idle below the 1000rpm. If I do I greaten the chances of whiping a cam lobe.
The idles screws on the corners of the carb don't seem to have much effect. If I back the throttle shaft screw all out, it idles very low. (650rpm) If I then back out the idle screws 3/4 turn each nothing changes. If I turn them IN the just backed out 3/4 and 3/4 more they litely bottom out and the idle picks up to 850rpm. This doesn't seem right so I put them back where I found them.
The plan today is to buy a wide band O2 setup and hook up the vac gauge.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

The die cast oil pump I built for you has the factory 5/8 thick impeller.
These tend to drop in prussure at idle and low RPMs and then quickly get to the relief valve pressure by 1600 - 1800 RPM.

If the low RPM / idle pressure never gets under 20 PSI, you are OK.
If the higher RPM pressure is in 45 to 55 PSI range, you are OK.
I set the relief valve spring to the "light side" because I don't like putting a lot of load on the drive gears. Once you have every thing tuned-in, you can remove the relief valve plug and add a washer to bump-up the high RPM oil pressure another 5 to 10 PSI. The plug is accessable from under the car, it's a 10 minute job.
Did you drill-out / deburr the oil passages in your block?
DD

I am not saying to lower your idle speed any. Reduce the initial timing to 6 or 8 BTDC, and then open up your throttle stop screw to bring your idle back up to 1050. I looked at the timing table from some OEM applications that MitchB sent me, and the idle timing is set at -5. This is so they can keep the TB open more, and idle cleaner. When the throttle is closed all the way down, the fuel does not atomize as well as when it is open a little bit. I think this might be why you are having trouble getting your idle circuits to respond correctly. This system of bring the idle down with timing instead of closing down the TB was developed by Mopar in the late seventies to get their cars to pass emissions at idle, and it became essentialy the industry standard after that.

When I was running Mega Squirt, I had the initial timing set at 2 BTDC, and it ran better that way then at 10. It was Dart 270 who talked me into that, and it was not only OK, but actually better.

What vacuum are you pulling at idle?

Sam

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Wiping the lobe after break in isn't likely. 20 minutes of running is the break in time. Vary the speed, etc.......

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

Race fuel & grey tail pipe is kinda normal. It real hard to tell anything about the mixer buy this. If anything it kinda says it MAY be rich. The description you gave of the idle screws says it rich also.

One thing to check is that you intake has no vacume leaks at all threw all the temp changes the engine goes threw. You may be having to open the throttle blades up so far that it is drawing fuel from more than the idle curcuit. Be sure your back throttle plates are closed or set where they should be. And remember that the mixer will be differant between race fuel & pump gas. Just addign race fuel richens the mix if I am remembering right.

Its not easy to tune out & match up everything with a new combo, and one that no one else has will be even harder & take a lot of tial & erea to get right. Just take small steps as always. And your plug reading can be your best friend. Get you one of them jewlers inpection eye pieces & leanr how to really read a plug. A plug being dark tan, or white, doesnt really tell you a lot. And it takes a new plug to get a proper reading after a change. You can just use one new plug for one cylinder instead of a whole set until you get it real close. Then you want to use a whole new set to be sure there is no one cylinder that is getting leaned out on you when you get the mix real close. It takes time & is not easy. But it is the best way out side of spending tons of money for dyno time. It can even tell you where to put the timing if you learn how to read them good. It can also pinpiont any cylinder that may have ping even when you cant hear it.


Jess

What do I make of this?
If I move the inital to 7 degrees my total would be 25 degrees. This gets half of whats being recommended. Half from one and half from the other.
Going to hook up vac gauge now. Ordered Wideband O2 today. It'll be in stock tomorrow.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

25 degrees total is what the turbo slant guys are running. A slant, having a small bore does not need much advance to get the flame to cross the piston at the right time. Don't be swayed by what small block Chevy guys are doing. They are very different animals.

I have cut the timing back to 15 BTDC under 8 lbs of boost. If your engine is as high compression as you think, maybe you are getting enough cylindar pressure to require that you back off your total timing as well. Of course, the vacuum advance will pull it up higher for cruise, and economy, but this will not be there under heavy load.

Honestly, when Lou backed a total of 6 degrees out of my timing, the car ran stronger under WOT conditions. A slant just does not need that much timing.
Don't be afraid to try some different things. You will have to work out the tuning that works best for your combination.

Sam

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I am leaving the vac advance disconnected for now. I didn't know that Slantzilla was a chevy guy.
Vac readings at idle are as follows:
1000 rpm 12in
800 in gear 7in
700 in gear and A/C on 6in

I also installed a 1/4" insulating carb to manifold gasket. The carb seemed very hot. Probably will still be hot but I don't see how it could hurt.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

Slantzilla is Mopar all the way. I am sorry, I thought he was one of the guys who suggested 25 dgrees. That is what Charlie told me he was running. Sorry if I got you confused. But try it at 25 total. It might work out well for you. It is certainly not out of the question.

The Chevy guys will run from 40 to 50 dgress total, and they were who I was refering to. Most of the literature out there will reference the SBC without even indicating that is what they are doing.

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I have 16 total with mine and 17psi. I took out the elongated spring in the distributor and left the lighter one in so full advance is in by 2000 rpm. I do not have the vac advance hooked up. Runs good.

Thats very low on Vacume. I wander if your PowerValve is seting there & bouncing off its seat because of the low vacume. Meaning the dieing problem that you have.

If it has a 7.5 PV valve, when you are in gear at idle then it will try and open.


Jess

Boy do I feel like a dope. I just noticed the specs on your cam, and torque converter in your signature at the bottom of every screen. That is a pretty big cam. I think those vacuum numbers are suprisingly low. You might play with the idle settings on your carb, and timing to see if you can get those numbers to come up. I agree with Jess, you are on the verge of your power valve opening at idle. My slant idles at 18" at 850 RPM with a stock cam. Do you think there might be a vacuum leak somewhere?
Sam

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As far as setting up the distributor goes. A cheap but fairly accurate tool to setup the mechanical advance is a small drafting protractor. Get a decent quality clear one from an office supply and glue it to an old (or new) rotor with epoxy. Be careful to get it concentric, centered with the shaft bore. Then you can work out a way to hold the distributor by the shaft and fashion a pointer from stiff wire. On v-8 distributors I have just used soft vise jaws on the pump drive tab or bottom of the gear, just stay off of the teeth. This is allot like setting up a degree wheel for cam timing, actually the same. It will be harder with a slant just because of the plastic gear. Then you just move the top end of the distributor by hand and measure the degrees. Remember it is half of what it will be at the crank. Make sure to rotor does not slip while doing this. You really only need a machine or running engine for setting the curve, not the total.

I would try to get it set right and not try to compromise on initial verses mechanical advance. So shorten up the mechanical. With your cam you really should need a fair amount of initial for it to run well.

I would try to get more miles on the engine and work on the general tuning before getting too concerned about the idle. Many performance engines with low vacuum do not idle that great when they are new. Even with a smooth bore finish, moly plasma rings and the use of a torque plate they loosen up and have less friction after a 1000 miles or so. Your idle will likely get better on its own, then dial it in for good. When you shut it down it stops abruptly, right? Thats the friction from the pistons and rings.

Boiling fuel can be a problem, I would run a heat shield under the carb as well as an insulator. Keep the fuel cool in the carb, and let it get hot when it hits the bottom of the intake. Even small bubbles forming in the emulsion wells really screws up the idle and off idle response. Even if it's not normally a problem, why ever let it be one in hot weather and traffic?

I missed what plugs you have, but if the compression is high you really need colder than stock plugs. This may have a major effect on the detonation. I have seen so many debate or dismiss this, but all I can say is they are wrong. By the time you control it with octane you have put out too much of the fire and are losing power. You really need the correct heat range plugs. The only catch is that at some point the plug that is right for hard running is not going to stay clean for lumbering around town. I doubt this will be a problem on your car.

Any update on what the real static compression ratio is?

I haven't bought or borrowed other tester yet.

I hooked up a new vacuum gauge get to make sure my readings where correct. Can you believe the stock 40 year old "Performance Indicator" is dead on.

The Wideband O2 is installed as of 10 minites ago. After the gauge startup procedger and open air calibration, I have at idle (1000rpm) 11.7:1. A little bit of power braking also yielded simalar results with the gauge bouncing up to 15:1 when the throttle is released.
Its a pretty cool gauge.
http://www.jegs.com/webapp/wcs/stores/s ... _672876_-1

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir