Ignition Advance question

[ozconv]

I have the following new engine build and have been trying to tune it.

-200 six, essentially stock short block rebuild but with ARP fasteners, 0 decked, double roller timing set, and H264/274 cam with 112 lobe center, advanced 4 degrees.
-Rebuilt OZ-250 head and intake, ported with 1.8" back-cut intake valves and 1.5" exhaust valves, 3 angle valve job, 302 valve springs.
-1.6:1 Adjustable roller tip rockers.
-Classic Inlines header with 2" dual exhaust and Flowmaster 40s
-Post 68 Pre DS1 dizzy with mechanical and vacuum advance, Pertronix Igniter II, Flame Thrower III coil, Pertronix Wires with 0.045" plug gap.
-Rebuilt 1.02 245cfm Autolite 2100 with manual choke, 48F jets.
-0.053" compressed head gasket with 6.5CC stock dished pistons for CR of approximately 9.3:1.
-stock C4 automatic
-7.25" rear end with 3.2:1 ratio.

I have driven the car approximately 20 miles so far (city and highway). In order to keep it from stalling in gear and being driveable at all, I have had to do the following:

1. 0.040" holes drilled in the throttle plates. Engine does not seem to run rich now and will stay running in park down to approximately 500 rpm although the idle is very rough. At this rpm, my base timing with the vacuum advance plugged is 25 degrees BTDC (using dial back timing lite and guestimating since the idle is rough and the timing mark is jumping around). Idle mixture screws still don't seem to have much effect at all on vacuum and rpm but I think a little more than before the throttle plates were drilled. Car will stall when one idle screw is turned all the way in though.

2. To keep it from stalling when in drive, I have to increase the idle rpm to approximately 1200-1500 rpm and use manifold vacuum to increase the timing at idle. At this point the timing is about 55 degrees (in park). The car hasn't overheated yet and the plugs look good, however, the engine seems to hit a wall at about 50mph and would not accelerate well when entering the free way.

3. I have checked my mechanical advance with the vacuum advance plugged and got the following measurements:

500 rpm 25 degrees
1000 rpm 37 degrees
1500 rpm 37 degrees
2000 rpm 42 degrees
2500 rpm 42 degrees

I have swapped the reluctor on the dizzy to limit the mechanical advance to 20 degrees instead of 30 and have verified That the balancer is reading true TDC. If I back the base timing to anything less than 25 degrees and do not use manifold vacuum advance, the car stalls in gear. I don't know the rpm in drive but I would guess around 800 rpm?? I am thinking that the mechanical advance is too aggressive. I have replaced the smaller spring with one of the Mr. gasket 925 springs and bent the post for the heavier spring inward though I am thinking that it is bent in too far. 20 degrees of vacuum advance also seems like a lot but again that is what it takes to get it to stay running in drive. So far I haven't gone past about half throttle for fear of damaging the engine. Also at about half throttle the exhaust goes from sounding great to kind of a resonant buzzing. I was under the impression from the CI tech articles that this cam was not too agressive for an automatic and that the vacuum would be higher though 14 inches at 800 feet above sea level is the best I can get and in gear is around 11 inches.

Any thoughts or suggestions would be appreciated.

 

[xctasy]

A couple of questions.

1. How many miles has the engine itself had since the rope seal was replaced? Often, the friction form the rope seal on a rebuild engine creates all sorts of problems with low speed tractability. It takes time to mate/knit into the macrotexture of the crank, creating a heasp of idle infuencing drag.

2. Do you have a later alternator. The later model alternators over 65 amps can cause load problems preventing stable idle.

Gas speed is critical on a high intensity cammed large port 2V six cylinder engine. The small Ford carb venturis on 2v heads will also cause drivability problems; I'd personally never use a small venturi carb with a large port 2V head. A 1.21 Autolite carb or Holley 350 cfm 7448 or older Ford replacement 425 cfm 7508 Holley should be a minimum. After that, the 4412 will work brilliantly but sometimes the 500 cfm carb suffers poor low speed vacuum in 200 cid engines. With due respect to your very detailed work, you'll find that cam timing can be savage on a log head without much influence on idle, while a 2V will be much lumpier as gas speed suffers.

I'd borrow a 350 cfm carb and see if that helps, and then keep the 1.02 as collateral for a swap to a 351C 2v Autolite if the 350 works better

 

[FalconSedanDelivery]

First off , if you have a stock Torque Converter , that will be your biggest problem , second did you Degree the Cam ? , I would need to know what Manifold vacuum you have , both in gear and at park , That cam would of been great with a Stick , But ANY cam over stock in a 200 with an Automatic and no Higher stall converter to make up for loss of low end that comes with the cam , is a recipe for disappointment. I could sugar coat it but it is what it is , the recommendations on this Site for Cams sound more like rehashed Magazine questions, Rather than based in experience knowledge.( this will probably be deleted now )

 

[ozconv]

The engine has been run maybe 3-4 hours total and does have the rope seal. Total road miles are about 20. As far as I know the alternator is a remanufactured stock style replacement for a '67 200 in a mustang.

I happen to have several other used 2100s (1.08, 1.12, and a 1.23) and a couple of rebuild kits. I rebuilt the 1.12 but the 1.23 has larger throttle plates so I'll need to check it with my carb adapter.

Cam has been degreed with the intake centerline at 108. Other valve event measurements seemed to indicate a 110 LSA not 112. Cam is marked as a 112. How likely is it for the cam to really be a 110LSA that is mismarked?

I understand about the torque converter but there doesn't seem to be a good option for the small bell C4 with the integrated ring gear. Also, what is the stock stall spec and what stall spec would I look for? I don't mind paying for a custom converter but not sure who to go to for it? If it is significantly more expensive than another cam and lifters, I may just go that route instead. Any suggestions for another aftermarket cam that would provide better vacuum and idle??

 

[wsa111]

You can get a custom build torque converter from Phoenix Transmissions. They have plenty of experience with the C-4 converters on the six cylinder engines.
http://www.phoenixtrans.com/

Next you need to get your distributor to a shop that has a sun distributor machine to dial in your advance curve.

16 degrees initial + 20 degrees centrifigul = 36 degrees total. Get your centrifigul in by 2700-3000 rpms.
I run a my vacuum advance to manifold vacuum, and use a borg warner can V398.

As Faron said did you degree your cam in???

Put a 7448-350 holley on the engine using 59-60 main jets.

Your camshaft is a good choice if you degreed it in properly. I would advance it only 2 degrees, but that depends on the rear gear ratio.

Make sure you don't have an intake vacuum leak because that will really screw up all of the above recommenditions. Bill

 

[CZLN6]

Howdy Ozman and all:

If one of your other carbs has been run successfully, I'd try that change first. It is very likely that your engines symptoms are a result of a mix of issues; too much cam, too tight torque converter, too much advance, and/or a bad carb. Swapping to a known, good running carb will narrow the searches. Advancing the cams timing will lower the torque curve of the engine and help with vacuum. IF your dual roller cam gear is adjustable that give you a good option. And getting your torque converter rebuilt and loosened up. Be sure to check the timing mark on the damper for accuracy.

You've got a really nice build. Getting it sorted out can be a bit frustrating, but it will be worth it. Hang in there.

Adios, David

 

[ozconv]

Phoenix transmission suggests a converter with a minimum of a 2800-3000 stall. Does this sound like the correct spec for my setup? What is the stock stall? I seem to remember a number like 2200-2400.

 

[FalconSedanDelivery]

Sounds good , keep in mind Stall ratings are FLASH not what it takes to move , stock flash is around 16-1800 , BUT that's with a all stock engine making lots of low end torque , Id go with the recommendation , you wont be sorry , I would add a Trans Cooler and a Temp Gauge to your car , the temp sensor should be mounted in a manifold coming out of the front line , BEFORE the cooler , a reading in the Pan is False Security, you want the temp to be under 230 and 180-200 is optimum , if you switch to Synthetic ( Amsoil is a great one ) it will also help , Oh and you can buy a Trans Temp Manifold from Autometer , OR , make one from a 1/2 NPT Tee