Cam and ignition timing question
 

I have checked TDC in relationship to the timing marks on the
balancer using a stop in the #1 clylinder, it is right on.
I have not run the engine under load yet. The engine runs the
best with 20 deg. initial and 48 deg. in at 3000 rpm. If I set the
timing at 10 deg initial and 38 deg. at 3000 rpm the pipes get hot
and it belches a little fire from the carb upon shut down. I am sure
it is running a bit rich. I will have new jets and power valve shortly
The cam timing is set in the 3 deg. advance position. Would this affect the timing marks? Am I paying to much attention to the timing mark? Or should I just let the beast run where it wants to?
It is a 460ci, 10.1:1 with alum. cobra jet heads. Cam is a Ford unit with .595 int. .621 exh., .310 and .320 duration and 95 deg.
overlap. I am using a Weiand stealth manifold with a 4150 hp carb
830 cfm and annular boosters. Thanks, Dan

Hey Dan,

I assume you degreed your cam? There must be some reason that you have it advanced 3 degrees. This just affects cam timing though, and not ignition timing.

Let me ask you this...does it seem to run ok otherwise? I'm sure you know this....but I'll just ask for precautions....Just because the piston is at TDC, doesn't mean it's the correct TDC. It could be the TDC at the exhaust stroke and not the compression stroke. If you're not sure, then take the #1 plug out, stick your finger in the hole (make sure the coil wire is off) and turn the motor over (preferrably by hand and not a starter) until it blows your finger out. Then put you a dial indicator in the #1 hole and make sure true TDC is at 0 degree on your balancer.

From here on out, I can't really suggest any timing settings...I know in my SB, I run 12 degrees initial and 32 degrees total. You'll have to get one of the other guys to recommend some settings for a big block.

I was also going to add that it sounds like you didn't have enough time in it when you went down to 10 degrees...if it's backfiring out the carb, then I'd say you need to go the other way. :) You were probably on the right track when you had 20 degrees initial in it. Without a dyno, it's hard to tell...

Yup, TDC comp. stroke. Degree wheel on the cam to match the cam card as close as possible wth only three choices.
It just seems to love timing advance, no pinging, no hard starts.
Sounds extremely healthy.
I am sitting here waiting for the body shop, going on 3 months now, lots of prep,they may spray this week. Dan

Dan, I say lay the advance to it....if it likes it without pinging, then go for it. I'd say you didn't have enough in it before...that's what caused the backfire out the carb....

Good luck bud.

Brent

Brent,

Unless I'm missing something, there IS NO difference with the timing marks on the crank damper whether your TDC following exhaust stroke, or TDC following intake (cpmpression) stroke.

- Jim -

Hey Jim...

That's right...there are no differences between the marks from exhaust to compression. It hits zero on the exhaust and compression at TDC. Did I miss type something in my first message? That's why I told him to turn the engine over and make sure it blew his finger out so he would know it was on the compression stroke...otherwise if he were going on the fact that the balancer said zero....it could be totally wrong.

I think what Jim was saying was that if the timing marks are right on when #1 is @ TDC the damper is okay, whether it was checked at TDC on compression or exhaust.
Dan, this is pretty basic, but could you be checking timing based on the "rong" plug wire? Do you have an MSD ignition, and if so, are you using an electronic (dial-back type) timing gun? MSD's are notorious for giving bad readings with some (most?) brands of dial-back lights...

Ken, thats what's confusing. I have an old fashion Peerless timing light. #1 cylinder. I use two plug wires stuck together to attach the plug lead to. (non inductive type lead). MSD 6AL ignition.
Fluid damper balancer. I'll go out and lineup timing marks and check rotor position to cap. Thanks, Dan

Regarding the checking of the timing mark on the dampner, it makes no difference whether you do that on the compression stroke or the exhaust stroke. The only time that makes a difference is when you're installing the distributor since the distributor revolves once for every two revolutions of the crankshaft. If you install the distributor on the exhaust stroke, you'll be off 180 degrees and the car shouldn't start at all. Instead of using my finger, I just stuff a paper towel or rag over the spark plug hole. When that blows off, I know I'm coming up on the compression stroke.

Dan, I had a similar problem with my 428. I couldn't figure out why it wanted so much initial advance. After tinkering with it for a few nights, I finally figured out that that cap wasn't sitting on the distributor properly. When I put the distributor in, I lined up the rotor to the #1 plug wire correctly but I had the distributor installed 180 degrees off. I hadn't realized that the cap would go on either correctly or 180 degrees off. It still clipped on okay, but the "rejection" feature on the cap caused the cap to rock back and forth a bit and I didn't notice it right away. Once I fixed that, the motor was happy with 15 degrees initial instead of the 30 or so that it wanted before the fix.

Chris

Chris, I have checked everything, cap location, rotor position at TDC and at 20deg. At first I had the original balancer. this had actually moved, the timing mark was 30 degrees off location therubber had degraded and allowed the outer ring to slip. The new
Fluid damper was right on out of the box.
This is my question of cam advance does it affect ignition timing.
I would assume, no. Who cares where the rotor is initially.
It seems to run great. Maybe when it gets out on the road with a load on. A little less advance will be required. Thanks again, Dan

I bet the dampner has an incorrect TDC mark on it. Thats why they make adjustable timing pointers, it is not usually right on the money.

Mr. Fixit, for once you are incorrect :) . I checked the damper with
A dead stop down the #1 hole. Rotated CAREFULLY in each direction and backed my adjustable stop out until I was within
5 degrees from top on each rotation. "0" remain in the center or
coresponding numbers each time it stopped on opposite rotation.
I have found my solution. According to Ford Tech, This engine is
very happy at 18-20 degrees intial advance and 38 total ASAP.
If racing, just forget the mechanical advance, lock it out and run
38 degrees fixed. Thank you all for your support. A special thanks
to Mr. Fixit, whom I have found, from all my searches, to be right
on the money 99.9% of the time. :) :) Dan

I thought I read your motor liked 48 degrees total advance? That's a bit much. 38 is in the ballpark. If you lock out the mechanical advance , you may have a difficult time starting the motor when hot, I'd go 18 initial, 38 total by 2500 rpm.

I was told by my engine guru that the cam determines the idle timing and the cumbustion chamber shape and piston shape determine total advance. Your cars weight/gearing/transmission determine the rate of advance.

For my engine for example it is 22*/34* in by 2800 and a Dart with a Magnum 360 (quench style chambers) and an auto would be something like 22*/36* in at 3600. With my open chamber design, I get detonation at 36*. Same engine, different heads/pistons.

Mister Fixit, I apologize, you are correct in that respect. I did have to go to the largest bushing to back off the total advance. In the begining I was using the smallest bushing, allowing 28 deg. on top of the initial setting. You are on the money. Your numbers are identical to the Ford tech. support numbers. Next time I start a
thread you will be paged. ;) Dan.

Brent, Only gurus out here are you guys. I'm just winging it. This web site can be very helpful and very humbling. Thanks, Dan

Sorry Fixit, I must have posted the same time. I could only generalize, glad you had some hard numbers for him.