Another Timing question! 340 based 416 Stroker - Is my vacuum advance improper?

[autoxcuda]

So your pistons say 21.5 cc dish?

Or they they flat tops?

Not sure 70.5 cc heads and 21.5 cc dish gives you 10:1 compression

But flat tops might.

I run the comp 274-S with 236/241 @050 and .502/511" not too far off from the OP

I'm at 32 even 31 total.

[72 Challenger]

Sorry for the slow response. Fathers day, repairs to my daily driver and weather got in the way.

I went with the Chryco method. I set the timing to 32 degrees all in at 2500, That put me at 12.5 degrees initial and I have left the vac. advance disconnected but I will plug the line to make it look correct.

The engine starts nice, etc. I Had to open up the throttle blades to get it to idle at 850 RPM. I believe this is causing my next issue. After I drive the car the idle creeps up, somewhere in the 1100 rpm range. If I reduce the idle the engine shakes and runs poorly when the engine is not 160 degrees or more, but warm enough to not be on the choke. If I leave the idle at 1100 it seems to diesel after I shut it off.

Again it's 94 octane, new gas. So I am now looking at my options.

1. I still think my stock rad is too small for the car and I will be looking at Glen Ray to see what he can do for a radiator resto. Just don;t think the 340 rad was designed to cool a 416 stroker.
2. Colder spark plugs
3. adjusting the carburetor air/ fuel. I also need to check but the carb is a 650, perhaps I could even look at a 750.
4. Colder plugs. I am currently running the Champion 12YC.

any ideas on direction?

[DeathProofCuda]

Shouldn't timing all in be more like 34 to 36 degrees?

Also, are you running a thermal or electric choke?  My electric choke is set up for a nice fast start, but it typically comes off before the car is fully warmed up.  Part of this is due to the fact that I have my heat crossover passage in the intake blocked off.  I just live with the fact that it takes a bit longer to warm up.  Tuning should be done when the engine is fully warmed up.

[tparker]

I am about to fire up my 416 and am doing a bunch of research. I was JUST looking at some timing vids and the guy's video was talking about tuning total timing especially for performance cars. He was saying that once you get that right you might find you have issues in other areas. He was saying you may need to adjust your fuel mixture. I would double check that as well as look at the heat range of the plugs. What plugs are you using? My understanding is as compression goes up you may want to run cooler plugs to prevent early detonation.

[72 Challenger]

I am about to fire up my 416 and am doing a bunch of research. I was JUST looking at some timing vids and the guy's video was talking about tuning total timing especially for performance cars. He was saying that once you get that right you might find you have issues in other areas. He was saying you may need to adjust your fuel mixture. I would double check that as well as look at the heat range of the plugs. What plugs are you using? My understanding is as compression goes up you may want to run cooler plugs to prevent early detonation.

My compression is still 10:1, it's not a high compression motor. I also thought my plugs were too warm but the more internet reading I do I am thinking that is not the case. I am going to play with the fuel mixtures again. I am using Champion 12YC's. The same spark plug I have run since I have been working on Mopars. It was recommended to me on that other "forum" we all came from lol.

[72 Challenger]

Shouldn't timing all in be more like 34 to 36 degrees?

Also, are you running a thermal or electric choke?  My electric choke is set up for a nice fast start, but it typically comes off before the car is fully warmed up.  Part of this is due to the fact that I have my heat crossover passage in the intake blocked off.  I just live with the fact that it takes a bit longer to warm up.  Tuning should be done when the engine is fully warmed up.

I am running an electric choke on an Edelbrock 1806- 650 vac secondary carb. The choke is set one marking towards rich. My heat crossover is also blocked.

As for the timing, If I advance the timing anymore at full advance, I end up with an initial advance that is up in the 14's. She does not like to start as easily especially when she is warm.

How long does your car take to warm up? I generally start mine up and idle it for 3 or 4 minutes before taking it out. The choke remains on for the majority of that. I can also see that when the car is warm, the choke cam and the high idle screw are not in contact with the throttle.

[DeathProofCuda]

Not sure, but I'd guess almost double that time on the warm up.  If I don't give it some time to warm up it will fall on its face when I try to pull out into traffic at the end of my street.

I'd still say to make any tuning adjustments when the car is completely warmed up.  If your settings are changing after taking the car out for a drive, then go back and reset them.  Dieseling is typically a symptom of having your throttle blades being open too far.

[Chryco Psycho]

I usually set the choke so it barely works at all as most of these cars are only driven in warm weather anyway .
I vote for tuning to prevent run on , you can try a cooler plug but it may foul .

[71383bee]

From what you are describing I would still lean towards more initial. I have had good results running around 18 initial and 34-36 total.

12 to me sounds a bit low.  I suggest a test of bumping it up a bit and checking to see how it starts and idles. 1100 also is a bit high and I would concur that your throttle blades may be a bit too open.   The initial should help with this and you should be able to idle her down.


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