Timing?
 

Where are you guys setting your timing on a mild 455 with Kre dports? Mine is at 14 degrees?

35 total with out VA hooked up.I have mine on 12 initial.Tom

My engine made best power with KRE D ports on the dyno with 36 degrees total. I am also at 4500 ft, so that may effect things slightly.

Im wondering if that is part of my problem with the car running warm. It got a lot better after the fan clutch but still runs around 210 degrees. Im going to put a new thermostat in it and see. Thinking a 160?

Where ever the dyno tells me the total needs to be to make the best power. Even with tight chambers I find 35-36-ish degrees to be the best on 91 octane.

The rest of the curve I taylor around that. Usually anywhere from 14 to as much as 18 initial and anywhere from 10-12 to as much as maybe 14-15 additional from the vacuum advance. All the while keeping the wot total at what the engine liked on the dyno.

When a car / motor has a cooling issue installing a lower temp stat will only serve to extend the time it takes in your case to reach 210, but not lower that peak temp that you have.

Car manufacturers for a very long time have considered 210 degrees normal.

If you have not done so I would pull the water pump to see if the impeller to baffle clearance that you have is excessive.

That condition reduces pump efficiency by a large degree.

Another thing to can do to check out what you have taking place is to advance your initial timing with the motor fully warmed up until the motor just starts to show signs of cranking hard.

Doing this will help out if the motor is running hotter then you like above 30 mph and with a throttle opening that is enough to unable the vacuum advance.

Also note that lean mixtures take longer to burn so at low speed and part throttle you NEED vacuum advance .
Having both conditions of lean mixtures and not enough timing leaves a lot more hot gasses in the cylinder and that will raise coolant temps.

Ribbed type flex hoses should not be used and your lower hose must have a spring in it so it does not get sucked closed by the water pump.

I've been running mine at 32 with no VA and a quick curve. Haven't experimented since I hit my number at the track.

I'm at 14 too, 32 total no vac advance, with iron heads. Idles at 800 rpm, 190 temps.

One thing to keep in mind is that as the cylinder bore increases, the flame propagation slows down, which requires a bit more timing lead to reach maximum power.

I've been doing a good bit of tuning on my engine this summer and most of what is working well for power and heat management has been almost exactly the reverse of what many people believe is what needs to be done with these cars. Including myself.

My combination is a +0.040 455 with the factory 4.21" stroke. It uses KRE D-ports with a 2.11/1.66 valve arrangement with Jeff's 310 cfm port. Port matched Torker II, a moderate 240/248 on 112 hydraulic roller and a FiTech system fuels and provides spark.

What I've found is that having more timing in the curve, while simultaneously slowing that curve down has resulted in the best power and street manners. I've also fattened it up more than I did in the past. I'm not saying that works for every engine, but it's working well for mine.

I idle the car around 13.5:1 afr with 22 degrees of timing in it. at 1100 rpm and increasing MAP, I don't drop the timing down further. I command 25 degrees at 1100 rpm and 95kPa MAP readings. At 3000 rpm the spark curve is around 34 degrees and between 3000 and 6000 rpm another 3 degrees is added. This puts my 36 degree total timing figure right at around peak torque that occurs at 4600 rpm.

My engine is very knock tolerant and it will handle a lot of timing, which is one of the reason I'm able to have a bit more in it everywhere. But in my case a slower curve is working a bit better. At cruise, I'm only adding around 5 degrees of additional advance and I'm targeting between 13.7-14:1 AFR. Fuel mileage has actually picked up a bit even though I'm running the engine a little richer.

For WOT AFR I command 12.5:1 that tappers richer to around 12.3:1 by 6000 rpm.

A couple reasons I'm asking about timing is after it is hot sometimes it has a hard time starting and it's seems a little sluggish.

Can you describe the symptoms? Does it not want to crank at all, or does it crank a lot and refuse to fire off? Then when it does, it sputters a bit?

Can you post some information about the fuel system?

Put in a Ing kill switch to get the fully warmed up motor rolling over first before the spark gets put in.

You might also just first kill the Ing just to see how much of a difference having no spark makes.

Your plug heat range might also be too hot because 14 degrees of initial to me with Aluminum heads does not sound like too much, but again your coolant temp does come into play a tad .

It will crank very slow.

This may be as simple as checking your starter and the wiring to it. At 14 degrees initial and assuming 20 degrees in the advance mechanism, I wouldn't say that you're trying to overdue it and if the engine is nominally 10:1 compression, teh factory starter should be able to cope with that.

But if it's struggling with some heat soak, check the solenoid, check that the power wire isn't corroded etc. If the starter is very old, it may need replaced or a rebuild. A heat shield can help as well.

Another option is to change your mechanical curve so that you can still meet your 34-36 degree WOT maximum, but lower your idle advance to help with starting.

Yet another option is a Progression Ignititon distributor. You gain a lot of timing granularity and you can set your crank timing low to help with starting, then put more idle advance in it if you need to help stabilize idle from a large cam.

Just for a test… set your initial timing at 18 just to see how that affects the engine temp. Sounds like the starting issue is a hot starter (headers?) and-or undersized battery cables.

So yesterday I had to take my Mother in law to the Doctor. Picked her up went to the appointment a 20 minute ride. So onthe way back 20 minute ride car sat for 5 minutes and then hard to start. After another 15 minutes of run time I took her home and the car sat for 10 minutes and started with no problem.

Certainly sounds like heat soak on the starter. Engine heat will spike shortly after you turn it off, then begin to cool. There's a period of time where that heat soaks into the starter before ambient temperatures start to cool and take heat away from the starter and engine. That may explain why after a short period you have trouble, but after a longer period of cooling, things start to work again.

Health of the battery, starter solenoid and the windings in the starter, or corroded/undersized starter wires may all contribute here.

32 degrees total 20 initial. Im surprised by the higher total numbers others have. I thought most were in the 28 to 32 range for these heads?

Im thinking it's more to do with the starter.

I'm nearly a mile high. The lack of oxygen requires a couple more degrees of ignition advance. I also run on 91, which is probably more octane than the engine really needs at 10.3:1 compression.

At sea level, I would bet I make peak power with more like 32-33 degrees of total timing.