Lots of initial timing scoop?

[rdorman]

Recently I have been hearing more and more about running a LOT of initial timing in the motors, recurving of course for the correct total timing. Any one have the scoop on this? Any experience with it?

Thanks
Rick

[Hotfingrs]

I run a lot on initial timing, but I'm not running a vacuum advance either. Just guessing without looking probably in the 30 degree range with total in at about 2300. I use a dial back timing light, and time for total advance, right now about 36 degrees, sometimes will time up to 38 degrees, of course that changes my initial also. Gotta be careful for pinging when you do this.

[Mike Simard]

I believe the idea is to avoid retarded timing after the initial startup, retarded timing puts alot of heat into the exhaust and gets the pipes red hot. It can bake the paint around the pipe opening and be an all around fire hazard.

[scottj]

Rick,
I run full advance at all rpm; the distributor is “locked”. Big cams, open plenums, large intake ports and carbs that are matched to this type of application require the engine to have more initial advance. Usually it is in by 2500 rpm. In my case there was no benefit to NOT locking the distributor. -Scott

[rdorman]

I have been hearing it a lot especially in conjunction with Demon carbs. That they like to see 20-22 degrees initial advance.

Jack, even that guy you gave the link to, 4secondsflat or something like that, talks about it. I will have to go back and re-read what his comments where.

So how much are people running and under what cersumstance do you feel it benefitial?

It has been recommended to me by a good source to run more total. Which I am going to try. While this will increase my initial and I may get some feel for what a lot more initial is like, I am looking for some experience in doing so before I recurb the distributor.

Rick

[Hotfingrs]

Rick, you been listening to those voices in your head again...

[rdorman]

They will not shut up unless I give them an offering to appease them.
Rick

[vettestr]

All engines love timing and some combinations insist on higher initial lead. That being said also beware that preignition-pinging etc.. is in simple terms the explosion of fuel charge before piston has entered its dwell or point that is has begun to change travel direction. The rings in their ring land fight with piston direction and rattle trying to deal with opposing forces. This brakes the ring or hammers out the piston groove they live in.
Pinging can harm engine and if you are comfortable it is being controlled then add timing. Many engines have knock sensors to eliminate this condition via the injection and electronic timing controls. In an engine that is not equipped with this electronic safety net you basicly have to increase until it becomes easy to detect and then remove say 3 to 5 degrees as a safe margin.
I respect those much more well versed than I and admit to taking a bit of liberty in description but beware of harm potential if not looking for the signs and know what they are. Others will explain better or differently but say about 39 total and 15 to 20 initial with delta of 24 to 19 mechanical is what was in most of these beasts on the strip in 66. They had much higher gas octane then with lead in 66 too! Remember to remove from the total if you add to the initial or mechanical because rule of thumb says about 39 is max.

[rdorman]

Because of the large chambers and lower compression it has been recommended to me to try something in the 42 to 46 degree range. Which I am going to inch up on a little at a time. Once that is set, I was thinking about adding more initial and recurving the distributor.
Rick

[PJS50]

I am glad to see you guys talking about this because I have a lot of questions about this topic also..
I have been looking into a new carb for my 460 crate engine and have been looking at the mightly Demon carbs...
1st, how the hell does the carb "know" what the initial timing is set at and why does it make a difference unless the carb is running rich on the idle circuit? Looking into that 4 seconds flat website, I kinda understand the advanced initial timing/idle concept but it seems to me that the advanced timing issue is just dealing with an "overly rich" mixture in the first place. Couldn't you get the same results by leaning out the idle mixture and backing off on the timing a bit? I think that I am missing something.....
2nd, when I picked up my Cobra, the initial timing was set at about 13 degrees and I was getting hesitation in off-idle performance and a bit of run-on when I shut it down. I don't know what my MSD distrib.is set for advance but when I backed off the initial timing to 11 degrees, I gained a little bit better throttle response, lost the run on, and also noticed a little bit extra tire spin on a good 1st to 2nd gear shift :-). I am running an admittedly poor Holley on the car now (vac. secondaries, electric choke, single pumper; what can I say the previous owner was NOT the wrench type!). I want to loose the air horn and get better flow to the engine but the Holley/Demon/initial timing/cam duration/tire diameter/leap-year-or-not issues are confusing me...
It didn't seem this confusing 15 years ago with my '67 Mustang which I could get to run like a raped ape with my eyes closed...
What am I missing?

[rdorman]

Any one? Beuller? Beuller?

Rick

[Hotfingrs]

PJS,

Don at 4secondsflat puts a smart chip in each carb that he sells....and it knows everything.

[MidOHasp]

Jack,

I went to that website and learned quite a bit about tuning my Demon carb (re: lots of initial timing).

Really valuable website! This winter, I'm going to recurve the distributor to run about 16-18* initial (currently running 12) and 32* total, all in at 2500 or so. Now, I am running 12* initial, 32* total, all in at 4,000. Runs good, but sometimes a stumble with light throttle application. Maybe I just need to stop being such a girl and give it more gas?

Did you actually send him some of your spark plugs? His logic looks sound, but I'd like to hear from a satisfied customer. If he can do what he says he can do, then wow.

[Hotfingrs]

Just put carb on today, as a matter of fact. Didn't take it for a drive yet. His calibrations are pretty much right on. Needed a little bit more fuel at idle...check that your accelerator pump is squirting as soon as you move the throttle. 32* total isn't a whole lot of timing. Probably should be in the 38-40 range. Put some lighter springs in the dist to bring the timing all in sooner. 4000 is way to high. You need to get all the timing issues solved before you start messing with the carb.

[scottj]

Originally posted by PJS50


I am glad to see you guys talking about this because I have a lot of questions about this topic also...

1st, how the hell does the carb "know" what the initial timing is set at and why does it make a difference unless the carb is running rich on the idle circuit? Looking into that 4 seconds flat website, I kinda understand the advanced initial timing/idle concept but it seems to me that the advanced timing issue is just dealing with an "overly rich" mixture in the first place. Couldn't you get the same results by leaning out the idle mixture and backing off on the timing a bit? I think that I am missing something.....

A large cam with alot of overlap is very inefficient at idle and at low engine speeds. All that overlap causes the intake charge to be contaminated with exhaust gas and as a result the mixture burns much slower than an uncontaminated mixture. In order for this slow burning mixture to have time to complete combustion, the engine will need alot of advance at idle. AND, in order to smooth out the idle and eliminate off idle surging, large overlap cams also require a very rich idle and off-idle mixture. If you don't run alot of advance your going to dump alot of that unburnt fuel out the exhaust.

Re: Demons liking alot of advance; it's not really a Demon thing in general but, a Demon (or any carb) that is calibrated for a bigger cam. Really, your matching the carb calibration and timing to the cam.

Also, many people think that if you keep advancing the total timing, power will keep going up, presuming no detonation. This is not true. The engine will make peak torque at a certain amount of advance and for maybe a couple of degrees more. If detonation prevents you from reaching that advance and maximun torque, then you have a problem with fuel octane or a problem with the engine combination. But, if optimum timing for max torque can be achieved, then advancing it further, without detonation, won't make more peak torque. My street engine made peak torque at 35* and at 36* torque was down. My builder timed it at 35* because that is where it made the best combination of torque AND hp under the curve. Because of my cam I can run it locked out at 35*. If I had a smaller cam with less overlap I could run into detonation problems at lower engine speeds with it locked out. By comparison my other engine with the good heads makes peak power at 31* advance.

[Michael C Henry]

Thirty years ago 38° was the desired FE goal.I've read where some are getting better results with less.I'm currently running 12° bftdc initial timing and think it is a little bit too much.starting is not a problem .I have a Hy Fire VI which has a programable automatic start retard that I have programmed in 8° retard any thing under 500 rpm so I'm actually starting at 4°ftdc. Make that livable.
Any time you start the burning prosces before or after it's correct time it should work against the motors performance.Manufactures use little advance ( like 10 degrees distrib ==20° crank. because they don't want to spend the time and money to make a each distributer advance the correct amount at the different rpm levels.And performance will impact their liability (warranties)I haven't had my car running that much since getting it together.but I'm sure that initial should be around 8° to 10° bftdc ,starting should be around 4°bftdc and total should be 36° to 38° bftdcThat means you'd have to have a distributer that advanced 28°to 30° currently mine goes 20°
Now when would you want that timing to start coming in?How much when?

[rdorman]

Some good stuff! Any one with specific experience with a open chamber, 4B Cleveland?
Thanks
Rick

[trularin]

Rick I have a 4B cleveland. It is a BOSS, but is essentially the same engine. I am running the GA BOSS heads with all ford BOSS parts ( SS valves and D221 springs ). My CAM is 288 at .540 lift with about .110 clearance. I have a IR distributor with NO vac advance made by Mallory. Accel super coil with 300+ series wires and #4 plugs gapped at .035. Plugs are seated to 10 foot pounds ( I think it's 10 ). I have a First generation Edelbrock Torquer intake with a -1 series Holley 3310 ( 780 CFM, Vac sec. ). Block is 4 bolt mains with ARP studs everywhere. 10.25:1 compression using forged TRW pistons and perfect circle rings.

I machined the oil passeges for .100 restrictors and use a 3/8 SS diverter from the oil pickup at the filter tot he oil pressure port at the top rear of the engine.

I run mobil 1, 15w - 50, 8 qrts with a billet drive to a mellings oil pump.

Thats the engine. I have the initial timing set at 18 and have 36 total at 2500.

How is that CAM change going?

[rdorman]

Is that 288 at .050???

Good info about your timing. I am going to bump up the total and see what happens.

Cam change is done. Really like the new cam. Just the little extra I was looking for.

Rick

[trularin]

Rick, I set the timing based on the total, NOT the initial. For my CAM, I need to hit the 32 to 38 range or I have backfires and power loss.