carb tuning / timing ???

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carb tuning / timing ???

Post  1951 ford on July 3rd 2013, 8:17 pm

Hey guys . So installed a new billet msd ready to run distributor . now not sure what my setup should be running. right now it looks like the advance curve is all in by 5500 rpm now with my setup that might bo late any sugestions


Last edited by 1951 ford on September 23rd 2013, 8:13 pm; edited 1 time in total
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Re: carb tuning / timing ???

Post  fordguy69 on July 3rd 2013, 9:28 pm

Every combo is different, but my street oriented 460/TKO 600 with a mild cam runs best at 14 initial, 38 total, mechanical advance starting at 1000 and all in by 3000. It's a 9 to 1 motor and I can run 87 octane with no detonation.

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Re: carb tuning / timing ???

Post  1951 ford on July 4th 2013, 12:39 am

i belive mine is 10.5 or 11.1 . fairly sure i need to adjust the advance curve and bring that down 5500 all in is no good. i think my cam is 1500 to 5500 so all at 3500?
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Re: carb tuning / timing ???

Post  Gregaust on July 4th 2013, 6:09 am

Try 1 heavy silver and one light for the springs will get all in between 3000-3500 I found to be a good start point

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Re: carb tuning / timing ???

Post  maverick on July 4th 2013, 11:14 am

If I was gonna run a curve, I'd bring it down to around 2800.
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Re: carb tuning / timing ???

Post  1951 ford on July 4th 2013, 6:24 pm

so 3000 to 3500 . but how much advance to run, right now the distributor is set up a 21 degrees with the blue bushing
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Re: carb tuning / timing ???

Post  1951 ford on July 22nd 2013, 6:48 pm

so what do you guys recommend for initial timing on this build ?
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Re: carb tuning / timing ???

Post  DeepRoots on July 23rd 2013, 7:33 am

converter? Stick shift? 4.10 rear end or 2.73?


I run 18initial 36 total with the same distributor.
10:1ish 429, 3000stall, 4.10 rear gear, 25.5inch tall tire, 4000lbs
Runs great, need to have a good battery, wires, and starter, or i'd need to drop initial down a lil.

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Re: carb tuning / timing ???

Post  1951 ford on July 23rd 2013, 9:18 am

so 429 11.1 ish 31" tall tires 3.50 gears 2500 stall c6
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Re: carb tuning / timing ???

Post  LivermoreDave on July 23rd 2013, 1:16 pm

May I offer another opinion? I didn't notice the type of cylinder head, cast iron or aluminum nor the camshaft specifications. The compression ratio you posted may work with aluminum heads although with cast iron heads you will need ALL the ajustability the distributor offers. I would assume all the advance would be offered at the engine speed you mentioned, it could/should be far less. How about locking the mechanical advance out and use ignition timing in the 32* to 35* area and see how the engine reacts, starting and performance.

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Re: carb tuning / timing ???

Post  1951 ford on July 23rd 2013, 7:02 pm

ah yes that might be helpful. Heads are a Dove-c reworked with cj valving so 2.25 intake and 1.75 exhaust . Cam is a comp cam xe274h
Specs are
Duration@ .050lift 230 in 236 exh
Valve lift .562 in 565 exh
Lobe Seperation 110
intake centerline 106
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Re: carb tuning / timing ???

Post  LivermoreDave on July 25th 2013, 11:14 am

Is the combination running and on the street yet? I'll step out on the plank here and pass on a few opinions. First of all, that combination of parts should make for a nice sounding engine. There are many variables of your application. The actual final drive ratio will be in the 3.2:1 to 3.25:1 range. If the application is lightweight or light in the back, laying rubber may not require much effort. I feel with the duration of the camshaft and the amount of converter stahl, the engine may be a bit sluggish at engine speeds below 2500 RPM. Especially with the tuning the ignition may require to control detonation. I have seen compression ratios as high as 10.66:1 (cast iron,well prepared combustion chamber) work, although a premium pump gasoline and a standard shift transmission was part of the application. I'm not sure if you can retard the camshaft to it's 110* IC and remove a bit of cylinder pressure and that may only offer less lower engine speed performance. You could add converter stahl, that would make a huge difference although the increased stahl may hamper converter lockup or slippage while cruising.

Just a few un-educated thoughts, I'm sure your combination will be fine!

Dave.

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Re: carb tuning / timing ???

Post  1951 ford on July 25th 2013, 5:41 pm

so engine is running driving in the truck in my posts. it is light in the rear end . so my question . having to much initial would that make it slugish out of the hole. not sure if im reading the timing light right but were i had it advanced seemed way out to lunch like 40 some degrees isnt possible is it?
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Re: carb tuning / timing ???

Post  kim on July 25th 2013, 5:55 pm

Best thing is to get a timing light that is adjustable, I have a simple craftsman light, has s dial at the rear. Mark zero, and then read anything from -20 to plus 60. Basically map your system where ever you want, any RPM, etc.........

40 initial on an 11-1 iron headed combination, I would figure your reading something wrong. Either that, or your confirmed deaf, as the detonation under any application of throttle would alert you that most of your pistons just ended up in the oil pan.

The issue with timing, you want max cylinder pressure at 10 degrees after top dead center as possible.

Unfortunately the air intake charge, cylinder temp pre ignition, etc.......... all change, so one value isn't perfect. Most of us need about 10 to 15 degrees BTDC advance to facilitate a decent cylinder pressure to ignite the fuel, yet low enough to prevent kick back, and of course detonation issues with part throttle application.

Piston speed, combustion chamber shape, head material, spark plug heat range, and fuel, all determine critical factors on how prone an engine is to detonate or not.
For peak performance, ID the max timing needed for peak HP at WOT, most fords like 32 to 40 depending on head, cam, etc................

Then the curve or mechanical advance needs to be worked in to go from a starting advance timing of something between 10 and 14, to max required. Most engines work best with all advance in under WOT acceleration with something between 2500 and 3000 RPM

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Re: carb tuning / timing ???

Post  1951 ford on July 25th 2013, 7:14 pm

so the timing light i have is one with the dial on the back . But im getting wierd numbers also were i had it set before i did not get any pinging and it wasnt hard to start . so its got me puzzled. but it does run at either spot no issues but i do have an adjustable timing indicater it is possible it has moved so to find top dead center you take compression tdc and exh tdc and you split it ?
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Re: carb tuning / timing ???

Post  1951 ford on July 25th 2013, 7:28 pm

also do most cams come ground a few degrees advanced
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Re: carb tuning / timing ???

Post  LivermoreDave on July 25th 2013, 9:16 pm

Maybe you can evaluate your timing light with this test. Mark you harmonic balancer's timing marks at 0* (TDC) and 20* BTDC. Your timing light as you described has an advance dial. With the timing light connected to power and the number 1 cylinder spark plug wire and the timing light dial at 0*, set your ignition timing at 20* BTDC as shown on the harmonic balancer timing mark. Now that you have verified the 20* BTDC setting, adjust your timing light advance dial to 20*. Does the mark on your harmonic balancer now indicate the 0* setting that shown on the harmonic balancer?

As to your 40* initial timing question, it probably won't make the engine sluggish, although I would think in your application detonation would be prevalent with any throttle action. At times to much initial ignition timing will create a miss in the engine's idle or steady throttle.

If timing issues continue, check the harmonic balancer's timing marks related to TRUE TDC at cylinder number 1.

Yes, most camshafts like the one you have chosen have a bit of advance ground into them. COMP, as well others incorporates this technology for the added performance of their street camshafts.

Dave.

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Re: carb tuning / timing ???

Post  1951 ford on July 25th 2013, 10:55 pm

thanks for the info i will try it out and throw up an update
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Re: carb tuning / timing ???

Post  1951 ford on September 23rd 2013, 7:35 pm

so im thinking i could use more advance still starts easily when warm and i think my build should have no problem kicking a stock 04 mustang gt's ass. But it seems to be running out of fuel so needs to be richend up? just grasping at straws any help would be greatly appreciated . Not sure how many times im willing to let my sister inlaw kick my ass in a mustang
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