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Old 11-16-2008, 03:56 PM
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timing question

Here are my engine specs. Fresh rebuild on a ford 289. bored 30 over. brand new edelbrock 600cfm. I did an Accell points conversion. Brand new Accel coil. Brand new fuel pump. I fired it up today after the rebuild and got it to idel real good. throttle response in park is good to. All appeared great.

I took it for a drive around the block and noticed the car wants to cut out around 30 miles an hour. I put the timing light on and get 10 degrees on initial and I only get about 24 degrees total advance. From what I understand I should be around 36 to 40 degrees toatl advance? I can advance it more by turning the distributor, but then my initial is around 20 degrees.

Any suggestions or thoughts?

Oh yeah, its a 1964 ford galaxie custom

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Old 11-17-2008, 07:01 AM
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24 initial is good (24 + 14 =38). you will like the power! however, it could make the engine hard to start when warm. you need to check that

a 289 will like around 38 total.

do you have a vacuum advance? driving down the highway, 50 degrees will give you 1 or 2 better mpg. 12 more from the vacuum advance would be nice.
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Old 11-17-2008, 11:55 AM
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a caution:

you likely do have the small chamber approx 54cc heads so the CR can be 10/1+ just in stock trim....
so creep up on the WOT timing which with a STOCK cam is typically 32*-34*.....
(unless you do have deep rear gears for the heavy car weight)

here's the stock 289 Ford tuning settings for whether it was/is a AT or STD tranny or 2V or 4V camshaft.....
(cent is written in dist *'s, multiply by 2 for crank degrees)

I've not done a Accell unit conversion but sounds like it is restricting the centrifugal travel somehow,,,....
{as the chart shows, even the 4V dist does add 20*'s cent to the base (10b+20c=30* WOT)}
"and/or"
the the dist body that you added the Accell to is "shot"
(rebuilt dist body with new bearings/plate/gear/etc/etc and new points are only about $50 at your local store)

wants to die=
"check simple first"
crack open the gas cap to be sure the tank "is" venting.....
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Old 11-18-2008, 08:12 PM
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Ok thanks for the reply guys. I slept on the problem, and decided I would remove the inline fuel filter since the new fuel pump had a canister filter already. The inline has always been finicky as far as fuel flow goes. As it turns out, the inline fuel filter was restricting my fuel flow to the carb. Car runs like a champ now.

Although one thing im still concerned about is the toatal advance im getting of about 24 degrees. It's my understanding you read total advance by bringing RPM's up and seeing where the degree marks stop advancing? Is this correct or am I figuring the numbers wrong? Keep in mind the car is running great where its at so im not sure I should be concerned at all.

Initial is 10 degrees
Total is about 24 degrees
Stock cam
stock refurbished heads
converted from points to electronic
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Old 11-18-2008, 11:49 PM
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My first inclination would be to think that the inertia ring on the harmonic damper has slipped rotationally in relation to the hub. This is a common occurrence. You're showing 24 with a light, when in actuality, timing is probably closer to 34. You can live with what you have or you can correct it. Up to you. Here's the procedure to correct it....
http://www.crankshaftcoalition.com/w...op_dead_center
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Old 11-19-2008, 10:25 AM
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"check simple first"
read the timing total at 4,000+rpms with the vac advance unplugged to be absolutely sure all of the cent timing has been added....
(some stock dist models, for a very heavy car or a truck,,,, don't have full timing till 3500+ for no ping on a hill or a heavy load etc...(by using heavy cent springs)....and not many of these cars today still have the true/correct original dist model)

post back results,,,,
(unless you have a total accurate history on the motor ya gotta go one step at a time to sort out what has been changed,,,,)

disagree with tech,
if the damper ring shifts it just moves the "0" reference point....
your dist cent plate is only moving in a 7*'s arc=14*'s on the damper (10*base+14cent=24total WOT)

if it did shift 10*, then the base would now have to be 20*'s to show 24 total actually means 34* total and on a 289 the Ford starter would crank slow and complain big time when the motor is warm....

it's absolutely worth while to sort out the lack of cent added....
just a 2*'s change can/will make a 10HP/30TQ+ power difference you will feel,,,,
just to demonstrate, turn the base back to the stock 6*- 8*'s and test drive,,,,the motor will feel "lazy" as hell,,,need alot more pedal to "go"....

as a very very general rule of thumb a motor needs 28* minumum total at high rpms to make atleast decent cylinder pressure....
(do not just add more base to make the total higher!!! 10*base is almost max for a stock 289 cam)

Last edited by red65mustang; 11-19-2008 at 02:28 PM.
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Old 11-19-2008, 01:03 PM
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here is a copy and paste from a timing article.

TIMING AND VACUUM ADVANCE 101

The most important concept to understand is that lean mixtures, such as at idle and steady highway cruise, take longer to burn than rich mixtures; idle in particular, as idle mixture is affected by exhaust gas dilution. This requires that lean mixtures have "the fire lit" earlier in the compression cycle (spark timing advanced), allowing more burn time so that peak cylinder pressure is reached just after TDC for peak efficiency and reduced exhaust gas temperature (wasted combustion energy). Rich mixtures, on the other hand, burn faster than lean mixtures, so they need to have "the fire lit" later in the compression cycle (spark timing retarded slightly) so maximum cylinder pressure is still achieved at the same point after TDC as with the lean mixture, for maximum efficiency.

The centrifugal advance system in a distributor advances spark timing purely as a function of engine rpm (irrespective of engine load or operating conditions), with the amount of advance and the rate at which it comes in determined by the weights and springs on top of the autocam mechanism. The amount of advance added by the distributor, combined with initial static timing, is "total timing" (i.e., the 34-36 degrees at high rpm that most SBC's like). Vacuum advance has absolutely nothing to do with total timing or performance, as when the throttle is opened, manifold vacuum drops essentially to zero, and the vacuum advance drops out entirely; it has no part in the "total timing" equation.

At idle, the engine needs additional spark advance in order to fire that lean, diluted mixture earlier in order to develop maximum cylinder pressure at the proper point, so the vacuum advance can (connected to manifold vacuum, not "ported" vacuum - more on that aberration later) is activated by the high manifold vacuum, and adds about 15 degrees of spark advance, on top of the initial static timing setting (i.e., if your static timing is at 10 degrees, at idle it's actually around 25 degrees with the vacuum advance connected). The same thing occurs at steady-state highway cruise; the mixture is lean, takes longer to burn, the load on the engine is low, the manifold vacuum is high, so the vacuum advance is again deployed, and if you had a timing light set up so you could see the balancer as you were going down the highway, you'd see about 50 degrees advance (10 degrees initial, 20-25 degrees from the centrifugal advance, and 15 degrees from the vacuum advance) at steady-state cruise (it only takes about 40 horsepower to cruise at 50mph).

When you accelerate, the mixture is instantly enriched (by the accelerator pump, power valve, etc.), burns faster, doesn't need the additional spark advance, and when the throttle plates open, manifold vacuum drops, and the vacuum advance can returns to zero, retarding the spark timing back to what is provided by the initial static timing plus the centrifugal advance provided by the distributor at that engine rpm; the vacuum advance doesn't come back into play until you back off the gas and manifold vacuum increases again as you return to steady-state cruise, when the mixture again becomes lean.

The key difference is that centrifugal advance (in the distributor autocam via weights and springs) is purely rpm-sensitive; nothing changes it except changes in rpm. Vacuum advance, on the other hand, responds to engine load and rapidly-changing operating conditions, providing the correct degree of spark advance at any point in time based on engine load, to deal with both lean and rich mixture conditions. By today's terms, this was a relatively crude mechanical system, but it did a good job of optimizing engine efficiency, throttle response, fuel economy, and idle cooling, with absolutely ZERO effect on wide-open throttle performance, as vacuum advance is inoperative under wide-open throttle conditions. In modern cars with computerized engine controllers, all those sensors and the controller change both mixture and spark timing 50 to 100 times per second, and we don't even HAVE a distributor any more - it's all electronic.

Now, to the widely-misunderstood manifold-vs.-ported vacuum aberration. After 30-40 years of controlling vacuum advance with full manifold vacuum, along came emissions requirements, years before catalytic converter technology had been developed, and all manner of crude band-aid systems were developed to try and reduce hydrocarbons and oxides of nitrogen in the exhaust stream. One of these band-aids was "ported spark", which moved the vacuum pickup orifice in the carburetor venturi from below the throttle plate (where it was exposed to full manifold vacuum at idle) to above the throttle plate, where it saw no manifold vacuum at all at idle. This meant the vacuum advance was inoperative at idle (retarding spark timing from its optimum value), and these applications also had VERY low initial static timing (usually 4 degrees or less, and some actually were set at 2 degrees AFTER TDC). This was done in order to increase exhaust gas temperature (due to "lighting the fire late") to improve the effectiveness of the "afterburning" of hydrocarbons by the air injected into the exhaust manifolds by the A.I.R. system; as a result, these engines ran like crap, and an enormous amount of wasted heat energy was transferred through the exhaust port walls into the coolant, causing them to run hot at idle - cylinder pressure fell off, engine temperatures went up, combustion efficiency went down the drain, and fuel economy went down with it.

If you look at the centrifugal advance calibrations for these "ported spark, late-timed" engines, you'll see that instead of having 20 degrees of advance, they had up to 34 degrees of advance in the distributor, in order to get back to the 34-36 degrees "total timing" at high rpm wide-open throttle to get some of the performance back. The vacuum advance still worked at steady-state highway cruise (lean mixture = low emissions), but it was inoperative at idle, which caused all manner of problems - "ported vacuum" was strictly an early, pre-converter crude emissions strategy, and nothing more.

What about the Harry high-school non-vacuum advance polished billet "whizbang" distributors you see in the Summit and Jeg's catalogs? They're JUNK on a street-driven car, but some people keep buying them because they're "race car" parts, so they must be "good for my car" - they're NOT. "Race cars" run at wide-open throttle, rich mixture, full load, and high rpm all the time, so they don't need a system (vacuum advance) to deal with the full range of driving conditions encountered in street operation. Anyone driving a street-driven car without manifold-connected vacuum advance is sacrificing idle cooling, throttle response, engine efficiency, and fuel economy, probably because they don't understand what vacuum advance is, how it works, and what it's for - there are lots of long-time experienced "mechanics" who don't understand the principles and operation of vacuum advance either, so they're not alone.

Vacuum advance calibrations are different between stock engines and modified engines, especially if you have a lot of cam and have relatively low manifold vacuum at idle. Most stock vacuum advance cans aren’t fully-deployed until they see about 15” Hg. Manifold vacuum, so those cans don’t work very well on a modified engine; with less than 15” Hg. at a rough idle, the stock can will “dither” in and out in response to the rapidly-changing manifold vacuum, constantly varying the amount of vacuum advance, which creates an unstable idle. Modified engines with more cam that generate less than 15” Hg. of vacuum at idle need a vacuum advance can that’s fully-deployed at least 1”, preferably 2” of vacuum less than idle vacuum level so idle advance is solid and stable; the Echlin #VC-1810 advance can (about $10 at NAPA) provides the same amount of advance as the stock can (15 degrees), but is fully-deployed at only 8” of vacuum, so there is no variation in idle timing even with a stout cam.

For peak engine performance, driveability, idle cooling and efficiency in a street-driven car, you need vacuum advance, connected to full manifold vacuum. Absolutely. Positively. Don't ask Summit or Jeg's about it – they don’t understand it, they're on commission, and they want to sell "race car" parts.
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Old 11-19-2008, 09:16 PM
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Great stuff thanks guys. I know the inertia ring didnt slip because its a brand new after market dampner. The old one did slip and is now in the metal scrap pile.

I think red65mustang has a good point. I might not be seeing total advance at 3000 rpms, due to heavy cent springs. Thanks for all the great info and thoughts. Tommorow im taking the car onto the freeway to see how it does. Ill post back if I have any problems.
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