how much initial advance for a SBF ?

[zrayr]

I'm just getting started to get acquainted with them, so far so good. I am curious as to how much initial advance you guys are happy with? Except for the Webers it's a stock 289 HiPo K code engine

thanks.

Z. Ray

[Rick Parker]

This will tqake a little experimenting but this will put you pretty close: 14-16 Degrees at about 1200-1300 RPM. Use a blue bushing in the distributor with 1 light blue spring and 1 light silver spring. Set max advance to 36 degrees (check at 2800 RPM). Use premium fuel and BF32 (Autolite) or the equvalent. Reset idle. The Webers will tone down a large part the of radical idle you previously encountered with a large 4bbl.

http://www.msdignition.com/product.a...ushing%20limit

[thehonest76]

I'm getting ready to fire up the new 331 for the first time. What info is needed to figure out what to set the initial timing to and how far (and quick) of an advance to use? I'm using an MSD billet distributor with mechanical advance. Should I use the springs that came in the distributor to fire it up the first time?

Let me know what info is needed and I'll list my specs. Thanks!

Winrar Free

[blykins]

You want a quick curve in a Cobra. I normally set my Cobra engines up to be all in by around 2600-2700.

It's easy to do with an MSD, so I'd go ahead and change it.

For initial, I'd start around 16-18° and use about 20° mechanical advance.

You can play with the amount of total timing later once you get acquainted with everything, and depending on the engine specs, it may like a bit less than that.

[wolf k]

Believe it or not, 25 deg initial, 38 deg total. Mechanical advance MSD distributor like yours. Had to modify a bushing to limit the total advance. Large initial advance made a huge difference in off line driveability for me. Although with your heavier Mustang your settings may require something less aggressive.

[blykins]

Should have just locked it out....

I do that a lot for larger cam/carb combinations, or on my CHI headed stuff that likes 28 degrees total.

[carmine]

what does running vaccum advance do to all the timing specs provided?

[blykins]

Adds more total timing in addition to the mechanical advance.

[ERA Chas]

Brent is right. Modern heads with heart-shaped chambers and quench like 28 to 31. If your original heads are unmodified then the higher numbers are suitable.
BTW-those Weber screens may be a 'rev-limiter'...

[zrayr]

got the best vacuum signal at 18 degrees BTDC, so that's my starting point, using the 21 degree bushing, giving a total of 39. Stock is 40 degrees , so I'm not too far off as far as that goes.

thanks for information.

by the way, I'm hearing that the screens I'm using are too restrictive ? Any one done a with and without comparison?


Z.

[dallas_]

Originally Posted by zrayr

by the way, I'm hearing that the screens I'm using are too restrictive ? Any one done a with and without comparison?
Z.

Do your screens have a foam filter media, or just the screen?

If it's just the screen you should be fine.

[zrayr]

Originally Posted by dallas_

Do your screens have a foam filter media, or just the screen?

If it's just the screen you should be fine.

just a mesh screen, no filler, foam, or fabric. You can see right thru them. Anything (hopefully air) smaller than a 2 year old child should pass right thru.

Z.

[Earl J]

Z. Ray, Jim Inglese sells what he calls debris screens that are really good and not restrictive as the ones you show. I have my GT350 and run 48 IDA Webers as well. As for your original question re advance. 38 degrees total all in by 2500 rpm, I had my OEM Hipo distributor re-curved with 29 degrees in it by 2500' 9 at the dampener.
~E

[zrayr]

Earl,

if I am reading your post right, you have 9 degrees initial advance, a mechanical advance of 29 degrees giving you total advance of 38 BTDC. ? And it's all in at 2500 rpm, right? If so that is very interesting. Most advice & comments I'm hearing (Jim Inglese included) suggest starting out with as much initial advance as possible, not less than the factory spec for a HiPo (which is 12 initial, plus 28 from a stock HiPo dist. equalling 40 total). But if that is working well for you I certainly can't fault what is successful.

I'm starting at 18 degrees at idle and finishing at 39 at 2300 rpm, so far. I'm still in an experimental phase.

by the way, I got the Weber's & manifold from Jim I. as well. He is claiming no difference in performance with the screens I'm using. I do have some performance issues to be resolved, but they are not related to the Webers. I'll be doing a dyno session sometime soon to provide a definitive baseline for future comparisons and changes. I'll be sure to do a run with and without the screens..

The engine and car are new to me and I have no confidence that it was assembled correctly at a restoration about 10 years ago, or with correct HiPo pistons, cams, etc. It not been driven much since then, until I bought it in May. I drove it a 1000 miles home from Illinois over two days, and about another 1000 miles since.

Maybe it has a wrong cam, or maybe cam timing is off, I don't know at this point. But if doesn't want to rev happily like other K codes I've owned. It will eventually get to 6000 rpm, but it seems like it takes a year to get there vs my GT350 which could go from idle to 7000 very, very quickly. I know my old GT350 had a free-er flowing exhaust, but the difference seems more than that would account for.


Z.

[YerDugliness]

Gotta LOVE those K-code 289's!!!

Dugly

[kiwigt]

Newb here, resurrecting a (slightly) old thread and seeking your collective assistance. I have a 66 Mustang GT Fastback with a Roush 342R stroker engine.
I am installing a brand new set of Jim Inglese 48 IDA's.

Jim advises I want to start at 8-10 degrees initial timing advance, and deliver a total of 38 degrees at the crankshaft, this would be 4-5 degrees initial lead and 19 total degrees of advance in the distributor.

I'm using an MSD distributor. Can anybody advise on bushing / spring selection based on the above please?

[blykins]

If you want to follow Jim's advice, then you would want to set the initial at 10°, use a red bushing, and try 2 silver springs.

I don't see why that engine would need 38° total timing. The intake manifold doesn't play a part in the amount of total timing...just the compression ratio, the combustion chamber efficiency, and how the quench is set up. That engine shouldn't need any more than 34-36 total.

[kiwigt]

Thanks for your advice. Would the silver springs recommended be the light, or heavy gauge silver springs?.

[blykins]

Light. In a lightweight car such as a Cobra, a quick timing curve is easily tolerated. Total advance should be in by about 2500. The next spring setup is a little past 3000 if I recall correctly.

[kiwigt]

Great - thanks