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Performance timing curve
https://slantsix.org/forum/viewtopic.php?t=26752		 Page 1 of 1
Author:  dave571 [ Sat Jan 19, 2008 1:43 pm ]
Post subject:  Performance timing curve
OK
First off, great board guys! Love all the info. I got refered here by slantzilla.

Second...
I do performance distributor recurves on mopar distributors. I have been sent a slant 6 electronic one from a guy. I have little experience with slant's, so have been digging for info, and would appreciate some info.

here's the low down...
84 dodge 1/2 ton
225 .030 over
4 speed
3.73 gears
28" tire
clifford intake and headers
600 eddy carb
holley elecric fuel pump
mopar electronic ign and dist
Head type and valve size... stock slant
Cam duration at 50 214
Lobe Centerline 110
Cam lift 449
Cam brand clifford
Compression ratio 9?(there's .100 milled off the head)
General elevation in our area is 2500

If it were a small block, I'd set the initial around 16 degrees, and the total at 35 nopt all in till 3K or so because of the weight (that's with the vacuum off, talking about mechanical only. I'd proably set the vacuum for 12 more once I was done with the mechanical)

What will a slant 6 like this want?

Thanks for any input! 8)
Author:  DusterIdiot [ Sat Jan 19, 2008 2:41 pm ]
Post subject:  Heavy vehicle...
Quote:
What will a slant 6 like this want?
The engine is well built (I hope), but the vehicle is heavy (even with the gearing...)...

The 'formula' for the slant is:

30 degrees total (most prefer to run a fair amount of initial like 12 BTDC... so the governor slot would have to allow 18 degrees of advance, you can save yourself a lot of 'welding' by finding a mopar EI governor that is stamped 9R.. like the 1976-1980 distributors)...

then he should have a vacc. pod which will add in the last 20 degrees for good 'mileage' (LOL) for a total of 50 degrees during highway cruise situations (truck my only want about 17 degrees)...

He'll have to give you the vacc. readings and cruise rpm's to figure out where the distributor and vac. can needs to come in at... for cars a fast first few degrees in the slot helps with a stiff limiter spring to allow the last 2-4 degrees just above the cruise rpm to come in... With trucks, since they are heavy the curve may have to be a bit 'lazy' to keep the thing from pinging under load (us car guys can take a faster curve as we don't have as much mass to 'throw'...)

Sadly, we all have different builds to work with so what each of us likes is based on our own trial and errors.. but the 'formula' of 10-12 init, 18 mech/ 30 total, then 47-52 (52 for the car group) with vacc. advance is a standard guideline to work from...

you can also look at a couple of long threads with some nice slot length measurements by doing a search on here.

Good Luck,

-D.Idiot
Author:  Aggressive Ted [ Sat Jan 19, 2008 3:24 pm ]
Post subject: 
Dave571,

Duster's guidelines are right on with what the SL6 likes.

As a reference: I have a 74 Dart Swinger with newly rebuilt SL6 and I like the following setup.

New electronic distributor re-curved with red primary spring and extra long looped secondary spring from a 400 distributor. It has a15R governor with a 11R V8 vacuum advance screwed in 3 turns. Blue Streak cap, MO-3000 Echlin rotor, Chrome Blaster 2 coil and 8mm Blue Summit wires. Timing set at 16 degrees initial, 16 degrees mechanical and 20 degrees with the vacuum advance for a 52 degree total.

By the way, do you have access to new distributor springs for Mopars? :?: :?: :?:
Author:  dave571 [ Sat Jan 19, 2008 4:01 pm ]
Post subject: 
I have been using new springs from a kit at the speed shop.

Mr gasket kit for the pre HEI(points) GMs. The hei ones won't work, but the pre HEI points spring kit, provides a nice assortment 8 springs in it or so.

I'll look this evening, and see if I have a part number for the kit.

Thanks for the helps so far guys!
Author:  dave571 [ Sat Jan 19, 2008 6:15 pm ]
Post subject: 
I've been using MR. Gasket 928 or 928G spring kits.

Cheers

8)
Author:  Aggressive Ted [ Sat Jan 19, 2008 6:29 pm ]
Post subject: 
Dave571,

The Mr. Gasket springs are very light. I have a couple of those sets. They need to be used with the correct governor to stop the advance.

The long looped MOPAR secondary springs will let you use governors with longer slots for a little more progressive advance instead of just coming full on.

Have you found any long looped secondary springs available anywhere?
Author:  dave571 [ Sat Jan 19, 2008 6:55 pm ]
Post subject: 
No, I haven't seen any of those new.

I usually shorten the slots with weld, to get my total number, so I never use the long looped springs.


The springs in the 928 kit are not so light, that they won't work. Several different tensions in there.

Curve can easily be manipulated to come in as late as you want. 4K or later.

I know the mr gasket springs that are specifically for a mopar are super duper light, and virtually useless for that matter. All in by 1200 -1500.

Thansk for the tips guys!
Author:  BigBlockBanjo [ Sun Jan 20, 2008 2:02 pm ]
Post subject: 
Jumping in here.....
I'm getting ready to recurve my distributor, and have been following the "curve threads" with interest. I've noticed that many folks say the Mr. Gasket Mopar spring kit is way too light.
Could a person use one of the light springs, along with the stock long-slot heavy spring? It seems that this would have a similar curve. Just curious about it...
Author:  Aggressive Ted [ Sun Jan 20, 2008 3:31 pm ]
Post subject: 
Big Block,

Yes, that is exactly how I used it. For a street car it works much better that way especially with a long slot 15R governor. If you have a medium build like mine it will kick the rear end loose pretty quick even with a 2.76 posi. I ran my car that way for about three months and decided it was a little too snappy of a take off. It would just dump at 2000 rpm and put you in the back of your seat no matter how easy you pressed on the pedal. It was fun for awhile, but I ended up mellowing it out some with a stock red primary spring out of a big block distributor. I also rotated the spring post around to where there was no slack or lag in the spring. That way I can feather the gas pedal better with out it being so peppy or aggressive. :D
Author:  BigBlockBanjo [ Sun Jan 20, 2008 6:52 pm ]
Post subject: 
Thanks Ted,
Well, I worked on it tonight. The dizzy I have came with a short-slot governor; slot is .380. Cut my light spring out of a longer, ''universal'' spring. I have all advance in (Incl. Vac.) at 2300. I now only run 2300 RPM at 55. I used to run about 2600. It still doesn't "get loose" like I think it should....
Author:  Aggressive Ted [ Mon Jan 21, 2008 6:50 pm ]
Post subject: 
Maybe your Edelbrock is still running too rich. If you lean it out some more it will perk up. As an example, I can feel the difference with jets that are too laarge in the 1920 Holley! It looses it's crisp response. A #59 or 60 jet is just way too fat. It's fun, but wastes to much fuel.

What do you have your initial timing set at? I like 16 degrees.
I am also running 16 degrees of mechanical for 32 degrees total by 2500.
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