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Discussion Starter #1
In a recent post, I complained about my built 289 not delivering the mail on the
1/4 mile. Several guys suggested too little timing and this is a followup on that.

My MSD Ready-To-Run distributor came configured with the heaviest spings
possible on the mechanical advance. This gave a long timing curve and my
timing wasn't all in until about 4000. I just changed the springs to bring it all
in by 2800 and then I upped the initial advance from 6 to 10 deg. so that my
total advance is about 32 deg. I took it out for a run and although I'm sorry
to report I still can't do a burnout, I definitely noticed an improvement at all
RPMs. It also seems to downshift the C4 more readily too. All in all, a
definite improvement, but may only be worth a few tenths.

Next I'll have to rig up a temporary tach and see where the shift points are.
I expect they'll be pretty tame, maybe as low as 3000 rpm.
 

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dont hesitate to manually shift the c4 if need be, just DONT throw it into reverse or park!
 

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Do you have stock heads? You could probably handle a little
more timing, As long as it doesn't ping.
 

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If my car's engine appears to be running decent yet the tranny shifts too soon even when the throttle is wide open I'd adjust the modulator....

I adjusted the modulator on my fresh C4...it shifted WAAAAAYYY too soon.....I unhooked the vacuum line at the back of the tranny and stuck my homemade tool ( a piece of coat hanger wire with a chisel end ground into it...basically a jewelers screwdriver) into the vacuum connection, and turned the adjustment screw clockwise a turn, test drove, and decided to turn it in one more turn...

the tranny is very responsive to load and shifts at good points relative to my throttle inputs now!
 

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Discussion Starter #6
I debated going to the next advance bushing, but frankly, since the bushing is
held in upside down by a locknut and washer, it seemed like it would take
some careful finger work to get it changed. But I should probably do it (once
things cool off around here a little - the garage is more like a sauna right now).

How far can a 10:1 with iron heads be pushed on total timing? Do I just keep
adding timing until I get detonation?
 

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Advance bushing? Can't you just turn the distributor? I think
advancing it tell it pings and then backing it off a bit is a good idea. I run 16 initial, 36 total with aftermarket heads.
 

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Yup, post the rest of the combo specs...I'll be particularly interested in the cam specs and converter flash/stall speed...

I ran a similar combo with an Isky solid lifter cam and 11" converter and 3.50's in my street racer 67 back in college...ran mid-14's with the 3.50's and 14.00's with 4.62's in street trim.

I think your problem is too tight of a converter and too tall of rear end gear...unbalanced combo...

IIRC, I shifted the street racer engine at 5500 and went through the lights at 4400 with the 3.50's and 5800 with the 4.62's...

FWIW, I've never touched the advance curve in any distributor in any engine I've personally built, and that includes ones which got the race car deep into the 11's.....I even bolted the distributor advance plate down one time, locking out any advance, and just set the distributor so the engine had 36 degrees at idle.....that 289, with an old 10.00 junkyard Duraspark and a MSD 6A was the quickest engine ever to reside in the car, running in the 11.20's @ 120 MPH. Of course, with over 12:1 CR and a stock starter (they didn't make HT starters back then), I had to spin the engine up to full cranking speed before hitting the ignition switch.

As I often preach here, although it mostly gets lost in the mix, is balance, balance, balance..*G*
Especially with a relatively heavy stock-bodied car...

Good luck!
 

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Discussion Starter #10
The combo looks like this:

block: 289, .060 over with flat top KB hypereutectic pistons
heads: stock iron ported by PowerHeads 1.90 in/1.60 exh
cam: Isky Mega 264, 214/214 @0.050, 264 adv.. .480 lift with 1.6 roller-tip rockers
spark: Pertronix 40kv coil into MSD Ready-to-Run billet distributor, dual (vac/mech) advance
timing: 10 deg initial, 21 deg mech
carb: Edelbrock 1406 (600 cfm), elec choke
converter: stock 10.?"
tranny: stock C4
rear end: 8" 2.79:1 open

I modified the timing curve because I was only up to 21 deg of advance by 3000 rpm and I wanted
to bring the timing in more quickly than that. The factory curve didn't bring it all in until over 4000.
I don't know for certain what my shift points are, but they feel low, maybe as low as 3000-3500.
(BTW, the MSD sets the max mechanical advance by means of a bushing that stops the weights
from extending beyond a preset point. There are 4 bushings of various sizes for this. I'm using
the one for 21 deg.)

I know I need more converter and more rear gear. My game plan is to move to a 2000-2400 rpm
converter and to bring the rear gear up to 3.25:1. I've planned this all along (I never forget anything
pat tells me to do), but it's not going to happen until the spring. Meanwhile, I'm scheduling some
time on a chassis dyno to dial the motor in. Once that's done, I'll know I'm getting the most out of
the engine at least.

FWIW, this pony is driven mostly by SWMBO and mostly around town (read: below 3000rpm/50mph).
It doesn't see the highway too often (although those rear gears do like the highway and the motor
_loves_ the higher rev range).

I'm also testing the throttle linkage per Johnpro, just so I don't overlook anything.
 

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Hi Rich,

Sorry if I forgot some of your combo...I see so many they all become a blur..*G*

Your choice of converter and gear will really wake up this combo...I'd wait to do fine tuning until you have them installed...the combo will change character markedly with these additions, trust me...

You should have a solid, reliable mid-high 14 second car when you're done, once the fine tuning of the drivetrain and suspension is completed.

Patience!! *G*

BTW, you just taught me more than I ever knew about the MSD billet distributor in the race car...I just dropped it in and went racing *G*
 
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