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Whats the next step to warm up my slant ?
https://www.slantsix.org/forum/viewtopic.php?t=13300		 Page 1 of 2
Author:  MileHighDart [ Wed Jun 08, 2005 12:24 pm ]
Post subject:  Whats the next step to warm up my slant ?
The car is a 68 Dart, with 225 slant in good running shape, has electroninc ign. I've already converted to Supersix with a fresh bbd carb. I've opened up the "outlet" on the exhaust manifold to 2'1/4", but still have smaller exhaust with turbo muffer. Obviously I need to get to the muffler shop to have a new 2-1/4" system put on it all the way back.

After that, whats next to get a little more power. This car is a daily driver and has 2:76 gears with a 904 auto. I drive it every day to work about 60miles round trip and most of it is 65mph highway travel. So for now i'm not looking at changing rearend gearing,,, maybe just working on the engine for power improvement.

So whats next,, a cam ? Or would a cam be a pointless change without doing some porting on the head.

Just want a little more Giddy Up with out loosing my highway drivability.

Thanks
Author:  SlantSixDan [ Wed Jun 08, 2005 12:46 pm ]
Post subject: 
A better cam would give you more "giddyup" without messing with your mileage too much...if you don't go overboard. Keep the duration change minimal; look at more lift.

I'm really happy with my MP 244 cam in my '62.

Intake duration/ Exhaust duration/ Lift/ Overlap

Your stock '68 cam is a 240°/236°/0.395"/16°
The MP244 is a 244°/244°/0.436"/28°

Have you recurved the distributor yet?
Author:  MileHighDart [ Wed Jun 08, 2005 1:14 pm ]
Post subject: 
I haven't started messing with recurving the distributor yet, I dont know that much about it.
But I did fool with my initial timing a little bit on saturday. My motors manual says a 68 slant should be set a 0 degrees. Mine was set a 2degrees advanced, which would be fine since i'm at 5500ft elevation and we've always set our cars a little more advanced than what the book says.

But i've read on here that most guys are running at 8, 10, or 12 degrees advanced.
The way my dist was installed, there was no adjustment left on the adjustment slot. SO, I removed the dist, and rotated the shaft clockways one tooth and reinstalled it, I was then able to get more adjustment (advance) out of it. I set it a 8 degrees and took it for a drive. It runs better, maybe revs up a little faster. At 8 degrees theres still no sign of pinging even on a very steep hill in 3rd gear.
Maybe I could advance it even a little more and i'll probably try that this weekend.

Thanks for the cam suggestion Dan,
Any more ideas -- anyone's opinion is welcome !
Author:  emsvitil [ Wed Jun 08, 2005 1:33 pm ]
Post subject: 
Quote:
The way my dist was installed, there was no adjustment left on the adjustment slot.
There's another slot on the bottom of the distributor (only seen when distributor is removed).................
Author:  MileHighDart [ Wed Jun 08, 2005 1:35 pm ]
Post subject: 
Quote:
Quote:
The way my dist was installed, there was no adjustment left on the adjustment slot.
There's another slot on the bottom of the distributor (only seen when distributor is removed).................
That slot was at the end of its adjustment also, I'm thinking whoever installed the MP eletronic dist got it in one tooth off or something. But I have plenty of adjustment now.
Author:  70valiant [ Wed Jun 08, 2005 5:39 pm ]
Post subject: 
After super sixing mine I went with headwork. I took had the machine shop take 0.100" off and do a valve job with new guides. with everything it was almost $500. I ported all the runners myself with a dremmel. I also added headers and a 2.5" exhaust to a 2 1/4" in and out turbo muffler with a 2 1/4" pipe out the back.
These mods dropped my ET by 1.5 seconds and gained 5.5 MPH in the 1/4 mile. you can check out my progress in the virtual dragstrip section.
Taking that much off the head may not be what you would want to do because it raised my compression to a measured and calculated 9.8:1 which necessitates premium fuel(93 octane)
This is my daily driver and I commute around 18 miles round trip all town driving and get 16 mpg but better than 20 mpg highway now with the 3.23 gears. back when I had 2.76's I got 17.5 town and 22 highway. Just a little real world food for thought. hope this helps.
Author:  Jeb [ Wed Jun 08, 2005 6:37 pm ]
Post subject: 
The next step up from your 60's cam would be the 71-77 cam. These are the nicest stock cams the slant came with.

With those 2.76 gears, you need more torque production than horsepower.
Author:  SlantSixDan [ Wed Jun 08, 2005 6:55 pm ]
Post subject: 
Quote:
The next step up from your 60's cam would be the 71-77 cam.
That cam is actually '71-'80 in North America, '67-'80 in certain other markets.
Author:  MileHighDart [ Thu Jun 09, 2005 7:25 am ]
Post subject: 
Anyone know the specs on the 71-80 cam, or how it would compare to the mp244 cam slantsixdan recommended ?
Author:  SlantSixDan [ Thu Jun 09, 2005 7:51 am ]
Post subject: 
'71-'80 cam is 244°/244°/0.414"/26°. Not worth switching to this one from the '65-'68 240° cam unless your original cam is wiped/dead.

The MP cam has essentially the same specs; the critical difference is the higher lift of 0.436". Remember, these "at the cam" lift values get multiplied by 1-1/2 by the rocker arms. So, the cam you have in there now opens the intake valve by 0.5925". The '71-'80 cam opens the intake valve by 0.621". And the MP244 cam opens the intake valve by 0.654". For comparison purposes, this means the '71-'80 cam opens the intake valve a little under 5% wider than the cam you have now, while the MP244 opens it a little over 10% wider.

That, however, isn't the only factor at work. The durations of all three of these cams are very similar (within 4 degrees). For any given duration, higher lift also means more rapid valve opening and closing events. The ramp on the cam is steeper to produce the higher lift, so the valve gets bumped open wider, quicker. This improves breathing. It also means the valve gets dropped closed quicker, which traps pressure in the cylinder better. And cylinder pressure is what you need to maximise.

(the above is very simplified, intended to give an overview of the basic principles of how it works).

I may be a leetle biased in my recommendation, 'cause I have a new MP244 cam for sale and Mopar doesn't sell 'em any longer :-D Seriously, I really, really like how my '62 behaves with this cam and a 2bbl carb. Torque monster! 70 mph with most of the pedal travel still left, and that's with 3.23 rear gears. Less asthmatic than with the stock '60-'64 (232°/228°/0.365"/8°) cam.
Author:  MileHighDart [ Thu Jun 09, 2005 9:53 am ]
Post subject: 
Thanks Dan, thats good info !

Slantsixdan,,, you have a pm
Author:  panic [ Thu Jun 09, 2005 4:17 pm ]
Post subject: 
"It also means the valve gets dropped closed quicker, which traps pressure in the cylinder better"
Backwards - fast ramps means the valve is OPEN a larger percentage of the duration before closing, doesn't trap any more compression.
Author:  SlantSixDan [ Thu Jun 09, 2005 5:20 pm ]
Post subject: 
Quote:
"It also means the valve gets dropped closed quicker, which traps pressure in the cylinder better"
Backwards - fast ramps means the valve is OPEN a larger percentage of the duration before closing, doesn't trap any more compression.
Nope. For a given duration, a steeper cam ramp means a given valve lift is achieved in fewer degrees of rotation ("faster") -- whether that given amount of valve lift is on the way open or on the way closed.
Author:  gmader [ Thu Jun 09, 2005 5:43 pm ]
Post subject:  Panic vs Dan-- The rumble on the forum!
:)
Author:  Ron Parker [ Thu Jun 09, 2005 5:48 pm ]
Post subject: 
Put the 3.23 gear in it and you will be a happy Slanter. Been There Done That. Thanks Possum :D :D











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