So who's running a Comp XE268?!

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Yeah, Sold the house but Packed up all of Garage and bought a 28' Trailer to store all my car stuff. Plan to move south in 2 years.

Trailer.jpeg
 
MoparMark91 said:
Yeah hope the carb will work out with this build and hope the vacuum secondarys wont give me trouble. The converter i was going to use was in a A904 that was behind a 69 2 barrel 318, so i will probably have to get a new one. The guy i bought it off of said it was rebuily and looks fairly good but i dont know the size on the converter, ill have to pop it out when i get home. Betting no matter what ill need a new converter for proper stall
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With your cylinder pressure,(175IIRC), I would use that TC and not 295 tires,lol. Those early TCs, IIRC were about 1800/1850 TC behind a 150/160psi 318. But behind a big 360 at 175psi, it will be a fair bit higher. If yur all about the torque,and on a budget, I would give that 69TC a go; you can always swap it out later for a couple hours of work. And by that time you will have a pretty good idea of what you want.
The 600/650 is a good size for street with 3.23/3.55s. You'll be spinning right thru first gear with it so let her buck to ~6300. Then on the shift the Rs will drop to 3750@56mph, about the torque-peak and you got a short pull with 3.55s to 60@4050..... the speed limit,lol. 4050 in second will be fine with that size carb;more will just spin the tires up a few milliseconds sooner.
I would run the 3.23s with 28s to hit 60@6000...... still in first gear,and possibly/probably still spinning. 175psi has a way of doing that......
The 69TC might be a tad sluggish at zero mph, but in about 1/4 second that will all change.
At zero mph your TM will be 2.45x3.23x~1.8 in the TC, so 14.24, compare that to a 4-speed at 2.66x3.23x1=8.59.
But your 14.24 will decay to something like ~2.45x3.23x1.2=9.5 in about 3/4 second, then continue to decay to about 2.45x3.23x1.08=8.55 around 1.5 seconds out, then probably stay close to that for the rest of that gear still spinning.
That now compares to the 4-speed about on an equal comparison.
This is why autos usually launch a tad harder on the street in first gear, with same rear gears. They have additional TM (Torque Multiplication) inside the TC. Make it stick and try to wipe the smile off your face.
Here's how I figure it;
Depending on your tires,you only need about 2000 ftlbs to the road at zero mph to initiate a spin. With 3.23s and 28" tires this comes to
2000/(ET(engine torque) x 1.8(TC)x2.45x3.23x24/28)=164crank ftlbs. Ima thinking any 360 can make that at 1800rpm.
 
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or the 701 (or most anything else)
depending on how he wants it to drive
the 701 would work better in AJ's converter scenario
No matter what I agree on testing the stock HP converter, doing a stall test etc

another trailer like that and you could have a portable workshop- I liked the way you made your old one look

60 ft times
when we tested for Chrysler with the Higher compression motor the 268 DC cam was a toss up (slower initial across an intersection) (but better in the 1/8)
If you went to the DC 268 both gears and converter were needed to = the 60 ft time of the 340 cam
(but again more in 1/8)
now you can get more low, mid and top than these 50 year old grinds
 
AJ/FormS said:
yur gonna need a 750 or better to feed that hungry brute, and I'd run a DP.

I have a 367 (4.04x3.58), same eddies, KB107s at .005 up out of the hole, .039 gaskets for .034Q.
I did run a Hughes HE2430AL cam, which was 223/230/[email protected] were 270/276/110+4,lifts of .538/.549 @1.6 arms. I think very similar to the XE268, except the Hughes runs a bit more lift.
At 185psi cylinder pressure that was a fantastically strong off the line cam, a tremendous midrange, died early compared to the previous 292/292/108 Dc cam, but still pulled pretty good to 6000, and I regularly took it to 7000. I ran it with 3.55s and a clutch. It had so much off-idle torque, that it was a dump-it-and-go routine most of the time.

So for just a gasket swap, keeping the Q to less than .040, you can save thousands of dollars over the course of the engine's life, in the fuel cost difference.
185psi is a sweetspot for that combo, embrace it. Running aluminum heads at 160psi or less, IMO, is a total waste. To break even in absolute power, with the same iron combo, it has been written that you need at least a half point more compression. That might be right for drag-racing, but on the street, IMO that .5 hike should be changed to at least 1.0; and the aluminums will like up to 1.5 points with tight-Q. I have run 11.3Scr with the 292/108 cam, full timing, and 87E10, with no issues.
With my Hughes cam above, I think it was 10.95cr, still on 87E10 and full timing.
BTW; full timing with those aluminum Eddies is between 30 and 34 degrees; I run about 32....... most of the time.
Click to expand...

You were running 32 total, what was your curve like- initial and when was it all in and everything?
 
I have a manual trans.If you run too much initial with a big cam 223 to 292 in mine, and lots of cylinder pressure,with a manual, then at low rpm,it tends to get jumpy; like an 80s Mustang. And with a manual trans, the engine is sorta married to the tires.
So to cure the bucking I run 12 to 14 initial,
and it doesn't start advancing until 1000 rpm.
I have a two stage curve using one spring with a long loop; so the first stage hustles up to
~28*@2800, then it slows down and
tops out at 3400 or so with 32*.
I tried 34 and 36 and my butt-meter couldn't tell the difference, so I called 32 done.This curve lets me burn 87E10 full time, yet car went 93 in the Eighth @3467 raceweight.
To cover the torque loss using the lazy timing curve below 2800, I modded my Vcan for 22*, and adjusted it to come in fast. So, at 2800, at Part Throttle, She could have up to 28+22=50* for cruising, which with 3.55s and 27s, is 63.5mph.
My cylinder pressure, with the Eddies, is about 177 IIRC.
 
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