Thanks in advance.

I have a newly rebuilt (500 miles) 1968 225 .60 over 10:1, holley 390 (54 F and 58 R), offy intake , shorty headers, 904 with 2600 stall, 3:21 gears, cam is 268 dur , 447 lift, stock distributor (36 deg total) with orange box. 2.5" mid pipe off of Y to a turbo muffler 2-1/4 tail pipe in a 68 Dart convert.

I am having trouble keeping the car running in drive.The converter is stalling on the breaks at 1600 rpm. Converter is new. Old converter ran the same with a 2100 stall. What to do? I'm planning on a set of 3:55 gears. Car runs 15" vac at idle park, 12-8"idle in drive and 15-22" on the highway at 60 mph. Car pulls like crazy on the high way but its a turd around town. I know the 3:21 gears are part of this, but this idle/converter issue is my problem. What to do?
Thanks again.

You say the converter is new. What kind of converter is it? A stock rebuilt unit? From where/what brand? Or is it a performance unit?
The two main things that determine stall speed, are the internal design/size of the converter, and the input torque. Are you sure the engine is running properly?

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Or your 2600 rpm stall is rated behind a V8, which makes it stall a lot lower behind a slant six. Also some of these larger cams have low torque curve until rpm climbs into the 2000 + rpm range, and a 3.24 rear is too high around town disallowing enough rpm to get into the useable torque curve; result dog around town.

I have about the engine build except my cam is a bit lumpier, rear gear is 3.55:1, and no low end torque; engine only starts to pull above 3500 rpm. I installed a 2600 rpm converter just to get the car to sit still in traffic with its 1100 rpm idle, and it tends to lock up around 2200 rpm during power brake.

It the time when the converter was selected I had no cam card to offer converter company so selection was a bit of a crap shoot. I have since used a degree wheel, decoded the cam, and mapped out the events on graph paper.

If I were to do it over again, knowing cam's specs, I would spring for a higher stall, more efficient (also more expensive) converter that would be street friendly, but allow enough rpm to get up into the torque curve.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Its been a long week. Thanks for the info. Converter is a stock slant modified to higher stall. This weekend I made some progress. Advanced the cam to 6 deg off of original setting with a offset cam bushing. Set lash .003" more than cam card requested. Vaccume is now at 14-15" in gear at 600 rpm. Engine now has some more grunt. The interesting thing I found is the timing. Idle is set at 20 deg and maxes out at 30 deg ( using a timing lite with adjustment dial). This engine won't ping any where? Running 180 deg F I'm running 91 octaine. I guess my next step is to rip the dizzy apart. Also, stall has gone up to 2200 rpm flash .

wjajr. I'm curious about you convert. Still have it? Also I'm heading to the track on Saturday. My engine is sort of a take off of your convert. Have you run the car? What times did you run? Also how much timing at 2000 plus rpm should I look for (ball park)?

You guys are the best! thanks again

[quote]I guess my next step is to rip the dizzy apart. Also, stall has gone up to 2200 rpm flash[/quote]

That increase is because the engine is developing more low rpm torque from cam degree change, and a now has a bit less overlap from loosening the lash. In other words you made the cam a wee bit smaller, but picked up better drivability, vacuum signal, and idle quality. On the other hand torque and hp may drop off a bit sooner at a lower rpm… Only a dynamometer will tell the story

[quote]I'm curious about you convert.[/quote]

It is as yours a stock converter modified to stall at 2600, but it has never stalled at 2600 perhaps around 22-2400 rpm; it’s hard to tell.

Timing at in park idle is 13 degrees, 1600 rpm = 15 degrees, 2000 rpm = 27 degrees, and mechanical + static all in at 2400 rpm for 30 to 31 degrees.

My calculated static compression is 9.5:1; I haven’t calculated dynamic compression lately, and can’t recall what it is. In gear idle vacuum is 4 to 8â€￾ Hg with a wagging needle, and at 3000 rpm under flat ground steady cruse vacuum is 16â€￾ Hg; once rpm reaches 4500 rpm add two more inches of vacuum making 17 to 18â€￾ Hg

My tires are 24.5â€￾ dia. 2000 rpm = 40 mph, and 3000 rpm = 60 mph

[quote]Have you run the car? What times did you run[/quote]

I ran it a few years ago before the carb was totally sorted out. It ran 1/8 mi in 10.3 seconds at 68.3 mph close to sea level. My ragtop is on the heavy side for a 1967, KH disk brakes & 10 drum at rear, sway bar, sub-frame connectors, spare tire, bucket seats and console, PS, 409, 8 ¾ sure grip, stock looking car in full dress with sound deadener, and 225 lbs. of lard ass perched behind the wheel. I have never weighed the car.

I’m only turning a calculated 5122 rpm at 68.3 mph in second gear at the 1/8 mile finish line. I use 6000 rpm as a red line; engine pulls hard to 6000 rpm, and I suspect the carb may be just a bit too small over 5500 rpm. This car is better suited for quarter mile track.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC