My 440 is a slug, please help.
#471559
09/18/09 09:27 AM
09/18/09 09:27 AM
|
Joined: Nov 2003
Posts: 154
Gator73
OP
member
|
OP
member
Joined: Nov 2003
Posts: 154
|
Like the title says, my 71 440 runs like a slug and has very little low end torque. It doesn't even want to spin the tires with 3:55 gears. We have a few theories on why it may be lazy but wanted to check here for some additional ideas. Here is the background on the engine. This was a bone stock 71 440 that has been in my 74 Roadrunner for years. It ran great when the engine was put in the car but over the years, the stock AVS would dead spot and no amount of tuning or rebuilding would fix it. Since there were some other small issues to address on the engine, we decided to remove it and replace the cam, timing, chain, carb and intake. Used a Crower 267HDP (220 and 223 @50 with 478 and 486 lift 112 lobe separation angle). On went a Holley Street Dominator and a new Edelbrock 800 Thunder Series AVS. It should be noted that we are using stock 73 HP Magnum exhaust manifolds. The car starts, idles,and runs nice and doesn't even really have any lope at all from the cam. The timing is set at 11 initial and doesn't ping. It bogs a lot when you step on it from a stop. Air door has already been adjusted some but hasn't cured the problem. So, anybody got any ideas? Is the Street Dominator killing off the bottom end in this combination despite the fact that it is generally known as a good low-end intake? I think the AVS carb should run pretty good on a stock-type engine and not be too much. The cam is also pretty mild and should not make a dog out of it. We have a Weiand Action Plus we can try to see if that brings back some of the low end but it is so dead I don't know what will help. A 440 like this should melt the tires. Any help would be greatly appreciated.
|
|
|
Re: My 440 is a slug, please help.
[Re: Joshs68]
#471567
09/18/09 10:30 AM
09/18/09 10:30 AM
|
Joined: Jan 2003
Posts: 5,444 Indiana
YO7_A66
master
|
master
Joined: Jan 2003
Posts: 5,444
Indiana
|
I agree with Josh. Initial timing is very important in a street car with a larger than stock cam and an auto. You wrote that you have 11 degrees initial timing, now once you know what your in gear (foot on brake, engine at running temp) vacuum reading is, you have a base line. Then I would suggest bumping the initial timing up to 15-18 degrees (since you have a larger than stock cam) and retune your in-gear vacuum to the highest number at the same rpm as you had with the 11 degrees. If your vacuum reading went up, then the motor wanted it. Then you would want to recurve your distributor for your total timing and then test drive the car. If you gained in gear vacuum, then you will gain bottom end response too if the carb is tuned correctly. That 800 Edy should be fine for your setup. Get the timing correct first and then finish tuning the carb.
1970 YO7 A66 [Canadian Export] F8 Challenger 340 (Currently in shop for stroker assy.)
|
|
|
Re: My 440 is a slug, please help.
[Re: Gator73]
#471568
09/18/09 10:35 AM
09/18/09 10:35 AM
|
Joined: Jan 2007
Posts: 780 Woodinville, WA
Viol8r
super stock
|
super stock
Joined: Jan 2007
Posts: 780
Woodinville, WA
|
Quote:
Yeah, I wouldn't think the SD would be causing the problem given the rave reviews it gets. Maybe it just works better on hotter engines rather than my relatively stock combo. Anybody ever use a SD on a stockish engine and have low end issues? I agree that changing carbs to a known good one regardless of the brand could elimiate a lot of guess work. I'll have to beat the bushes to see if I can scare a good candidate up.
You will lose a little bit of bottom end with the SD vs. the RPM (or dual plane). A few things jump out at me. Not enough compression, no stall, not enough initial timing, and the wrong carb.
|
|
|
Re: My 440 is a slug, please help.
[Re: Viol8r]
#471569
09/18/09 10:47 AM
09/18/09 10:47 AM
|
Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
|
fix the timing and the bog in the carb. EDIT all oe AVS's are emissions era carbs & you might get an eddie strip kit & some flat metering rod caps & richen it.
Last edited by RapidRobert; 09/18/09 10:51 AM.
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: My 440 is a slug, please help.
[Re: terzmo]
#471574
09/18/09 12:37 PM
09/18/09 12:37 PM
|
Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
|
what kind of vaccuum are you pulling at idle?
did you do a compression test?
if you have a lot of vacuum at idle (13+" In gear), changing the stock orange step up springs (5" vaccuum) to the pink or natural (7 or 8") will help a lot with a lean bog at tip in.
also, there's 3 holes on the acc pump lever to adjust the volume of the pump shot, closer to the carb the hole is, the bigger the shot. play around with that adjustment as well.
do you have any vacuum leaks?
if your compression test shows low, did you degree in the cam? If it's installed slightly retarded (say, 112 ICL instead of 108) the later intake closing point will cause the cranking compression will drop, and low RPM torque will be reduced.
Last edited by patrick; 09/18/09 12:40 PM.
1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!*** 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
|
|
|
Re: My 440 is a slug, please help.
[Re: Gator73]
#471577
09/18/09 03:18 PM
09/18/09 03:18 PM
|
Joined: Jan 2007
Posts: 780 Woodinville, WA
Viol8r
super stock
|
super stock
Joined: Jan 2007
Posts: 780
Woodinville, WA
|
This combo is just not a barn burner, sorry my friend. An 8.5:1 iron headed, stock bottom, no stall 440 is just not going to feel real quick. Especially with a single plane intake and too much carb.
There is good chance those pistons are way down in the whole with a early 70's block. I am guessing 6.5:1 dynamic compression.
I would cut .040" off the heads, get a dual plane, go to a 750 Holley, headers, that will wake her up.
|
|
|
|
|