no power when under heavy load (brake torque)

[belvy1]

Seems like I've tried everything over the past few years....3 different carbs (625,650, and 750), different intakes, metering rod swaps, step up spring swaps, bigger squirters, etc, etc. I just can't seem to find the right combination to get any low end torque. If i stand on the brakes, the motor bogs down, but still runs, but tires barely brake loose most of the time. if they do break loose, it does an awesome burnout! Even if I am not attempting a burnout, but just launching, it doesn't really get going until the midrange powerband. Mid range and high end power are great! Timing is set at 22 initial, 38 total, all in at 2400, I have a '66 belvedere with a 360, mid range cam, edelbrock performer rpm intake, msd ignition and distributor (no vacuum advance), dougs headers, flowmaster exhaust, 727 auto with 2600 stall (changed form 2000 stall), 355 gear with sure grip. currently running the 750 carb, but still had the torque issue with 650 and 625, and had less mid range and high end power.

 

[beanhead]

Mid-range cam and 2600 stall...sorry not trying to be a smart-*** but it kinda sounds like your combo is set up more for mid to high range. Cam specs will tell a lot. Have you done a compression and vacuum test to see where the motor is at?

 

[belvy1]

I realize it is a mid-range setup, but it should have some decent low end. No compression check....car runs strong other than the anemic bottom end.

 

[PurpleBeeper]

My gut instinct agrees with beanhead. Your cam might be more of a top-end cam than you think.

 

[belvy1]

Here's my cam specs....
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=620&sb=0

 

[Jackpot50]

Are you sure it's a 3:55
What tire?

 

[belvy1]

Are you sure it's a 3:55
What tire?

Positive...had it put in myself. Tires are 255 60 15's

 

[Bruzilla]

Maybe I'm off base, but what exactly are you expecting from a 360? You can have lots of torque, but you need the right amount of horsepower to use it.

 

[Rick Carson]

sounds to me like you got every thing but compression. is it a stock piston and cylinder head? if so with a healthy cam you would be lucky to have 8to1

 

[belvy1]

sounds to me like you got every thing but compression. is it a stock piston and cylinder head? if so with a healthy cam you would be lucky to have 8to1

Thanks Rick....this is what I think is the main torque issue also. Any suggestions? Would a thinner head gasket give me anything that would make a difference? Or is it only achieved internally (pistons, heads, etc.) I was leaning toward some eddy aluminum heads, but not sure if they will add, or take away from the bottom end. I don't do any internal motor work, so I'm all ears to suggestions.

 

[beanhead]

If your issue with it is, it just has to get a little RPM to really go but it runs good from there, you're a little high on stall speed IMO for your combo

 

[belvy1]

If your issue with it is, it just has to get a little RPM to really go but it runs good from there, you're a little high on stall speed IMO for your combo

I had a 2000 stall in there initially.....same result. I put the 2600 in thinking that would help it get to higher rpm's before launch. Wouldn't this be the case?

 

[beanhead]

Ah so if you had a 2000 and it still wasn't happy down low than you have other issues. Trans could be slipping, or many other things.. check your compression and put a vacuum gauge on it to make sure those are good

 

[forphorty]

There may be other issues as well , but I bet it would like more converter. Check out the link I'm sending. Smog 360 has a xe262 (a bit milder than yours). Column 5 and 6 you will see that peak torque occurs at 3700, and at 2600(your stall speed) it is down substantially. http://www.compcams.com/information/Articles/Type/Chrysler/CC_MM0501-001.asp

 

[POMONAMISSEL]

belvy1, lov da avatar ,

 

[beanhead]

belvy1, lov da avatar , View attachment 439206

Is that the inside of an old bus? Super cool!....to the OP, a general rule of thumb for stall speed is to be around 500 RPM over the bottom of the powerband of the cam, and your a tad over that, but not bad..again compression and vacuum test will tell you lots...could even be something like a distributor advance problem

 

[belvy1]

There may be other issues as well , but I bet it would like more converter. Check out the link I'm sending. Smog 360 has a xe262 (a bit milder than yours). Column 5 and 6 you will see that peak torque occurs at 3700, and at 2600(your stall speed) it is down substantially. http://www.compcams.com/information/Articles/Type/Chrysler/CC_MM0501-001.asp

Interesting article...mine is a 1973 360, but has had all of the smog related stuff yanked, although the pistons are probably the stock ones mentioned in the article. Thanks for the info.

 

[belvy1]

belvy1, lov da avatar , View attachment 439206

 

[belvy1]

Is that the inside of an old bus? Super cool!....to the OP, a general rule of thumb for stall speed is to be around 500 RPM over the bottom of the powerband of the cam, and your a tad over that, but not bad..again compression and vacuum test will tell you lots...could even be something like a distributor advance problem

Distributor advance problem? Are you thinking too much timing?

 

[POMONAMISSEL]

beanhead , yes its my lybraree , lol .