I think that's what I'm going to do. I had one on the car a long time ago when I had regular headers and never put it back on when I put the sidepipes on.

Thanks all for some great advice. That's why this is a great forum. It might be a while till I get to this since I am still working on the @#$% kitchen but this spring before getting it on the road for sure.

Jim

 

Good idea to just put it in for tuning and getting a base line for various conditions. It will eliminate guess work.

 

I would spend the time trying to get the carb tuned out before making any major changes. You can try the baffles after and see if it improves.


They are not helping the situation, but as everyone has been pointing out getting the tune right first is the biggest problem. Yes, they are not optimal, but what the exhaust pulse will do is kill midrange torque. I have seen it on a dyno kill as much as 50 rwtq, but the top end stays the same. Every engine reacts differently and a lot of things go into this equation from camshaft specs to valve sizing in the heads.

 

A little dark brown soot is good, what you have shows you are way to rich.
Is the front of your stinger hood scoop open to the outside air?
I can't tell in the picture.
Another thing you might want to check is how much air flow is being restricted by the drop base air filter.
Some cause the air cleaner lid to be to close to the top of the carb's air horns and are prone to restricting air flow into the carb.
If you have room, you might also add a taller element.

 

I agree the AFR is off. The cam appears pretty mild 221/226 dur @ .050, so it should have plenty of TQ in a big 383. You apparently have multiple tuning issues that are all dropping the TQ.

My question is: What is your initial timing setting?

I have not seen as much talk about the timing as I would like, and I never saw an initial timing reading. Your low rpm timing could easily be down 10 degrees at low rpm and that will also destroy low rpm TQ, an easy 20% drop. Does Blueprint say your total timing should be that low? 36 or so is much more normal. That is 4 degrees off from normal. But my biggest concern is what is your timing setting at idle? 14 degrees or so at idle will give you great bottom end TQ. 4 degrees at idle will kill it. (That was GM's emission strategy in the 70's) That 10 degree below "optimum" timing will continue to lag very low until near 2500-3000 rpm, when it "catches up". Does the engine appear to wake up as you rev it past 2500? With that small of a cam it should not. It should already be making a boatload of TQ. It is very important to hit both timing specs, at idle, and at 3000 rpm. Not just one of them. Many distributors have way to much timing in the distributor to give you this curve. If that is the case you need to limit the timing in the distrib to near 20-22 degrees, (above the initial). I have seen as much as 32 in the distrib, and it kills the low end. You really should shoot for around 14 at idle and 36 at 3000.

Who was it that said most "carb problems" are usually really timing problems? I normally agree with that but in your case I think you have both issues.

 

Do not worry about your pipes. JK here has a 355 with side pipes and its an easy 11 second car. I had the factory pipes on my 327 when I had a 12 second car, so no that is not our issue with a 383.

 

You should get a dial indicator and verify your cam specs as well. YOu can do it with the heads on at the top of the llifter. Pumped up or not if you go off the edge that is solid to the base you can verify the specs of the lobe. And then get the AFR gauge installed. You cant beat them for ease of tuning. THen find some exhaust hose that mechanics use to run the exhaust out of your garage so you can turn it and stay warm. Good luck with the kitchen, I guess thats a priority of you like eating.

 

Black soot in the exhaust is a byproduct of unleaded gas not bad air fuel ratio . If you want to tune by the exhaust pipe color then fill it up with race leaded gas otherwise your exhaust will always have black soot

 

Wow, I wonder what is wrong with my 73?
I run unleaded pump gas and I don’t have black soot in my exhaust.
I guess I better pull the engine!

 

interesting, never had anything but unleaded in mine, no black soot.

 

This is just pernicious non-sense.

Scotty

 

Hate to reveal this, but this is not a carb, timing, or tuning problem. It's a driver problem. Any car with a manual transmission can spin the tires off the car in 1st gear. My '75 Pinto had 83 horsepower, and I could light the tires up in a cloud of smoke at the local autocross any day. I'll bet anyone here that I can take Jim's car and smoke the tires through 1st gear and chirp them loose going into 2nd. This is an issue of knowing how to how to launch the car, how to shift, and how to drive it.

Jim -
You're too afraid of "breaking the car." With stock tires, you're not going to break anything, so launch it as hard as it should be! At what rpm are you launching the car? At what rpm are you shifting? Are you "lifting" on the shifts? I don't think you have a tuning problem as much as you have a driving issue with not driving the car right. At launch, you should be dropping and side-stepping the clutch at about 2500 rpm, pounding the throttle, and then feathering the throttle to minimize wheel spin until it hooks. Shift around 5500 without lifting the gas and it will jerk it loose going into second. If you drive it like your grandma drove her Rambler American, it will perform as such. Drive the car, man... drive it!

Lars

 

The 66’ L-79 in my Avatar was a good running car….mid 13’s on a clear dry day…but with maybe 350 ft/lbs. torque it wouldn’t pull a wet noodle out of a ****** ******* unless you clutched the damn thing….it is not the way to make ET’s….but it looked impressive….the purists hated it too….
My Dad had a 63’ in 1983-84 that he would take me for rides in…..he beat the **** out of that car….never hurt anything….pulled the original shifter damn near out of the floor….in went a Hurst…..I was 12 years old….noise, smoke…mayhem….best **** in the world…..

My 72’ 406 spends some afternoons drifting at 70 MPH around a long banked turn on a Farm Road by me…..second gear at 5000 rpm spinning….feeding opposite lock….

Like Lars said….Drive It!

Jebby

 

Good stuff... hit the car hard and drive the heck out of it. Get that rpm up into the power band and dump that clutch! Get the tires spinning and control it with throttle... If it breaks, fix it! Make it better until it doesn't break, and then hit it hard again. Don't be afraid to have fun with this stuff - it's just a lousy Chevy, and you can run the crap out of it on street tires - no problem. Get the rpm up and dump the clutch. These ain't no lousy British "sports cars." It's American Heavy Muscle. Abuse it!

Lars

 

I really do not know what spiral baffles some are using. But I can tell you on my 454, that these killed 5mph, and 4 tenths in the 1/8 mile. https://www.speedwaymotors.com/Patri...ch,302077.html

 

These ones for me.
https://www.spiralturbobaffles.com/c...e-application/

 

Lars you may have hit the nail on the head. I am afraid to break something so I am going easy on it. OK... enough of that.. Can't be accused of driving like my grandma! haha. Although it does sound like I am running rich so I will get an AFR gauge hooked up and see what it says and go from there to lean it out if needed.