Tuning a TBucket Dart 400 cuin Engine

"My back pressure exhaust test was approaching 4-5 psi."

the change in headers or their design, will have little effect,
IF its the mufflers and exhaust pipes too the rear of the collectors,
that are most likely restrictive too flow
 
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In most situations that would apply, but in my case with a TBucket and side pipes that will
ALL be changing with a complete header change. I fully understand what you are
speaking about would apply to most normal cars with a full exhaust system.

In my situation the complete exhaust system will be replaced from front-to-back.
 
getting the exhaust back-pressure , measured in the collectors on the headers, below 2 psi at w.o.t. at 6500 rpm under full load would be one goal Id try to achieve,
that may sound difficult and it is if the mufflers are restrictive but it can be done ,
Ive done it with a couple cars with 3" exhaust systems with (X) pipes, and race type mufflers,
now I won,t say they were quite cars but they did not get me tickets as long as I drove carefully ,
and tried hard to never exceed 1/4 throttle and 3000 rpm on the street...
once your accelerator petals firmly on the floor, and the engines at W.O.T...
and your power shifting at 6500 rpm of course the noise level is significantly louder

yeah its difficult but hardly impossible
http://garage.grumpysperformance.com/index.php?threads/x-or-h-pipe.1503/

http://garage.grumpysperformance.com/index.php?threads/calculating-required-exhaust-pipe-size.11552/

http://garage.grumpysperformance.com/index.php?threads/high-flow-quiet-exhaust.10558/#post-45047

http://garage.grumpysperformance.com/index.php?threads/building-an-exhaust-system-for-your-car.1166/

http://garage.grumpysperformance.com/index.php?threads/spiral-mufflers-anyone.10365/

http://garage.grumpysperformance.co...ave-resonator-tube-to-reduce-stop-drone.7590/
 
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Rick, do you have, or can you borrow another carb to try?
Not that anything is wrong with yours, just another X to Y test.

I'm completely surprised by your back pressure results.
 
It doesn't. Just a test to rule out anything might be wrong with your carb.
I'm not saying there is, but you will never know for sure until you rule it out.

Here is a story. I had my electronic quadrajet modified by The Carb Shop.
It ran great for a while, but then the idle circuit would screw up on 1 side.
I took that carb apart so many times that the screw threads started stripping.
I'm convinced that there is a drill shaving in the idle pick up tube, and there is
no way to remove the tube without destroying the carb. I don't need it anymore.

You did a lot of drilling and tapping to your metering blocks. 1 chip can totally
mess with its calibration. A back-to-back test with a known good carb will verify.
 
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This is one of the main reasons to switch to efi. Allot less variables in tuning yes it is an investment but looks are no longer an excuse.
 
Cap contacts I do not remember which ignition you are running it's been a while since I read through your whole build.
 
Also remember Rick Peak EGT is 14.68:1 running a little richer will reduce those temps considerably cooler. Do yo have EGT sensor?
 
They are not that expensive might wanna consider one pm your email address and I will send you a pdf present tomorrow.
 
I made a trip to the "Lake of the Ozarks" in Missouri. The trip mileage was 874 miles. The
battery failed two hours from the hotel. Another NTBA member on his way saw us on the
side of the road. We unloaded his car and put mine on the trailer. It's very hard to find an
Odyssey PC-680 battery in a resort town, but it just so happens that a NTBA member had
a new one still in the box.

But now the real reason for this post, the spark plugs. The 1st pic is before I left and the 2nd
is after returning, 874 miles later. Seventy percent was highway cruising at 50-65 mph. It's
hard to keep 25 TBuckets inline and moving at a fast pace, were trying to keep everyone together
and some are not speed fanatics like the rest of us. The rest was in town. The last one mile after
the trip home at 70-75 mph [Interstate, 400 miles], was in town driving.

Both pics are with the darkest part of the porcelain facing the camera. Keep in mind when viewing
the pics that they are magnified, which makes the build-up look worse than when holding them in
your hand.

SparkPlugs1-8_00027_00028.jpg
SparkPlugs1-8_00029_00030.jpg
 
the amount of accumulated burnt ash, in the photos in that short of time / mileage seems a bit excessive to me,
yes its obvious the new ignition is helping reduce that ash build-up so thats a good improvement,
that, improved ignition efficiency, alone may be a large part of the key in reducing that ash build-up.
the most likely sources are the amount and quality of fuel and oil being burnt in the combustion chambers ,
Id suggest swapping too the next thicker viscosity of synthetic oil first,,, I.E. if your using 10w30 oil I'd swap to 15w40
and swapping to alcohol free fuel if your currently using that, common blended 10% ethanol, fuel, as typically ethanol blends leave more ash build-up


heres a link to locate the gas stations selling ethanol free fuel
https://www.pure-gas.org/extensions/map.html
 
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Grumpy said:
the most likely sources are fuel and oil being burnt in the combustion chambers
Click to expand...
I'm still using oil, about a quart every 750 miles. It does seem better, but at say 2000 miles
I'd see some smoke coming from the exhaust, mainly when the headlights hit the smoke at
night. Now I don't notice it. I wonder about the quality of the cylinder honing process when
I built the engine.

Grumpy said:
Id suggest swapping too the next thicker viscosity of synthetic oil first,,, I.E. if your using 10w30 oil I'd swap to 15w40
Click to expand...
I'm using 10w30 now and have 20 psi at idle and 50 psi at 2000 rpm. The engine temp is
180°F or less on this last trip. Would you still change viscosity?

Grumpy said:
and swapping to alcohol free fuel if your currently using that, common blended 10% ethanol, fuel, as typically ethanol blends leave more ash build-up
Click to expand...
I always use 100% gasoline when in town, but on the highway it's usually has 10% ethanol.
Nothing I can do about that when traveling.
.
 
yes ID still swap to the thicker viscosity synthetic oil and maybe its just me,
but Id add a pint of marvel mystery oil, to the new oil,
at the next oil changes I've seen it clean up some ash build up.
BTW its obvious the new ignition is helping CONGRATS
and yes I fully realize the difficulty in locating good fuel while traveling, especially if your not near home
 
Grumpy said:
yes ID still swap to the thicker viscosity synthetic oil
Click to expand...
I'm using the Royal Purple HPS synthetic 10w 30 oil. It's front says "Zinc / Phosphorus Fortified".
Maybe that's my problem with ash build-up on the plugs.
 
it might be, but the best way to prove that would be new spark plugs a new oil filter an oil change to a totally different brand of oil and several thousand miles of driving
 
I wish all of your plugs looked like #8.
It sucks that you are burning oil, making me think that the rings are not seated......... yet (hopefully).
How soon did you run synthetic after the break-in?
And what did you use for piston rings? Hopefully not Total Seal. Mine never fully seated on my 334.
We all hate to see high coolant temperatures, but you might want to put a 195* in there.
Besides, the weather is getting cooler now.
 
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