BBC Tuning

[Regal502]

Hello All~
I'm new to the forum; however this site came hightly recommended for it's great knowledge base.

I have a 468 in a '69 Chevelle that is a pretty radical street car. Motor is 12.8:1, with a solid roller, and 1050 Dominator. I've been having a bear of time, trying to tune the beasty Dominator for the street. I'm currently using Autolite AR 3923 plugs, and still seem to be observing very black and sooty plugs. I have the Percy's Adjust-A-Jet system, and the jetting equivalents are: 83 front/ 86 rear.

Any thought on getting this Domintor tuned for sometwhat better street usage??

P.S. A few have recommended using the EGT (exhaust gas temperature) method of tuning for more accuracy. (?????)

Thanks in advance for any and all help!

~Tom

[DOTracer]

Forget the exhaust gas temp setup and install a Wide Band O2 system. You'll get much more useful information for dialing in the tune.

I run a 4150 on a 461 BBC and it's been a great carb. It's one of Patrick's (Pro Systems) 1000HP models.

I think you may be better served by using a 4150 carb assuming the car is on the heavy side and is footbrake launched. If you use a t-brake, then maybe the dominator can be made to work, but it's tough to beat the throttle response of the 4150.

If running on motor only, maybe try a non-resistor plug one heat range hotter, AR3934 or a NGK 5671A-8.

What's your timing curve? how much at idle, how much total, and all in by what rpm?

Maybe your idle is just a bit rich and could be adjusted either with the idle mixture screws or worste case an idle air bleed change.

Two or three circuit dominator?

Seriously, for much street driving, you can save alot of hassle by putting on a 4150 carb. I just don't see a dominator making it any quicker, just for looks really.

[Regal502]

Hey! Thanks for the info. I guess I forgot to mention. The car is a stick-shift. And also, I don't think one can use any type of O2 sensors with "leaded" race fuel.

Not ready to give up on the Dominator just yet for another carb.

~Tom

[DOTracer]

I run a WBO2 running VP C-12 race gas (leaded) with no problems with the sensor. I'm on the second full season of using the WBO2 system, same oxygen sensor. The key is to get a system using the 5 wire heated sensor which helps with its life span by pre-heating before starting which helps keep contaminants from damagint the sensor prematurely.

Just curious to know why you put a dominator on it to begin with? I see many combinations out there running the 4500 carbs, and many cannot efficiently make use of it and run slower with poor driving manners because of it.

Do you regularly race the car? What kind of times does it turn? What kind of vehicle weight?

[Regal502]

Thanks for the info. I'll have to check into that style of sensor.
The motto of most of the vehicles that I and my facility builds are RADICAL street cars. (the name of my facility is Radical Street Assemblies). This car and/or motor has not been to the track. It was just fired for the first time last week. Hence my tuning saga that I'm currently in. Based on previous vehicles and similar engines we've done, this car should be a 10.50-ish car, about 750-ish HP- conservatively speaking. I've invested a fair amount of money into this carb (with the Percy's Adjust-A-Jet, etc. etc.) so I'd prefer to at least make it work reasonably well; instead of just scrapping it.

~Tom

[DOTracer]

Tom,

I'd be interested in hearing your engine combination for comparison to my own.

I run a 461 bbc, 13.4 to 1 compression, 310cc BMF heads, 269/276, .738"/.710" lift Bullet roller, th400 with an 8" ATI flashing to 5800-6150 rpm (footbrake launched only), 4.10 gear, stock suspension car weighing 3400 lbs w/driver.

Running the numbers, I come up with mine making around 740 flywheel hp in real good air which gace a best ET of 9.47 @ 140, 1.29 60' on a 325/50-15 M/T ET Radial DOT tire. In average air conditions, the power is down and runs 9.50's to 9.60's @ 138-139 mph, and worst east coast air conditions it runs 9.80 @ 136-137 mph swapping to slicks for hot/greasy tracks.

good luck with the new combination as the tuning progresses.

Todd

[Regal502]

Briefly, my is a BBC 468, 12.8:1, with fully CNC ported Aluminum Canfield 310 heads. All the best valves, springs, etc. T&D shaft rockers, Merlin Dominator Intake, the cam-- well the cam is a Shaun Tiede cam (Shaun I believe used to have an affiliation with Bullet), but Shaun respecfully asks that cam specs are strictly confidential and proprietory. (I have to respect his wishes). Trans is a highly worked over Muncie M22, with all the latest (and best) and great internals. yes, that's right-- I'm "old-school" and prefer a clutch. :) Stock-type suspension (though all my control arms are tubular and adjustable), all steel body '69 Chevelle with exception of the 'glass hood; and all the necessary weight reductions efforts...hahaha (nothing under the dash, wiper motor gone, no innner fender wells etc. etc.) Have no idea on weight. Rear end is a re-worked, enhanced and strengthened 12-Bolt with all Mark Williams internals: 4.88 spool, and 35 spline Mark Williams axles.
Honestly, the car was intently purposely build as a street-light-to -street light animal; with careful street racing here and there.

[amature]

I run a 540 BBC w/ a 1090 King Demon on the street that has very good street manners. It runs on pump gas and throttle response is great. I use an NGK -7 (BKR7E-11) range plug. I have a 99 jet in the back and a 91 jet in the front with a power valve in the front as well.

The air bleeds on the car are what needed attention in my tuning. There would have been no way to dial it in as good as it is without a wideband O2 sensor setup. Having that helped me throughout the entire range.

One of the things that plagued me making it appear/act rich was a poor power system. I was trying to use a one-wire alternator. Once I switched to a three-wire and put the sense wire on the ignition, all has been great powerwise.

It would be VERY beneficial for you to pick up a wideband O2 system. If not to just run on this car, then pick one up to tune all the cars you build/tune (using a sniffer pipe).

[Regal502]

Suggestion on WBO2 systems? Or should I just pick up a Summit or Jeg's and start looking. (Don''t really know what I'm looking for/at).

[DOTracer]

Suggestion on WBO2 systems? Or should I just pick up a Summit or Jeg's and start looking. (Don''t really know what I'm looking for/at).

The innovate Motorsports is probably the most widely used system. It's about the size of a digital multi-meter and can be moved from one car to another pretty easily.

I have a unit made by Daytona Sensors which is tied into a true data logger. Just another option.

There'a also a couple more popular systems like FAST, etc.

[amature]

I have a Techedge unit from Australia http://www.wbo2.com

I prefer their units over the innovate motorsports units because they have the datalog capabilities already built in without extra components. They have a few different styles. If I were to buy one for a shop, I'd get the 3E2. Their site also has a ton of tech info including a good diagram of how a sniffer pipe should be built. http://www.wbo2.com/lsu/position.htm

Almost any unit you get these days will get the job done, especially considering the alternative (no O2 info). It is just a matter of what sort of features you want/need.

[Regal502]

This is getting complex! :confused: Several people on other forums have simply suggested biting the bullet and just sending the damn carb. into Pro-Systems to work their "Magic". I guess it's a toss up. $400 for Pro-Systems to set up the carb to meet my EXACT combination, or spend $350+ on test equipment to continue to fumble around myself????? I guess ultimately it's my decision-- but I can't afford both (or either really, for that matter).

[DOTracer]

I've run three or four of Patricks carbs. His stuff is great, but still needs some final tweaking to each combination.

What I'm getting at is your still gonna be tuning either way. I'd say get the WBO2 for now and tune and see how it goes. If your still struggling, then maybe it's time to send the carb to Patrick, or replace it with a 4150 ;)

[Regal502]

Or I could start out with a $50 EGT probe and go from there. (my original quest)
Afterall, I originally got the idea from the great Smokey Yunick book I have.

Damn........ where is my VODKA bottle!!!!! LOL

[DOTracer]

What help would EGT be? I never much cared for them myself. If your timing is off, it will affect the exhaust gas temperature skewing the data you get from it. Also, EGT's don't respond as quickly as WBO2.

If you can't afford the WBO2, then learn how to read plugs. I myself am not smart enough to read plugs, so I'll stick with the WBO2.

[amature]

Do you have any local race/performance forums for your area? In all likelyhood, you probably have a few locals that have a wideband setup that may be willing to help ya out. If you lived near here, I wouldn't hesitate to help get'er done.

[Kevin Zaske]

You might hook up a vacum gauge to a port below the butterflys and measure the amount of vacum you have while cruising and verify the power valve is not opening and spilling fuel. Or block the power valve or valves. This is assuming you still are using them. I would at least use the front. Of the correct vacum of course. Good luck and let us know.

[R/T]

Hello All~
I'm new to the forum; however this site came hightly recommended for it's great knowledge base.

I have a 468 in a '69 Chevelle that is a pretty radical street car. Motor is 12.8:1, with a solid roller, and 1050 Dominator. I've been having a bear of time, trying to tune the beasty Dominator for the street. I'm currently using Autolite AR 3923 plugs, and still seem to be observing very black and sooty plugs. I have the Percy's Adjust-A-Jet system, and the jetting equivalents are: 83 front/ 86 rear.

Any thought on getting this Domintor tuned for sometwhat better street usage??

P.S. A few have recommended using the EGT (exhaust gas temperature) method of tuning for more accuracy. (?????)

Thanks in advance for any and all help!

~Tom
Do you have power valve in the front metering block? This would help when you drive it on the street ..

[Kevin Zaske]

Do you have power valve in the front metering block? This would help when you drive it on the street ..
:-Daw Holy Snits nice picture!

[Regal502]

Kevin & R/T~
You guys must be unfamiliar with Dominators. They do not have provisions for power-valves or any vacuum ports whatsoever.

At this point, I've decided I'm sending my carb to Patrick at Pro-Systems. I'm done dickin' around with it. When it comes back, it should be a bolt-on and run!!!! :)

One question though, how does one use a WBO2 with LEADED race fuel????

[DOTracer]

Kevin & R/T~
You guys must be unfamiliar with Dominators. They do not have provisions for power-valves or any vacuum ports whatsoever.

At this point, I've decided I'm sending my carb to Patrick at Pro-Systems. I'm done dickin' around with it. When it comes back, it should be a bolt-on and run!!!! :)

One question though, how does one use a WBO2 with LEADED race fuel????

The use of a WBO2 is no different when using any gas be it either leaded race gas or unleaded.

With my Daytona Sensors WBO2 I have to turn the key on and let the oxygen sensor warm up before starting the engine. That's usually around 20-30 secojnds wait time. But this proceedure is the same no matter what fuel you would run.

BTW, years ago I bought a used 8896 dominator that was used for a half dozen dyno pulls and put back in the box. That carb did have a primary power valve. Some list numbers have them, some don't. I too had to send that carb to Patrick as it flat out wouldn't ide on it's own, way too rich. Patrick informed me that for some reason Holley really missed the target with some of their out of box calibrations and that 8896 sure was one of them. Buddy of mine runs a box stock 9375 which seems to work fairly well for him, but again, he'd run quicker with his old 4150 on it as it's barely making 600hp running 10.70's @ 3600 lbs, footbraking.

[amature]

The same way as with unleaded. :) No different procedure what-so-ever.

If your question is "why does it work when I have heard it doesn't?", then it is because it is a wideband, not narrowband found on typical street cars.

Narrowbands rely on the heat of the exhaust gas to get them to temp. Widebands have a seperate controller box that regulates the temp of the sensor with an internal heater. It helps to keep the sensor clean. In fact, you aren't supposed to ever run a car equipped with a wide band unless the sensor is on and functional. Doing so will destroy it since there is no cleaning action from the heat.

Grant it, leaded fuel does decrease the life span, but, people should be using their spark plugs as a tuning tool as well. What is the life span of those in a race engine (when used as a tuning tool)? Last I checked, if doing it right, it was a set per pass. This equates to ~$20-25 per pass for plugs. A new WB O2 sensor costs $70 and will last many many passes. My first sensor lasted me two years. I'm still on my second.

From Tech Edge: "Extrapolating this Bosch data suggest that at 1.5 g/l the life may be as low as 2,000 km or just 20 hours at 100 km/h. AvGas 100LL has 0.56 g/l Pb, suggesting a sensor life of 200 hours. Compare this to a suggested life of 1,600 hours for unleaded."

[Regal502]

Greg~
Good info. I will assimilate to my confidants and co-racers.
I'm not sure about one-set of plugs per pass (this is "only" a 10 second street-race car), but I understand, nonetheless.
The WBO2 system I'm currently looking at is by NGK #91101 (it's new)- check it out. Looks pretty sweet!

Thanks Again Greg, for clarifying this snowballing issue.

~Tom

[Kevin Zaske]

[quote=Regal502;368157]Kevin & R/T~
You guys must be unfamiliar with Dominators. They do not have provisions for power-valves or any vacuum ports whatsoever.

Yours doesn't and I didn't say to hook the gauge to the carb. I don't appreciate you mouthing about what the phuck I know about your bastard carburator when I was making suggestions to help you with out you spending money. You gave no PN on the carb.

[Regal502]

Wow Kevin! A little thin-skinned?? You mentioned "below the butterflies" which I assumed meant in a "port" within the baseplate- which Dominators don't have.

I assure you there was no bad mouthing.

Nonetheless, the situation will be resolved. The carb is being sent to Pro-Systems tomorrow.

[amature]

That NGK unit looks perfect for what you are trying to accomplish.

[68Bird]

My King Demon had power valve provisions front and rear. Even though I never used them because it still had decent street manners. I think you need a power valve up front and to play with the air bleeds. The LM1 wideband is a nice setup for tuning. Personally I have a Dynojet wideband commander but if I were to do it over I'd buy the LM1. BTW, they (innovate motorsports) have a tech section that is AWESOME on carb tuning using a wideband.

http://www.innovatemotorsports.com/resources/carb-central.php

Good luck,
Craig

[R/T]

Kevin & R/T~
You guys must be unfamiliar with Dominators. They do not have provisions for power-valves or any vacuum ports whatsoever.

At this point, I've decided I'm sending my carb to Patrick at Pro-Systems. I'm done dickin' around with it. When it comes back, it should be a bolt-on and run!!!! :)

One question though, how does one use a WBO2 with LEADED race fuel????
Never said there was a vacuum port on a dominators. Then I guess Patrick from Pro-Systems is wrong. Pro-Systems did my dominator and it has a power valve in the front metering plate.

[Regal502]

I think we've beat the dead horse/power-valve issue enough.
Anywho~
I've decided to pull the trigger and send my carb. to Pro-Systems to work their "magic".
Thanks for all the advice and forethoughts.

~Tom

[amature]

Be sure to let us know how it works out for ya.

[Regal502]

Will do for sure-- even in spite of the egos that feel they've been pee'd on. :)

~T

[Mills588]

I agree with Todd - drop the dominator and get a Pro
Systems 4150... and or Wide Band 02. I ran an outta the box 3310 Holley for years on my 468ci. Also, try a AR3935 plug; although I think your plug problem has a lot to do with how the dominator is tweaked. If you consider a 1000cmf 4150, let me know - we are direct with them. Good luck.

Also, Todd - did you find some Isky EZ Roll Lifters.. or still deciding on what you are gonna go with.. I can still get them for you.

Happy Holidays Everyone!

[TOPLESS63]

This is getting complex! :confused: Several people on other forums have simply suggested biting the bullet and just sending the damn carb. into Pro-Systems to work their "Magic". I guess it's a toss up. $400 for Pro-Systems to set up the carb to meet my EXACT combination, or spend $350+ on test equipment to continue to fumble around myself????? I guess ultimately it's my decision-- but I can't afford both (or either really, for that matter).i spent $660 with pat $400 in shipping (it been back twice) and $100 in carb parts and still wont come close to my hard core 1050. my motor is a 565 dynoed at 1030 hp. i think pats going to buy it back or look on ebay for a cheap carb soon. nice guy but he missed the set up by a mile on my car. between me and my freinds we have 12 of his carbs and mine is the only piece of shit

[BTL FED]

I have basically the same motor with better heads and have no problem what so ever with a dominator. I have been running dominators since 1993 on all my motors, including small blocks.

You cannot run a dominator unless it's square jetted, period.
Is it a 8896 or a 9375?
I have had the best luck with motors simular to your combo work well with a standard 8896 with a 4.5 power valve and squared 100. Yes 100!! I'll drive it all over downtown Atlanta idleing in traffic and all with no problems.

[seanss454]

Here is what I do. I change the progressive linkage to 50/50 and run a 3.5pv 87-96 on the jets. Never had on eissue and the motor does not load up or kill you with the fumes. It makes it not dump so much fuel in the motor when the blades get to open half throttle. Plus you wont suck the fuel down. $20.00 fix.

Sean

[Collinsautomotive]

how much overlap in degrees do you have.