Technical Engine runs extremely RICH?

I agree. I would not have it set at the theoretical MAX pressure, it's like asking for trouble. 5 would be fine.

 

A light car like yours with a manual trans can take timing quickly. Check your advance weights make sure they move freely put in the lightest springs that came with your MSD distributor. Your Brawler comes with a power valve blowout protecter but without a va*** gauge you wont know if you have the right one might be bleeding in as others have said. Good luck.

 

You don't say what plug you are using, you need to use a projected plug, like an NGK R5672A-8 for this time of year, I can't tell if the plug in the photo has the projected tip or not. You need the projected tip for street driving today's gas, if you have the non projected tip (like for a race motor) they'll look exactly like what you show, all carbon fouled and sooty. When you put them in they'll act fine but as you drive they get progressive worse, esp if you have some compression in the engine.
What spark plug is it?

 

Yes. The Quick Fuel Brawler carbs are extremely tunable. About as many features as anyone could want or need on a Holley style carb.
If I recall correctly the stock air bleeds were .070 on mine, and I had my idle air screws nearly closed. I went to .074's and now have the idle screws at about 1 turn open.

 

The plugs are NGK R- BKR6E
New part #NGK 6962

 

Pretty amazing, isn't it? A sheet of paper or a human hair measure at right around .003". Open up an idle air bleed just slightly more than that and suddenly you can back the idle mixture screw out where it belongs and you can do some accurate adjustments.

 

Increasing the bleed diameter from .070 to .074 increases the area by 11.8%, almost 1/8th larger.

 

That is the correct plug, so it is a question of raw fuel. I'd pull both bowls and metering blocks to see if there is fuel in the cavities in the throttle bodies for the power valve, those carbs have a history of not being able to seal the gasket between the metering block and throttle body, that cavity is under vacuum and will pull fuel into it thus into the engine. The Brawler is a ***y looking piece and 'tunability' but they have a lot of problems. The other thing you can do (again, #1 check the cavity for raw fuel) is to look down into the carb while at rpm, it won't take much, under 3000, look down into it and see whats going on, the fuel should be coming from the main boosters only the secondaries won't be open at this rpm, if that looks normal, no dollups of fuel, then check the cavity behind the metering blocks and see if it is wet.

 

Well, sure . . .

But you kind of **** all the "magic" out of it when you explain it mathematically!

 

Quick Fuel tech told me to go to a #.078 bleed screw, which I felt was way too big. I opted for the #74 and it was perfect.

 

Just wondered if this ever got fixed and what the builder said?

 

I have spoken with the builder as well as sent him photos of the plugs. He readily agreed to sort it out. In the meantime my wife is having some medical issues which have taken me away from this. She has had surgery and I’m her caregiver. Her outlook is good and as soon as I can I’ll get back on the car. ‘Promise I’ll not leave you guys hanging…will write up the solution once I can get the engine back to the builder. Merry Christmas!

 

Thanks for the update, take care of family first. Glad the outlook is positive.

 

I agree with the comment regarding the power valve. I was experiencing the same issue, the engine ran so rich it would burn my eyes standing behind the car or if it idled in the garage even for a short time. I tried different carburetors, timing, plugs and had no luck. I replaced the power valve and it cured my problem. There is a formula based on your idle vacuum. Summitt tech support or holly can help with that. Good luck, hope you get it resolved.

 

Four corner idle carb on a street car? Why. From reading it seems to me not enough secondary air at idle. 850 holley 4 corner idle carbs come with the secondary ****erfly's drilled for more air. Not saying that's your problem could you just have too much carb? Lippy

 

Sorry to hear about your wife, hoping for a speedy recovery. Meanwhile , sounds like you will have plenty of HAMB time, and there are several good books out there about Holleys, if you like to read. The best advice I could give you is not to get caught up in race tuning. Its not really that difficult to make them run wide open, or even to idle, but that stretch in the middle where you drive on the street can get to be aggravating.
Good Luck and Merry Christmas!

 

In the 50's I worked in a gas station and an old lady complained of the same thing. When we checked the car no adjustments were needed. Then we saw her get in the car, pull the choke lever out about an inch and hang her purse on the choke. We told her to put the purse on the seat and problem solved.

Set the choke to "Just" all the way open with the engine hot and take what comes when the engine is cold, that way you'll be sure it is open when the engine is warm.

 

What are the cam specs. LSA plays a huge part in idle characteristics and carb mods. I fought this same issue, until I found my cam specs, which showed a 108 LSA, not the 114 I had thought it had(not an L79 cam as advertised)this may not fix it, but it can point you down a path

 

When I worked at a dealership parts counter, one of the best carb and tune-up techs in the shop was also a great story teller. Not a bull-****ter, just very capable of expressing himself in a very interesting and colorful manner. Vans were referred to as "hippie haulers", drag racers were called "spin-tire" racers, etc.

On more than one occasion I heard him refer to a car with a manual choke as having a "purse hanger" on the dash. Not surprisingly, he knew of what he spoke.

 

UPDATE…2/16/23

Here is they update I promised. I took the engine (in the car) back to the builder who kept it a couple of days and fiddled with the tune. It was m***ively rich, to the point of fouling the plugs so as to be virtually un-driveable after just a few miles. He checked timing and all the usual suspects, but the main thing he did was drop the jets down 10 sizes in the main and 8 in the secondary. It runs and accelerates a little better, but still no cigar. After I returned home I filled the tank with some 90 octane non ethanol and dumped in a bottle of Lucas Octane Boost. That made a Big Difference! It’s almost fun again. This got me thinking that I might try a tank of 93 Octane ethanol next time. The car has Teflon fuel lines and I’m thinking the carb surely by now has internals that will stand up to today’s gas.

It still, even with the Octane booster, has a flat spot/hesitation when the throttle is floored and it doesn’t run very well in 5th gear. Maybe there’s too much cam?

 

i have a similar problem but with a 327 cam and 350 heads and a edelbrock on a weiand xcellerator manifold

 

Drop carb size ,CFMs ,8 jets size is a big swing from out of the box ,
turning still required.
& ethanol base fuel is still hard on modern carburetors
If not yet done add a good wide band O2 gauge for tunning !
What Else was done with carb beside Jet change?

 

It sounds like the first job is to try to remove the carbon buildup in the combustion chambers and the back of the valves.
The proper fuel additive in a tank of gas, plus a couple hundred miles going down the freeway should help.
I suggest highway speeds as it should run lean and the fuel and additive will flow through at a good rate.
This is one I like, but there are a lot of choices at the auto parts store:
https://www.chevronlubricants.com/en_us/home/products/techron-complete-fuel-system-cleaner.html

After carbon cleanup, more fine tuning may be in order. It's hard to imagine how far off the jetting was.

 

If you're down to 58's and 64's on a 347 and it's still not right I'd take it to a shop that knows what they're doing. Something sounds fishy with what the "reputable engine builder" is doing. The reduction of 10 jet sizes and you saying it's still not right makes me think that's a bandaid and the real source of the problem is still there. Are the intake valves maybe not sealing?

 

I think some of the fouling on the plugs is happening at startup, and idle, and isn't burning off during cruise speeds. If you let the engine idle and the exhaust smells rich, or burns your eyes it needs to have the idle mixture leaned out also. I'd almost guarantee the Brawler will need larger air bleeds in order to be able to lean it out enough.

 

Borrow a small 600-650 cfm and see if there is any change. Most of these Quick fuel Q series , Holley HP are calibrated for long duration Cams, lots of timing. Not sure which Brawler you have but if it's the race version it may take quite a bit of tweaking to ever make it run clean.

 

Thanks for the input. Next step will probably be try a different carb. It’s frustrating because it is “sooo close” to being right. I think I’m going to try to find somebody else locally to take a look as well.

 

An increase in octane by itself should not make an engine run any better. It will allow a hotter state of tune though and supress detonation, allowing increased performance from increased compression, advcanced spark. But just increasing the octane rating won't improve problems with flat spots or overly rich conditions.

 

I had a friend call me over for a similar problem once upon a time. The Holley carburetor had the wrong gasket between metering block and main body, so fuel from the bowl was just dumping down the power valve vacuum port..... Might be worth a look to pull the carb off and inspect it.

 

That's the way I've always done it.... Worked like a charm every time....