Technical Engine runs extremely RICH?

That seems to be another finger pointing at the power valve having an opening point way to low for the engine. Have you looked at yours to see what the value is? And checked your engines vacuum reading? I'd do those before anything else.

 

Some engine builders have a hard time outside their wheelhouse. If their successes are on a race track that's the target almost all the time. This is not to say they can't dial in a road car but when you know how to squeeze every spec of TQ/HP from any given engine it's hard to call foul when drivability suffers. Please be clear, I'm not kicking the builder here. It would be like me making a fender repair look like a Ridler Award winner on a mundane daily driver. Just wouldn't match. This is what I suspect.

Also, these timing numbers bandied about up above, sometimes it isn't a fixed hard rule. Stroke, piston speed, rod length, compression, timing is sorted out based on loads applied at any given time. "Plug n play" to me means go play with yourself this is what you get. Don't like that ****. I'm offering brain food here. You have the car, motor, you know what you have to work with. So far I'm surprised someone didn't suggest try another carb before you start tuning yours. If a carb swap shows instant improvement then go there. If not 1 parameter eliminated.

 

What type of MSD IGNITION is on it? Is it electronic or points?

 

There really isn't any factory setting on them. You adjust them to get a clean idle and light cruise condition. It could be 3/4 turns out to 1 3/4 turns out. Have you checked the idle transfer slot making sure there isn't too much of it exposed? Not sure if there replaceable in Brawler carbs or not but you could also play around with the idle feed restrictors. They also play a big part in idle and light cruise driving. I can't speak for Brawler but Holley carbs tend to run pig rich out of the box.

 

I know it’s an MSD ignition but is it possible the spark just isn’t hot enough? Low voltage feeding the coil? Resistor where it shouldn’t be or wrong resistor?

 

Yeah you'd think with the msd that it would be much hotter and burn the plugs clean. I have always been to to run the car down the road, then pull over and shut the car off immediately, without idling it, to read the plugs correctly. But as a body man, I suggest that the power valve is opening and dumping raw fuel into the plenum. I'm from the school that says you have to shake the car to see fuel in the sight plugs. I would start by dropping the float level and trying that, then pulling the bowl off and dropping the size of the power valve if the float adjustment doesn't help.

 

I don’t trust the site gl***es. I would pull them and bump the car to watch it spill out. Bottom of the screw hole.

 

Poor engine ground also a possibility.

 

Ignition is MSD electronic. PN 835231. It came with a vacuum can…with parts to lock-out the vacuum advance if so desired. For some reason the builder chose to install the distributor w/o the vacuum. Tomorrow morning I will ask him why?

 

@seadog .... I suggest that you do your due diligence, it appears you have allot of faith in the engine builder/dyno testing.... your descriptive of the tune-up if done on the dyno are in need on tweaking. Make an appointment with the engine builder and have him correct the issues.

 

Your dyno time should have also included air/fuel at idle and all thru the max torque/Hp. There are many columns on the printout. I’d start there. It seems most only care about max numbers but a street engine dyno runs has way more to offer if done correctly.
What size Brawler? The smaller CFM’s make very good street carbs. You’ve never said once what the idle vacuum is eventho many have asked. That must be known first to use the proper power valve which many have too high from my experience.
Not knowing your cam information was and is poor communication with your machineshop/engine ***embler. The cam was in a box with a cam card with all the information. This should have been given to you along with other information on the build. ie: bearing clearances, valve clearance if solid lifters, ring gaps, etc. All this should be on the completion receipt.
Good luck.

 

Ya, a lot has changed. Now they have large sight gl***es and shinny coatings and marketing names like "Brawler", Hah, LOL. I'll stick with the old school stuff.

A mechanical distributer can run on the street no problem with the right curve. A vacuum gauge should be used to aid in tuning the idle screws and the power valve (while driving). Basic stuff. Pretty sure that hasn't changed since the seventies.

 

What's a pooda?

The Urban dictionary says:

"Pooda is An amazing, talent, cute woman. Pooda can keep secrets and won't tell anyone about it,she a keeper when it's come down to dating'In the future pooda will be a great wife and mother , grandma aunt, sister"

So I'm still a bit confused, or maybe just out of the loop.

I suspect that your engine builder and dyno-tuner may have been under the false impression that you wanted a rip-***, high output compe***ion engine built. Something that spent little or no time idling at traffic lights or trundling it's way through in-town traffic. So he spent no time making the necessary compromises and adjustments to make the engine at least somewhat more "streetable" under a wider range of driving conditions.

If your spark plug photo had been taken immediately after a hard pull on the dyno it would probably be telling a completely different story.

To keep your diagnostics simple, I'd start with backing the fuel pressure down a bit. If it doesn't make an improvement, set it back where it was.

Try bumping up the initial timing a bit. If it doesn't make an improvement, set it back where it was.

Try dropping the float level a bit. If it doesn't make an improvement, set it back where it was.

I hope you're starting to see a pattern develop here.

Get your vacuum gauge hooked up to a known source of full manifold and plan on leaving it connected there for a while. Check vacuum at idle in neutral, in gear if an auto trans, and at light throttle cruising speed and report back. And find out what power valve it currently has.

And please tell me that "pooda" was some kind of an auto-correct typo.

 

That's how I do it

 

Hahaha...I'm an old guy. Back when I was a pup "pooda" was simply another word for "here's the poop" as in here's the background information. My vacuum gauge is currently busted (it was run over...don't ask). I agree with many who have replied that checking vacuum is the first step. I'll get a new gauge tomorrow morning.

 

Well, what do you know? . . . If you ain't careful, you'll learn somethin' new every day!


Except now I'm really curious about how you ran over your vacuum gauge. But as a courtesy, I won't ask.

 

I decided to go to the parts place today. I now have a working vacuum gauge. Baseline reading is 13 inches at idle. Now to fiddle with the idle mixture screws. Unless I get drafted to put up the Christmas decorations I should have more to report later.

 

No, don’t notice this. Exhaust seems normal.

 

^^^^

Yup, sometimes 1 backfire will make em useless. I've gotten 2 or 3 backfires in the past but today? New gas ain't the same.

 

Did you try running it without air cleaners?

 

You said in the first post you have 68's and 72's in the carb. Usually with a PV in the front you have a bigger spread because you lean the front out and the PV richens it up. I have been tuning on a flat top Chevy with a 700 dp and I have it jetted down 64's and 72's with a 4.5 PV in it. And it could stand to be a little leaner driving around. And this motor has about 11 in. of vac. With about 38-40 degrees of timing with no vacuum advance.

 

OK, it has a hot ignition. That will burn hotter. At least you have the option of a vacuum advance. Centrifugal only on a street driven car can cause irritation unless it is a SATURDAY NIGHT SPECIAL and you are prepared for it. And the advance curve has to be set correctly for a street driven vs compe***ion engine. Sounds like it was jacked-up for strip.

Fuel trim and plug heat range. Once you have those somewhat correct you might try a hotter plug if she still loads up.

 

this……..

because if you keep messing with it, he won’t want to correct any issues….

 

I think you’re right…in fact I KNOW you’re right. I’m calling him tomorrow.

 

Ok, I was waiting to hear about the vacuum reading at idle. 13" is good. You can tune the engine without a vacuum advance-style distributor. Lets not spend money unless we have to. The idle system on a carb actuallly goes a lot further when driving. There is an eventual transition into the main jetting system. The idle system goes from idle to cruise to about 2200 rpm give or take a few hundred rpm. If the carb is rich at idle then it best to start there. As others have mentioned get your initial timing in the 16 - 22 degrees area. You can start at 16 and increase it 2 degrees until the starter kicks back when restarting her. Then back the initial timing to the last setting. Lightly seat all of your idle mixture screws then back them out 1 turn. You want them all equal. At this point you want clean spark plugs. Clean the existing ones by hand with a br*** wire brush. You will need to read them as you tune. You will need to perform and full throttle run to "color" the plugs, shut the engine off, let her cool enough to pull a couple of spark plugs (opposite sides of the engine) and read them. If you hear pinging or detonation back off the throttle as your mechanical advance is too high. That will need to be addressed immediately. If this is not possible then do a spirited run and get her back to your shop and read them there. Post some pics and identify which cylinders the plugs came from. We can give more tuning advise from there.

 

Also, the power valve adds extra fuel when under low vacuum conditions as a steep grade or accelerating more than gradual. The main jets and power valve do no operate at idle, however a leaking power valve will cause a rich condition throughout.

 

As others have stated, a vacuum advance is better for a street engine and will provide better mpg and in some cases driveability but it is not impossible to tune and drive a street engine without it. The main thing is to control the curve whether it has vacuum advance or not.

 

One more thing, if it has back fired the power valve is probably bad. Many may not like this but they are ez to test by ****ing on them and letting it stick to your tongue. If it stays its good; if it doesn’t it’s bad. When I ran Hollys I would remove the stock 105 and put in a 065 valve.

 

Or you can use a hand vacuum pump a straight spark plug wire boot and a piece of hose to test them. You would be surprised how many are bad when tested.