[gtorich]

Took these plugs out somewhat after a good blast with some ideling time........

Im enclosing a pic of a plug & dyno chart I had awhile back, was told a little too rich, dyno run shows that also. The first pic is with the plug at 74-65-74.

Last two pics are with the 73-64-73 jets, also using a NGK 4, might be a 5, gotta double check.

I know its hard to read plugs with todays gas, always used real gas with this car.

Seems like a big change from the 1st pic to the last, and that was only going down 1 jet size........just wondering what you guys think.

I can see im gonna half to get a A/F guage, im tired of this guessing game.

463 motor, kre heads 290version, 66 tri power.

Thanks

Rich

[gtorich]

Ahhhhhhh, as usual forgot some info, 10.6 comp, 6AL box..........getting confused here, if a 65 center jet is too rich, and say a 64 is too lean..........where does a guy go from there. LOL

Rich

[geeteeohguy]

First pic is too rich, second and third pics look about right. I think you have it pretty darn close to where it needs to be. JMHO.....

[zeebo]

Originally Posted by geeteeohguy

First pic is too rich, second and third pics look about right. I think you have it pretty darn close to where it needs to be. JMHO.....

so should the insulator have a shade of light brown on it? that's how I was told your plugs are the correct heat range and your fuel mixture is on..? I was told the above plugs look to have a rich idle and too lean a part throttle...?

[prostreet64]

Pontiac Dude has a good plug reading section on his web site; iirc the soot on the ring base tells you if the mixture is lean or rich and the color of the outer electrode determines if the heat range of the plug is correct. The porcelain color is not a good indicator when using lead free gas. I think you look for a thin soot deposit on the ring and for the electrode to be clean to a point in the 90* bend, but not all the way to the ring.

[Formulajones]

Plug reading is hit and miss with unleaded fuel, they just don't color like lead gas does. Toss in the ethanol blend and things change more. At best it's just a guess that will get you in the ball park.

The best thing you can do is get yourself a wideband. A wideband is your friend. I tune every car with that, it takes the guessing out of it. It's the only way to tune a car properly and know you're safe.

Keep in mind with this 10% ethanol blend fuel we have now, stoich is no longer 14.7:1. Stoich with E10 is 14:1. E15 drops stoich to 13.8:1. To throw more fuel in the fire, using a small ethanol test kit I find different fuel stations have varying amounts of ethanol on any given day. I've seen as much as 17% where only 10% is advertised on the pump, but haven't seen lower than the 10% advertised. This fluctuating ethanol content changes the AFR requirement (needs to be richer). With that much change possible from one pump to the next, I prefer to tune everything (mainly customer cars) a tad on the safe side, (a little rich) to compensate, and then leave it be. I give up a few HP but the engine lives a safer life. Just food for thought, hope that helps.

[johnta1]

Spark Plug Reading

[HWYSTR455]

Originally Posted by Formulajones

Plug reading is hit and miss with unleaded fuel, they just don't color like lead gas does. Toss in the ethanol blend and things change more. At best it's just a guess that will get you in the ball park.

The best thing you can do is get yourself a wideband. A wideband is your friend. I tune every car with that, it takes the guessing out of it. It's the only way to tune a car properly and know you're safe.

Keep in mind with this 10% ethanol blend fuel we have now, stoich is no longer 14.7:1. Stoich with E10 is 14:1. E15 drops stoich to 13.8:1. To throw more fuel in the fire, using a small ethanol test kit I find different fuel stations have varying amounts of ethanol on any given day. I've seen as much as 17% where only 10% is advertised on the pump, but haven't seen lower than the 10% advertised. This fluctuating ethanol content changes the AFR requirement (needs to be richer). With that much change possible from one pump to the next, I prefer to tune everything (mainly customer cars) a tad on the safe side, (a little rich) to compensate, and then leave it be. I give up a few HP but the engine lives a safer life. Just food for thought, hope that helps.

Just went through this with the clone, with the cam profile I have in there, gears, converter, etc, idle and part throttle is in the 13.1 - 13.6 range, any leaner and it will ping or run hot on the highway. (or tip-in suffered). WOT blasts I believe were in the 12.2 - 12.6 range for best performance. I actually had to bump the PV to the next size also to help with tip-in and prevent ping. Whole time doing this I also had to play with vacuum advance some, and think it still needs a little work.

I was actually puzzled to a degree that it was taking so much jetting, would have thought it wouldn't need that much of step-up from out of the box getting on the Holley I'm running.

.

[gtorich]

Well guys, thanks for the tips, looks like im gonna have to get one of those wideband deals.

Also gonna try another set of plugs, some 3924"s see where they are at, just hard to believe how rich it was, and only dropping 1 jet size is making that much difference.

Rich

[HWYSTR455]

Well, technically, it's 3 jet sizes.

You running progressive linkage or what?

.

[gtorich]

Originally Posted by HWYSTR455

Well, technically, it's 3 jet sizes.

You running progressive linkage or what?

.

Mike, you are right, one for each carb. Running the regular tri power linkage, im wondering if I should just go back to the 74"s on the ends.

Just hate messing with these jets, PITA taking the fuel lines off everytime, not to mention trying to get the jets in while on car.

Right now im at 2 turns out with the mixture screws, im gonna try going 2 1/2 out and see what that looks like.

Did a search on some of those wideband units............looks like another headache in the making. LOL

Question, are these plugs looking lean to you..........

Rich

[HWYSTR455]

Honestly, I've never been able to accurately read plugs with an MSD unit or other bug zapper. And today's fuels make it even that much more difficult. Maybe if I held it in my hand might be able to tell, but can't by the pics.

My guess is if it was fat to a point that it blackened the plugs, it's real fat, and it's going to take some driving to clean up the chambers some. But yeah, the second pics above still looks a little fat to me. Grain of salt though, hard to tell.

I'm not a pro with tri powers, but still think turning idle mix out makes it fatter. Also think there were 2 different types of linkage, one that was mechanical, where all open roughly at the same rate, the other progressive, where the center, primary carb would open first, then the outer carbs. Makes a diff on how they are tuned, so maybe post a pic so we know.

If the outer carb jets are effecting part throttle, my guess is it's mechanical linkage, and you need to go leaner on the ends. But I'm just guessing there, post a pic before you muck with it anymore, it should help.

.

[Formulajones]

Originally Posted by HWYSTR455

Just went through this with the clone, with the cam profile I have in there, gears, converter, etc, idle and part throttle is in the 13.1 - 13.6 range, any leaner and it will ping or run hot on the highway. (or tip-in suffered). WOT blasts I believe were in the 12.2 - 12.6 range for best performance. I actually had to bump the PV to the next size also to help with tip-in and prevent ping. Whole time doing this I also had to play with vacuum advance some, and think it still needs a little work.

I was actually puzzled to a degree that it was taking so much jetting, would have thought it wouldn't need that much of step-up from out of the box getting on the Holley I'm running.

.

When you run a healthy camshaft that has alot of overlap, you get reversion in the intake track (intake and exhaust valve open at the same time). With this overlap it will require more fuel in the idle circuit and sometimes the pump shot or power valve circuits to overcome the reversion and get a decent consistent idle out of it and also good low throttle drivability. Of course how you have your timing set up will play a roll as well, but your AFR of 13.1-13.6 for idle and part throttle is pretty normal from what I see on most cars with larger camshaft overlap. Trying to idle them any leaner usually causes an irratic idle or sometimes a car that doesn't like to idle when it's cold or even luke warm, especially if you have the heat crossover blocked off.
Your wide open throttle is right in range of what I shoot for on E10 pump gas, it's pretty safe right there. Might find a few more ponies leaning it up top if you wish to tune closer to the edge. Every combo is a bit different in regards to what it will like for an AFR. Compression, camshaft profile, intake design, exhaust etc...

[Formulajones]

Originally Posted by gtorich

Just hate messing with these jets, PITA taking the fuel lines off everytime, not to mention trying to get the jets in while on car.


Did a search on some of those wideband units............looks like another headache in the making. LOL



Rich

Tuning can be a hair pulling experience. I know what you mean about metal fuel lines etc... Most of the time I do my jet changes with the carb off the car. I prefer to keep the fuel mess as little as possible on the car. Q-jets are one of the few carbs where "on car" jet changes are a little more pleasurable due to their design.

On widebands, there are many to choose from. Personally I'd recommend a mobile unit that can be used on multiple cars and get your moneys worth out of it. I have had my Innovative LM1 wideband for many years, and has provided trouble free tuning. I keep a box of bungs on hand and weld them into every car I tune, and it also links up to my laptop software to tune the fuel injected cars. It's one of the best tuning tools a car guy can have if you are serious about tuning. If you plan to tune more than one car, and I don't know a car guy that wouldn't, then you'll certainly get your money's worth out of it.

[gtorich]

Originally Posted by HWYSTR455

Honestly, I've never been able to accurately read plugs with an MSD unit or other bug zapper. And today's fuels make it even that much more difficult. Maybe if I held it in my hand might be able to tell, but can't by the pics.

My guess is if it was fat to a point that it blackened the plugs, it's real fat, and it's going to take some driving to clean up the chambers some. But yeah, the second pics above still looks a little fat to me. Grain of salt though, hard to tell.

I'm not a pro with tri powers, but still think turning idle mix out makes it fatter. Also think there were 2 different types of linkage, one that was mechanical, where all open roughly at the same rate, the other progressive, where the center, primary carb would open first, then the outer carbs. Makes a diff on how they are tuned, so maybe post a pic so we know.

If the outer carb jets are effecting part throttle, my guess is it's mechanical linkage, and you need to go leaner on the ends. But I'm just guessing there, post a pic before you muck with it anymore, it should help.

.

I'm not a pro with tri powers, but still think turning idle mix out makes it fatter. Also think there were 2 different types of linkage, one that was mechanical, where all open roughly at the same rate, the other progressive, where the center, primary carb would open first, then the outer carbs. Makes a diff on how they are tuned, so maybe post a pic so we know.

Ok, Mike heres a pic of the linkage, I thought mine was mechanical, im on the center carb and when I give it more gas the outers kick in, guess its the other way around. LOL

Im gonna mess with it some more this week, was paranoid that I might have went lean, and started wrecking stuff.

Digging around with the search, im seeing quite a few guys with 389-400 motors with higher jetting than on mine...........not sure of the stock specs, but im not that far off, and im running a 463, just seems odd.

Rich

[HWYSTR455]

Yeah, I see now, the secondaries don't kick in until the slack on the primary slide is taken up, in the linkage. Mental note made!

OMT helped out writing an article a while ago on rebuilding tri-powers, this was the concluding paragraph:

Conclusion
As you can see, it is important to save every available Tri-Power core. Once we were finished, Taylor had some parting words of advice. "There is no reason that the carbs we just finished can't be in use 50 years from now. It is important to use new lock washers on every screw, and lube every thread with oil or anti-seize compound. Over jetting really hurts power and parts--start with original #62 or #64 jets in the center, and #66 or #68 jets on the ends. Also, never fool around with the venturi cluster air bleeds. If you do Trips right, you will find out why they are famous."

Read more:

http://www.highperformancepontiac.co...#ixzz34q5tG6Zf

So, with that said, not sure you would need to go more than maybe 4 or so jet sizes larger, which is a general rule of thumb. Even with more displacement, the carbs only flow so much, so kinda have to keep that in mind. As long as it doesn't ping, or run hot, you shouldn't really mess anything up by going more lean than you are. Maybe start with 68-64-68, and see where you are then. Off idle and part throttle really is only the center carb, so maybe drive it with the 64s without getting into the others and see how it feels. Then start jetting up if need be on the ends.

Would be nice if others with more experience with tri-powers would chime in, like on base jetting.

I use an LM-1 also, have bungs in all my cars. The LM-1s you can find used affordable, since the newer ones are out. You could use just the dash mount gauge ones and make it work with a cigar lighter plug, would be cheaper, but not as pretty. Those I think you can get for like $150 or so.


.

[gtorich]

Hey Mike & Formula Jones............Sun Tuned called me today and said my distributor that I sent him was ready, this one has the vacuum advance at 10 degrees, 18 on the advance and whatever I use for initial. So maybe that might be different'

Im gonna throw in some 3924 plugs and just try using the center carb, and see what I get.............im gonna look into that LM-1, hopefully I can get a used one.

Thanks again

Rich

[Formulajones]

Originally Posted by gtorich

Hey Mike & Formula Jones............Sun Tuned called me today and said my distributor that I sent him was ready, this one has the vacuum advance at 10 degrees, 18 on the advance and whatever I use for initial. So maybe that might be different'


Thanks again

Rich

I just noticed you posted a dyno graph. According to that wideband you're pretty darn rich, I never see the AFR even reach 12:1 and looks like it floats in the 11 AFR range most of the time. You'll probably see another 10-15 HP out of that combo with the AFR straightened out. Usually on an engine dyno like that in a controlled environment, I find that the engine will fatten up slightly once installed in the car, so a few points on the lean side while on the dyno usually puts the engine nearly spot on when in the car or pretty darn close. I see alot of room for improvement on this one.

Your distributor sounds exactly like I prefer to set them up. Now you can dictate your total timing with your initial setting based off what the engine likes best. Compression, cam, and octane used will affect it. Initial will need to be ~14 to reach 32 total, a good starting point. That dyno session should have told you where the engine made best power vs total timing.

[gtorich]

Thanks Formula, that dyno run was with the old jets in there, 74-65-74, and that was done on a chassis dyno, not sure how much difference that makes, so I figure by going to 73-64-73, it should help some, hopefully.

Hopefully I can get that distributor in this week and see what happens.

Rich

[Cliff R]

An A/F meter or plug reading is not needed for tuning. A mentioned it's difficult, if not near impossible to read plugs on this piss-water ethanol enhanced crap anyhow.

Tune the primary carburetors for best idle quality at the leanest settings.

Tune the jet size for best light throttle and part throttle power, smoothness and fuel economy. As you lean it up stop going lean when the engine starts protesting the leaner mixtures. Fatten it backup till it runs the very best without excessive fuel consumption.

It may take several attempts to nail down the correct jet size. Don't forget that the vacuum unit is also a big player in light throttle tuning, and adding advance will burn leaner mixtures without loosing power, but there is a point of no return with these things.

For the end carbs, you need a chassis dyno or drag strip to find out exactly what jet size is most ideal. I'd stay pretty rich in that arena as there are no negatives anyplace from a little too much fuel, but BIG negatives when you go too lean, as EGT's rise quickly and detonation will destroy the very best prepared shortblock.......Cliff