[Old Man Taylor]

With a similar combination to yours, I ended up at 70-63-70. I would also get the power valve spring set from Carbking and change your PV spring. Jon can probably recommend the best one to try of the three.

[Dick Boneske]

Remember, the main jets in the center carb have nothing to do with idle mixture. Idle mixture is controlled by the idle tubes, idle air bleeds, and idle channel restrictors in the venturi cluster.

Do your throttle plates in the center carb have holes in them? A stock '65 Tripower should have no holes in the throttle plates if you're using a mild cam.

The idle mixture screws should be optimum at about 2 turns out.

PM me if you need jets and/or new throttle plates.

[carbking]

Originally Posted by Hurst65

I finished installing the wideband gauge this morning and started to do a little tuning.

The idle was pig rich! Jon, you were right! The gauge was reading between 12.12 & 12.5:1 at idle. So, I turned the mixture screws in all the way and then back out 1 turn. That proved way too lean-- the car wouldn't idle well and the gauge was pegged out. I then went another turn out, for a total of two turns. That was a close but, a little too rich. Right now, I'm at 1.75 turns on the mixture screws and the gauge is reading about 14.5:1.
I never knew that the mixture screws were that sensitive. The slightest little turn makes a big difference!

I think I'm okay with the idle. It idles real nice at a steady 900 RPM, w/15 degrees of timing, pulling 11" of vacuum, and the wideband gauge reading 14.5:1. The idle is really smooth-- almost stockish.

Ok.... so, then I went for a short drive. The mains are pig rich too! The gauge was reading about 11:1 to 11.5:1, in any gear, at 2500 RPM. How much of a jet change do you guys think I need to make?

Thanks!

Have you changed the spark plugs yet?

Running as rich as the engine has been will foul the plugs to the point the wide-band will not be as accurate as possible; as the fuel-fouled plugs will not produce the same spark as they would when new, thereby sending a false reading to the wide-band.

Once you get close on both idle and main...............CHANGE THE PLUGS! You will probably find you need to adjust a wee bit more (leaner) on fresh plugs.

And yes, if you need the spring kit, we still have them.

Jon.

[Hurst65]

Originally Posted by Old Man Taylor

With a similar combination to yours, I ended up at 70-63-70. I would also get the power valve spring set from Carbking and change your PV spring. Jon can probably recommend the best one to try of the three.

Thanks! I kinda have a feeling that I'm going to end up somewhere really close to that.

[Hurst65]

Originally Posted by Dick Boneske

Remember, the main jets in the center carb have nothing to do with idle mixture. Idle mixture is controlled by the idle tubes, idle air bleeds, and idle channel restrictors in the venturi cluster.

Do your throttle plates in the center carb have holes in them? A stock '65 Tripower should have no holes in the throttle plates if you're using a mild cam.

The idle mixture screws should be optimum at about 2 turns out.

PM me if you need jets and/or new throttle plates.

No holes in the throttle plates.

[old66tiger]

The holes are only if you need more idle air. You need to look at the throttle blades to see how much of the teansition slot is showing. Should not be more tha 0.030" otherwise you are riding on the main circuit of the carb. Any nozzle drip ? If so you are not on the idke circuit and need bypass air.

[Hurst65]

Update:

I received some new jets from Dick Boneske and the power valve spring kit from Jon. Thanks, guys!!

Ok, so... first thing I did was install new AC Delco R45S plugs then I installed 63's in the center and the yellow power valve spring (which is the middle of the 3 springs). I went for a short drive and the gauge was reading about 13.1 during cruise. Still too rich. Driveability improved but, it was still reading rich.

I came back and installed 60's in the center carb. I then rechecked initial timing, tweaked idle mixture, idle speed and then went for a drive. It's now reading around 13.5:1. Still a little rich. Hummmm....??

Here's the thing - the gauge fluxuates at idle and during driving. For example, I can adjust the idle mixture screws to get a steady 14.5 - 15.0 reading but, after movement of the throttle, the gauge will read a steady 13.0 - 13.5. Also, while driving, the gauge will sometimes go rich for some unknown reason. Any ideas? I'm still questioning the power valve spring. Maybe I need to put the lightest spring in there.

I also picked up a fuel pressure regulator (as recommended in Mike Wasson's tri-power DVD) and I'll install that tomorrow.

The good news is that the driveablilty of the car has improved. It used to buck and kick when cruising really slow through a parking lot. That has gone away. Yea!! I am making some progress.

[Hurst65]

I hate to sound like I'm chasing the gauge -- I'm sure some will probably frown at that. But it seems like when the car goes rich, for a moment or two, that's when the stink really comes on strong. Like I said before, it's really hard to tell because once that smell is in your nose - it's there and it ain't leaving! Ugh!

The ultimate goal, here, is to have a good running car without "The Stink". I may be making a little progress toward getting rid of the stink but, at this point, it's really hard to tell.

[Old Man Taylor]

Try the other spring in Jon's kit (the stiffer one). IMHO your jet size is too small for the A/F readings you are getting. The highest vacuum I could get with my cam was 10". I used the yellow spring and it seemed to work out well.

[Dick Boneske]

If you adjust to 14.5 -15.0 and then open the throttle, the accelerator pump squirt would have momentarily richened the mixture. If you do what you describe and then wait a minute or so, does the reading return to 14.5?

It's surprising that the .060" jets show too rich a mixture while driving. Maybe there is not enough vacuum to keep the power valve closed. Maybe the weaker spring on the power valve is the answer. Stock power valve spring measures 150 grams on the setup I use to check them. If you remove 8 turns of a stock spring, the result is about 80 grams of force to move the spring off fully extended, which is still plenty of pressure to open the power valve when vacuum goes down when the throttle is opened under load.

Keep us tuned in!!

Thanks.

[Dick Boneske]

I posted just after OMT's post--sorry I didn't see it. In any case, a weaker power valve spring will lean the mixture, a stiffer spring will richen the mixture---under conditions when the power valve is operating.

[Hurst65]

Originally Posted by Dick Boneske

If you adjust to 14.5 -15.0 and then open the throttle, the accelerator pump squirt would have momentarily richened the mixture. If you do what you describe and then wait a minute or so, does the reading return to 14.5?

It's surprising that the .060" jets show too rich a mixture while driving. Maybe there is not enough vacuum to keep the power valve closed. Maybe the weaker spring on the power valve is the answer. Stock power valve spring measures 150 grams on the setup I use to check them. If you remove 8 turns of a stock spring, the result is about 80 grams of force to move the spring off fully extended, which is still plenty of pressure to open the power valve when vacuum goes down when the throttle is opened under load.

Keep us tuned in!!

Thanks.

No, the reading does not return to 14.5 after the pump shot. That's what's weird. It doesn't do it every time. It's very random. Something funny is going on and until I figure that out I'm going to be chasing my tail. I'm thinking it's the power valve. What else could it be?

I agree with your thoughts on the 60's. I think I'll put the 63's back in tomorrow. I don't have data to back it up but, I think the 63's felt better. My seat-of-the-pants meter liked the 63's better.

[Dick Boneske]

Yes, it could be that the power valve spring is too strong for the vacuum your motor produces. Try the weaker spring.

But, first, does all flow of gas into the throat stop when you shut the engine off? If there is any evidence of gas after shutoff, the needle & seat is not closing completely--due to too much fuel pressure or the seat is loose in the airhorn theads.

Also, does gas drip off the venturi nozzles when idling--in the center carb and/or each of the end carbs?

You may have a problem with the end throttle plates not being sealed tightly. You can check this by putting your hand over each airhorn and observing whether idle changes. If is does, your throttle plates on that carb are leaking air.

[Hurst65]

Yep, I'll try the lightest spring tomorrow. I hope that does the trick.

I've never noticed any nozzle drip with these carbs at any time. That is one thing that I regularly check. I've also installed (last summer) Mike Wasson's 1/4" phenolic carb spacers to help keep them cool.

I rechecked the end carbs, as you described, last week. I'm pretty certain that they are sealing good.

Thanks!

[Dick Boneske]

That means it's likely the power valve. If now, keep giving us info and we'll track it down!

[Kenth]

What is the fuel pressure?
TriPowers do NOT like more than 5psi.

What about inlet valves?
Center carb should have a .101" sized and the outers should have .086" seats.
Generic kits can contain any size, mostly too large seats.
Also put a drop of light blue Loctite on valve threads to secure them tight.

Float settings?
Setting should be 23/32" on all three.

Also, using the correct PCV-valve?

[Dick Boneske]

Kenth is right about fuel pressure--it needs to be less than 6 psi. Too much pressure that would force fuel past the needle/seat would explain the varying ratio, also.

Kenth's point about the size of the inlet valves (needle/seat) is likely correct, but not pertinent to Hurst65's problem. It's true that larger seats tolerate less fuel pressure, but anything up to 6 psi, in my experience is not a problem. 95% of the running Tripowers today have all three carbs with the same size inlet valves, including my own, with no issues.

Regarding the correct PCV valve--What would be the "correct" PCV valve for an engine with this cam and other mods? With the reduced vacuum produced by the Crower 60423 cam, the stock PCV valve would not be opening as much as "normal." Is it possible that the PCV valve is the reason for the varying fuel/air ratio because it is not operating consistently due to lower vacuum? I doubt it, but it's a possibility.

[Hurst65]

Ok, made a few changes today...

I installed this fuel pressure regulator between the filter and carb inlet.
http://www.summitracing.com/parts/mrg-9710/media/images
Pressure set to 3 psi. as recommended in Mike Wasson's DVD. I don't know if is made a difference or not but, it should eliminate that variable.

I removed the 60's and reinstalled the 63's in the center carb.

I removed the Yellow PV spring and installed the Red PV spring (the lightest one in the kit).

I remeasured the float level on center carb. It was good.

Ok, sooo.... I went for a drive, even thou it's raining and I don't normally drive this piece in the rain. Here's where I'm at, now -
1.) idle readings are (maybe) a little more consistent. I'm not sure but, they seem to be. I'm also not sure how much of an effect the rain is having on it.
2.) The mild bucking and kicking is back. It's not bad but noticeable.
3.) At 2500 RPM in 4th gear (steady cruise) the gauge is reading 12.7 - 13.2:1
4.) When rowing the gears the gauge is always reading rich - anywhere from 11.5 - 12.5:1. Once it gets up to cruise RPM it will settle out at about 12.7 - 13.2:1. When you come to a stop at a light the gauge will come up to the idle setting.

I'm not sure where to go from here....

[geeteeohguy]

When you get off the gas to shift gears, emissions will increase a bit. This is normal. In the '70's, a lot of stick cars had a decelleration valve to delay throttle closure just to reduce emissions. You don't have that. I would NOT pay any attention to your AF ratio except at idle or at steady cruise, and only after cruising for about 30 seconds or more. Ditto with idle. It takes about 30 seconds for everything to stabilize for an accurate reading. If you can get a steady 13.5-14.5 AF ratio at cruise, you are there. 14.7:1 is the magic number, and is the ideal stochiometric air/fule ratio all cars are calibrated to run at these days.

[Dick Boneske]

Good info geeteeohguy. Now, Hurst65, you need to try what he suggested---cruise for a few minutes and observe the gage.

I've learned a lot from this thread!