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Hurst65 · 02-06-2013, 05:19 PM

Quote:

Originally Posted by 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.

Hummm.... interesting... If I could get my cruise reading up to around 14.5 - 15.0 I would be a lot happier. But as of now, with the 63's, I'm right around 13.0:1.

Dick Boneske · 02-06-2013, 05:21 PM

You said the bucking was back. I had that with my '64 GTO, too, until I went to smaller main jets. I would try the 60's again.

Hurst65 · 02-06-2013, 05:23 PM

What would happen if I removed the spring from the power valve?

Dick Boneske · 02-06-2013, 05:41 PM

The power valve in the bottom of the float bowl would never open if there was no spring. Remember, vacuum pulls the rod off the power valve against spring pressure. It takes 10-20 grams of force to open the power valve. The stock power valve rod has a 150 gram spring, which we often modify to 80 grams by removing about 8 coils.

If you had no power valve, acceleration would be as though your engine was always cold--too lean. Try it to confirm whether the power valve is causing the "bucking."

Hurst65 · 08:17 PM

You guys are going to get a kick out of this!

I removed the power valve spring. Guess what-- ZERO effect on driveability! ZERO, ZIP, NADA, ZILCH! No bucking, no kicking, no stumble, no falling on it's face, nothing! In fact, without it, it doesn't go nearly as pig rich after a gear change. It still goes rich, due to the pump shot, but not filthy pig rich.

Ok, so then I decided that I would just leave the PV spring out of the equation until I nailed down the main jets.

I pulled the 63's and reinstalled the 60's. I'm now reading 14.0-14.5 at a 2500 RPM steady cruise. Much better! And I think my "seat-of-the-pants" meter, that I mentioned yesterday, needs to be calibrated because, today I think the 60's feel just as good as the 63's. Haha! Hell, I'm almost tempted to pick up a pair of 58's and try them.

So, the good news is that I'm making progress. I know that the PV is there for a reason and I should have it activated but, I think it's window of operation should be VERY VERY narrow. I may clip a few coils off of the Red spring and try that.

geeteeohguy · 02-06-2013, 08:37 PM

If you're reading 14.5:1, that's about as good as it gets. 14.7 is what today's fuel injected computerized cars run at. You do NOT want it to run at 15:1....that is too lean, and you will see lean misfire/drivability problems crop up. Sounds like you've zeroed in on it, though. Congrats!

Hurst65 · 02-06-2013, 08:47 PM

Quote:

Originally Posted by geeteeohguy

If you're reading 14.5:1, that's about as good as it gets. 14.7 is what today's fuel injected computerized cars run at. You do NOT want it to run at 15:1....that is too lean, and you will see lean misfire/drivability problems crop up. Sounds like you've zeroed in on it, though. Congrats!

Thanks! I don't know if I would say "I've zeroed in on it" yet but, I'm kinda sorta starting to get a smile on my face. I'm still not sure about "The Stink" thou...

Ok, so what should I be shooting for during WOT? Right now, I'm reading about 12.0
I was able to get one small WOT pull late this afternoon after the rain stopped and the roads started to dry out. The gauge will go rich (with the pump shot) then it will lean very briefly and then settle out around 12.0:1. I'm thinking that VERY brief lean spot is when I need the PV to open. Thoughts??

Dick Boneske · 02-07-2013, 01:13 AM

What you've discovered here is surprising to me--I've never tried running without the power valve. Of course, the end carbs don't use a power valve, as they were designed to operate at wide open throttle only. They are kind of like a power valve for the center carb.

The result you've experienced with the power valve disabled makes me wonder what would happen if the end carbs were disconnected so the center carb could operate full throttle with no richening from the power valve (or end carbs). The richening provided by the three accelerator pumps (momentarily) masks the operation of the center carb with no power valve. If the end carbs were disconnected, I think the engine would fall flat on its face with these conditions.

In any case, it appears that selecting spring tension for the power valve rod is critical to maintain optimum fuel/air ratio under low vacuum conditions--part throttle. If the power valve is opening and closing randomly at light loads--bucking will be the result. That suggests the power valve spring needs to be much weaker than stock on a cammed engine that has low vacuum at light loads like yours has.

I just recently set up a '64 Tripower for a 389 with a mild cam--(Stump Puller). The engine was started for the first time on a dyno last month. The dyno operator said the fuel air ratio was near optimum thoughout the rpm range from part throttle to wide open throttle. This setup has .062 jets in the center carb, .070" jets in the end carbs, and 8 coils cut off the power valve spring. During the run, it had a "stumble" on initial acceleration with the center carb only. I determined that the accelerator pump was not functioning after the dyno run and I fixed the problem.

I must have guessed right with the jet sizes and power valve spring on this one.

Hurst65 · 02-07-2013, 11:58 AM

That's pretty much what I'm thinking, Dick. Having 3 carbs, each with acc. pumps, really limits the window of operation for the PV. I'm thinking it's just not needed most of the time. It's certainly not needed just driving around town.

I'm thinking it's window of operation is - during full throttle operation , on the tail end of the pump shots, and as the end carb main jets come into play. That's a VERY narrow window but, still one that needs to be addressed.

More tuning to come....

Hurst65 · 02-07-2013, 04:09 PM

This morning I pulled the 70's out of the end carbs and installed the 68's. No changes to the center.

I then got some good driving time (no rain). Yea! I've put about 55 miles on her today. I went the car wash to vacuum out the interior, went to lunch, went to the pet store to get my kid some more food, and made a lot of laps around my test track (down the feeder road two exits and back).

The car is now running the best it ever has. It cruises at 2500 - 3000 RPM with the wideband reading a consistent 14.0 - 14.5. The idle readings are pretty consistent-- the same as the cruise readings. Every now-and-then, for some unknown reason, the idle readings will go a little rich but, they clear up after a little bit. WOT readings are around 13.0. I kinda need someone, that knows what is going on, to ride with me and observe. Overall, the car runs pretty darn good. I think I'm really getting down to the nitty gritty. Honestly, I'm wondering if I should just leave the Power Valve INOP. The car runs really good without it. I don't know if it's worth the trouble. Any thoughts...??

Hurst65 · 02-07-2013, 06:53 PM

Here's a few pictures, of my set-up, that I took today. They're not very pretty right now. I'm thinking that once I get them dialed in I may send them in for a full cosmetic restoration.

Dick Boneske · 02-08-2013, 10:42 AM

The power valve would come into play if you're cruising at high speeds with only the center carb. I would like to see how your mech. linkage is set up--the pictures only show the passenger side.

With the '65 "J" center carb lever, you have a choice of two positions for the top stud that operates the slotted rod. The top hole int the lever gives you more throttle opening with the center carb before the ends engage. IMO, that position gives you the best driveability. If using the lower hole, center carb opening before the secondaries begin to open is really limited.

It's amazing to me that elimination of the power valve has so little effect on overall driveability. This very likely is the key to eliminating the bucking problem so many Tripowers have at light loads/low speeds. I've "fixed" several of these, but only after making a lot of changes which always included changing the power valve spring pressure.

FWIW, I checked a dozen power valve rods for spring pressure last night. The weakest spring required 100 grams to compress, the stongest 180 grams. Then I checked a dozen power valves for spring pressure (not the rod, but the power valve itself). They all require less than 35 grams to open. The ones with the large (.073") holes take about 15 grams to open. The ones with the smaller holes (about .060") have stiffer springs. Nearly all of the Tripower center carbs I've worked on use the power valve with larger holes. That tells me the 8 coils cut off the power valve rod spring with the resulting 75 grams of pressure still comfortably will open the power valve.

I'm going to set one up for about 50 grams of pressure and see what it does for my setup--and my wife's setup. They both exhibit some bucking at low speeds in third or fourth gears at light loads.

Thank you very much for your efforts and postings. Your efforts to troubleshoot your Tripower and your postings are really thought-provoking and helpful. What's that expression---So many Tripowers and so little time!!!!!

Hurst65 · 02-09-2013, 03:03 PM

Here's a picture of the other side. I'm kind of embarrassed by this picture. I really hate how ugly all that linkage looks. What's the best way to restore the linkage? Replate them or buy new?? I may be able to do a decent job refinishing the carbs with the Eastwood product (not sure...never used it) but, how does one do all the linkage? Ugh! It's never ending...

Dick Boneske · 02-09-2013, 03:17 PM

If you want to redo your carbs and linkage at the same time, let me know. Since your carbs are OK, disassembly, cleanup, dichromate, plate linkage levers & rods would be all that's necessary. If you can wait 'til April, I'll gladly do it for you so the Tripower looks like the pictures attached.

The Eastwood product looks OK for a little while, but after the carbs have gas in them, and a little leaks onto the carbs, the paint disappears. It's no more work, and not a lot of expense to do it right!

PM me for pricing and details.

Hurst65 · 02-09-2013, 03:29 PM

Wow! Those look awesome!

I'll PM you.

Hurst65 · 02-12-2013, 07:40 PM

Quote:

Originally Posted by Dick Boneske

The power valve would come into play if you're cruising at high speeds with only the center carb. I would like to see how your mech. linkage is set up--the pictures only show the passenger side.

With the '65 "J" center carb lever, you have a choice of two positions for the top stud that operates the slotted rod. The top hole int the lever gives you more throttle opening with the center carb before the ends engage. IMO, that position gives you the best driveability. If using the lower hole, center carb opening before the secondaries begin to open is really limited.

It's amazing to me that elimination of the power valve has so little effect on overall driveability. This very likely is the key to eliminating the bucking problem so many Tripowers have at light loads/low speeds. I've "fixed" several of these, but only after making a lot of changes which always included changing the power valve spring pressure.

FWIW, I checked a dozen power valve rods for spring pressure last night. The weakest spring required 100 grams to compress, the stongest 180 grams. Then I checked a dozen power valves for spring pressure (not the rod, but the power valve itself). They all require less than 35 grams to open. The ones with the large (.073") holes take about 15 grams to open. The ones with the smaller holes (about .060") have stiffer springs. Nearly all of the Tripower center carbs I've worked on use the power valve with larger holes. That tells me the 8 coils cut off the power valve rod spring with the resulting 75 grams of pressure still comfortably will open the power valve.

I'm going to set one up for about 50 grams of pressure and see what it does for my setup--and my wife's setup. They both exhibit some bucking at low speeds in third or fourth gears at light loads.

Thank you very much for your efforts and postings. Your efforts to troubleshoot your Tripower and your postings are really thought-provoking and helpful. What's that expression---So many Tripowers and so little time!!!!!

Dick,
Your info about the power valve is very interesting. If your info on the power valve hole sizes are correct, I think I found a problem.

I decided to reintroduce the PV spring today, now that I'm somewhat happy with the center main jets. No matter which spring I tried I still had a lean area during heavy part throttle acceleration. Very aggravating!

So, I pulled the PV out for inspection and measured the holes. The holes in mine are about .060". If this is the incorrect PV, this would explain a lot. I don't remember is this was the PV that was in this carb, when I bought the car, or if I installed a new one when I rebuilt the carbs several years ago. I don't think a new PV came with the rebuild kits but, I honestly don't remember.

What's your thoughts on this?

Thanks!
Eric

Dick Boneske · 02-12-2013, 10:24 PM

If you bought rebuild kits from a parts store, they had no power valve included. I've not found a pattern of which carbs use the .073" power valves and which use the .060" holes. I know that my car and my wife's use .073" power valves and the '64 NOS carb I have has the .070" power valve.

I can't say what results you get using the .060" power valve, but it's obvious the smaller holes would result in a leaner mixture when the valve opens than with the larger one.

If you want a larger power valve for your setup, let me know tonight, as tomorrow will be our last day at home for a month. I could still ship it tomorrow. I'll supply this at no cost to you as appreciation for the data you've supplied!

Dick

Hurst65 · 02-12-2013, 11:16 PM

I think I got the kits from AMES... not sure. They were in small, thin, white boxes.

Anyway,.... so, I just went out and took some measurements on the PV.

Top edge of float bowl down to the tip of the PV stem itself- approx. 1 20/32"

Edge of the bowl cover w/ gasket in place to the tip of the PV piston w/ piston retracted - approx. 1 20/32"

Edge of the bowl cover w/ gasket in place to the tip of the PV piston w/ piston extended - approx. 1 26/32"

The little stem, in the center of the PV, sticks up about 1/16".

So, the mechanics of the PV should be good. Right?

Yeah, if you don't mind, I think I'll try a different Power Valve.

Dick Boneske · 02-13-2013, 12:03 AM

All sounds good. I'll send the right power valve tomorrow.

Hurst65 · 02-20-2013, 07:37 PM

Update:

I've been doing some more work the past couple of days. I installed a new cap, rotor, and Taylor wires. I also decided to recheck my valve adjustment. I think I found a couple of valves that were probably a little on the tight side.

CHECK THE BASICS! I set them all a 1/4 turn past zero lash. I think it made a tiny bit of difference. The rockers are a little noisy at start up, but they get quiet after a few mins. I'm using Rotella 15W-40 with a bottle of the Lucas ZDDP break-in stuff. Any recommendations on something better?? That Rotella is some thick stuff.

I also put the 63's back in the center carb. They are rich at cruise (13.0) but, they don't go lean during heavy part throttle. I'd like to improve that cruise reading but, I don't want to go lean anywhere either. [shrug]

Here's a few pics of my new wires.

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