[Hurst65]

Ok, sooo... Here's a question that I hope someone can answer.

I pulled the plugs today to have a look at them. Number 5, 7, and, 8 are almost bone white. The rest are a medium to dark brown.

Here's a couple pics of 5 and 7. Number 8 is very similar.

[geeteeohguy]

They look fine to me. You're splitting hairs here...it's dinosaur technology you're working with. I think you're doing great!

[Hurst65]

Here's a couple pics of number 1 and 2. Numbers 3, 4, and 6 look the same.

Sorry for the crappy cell phone pictures.

[Hurst65]

Originally Posted by geeteeohguy

They look fine to me. You're splitting hairs here...it's dinosaur technology you're working with. I think you're doing great!

I hope so... I think I'm getting close. It really is amazing how close the Rochester people got these carbs without the use of O2 sensors and computers. There were REALLY close! Especially on the idle transfer area. The idle transfer on this carb is probably the most efficient spot. It consistently reads in the 14.7 range.

[Hurst65]

If you study the runner layout of the tri-power intake manifold it would kinda make you think that there was a problem with the rear carb.

So, I isolated the rear carb from the others, ran the engine, and found that the rear carb is flowing fuel as it should. Lots of fuel coming from the boosters when you open the throttle.

Very interesting.... I'm not sure what's going on... or how to proceed. Any ideas? Stagger the jets between the front and rear carbs?

[Greg Reid]

That is a very neat job on the wires. Did you custom fit the lengths?

[Hurst65]

Originally Posted by Greg Reid

That is a very neat job on the wires. Did you custom fit the lengths?

Thanks! Yes, I did. These are the wires I used.

http://www.summitracing.com/parts/tay-83053/overview/

[Greg Reid]

Originally Posted by Hurst65

Thanks! Yes, I did. These are the wires I used.

http://www.summitracing.com/parts/tay-83053/overview/

Were they shipped assembled and you pulled the boot off to custom fit or were they designed to be cut to length and then assembled to the boot?
I don't want to belabor such a minor point but this has always irritated me....Spark plug wires bought for a specific model and having several that are just too darned long. After paying about the same price for mine, I was hesitant to start pulling the boots off and chopping them up...

[Hurst65]

No problem. The spark plug end of the wires are assembled. You trim to length and assemble the end that goes on the distributor. It does take some time and you'll need a special crimper to crimp the ends on the wire.

This is the crimper that I use. I works perfect! Just don't forget to put the boot on the wire before crimping the end on!
http://www.summitracing.com/parts/msd-3503/media/images

It really is the only way to do it and have them look exactly like you want them to.

[Greg Reid]

Ok, thanks. The next set I get, I'll make sure they are the ones designed to be cut to length. I have a set of Taylors now but they were already assembled.

[Schurkey]

Originally Posted by Greg Reid

this has always irritated me....Spark plug wires bought for a specific model and having several that are just too darned long.

Welcome to Opposite-land.

Plug wires sold as "custom-fit" are always too long, so that one part number can accommodate the widest-possible range of vehicles. They are actually built to be as "universal" as possible.

Plug wires sold as "Universal" fit, are intended to be custom-tailored to the individual vehicle.

[Greg Reid]

Originally Posted by Schurkey

Welcome to Opposite-land.

Plug wires sold as "custom-fit" are always too long, so that one part number can accommodate the widest-possible range of vehicles. They are actually built to be as "universal" as possible.

Plug wires sold as "Universal" fit, are intended to be custom-tailored to the individual vehicle.

Yeah, that is funny. Park in a driveway and drive on a parkway...lol

[Hurst65]

Update-

I've done a little more work and some tuning this week. I think I'm pretty damn close to dialing this thing in so, I'll try to wrap this thread up. So many threads get started and never get finalized so, here goes --

I've pretty much been focused on the center carb recently. I replaced the throttle shaft because the old shaft had some play in it. I tried to measure how much wear was in the old shaft with a dial indicator but, it's not an easy thing to do. Depending on the position of the shaft, in the base, I was getting between .008" and .010" of play. The new shaft took a lot of that play out and fit very well.

I also installed an uncut original power valve piston spring. It works! No dripping! Yea! It's probably on the edge of activation but, I think that's a good thing. As long as it's not opening at idle you're probably ok. The lesson here is - DO NOT CUT YOUR ORIGINAL SPRING!! If you think the PV is opening, at idle, with your stock spring -- simply remove the spring and try that. It's ok to run and even drive the car without the PV, as long as you don't do any heavy acceleration. If you need a lighter spring, then order the PV spring kit and try one of those. There's no telling how many original uncut springs are left. You may want your original spring one day.

Regarding the Power Valve itself -- I've learned that the power valve in these carbs is really more like a switch. It's pretty much all or nothing. Also, the power valve does not decide or limit the amount of fuel added to the main wells. There is an internal restriction that limits the amount of fuel into to the main wells. You can't see them but, they are there. I'm guessing that they are approx. .025" dia. holes. .030" safety wire will not go through them but, .020" wire will.... just in case you're curious...

Jets - right now I'm running 61's in the center. The 60's were almost perfect at cruise RPM but, were a little bit lean with heavy part throttle acceleration. The 63's ran good but, were rich at cruise. I feel like the 61's are a good compromise. With the 61's, I'm running in the 14.0 to 14.5 range during cruise and I'm in the 13.0 range at WOT (on the center carb alone). I'd love to run the 60's or maybe even 59's but, there's just no way to have a gradual increase of fuel during heavy part throttle operation. If these carbs had a two-step power valve or metering rods, that may be possible but, as it is, you have to make a compromise. For me, I think the 61's are a good compromise. This is really splitting hairs! But, I think it's interesting...

In the ends I'm running 68's. I have not been able to do many wide open runs but, from what I've seen, I'm in the 12.5 to 13.0 range. I think only some good track time would give me the info to be able to nail down the end carbs. I think I'm in the ball park, thou...??

Note -- All tuning was done was done at an elevation of approx. 75' with temps in the mid 60's to mid 70's. I'm not sure how much of a Jet change would be required for cold or hot temps. That will remain to be seen.

So, this is where I'm at now--

Center carb - Idle tubes at .035", stock uncut power valve spring, and #61 jets. The idle mixture screws are approx. 1.75 turns out.
End carbs - #68 jets.

The car idles at a nice 750 RPM pulling about 11" of vacuum.

I still have not been able to figure out or explain why the idle mixture has a intermittent rich fluxuation. It's driving me nuts! It only seems to happen when the car has been running for a while and is completely heat soaked. When this happens, the idle mixture will start to creep down to around 13.0, when sitting at a light or in stop-and-go traffic. It's really weird! I don't know what causes it but, I hate it! Ugh!
You're probably saying "whats the big deal?" right? Well, here's the thing-- when the idle mixture goes rich, that's when "The Stink" really comes on strong. If the idle mixture is rich or lean it will stink badly. I'll give you an example-- I stopped to get some air in one of my tires that has a slow leak. When I pulled into the service station, the idle mixture was reading in the 14.5 range. While I was putting air in the tire, "The Stink" hit me and I was like "WTF!?!". I looked in at the gauge and it was reading around 13.0. Ugh! I can't figure it out. Maybe it's because of the ethanol in the gas... If anyone knows why or can help with this, I would greatly appreciate it!

I apologize for any misinformation earlier in the thread. I know a lot of it was incorrect. This was very much a trial and error learning experience! I've gotten really good at changing jets! Lol! I hope this clears things up for anyone interested.

Eric

[Hurst65]

Here's a cool little tip that helps tuning the idle mixture screws.

The idle mixture screws are very sensitive! 1 quarter of a turn, one way or the other, makes a HUGE difference in the idle mixture readings! You need a reference point/index mark to know where you're at with these guys! But, here's the thing -- if you only put one mark on the screws and they get in a position where you can't see them, you're guessing again. Ugh! It's easy to get them unequal while tuning because they're hard to see. I use a long 1/4" wrench to adjust them.

So, put two different marks, in different colors, 180 degrees apart, on the them!

See the pics. I used a black permanent marker on one side and a red marker on the other side. Now, I know exactly where they are at and I can keep them equal.

[old66tiger]

I think I know why you are getting stinky on the idle when the car is hot. The lines are made out of aluminum and soak a bunch of heat. The heat causes the fuel to expand in the lines ahead of the needle and seat. Get the pressure high enough and it blows past the needle and seat and pours over the venturi cluster. When the car is running and it starts to get smelly, take a look down the carb and see if you have some fuel dripping past the venturis. Easy fix here. Add a Tee after the pump and put a 0.030" orifice in the t-portion and plumb that to a return back to the tank. This bypass will keep the fuel from gaining pressure by bleeding a small portion back to the tank. I won't affect the pressure or flow volume of the pump. On my old tri-power, I had problems with pressure creep after I turned the engine off. The cluster would be bone dry when running and when the engine shut off, the pressure would build and push fuel past the needle and seat and the fuel would creep over the clusters. IMO...the float system on the 2GC carb is probably one of the worst of any carb out there. Easy for fuel to push past the needle and seat.

[Hurst65]

That's interesting! I've wondered about that. I'll have to check that the next time I see it.

I wonder if wrapping the lines in some sort of reflective or insulating wrap would help...??

I could try lowering the setting on the pressure regulator. I have it set at 3.5, now.

[Jurassicgto]

Yes what old66tiger says is true about the return line. Just make one and be done with it. I run 6 carbs and the return line solved a lot of problems. You can fab one up really quick with some cheap rubber fuel line, a carb jet shoved in there, run it to the tank breather and see if it works. If it does then make more permanent mods with better routing, stainless braided line, whatever you want. I tried insulation only at first too but that didn't solve the problem.