[gtofreek]

I built a 1964 326[now 331 CID] for a customer. It's a mild rebuild, with bowl ported heads, and a Voodoo hydraulic roller cam[219°/227° @ .050"]. He installed a 1964 tri-power unit on it. He had the tri-power setup all done up for the 460 stroker he had in it, but decided to use the 460 in something else, and put a 326 back in the car, a 64 LeMans. Now it runs really rich. Does anyone have any suggestions on approximately where the jetting should be for an engine this small? Re-calibrating carbs is not my thing.

[CROCIE JR]

Find the stock jetting for THOSE carbs. Go up 3 center and 3 on the ends. Good starting point.

[steve25]

What about the power piston spring?

[77 TRASHCAN]

FWIW, the last 3 2G's I worked on all had float issues...

[gtofreek]

Thanks for the suggestions.

[b-man]

Contact Dick Boneske, he's pretty much considered to be the PY forums Tri-Power expert.

He'd probably have a good idea where to start.

If it were my engine I'd put the stock jetting in it for a 389, it can't be that far off from what you'll end up needing.

[gtofreek]

Customer called the guy that built his Tri-power and he said his carbs had 74 jets in the front and rear carbs, and 64's in the center. Then he told him to switch them to 64's front and rear, and 62's in the center. He managed to find 2 sets of 64's, but no 62's, so now it has 64's in all carbs[until he can find some 61's or 62's]. He drove it and it's much better. Said it runs real strong.

We built him a 460 stroker a few years ago for this car, but he wanted to use the 326 heads on it to look stock. Because the heads were so tiny, the engine only made 386 HP, but crap loads of torque. It was all done by 4500 RPM, so the car would take off real quick, but peetered out by the 1/8 mile. I told him these heads are better suited for the small engine, and would probably run pretty good on it. The 460 is just trying to breath through a straw with them. He decided to have us build the 326 to put back in the car, and use the 460 with better heads for something else. He said this 326, to him, feels faster than the 460. Said it pulls real hard all the way through the rpm range now, and can't wait to get it back out to the track to see if it is actually faster than the 460. I can't wait either. It will be interesting. The 326 that could?

[gtofreek]

Originally Posted by b-man

Contact Dick Boneske, he's pretty much considered to be the PY forums Tri-Power expert.

He'd probably have a good idea where to start.

If it were my engine I'd put the stock jetting in it for a 389, it can't be that far off from what you'll end up needing.

I was hoping he would answer. I was thinking about PM'ing him, but it seems like it might be getting close. I may still PM him just for the second opinion. I guess Mike Wasson[spell check] built the carbs originally.

[b-man]

1957, front-56 center-61 rear-56
1958, front-56 center-60 rear-56
1959 auto, front-66 center-65 rear-66
1959 stick, front-66 center-62 rear-66
1960 auto, front-66 center-63 rear-66
1960 stick, front-66 center-60 rear-66
1961, front-66 center-62 rear-66
1962, front-66 center-62 rear-66
1963 389, front-66 center-62 rear-66
1963 421 auto, front-73 center-61 rear-73
1963 421 stick, front-73 center-64 rear-73
1964 389 auto, front-68 center-62 rear-68
1964 389 stick, front-68 center-64 rear-68
1964 421 auto, front-71 center-62 rear-71
1964 421 stick, front-71 center-65 rear-71
1965 389 auto, front-68 center-60 rear-68
1965 389 stick, front-68 center-63 rear-68
1965 421 auto, front-73 center-60 rear-73
1965 421 stick, front-73 center-61 rear-73
1966 389 auto, front-68 center-60 rear-68
1966 389 stick, front-68 center-62 rear-68
1966 421 auto, front-73 center-60 rear-73
1966 421 stick, front-73 center-62 rear-73

[gtofreek]

Looks like he might be pretty close with 64-62-64 then. It has a 200-4R tranny and 3.73 gears also.

[Dick Boneske]

Got your PM. I would try .061" jets center carb and .066" or .068" jets in the end carbs.

I think .064" for the end carbs is too small, but you would feel a lean hesitation when hitting WOT if that's true.

If the center carb venturi cluster was reworked for more gas at idle by enlarging the brass idle tubes (stock about .035") and idle bypass restrictors (stock about .046"), you may need to get another venturi cluster with smaller passages. For a bigger engine, these are often opened up to about .041" for the idle tubes and .052" for the idle bypass restrictors.

If you need pictures or more info, let me know. Remember, you can't post pictures with a PM, but I can put them on here.

[b-man]

Dick, please check your email.

[gtofreek]

Dick, he said when it gets around 5000 rpm, it's starts to misfire a little bit. Maybe it is a little lean.

[tom s]

With our percentage of ethenal is not a little riching necessary?Tom

[Dick Boneske]

If the secondary carb mixture was lean, you'd expect hesitation when the end carb open instead of a "kick in the pants" feel as there should be. I don't think the misfire is a symptom of lean mixture in this case.

To troubleshoot the misfire, I'd disconnect the end carbs and run it up to 5000 rpm on the center carb to see if the misfire persists. With the .064" jets in the center carb, I don't believe there could be a lean mixture from that carb alone.

As one of our forum members often says: "90% of carburetor problems are electrical."

[Dick Boneske]

Bart, I don't see an email from you.

[carbking]

I would suggest 0.064 in the center.

Don't know what vacuum readings you are getting with that cam, but MIGHT (check vacuum gauge FIRST) need to change the spring on the power valve actuating valve. If the power valve is coming in to soon, it would effect what you think you are seeing from the main jets.

Also, check the orifice size of the fuel valves (one size may fit all, but it doesn't necessarily work for all); as well as the fuel pressure at the carburetor inlets.

To large a fuel orifice, or too much fuel pressure will raise the fuel level in the bowl, effecting the A/F ratio.

Get the center perfect FIRST, then worry about dialing in the ends. I would suggest block-off plates for the ends until you dial in the center.

Jon.

[b-man]

Originally Posted by Dick Boneske

Bart, I don't see an email from you.

I sent it to you again.

[ho421]

Great thread guys.

[Cliff R]

2GC's are no different than anything else when it comes to basic tuning. The center carburetor needs to be set up exactly for the application. If it was modified in the center cluster as mentioned for a much larger engine with pretty hefty cam in it, probably going to be and act rich on the little 326 with a smaller cam. Quite a bit of fuel is supplied by the idle system at low throttle angles and thru transition onto the main system, so jet size alone is not always the answer to correct running issues.

I'd also add here that an engine being larger or smaller doesn't dictate jet size all by itself, it's all about the characteristics of the engine in question, and how much vacuum it makes and air it moves at idle, off idle and in the "normal" driving range.

For most set-ups like the one in question here, go after idle system first, then the jets. It should be fine with 64 or even 65 main jets in it, if the idle tubes, idle bleeds, etc are sized correctly.

Also nothing has been mentioned about timing. How much timing is being added by the vacuum advance is a major player in how lean you can get by with on main jetting. If you are going to try to run smaller jets in it, it will also require quite a bit of timing advance at light throttle cruise as well.......Cliff