Seeking tri carb help

[jeffsautomobilia]

I am seeking some help with my 62 Tri-carb. I restored the car apprx. 10 years ago and have had trouble getting it to run correctly. Staring with the basics,It has 150 pound compression on all 6 cylinders. It starts right up and idles smooth but when I lift the suction piston on the front carb, it has no running effect on the engine whereas the rear carbs the engine will stumble. I can pull off the plug wires off of the front two cylinders (which have great spark) and it does not effect the running.I have checked everything for a vacuum leak, float adjustment,installed new needle and jet head. There is no restriction in the fuel supply from the float chamber to the jet head. I am running out of ideas, any help would be appreciated.

 

[GregW]

It starts right up and idles smooth...


...I can pull off the plug wires off of the front two cylinders (which have great spark) and it does not effect the running.

Are you saying the engine runs smoothly while only four plug wires are connected?

 

[Randy Forbes]

I'm in Toledo, and at one time, I had a stellar reputation for tuning dual & triple SUs.

Nowadays, I keep the three (3) Weber 45DCOEs from fighting with each other.

PM or E-mail me, if you want to set something up.

 

[terp83]

I'm in southeast Ohio, with nowhere near Randy's experience and expertise, but I have owned a '62 BT7 for the past 35 years. How does the sparking end of the #1 and #2 plugs compare to the others? I would also check to make sure that the #1 and #2 plug wires aren't reversed, even though I assume that the engine wouldn't run so smoothly if that were the problem.

Please keep us posted on the solution to this puzzle.

 

[jeffsautomobilia]

The firing order is correct and the spark plugs are new and gapped correctly. And yes it idles smooth with the front two plug wires removed.

 

[GregW]

And yes it idles smooth with the front two plug wires removed.

Well that defies logic. Is the butterfly on the front carb working?

 

[terp83]

In my earlier post, I was referring to the condition of the sparking end of the plugs (e.g. wet, gray, black) after you have run the engine. I was wondering what the plug conditions were for each plug. Just trying to determine what is going on (or not going on) in each cylinder.

Jerry

 

[jeffsautomobilia]

Yes, the butterfly is working properly, I will pull the plugs out tonight and take a look (I just replaced them last Thursday). I'll keep you all posted.

 

[Putzkes-FAHRSPASS]

How can a 6 cylinder run smooth on 4 cylinder?

 

[Johnny]

I have to ask at what RPM's does it "run smooth" with 2 plug wires removed? Might try speeding it up a bit. Although I would think you'd be able to notice a difference at any RPM.

 

[BlueRidge1]

Wow, I would think taking the front 2 cylinders out would make a huge difference. Try running the engine with all six plug wires on and then remove the back two and see if it sounds differnt than when you removed the front two. I also have a 62 tri carb, actually I just got in from taking it for a ride... felt pretty good to be out as this is the first I have driven it since Dec 2. Sorry I can't offer you any advise in tuning your carbs. Mine may need some adjusting as well as I have to pull it full choke and turn it over quite a bit before it will start running. It seems to run fairly good after warm up but I still get some poping on heavy accelertion and it sounds a little flat when I first start it up. I wish Randy lived closer so he could check it out. I guess I will take it to Von Patterson who previously owned Von's Austin Healey near Charlotte and have him dial it in for me.
I am also running a larger than stock cam and I only have the timing set by the guess method so he should be able to correct that as well.
Good Luck
Bob

 

[jeffsautomobilia]

When you pull any other spark plug wire off, the engine stumbles and nearly stalls. To answer Johnny's question, The idle (engine warm, choke off) is aprx.700 rpms.

 

[GregW]

What I would try is get the engine running. Spray a quick burst of starter fluid into the front air cleaner while giving it a little throttle. If the front cylinders start firing, you know it is a fuel starvation issue. You may need to disconnect the cross over pipes to isolate the front carb.

 

[jeffsautomobilia]

An update on tonight's progress on the big Healey. I double checked the butterfly was opening properly. I removed the piston from carb 1 and exchanged it to carb 3. The problem followed to the rear carb and cylinders. Now I can remove the plug wires from either of the rear cylinders with no effect (as it did on the front two cylinders). So the problem has to be with the suction piston. Here is a question, The only difference I could see between the two pistons is the small brass spring loaded plunger in the base of the piston does not move in the bad piston. Could this be the culprit and what is its function? Does anyone have a spare HS4 carb piston, the number is AUC2071?
Thanks to everyone for there advise.

 

[Randy Forbes]

While you're only doing this for diagnostic purposes, I would not mix up the parts between carbs; keep them with their original mates.

I cannot believe that a jet/needle would be centered when swapping parts, so therein may lie your problem...

Were the carbs rebuilt, and did they have the jets centered afterward?

Are all the jets set at approximately the same height?

Are all the needles set to the same elevation, and have the same calibration number?

Are you saying that you have (at least) two (2) different styles of needles?

The main jet and needles are definitely wear items, and should be replaced in sets, but worn ones usually lead to a rich mixture. This can be verified by looking for shiny spots on the needle. In extreme cases, the altered profile can be visible.

 

[SideShifter Tri-Carb]

I wouldn't take it t Von for carb work. He did mine in Charlotte and it was so bad, I could hardly crank it when hot. It was waaaay rich. I saw Rich Chrysler at the conclave and he tuned it and it never drove better until I put the Pertronix in.

 

[GregW]

Welcome to the Forum.
So in other words, Rich leaned it out? :laugh:

Woops! I just saw you joined 6 years ago. So I'll say now that you've broken the ice, keep postin' :thumbsup: