Mark Maras

Looking at the cut end at the bottom of the springs and the rust on the lower half, I'd guess there was a acetylene torch involved.

Well, it would appear we're back to the rear carb. How many turns down are the mixture screws on both carbs?

I agree with Cliff. It seems to be a rear carb mixture problem of some sort. How many turns down are the nozzle screws? However, that doesn't explain #5 and #6 looking like #4. As I recall, #4 alone was the problem child. @jalexquijano What was the outcome of changing the valve seals? Was one of the seals on #4 damaged and did you change them all or just #4?

The problem I've experienced with flux core and repeated small welds is the flux left on the finished weld. When it cools it prevents instant conductivity to start the arc when doing small welds. If it doesn't arc instantly you're left with a longer wire which will act like you've turned down your welder. You'll have success if you clean each weld before attaching another weld to it. I usually try for very small gaps and I run it a bit hotter (instant arc) than I would for a continuous weld. I would also suggest the smallest wire you can find and an auto darkening hood (for precision).

I prefer flux-core for welding rusty, crusty or plated thicker steel. This paper thin sheet metal, if properly cleaned and has minimal gaps is best welded with a MIG using Argon or a Argon-CO2 mix if TIG is not an option.

.035 is the measurement that I always used. Good luck on the floats. Just for clarification, the float level doesn't have to be exact, just close. If you want it exact, the fuel level should be 3/8" below the carb bridge. That's 9 5/8 nozzle screw turns down from the top.

It may be time for a new set of BP6ESs too. I've experienced a high RPM stumble that was cured by new plugs.

Check the float levels. you may find that elusive 5%.

I don't recall any talk of adjusting the float levels (the primary mixture adjustment). The easy way to check them is remove the domes and pistons, raise the mixture screws to the top, then lower them 9 1/2 - 10 turns down from the uppermost position. The fuel level should be close to the jet height at 9 1/2 - 10 turns down. Then raise the jets back up to 2 1/2 - 3 turns down from the top. How many turns down are your mixture screws now?

I've set them cold and hot. Both methods worked for me.

That brings back the memories of my first car, a 64 Catalina land yacht.

Early to bed and early to rise, your girl goes out with other guys.

#4 looks to be a radio bracket.

Sputtering at 3500 rpms while climbing a hill sounds like fuel starvation to me. Especially if it will rev to high rpms in neutral (no load). Fuel filters, float levels, carb balance, fuel pressure, and fuel volume, are where I'd start looking.

@jalexquijano take a look at the video above.

Welcome. We'd love to see some pics.

It's possible that Columbia Rubber Mills in Clackamas, Or (just south of Portland) could refurbish the bushings. I've not inquired about that type of bushing but over the years I've used them on other projects with great success.

Both are excellent suggestions. As I recall he has a reasonably new set of NGK wires and we tried swapping two wires. He eventually bought a Bosch cap and rotor and verified a hot spark. I hadn't thought of a helicoil.

My first one required a pipe wrench and a jack. Much like Cliff, I recall a bit of vehicle lift before it loosened.

We narrowed an ignition problem down to cap, rotor, wire and their connections because it affected one cylinder. I thought we had ruled those out in the beginning. Thoughts?

I expected that answer from C.D. No crystal ball needed. C.D. is a likely person to point a finger at but the question is ,where do we go from here? He's not going to offer any help. If it were mine (I wish), I'd either pay someone with a good borescope to take a look in all the cylinders or buy a good borescope and take a look myself. The cost of either option may be similar, IMO. Looking down the road, I'd also be keeping my eyes open for a used engine.

I shudder at what I'm about to theorize and I hope I'm wrong. I'd like to hear everyone's opinion on this theory and if there's a method of confirming it or hopefully blowing it out of the water (borescope?). So far, we've crossed off ignition problems, valve seal has been renewed, several compression tests have always been within specs or explainable if they weren't (throttle closed), carbs are tuned, valves have been set, I'm now down to asking myself what could foul #4 plug and I'm left with a broken oil ring in #4, If the top ring compression ring is good, that could explain no compression loss. What do y'all think?

@jalexquijano Give us the details of the compression test. Throttle open or closed? Oil or no oil in the cylinders? I'm pleased and bewildered that the compression is that even. I too expected something closer to 160 psi and #4 lower than the rest. If the throttle was closed during the test, I'd like to see the #s again with the throttle wide open.

I can't be the only one here who has never used a torque wrench on lug nuts.

@jalexquijano Do you have access to a borescope? It would be interesting to look at the cylinder walls of #4 as well as a wet, dry compression test before you consider pulling the head.