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Kawboy wrote: LEDKZ1300 understands how to set up carbs !! Nice !! Great explanation Bud.

Thanks man. A lot of credit goes to what I've learned from other members here plus lots of reading up on Mikuni CV carbs... then lots of practice fiddling on my end. I went through every type of adjustment possible trying to get my carbs set correctly... then tearing them down and rebuilding them... then fiddling some more. I went through just about every carb problem possible on this beast. A few months ago barely understood how one worked and had never taken one apart or adjusted one. This weekend I'm rebulding the holley carb on my old dodge van.

I don't know everything there is to know to be sure but I'm better off than I was. Still learning every day.

RickG:

We used to have 93 octane but alas, no more. Our regular is 87, premium is 89, super is 91. Still too damned low and my old van has a spark knock with the 91 hence why I'm stripping and rebuilding that carb before I start buying octane boost or mixing race fuel in. I've already fiddled with the timing as far as I can. The only plus is the 91 is ethanol free.... in theory. I say in theory because a few years ago the refinery had trouble and there was no 89 or 91 available for months... but for a few weeks they neglected to tell us and sold us regular priced as super so who really knows at the pump? Irving are crooks and supply all the fuel in our area regardless of brand. They supposedly have different mixtures for each brand but I think that is a load of crap.

You guys use the RON method in Australia. We use the AKI system which is an average between the RON and MON method which results in a number 4-6 octane numbers below RON for the same fuel. We still don't have 93 which would likely correspond to your 98.

LEDKZ1300- I was a Chrysler Dodge mechanic between 1973-1980 and every engine we had from the 318's to the 440's all needed valve seal replacement at 60,000 miles. If you didn't change them the intake seals passing would allow the engine oil in to the combustion chamber and burn leaving high carbon deposits on the piston top, combustion chamber and exhaust ports. the more build up the more pinging (engine knock) Chrysler used to put out an aerosol can of "combustion chamber cleaner" for cleaning out the carbon deposits. If you cleaned out the carbon you can get back to the regular 87 ron fuel.

Kawboy wrote: LEDKZ1300- I was a Chrysler Dodge mechanic between 1973-1980 and every engine we had from the 318's to the 440's all needed valve seal replacement at 60,000 miles. If you didn't change them the intake seals passing would allow the engine oil in to the combustion chamber and burn leaving high carbon deposits on the piston top, combustion chamber and exhaust ports. the more build up the more pinging (engine knock) Chrysler used to put out an aerosol can of "combustion chamber cleaner" for cleaning out the carbon deposits. If you cleaned out the carbon you can get back to the regular 87 ron fuel.

Thanks Kawboy! Great info.

I will track down some combustion chamber cleaner and give it a whirl.

A photo of one valve seat after I did a quick clean off of the carbon crap. They all pretty look much like this.

Yaegunp wrote: A photo of one valve seat after I did a quick clean off of the carbon crap. They all pretty look much like this.

Time for a "valve job" Bro. I can see carbon impregnations in the valve seats and the contact area ( the shiny part in the middle) is too wide. When the contact area is too wide, the sealing pressure is marginal and that's when you end up with the carbon impregnations. I suspect that if you look at the valve faces, they'll be cupped. Hopefully, there's enough material on the valves to reface the seats. The head won't be a problem.

For the record- because the valve seats are too wide, you can't just use valve grinding compound and clean up the seats. It's beyond that.

Anyway, you've gone this far. Get the valves and valve seats cut and carry on with your rebuild. It's all good. You'll get a lot of joy out of your rebuild after it's all done.

As Kawboy has said the head needs a complete resto. The valve guides in the exhaust port is a bit frazzled.
You probably wont find a used head in any better condition so just bite the bullet and get it done it will be worth the cost.