Locost tuning

[MustangSix]

Getting the six carbs synched is proving to be a challenge. Change one, two others move. Adjust the idle, three carbs respond. Adjust mixture, another carb goes south. I'll get there; it's gonna take time.

There is some oil seepage on the lifter side of the block. Apparently my block mods didn't extend quite far enough to catch the front and rear oil return passages. I'll have to examine that more carefully on x-flow #2. It's only slight seeping, but it'll leave a drop or two in the morning. :x

So far, no blatant overheating, but the temps do tend to get hot. I blame that on the lack of an adequate fan. We'll see what it does under load.

It is god-awful loud. The cam comes on at 1600-1800 rpm and the noise gets pretty wicked. Between the six carbs and the exhaust, you can't hear if anything bad might be happening. Not sure what it will pull under load, but it will easily rev to 6500 in neutral. 8)

 

[100_2023]

Jack

Sure wish I was there to help you tune those carbs!!! I bet it sounds awsome!!! Are you using a Uni Sync gauge or what? Just wondered about the seepage you were talking about. Do you mean the section you welded on to the block should be a little bit longer or wider? I'm sure the temps will be fine with airflow through the radiator, instead of just sitting still. You know how cool these engines really run, and how easy they are to cool. I bet you can't wait to take it for a spin!!! Thanks for sharing with us, and keep us up to date.

Darrell

 

[xctasy]

Wouldn't worry too much over the oil leaks. Hylomar (sp) can be used, even though its not recomended.

The carbs should be syncrotested.

Any one want to pitch in for six thermocouples for Jacks project engine? A few weded in unions, and then some resistance temperature bridges. It'd take all the heartache out of the operation.

That way he could tune it via exhast gas temperature like a plane mixture and six borroed multimeter. This is cutting edge stuff, with far more adjusting points than the most complicated EFI set-up.


Any diode fans here who want some free air coverage?

 

[MustangSix]

On the top of the carbs there is a small nipple to connect a vacuum gauge. There is a special tool used for cycle tuning that reads four at a time. I am using two of these gauges, so I can see each carb simultaneously.

The seepage is at the end of the added piece on the block. The oil return passage is not being completely sealed off. This is not under pressure, so it's minimal, but annoying. I think a slightly different approach will take care of that.

 

[MustangSix]

Chris came over today to help me finish off the fuel line, so now the car is running off the spitfire tank instead of a hose stuck in a Gatorade bottle.

Still a couple of tuning issues. She is running way too rich. I have turned the idle mixture screws to only 1/2 turn; better but still not right at idle. I think I will have to do a float bowl reset.

And #6 is still difficult to adjust. I can't get the idle consistent on it. It keeps closing off at idle, leading to extreme vacuum in the cylinder which suck in oil.

OTOH, it is still not overheating so the block and head mods may be working.

 

[Asa]

good to hear that the block/head mods are doing well so far

what's the longest you've had it running so far?

 

[MustangSix]

Today it ran at a fast idle for over 30 minutes while I tried synching the carbs again. It is getting up to operating temps and holding, no coolant leaks or steam.

 

[Anonymous]

Jack, do you have a carb syncronizer? I do if ya need to borrow it...

 

[MustangSix]

thanks, Stan. I have two cycle synchronizers.

It's the arcane way that Mikuni linked them all together that is giving me fits. It's all springs and screws with no positive stops on each idle setting. Change one, it affects others. I'm going to try redesigning them.

 

[rbohm]

8) it seems you have given us another viable head option for the US six.

 

[MustangSix]

8) it seems you have given us another viable head option for the US six.

Only if you want to fabricate an intake manifold. The distributor clearance issue is still there. I have enough room (barely) to fit the #1 intake runner, but cannot remove the distributor cap without removing the carbs and manifold. While the electronic ignition should not need attention for a long time, maintenance is an issue.

OTOH, this engine revs like nothing else I have ever built based on a 200.

 

[rbohm]

8) that is true on the 200, but a 250, like i have, should have plenty of clearance.

 

[MustangSix]

Forgot the 250. That would work. CR will be an issue with the samll chambers, but you could open those up.

The last 250 I built, I used 255 pistons. I now think the better option is 2.5 HSC rods with stock pistons. Deck to zero and open the chambers to whatever is needed.

 

[Asa]

a fuel injection head type intake should work, yes? bend the tubes where you need them to clear the dizzy