Need advice on my predator212 hemi build.

[Motoman]

And the keyway on the predator engine was in the same location as the Coleman's flywheel

 

[Motoman]

So this took me allot longer to figure out than I like to admit. the reason my predator212 build wouldn't rev out past 4500 rpm was due to the air filter I had installed on the mikuni.

After switching back to the deformed filter that came with the mikuni kit It finally revved out nice and smooth all the way up to 7000-7500 rpm. Attached are some photos of the filter boot I had issues with (left) and boot that the mikuni came with (right) along with the pictures of the ports on the carb the problem boot was covering up.

So glad I dont have to buy my customer a new tillotson motor wich I was about to do because I was tired of telling my customer I cant figure out what's going on with it.

 

[Motoman]

I also did plug readings all the way through the assortment of jets that I had with me. The largest being a 134. I still have to read the plug from that test pass but the 130 jet was reading lean from wot plug read so I put the 134 jet the largest I had with me in and it felt strong. I need to wait for another test day when I can take it back to the parking lot and finish tuneing it.

I'm just happy that I can finally move forward with this build and deliver it to my customer.

 

[Motoman]

Thank you all for the help.

 

[Kentucky Boy]

I would watch your fuel system if you are using a fuel pump with the stock tank. I dont think you would actually need it with the stock tank. I’ve never had a problem relying on gravity feed with the stock tank and a Mikuni. It may flood out your motor, especially if you don’t have a return line going back into the tank.

 

[Motoman]

sorry i have been away on vacation and have recently gotten back.

@ Kentucky boy the way the fuel line has to run to attach to the mikuni carb it sits at about half way up the tank which once the fuel reaches that level it wont be able to gravity feed anymore.
I haven't had any issues with the pump overpowering the needle and seat and all seems to be OK with the pump set up

Update on the build
Today I ran it until I ran out of daylight, I was able to tune all the way up to a 142 main jet and the plug looks like this (will upload photo on next post) what is everyone's opinion on the plug reading?
My professional opinion is that the motor is still asking for more fuel (plug reading is lean) if i am not mistaking let me know what you guys think.

 

[Motoman]

Here are the photos of about 10-15 min running back and forth at wot with a 142 main jet

Let me know what you guys think should I keep adding more fuel?

 

[Kentucky Boy]

Lean for sure. Are you doing a proper plug chop? Hit the kill switch while at WOT then check the plug.

 

[Motoman]

yes I am doing a proper plug chop killing ignition at wot

 

[KartFab]

for what its worth, you cant read plugs like you used to back in the day when leaded gas was a thing. Ive seen plugs like that come out of the predator 212 engines after dyno break in at WOT. Granted, with stock engines, but "lean" might be okay.

I have also done some dyno time and that tan/brownish color (didnt look rich at all from what i could tell) was present at 11.3:1 AFR, which is too rich.

This is part of the reason why i bought an AFR meter, was like $160 but worth it IMO because I cant read plugs worth a darn.

 

[65ShelbyClone]

I'm glad you said all that because it saved me having to.

Your observation of the relationship between plug color and AFR just illustrates that the old color-vs-mixture charts are useless in this age of unleaded and oxygenated gasoline(it's not you; it's the fuel). I've been there and done that too. It's aggravating to do plug readings and the plug looks lean enough to melt a piston, yet the mixture is so rich that you can feel it's down on power. Then after running it like that for a while, the plug doesn't turn brown, it turns gray. That's not on the charts, so now what?

What is this plug saying?

How about this one?

About the only thing a new plug can tell you is whether or not the heat range, timing, compression, and octane are playing well together like the one above. This is where I'll point out that

10-15 min running back and forth

was way too long and erased those results.

 

[Motoman]

So with the new plug how long should I run it to have it tell me all of that? I've basically been going up on jet size either waiting for it to become excessively rich and start stumbling at wot so I can then go down a jet or 2 to get the tune as close as possible without being to lean. Im also looking at rpm to see where it tops out at each wot pass.Each time I've gone up a size in jet it seems to like it at wot so I keep going up.

What I'm looking at while reading a plug is after about 10-15 min of run time I'm looking for a clean tan color to appear on the porcelain, I'm basically looking for a slight color change indicating to me that it's on the slightly richer side of things than the leaner side of things.

I know needle clip position helps between 1/2-3/4 throttle but I think on my next test runs I'm going to jump the needle up a notch (raise the needle) and see what happens

Now my next question is what engine temps and exhaust temps should you see at max on thease engine. Basically can you tune by temps?

 

[KartFab]

If you don’t have a dyno or AFR meter, then just do an acceleration test at WOT. Whatever gives you the best acceleration will be the best jet.

If you are wanting to look at exhaust temps, getting a wideband AFR costs the same as an EGT meter, doesn’t it? You can tune by temps (hottest EGT wins?) but ever since wideband came out, EGT is seen as more of and old school method.