440 MW clone tuning/plug read

[khryslerkid]

This sounds so familiar with my setup for the exception that I'm running two 600's "inline".

A good carb tuner will tell you that the timing is more critical to get things right before tuning the carbs.

Your plug straps showing too much timing might make you double check again. Using the ported is what you want with a good vacuum cam. Mine didnt like manifold at all. Straps were showing too much timing so I double checked what the vacuum advance was doing when hooked up and at 2000 rpm and it was off the chart (past 60*). I had to limit the vacuum advance can to get it on the scale at 55*. That's where the low timing mark on the strap was coming from.

I'm using a Mallory dual point and a dwell meter is a must. 32* to 35*. I had to limit the points plate also because the factory setting was way too much. The springs will have a bearing on how fast your "all in" will take place too.

Now that I have my timing all worked out I went back to the carbs. I tried fattening up the rear carb because using a progressive setup, the front cylinders were way lean. Front cylinder exhaust temps were 700* compared to 600* on the other cylinders. (Useing a temp gun can show you what's going on)

I ended up going to "one to one" on the carb linkage and installing the factory rods. Using a vacuum gauge on manifold, turn each idle screw in, one at a time until you get a drop in vacuum and or rpm. Then back it out to get the highest reading. You could leave it there or turn it back in 1/4 turn. (I left mine at the highest vacuum/rpm.)
Each idle screw was responsive on both carbs and ended up in the same position when all done. Plugs are all reading good now and the engine is running great. This weekend I was getting 12 mpg.

 

[miller]

Here's a photo of my #1 plug, after 100 mile run. After a little research, am I looking at too little timing?? Or something else?

On the strap, directly over the center electrode, a 'clean' area, that's at the bottom and one side of the strap.

I've read many guys seem to set initial about 20 degrees...wondering if I'll need to try different timing. After first start, engine fires off, just touching the key. No missing, no pinging, no hesitation period, and great throttle response. Sure, understand doesn't mean that much...if somethings are off.

Sorry on the poor pics...camera is old, like me!

 

[Ski 61701]

How quick do they pop up when you rev the engine? Should be instantaneous pop up. If not might have to go to a slightly heavier spring, do you have the orange coloured spring in the carbs now? Those seem to be the most used. I have them in my carbs and they hold rods down but as soon as you blip the throttle the rods pop up.

 

[Ski 61701]

Went to the website that offers the carb hats/sync tool, and read the instruction sheet. Said it was to enable getting a balanced lower idle speed...that's it? Already have mine at 750 RPM idle. Or, am I missing something. Yes, understand the balanced vacuum value.

Have the idle speed screws adjusted both the same, and mated with the linkage, so they open exactly the same.

It's the mixture settings, I'm looking at. Not sure why I'm not getting much action with a vacuum gauge, though not wanting to get too wild with my screw turning. Too lean would be a bad deal.
While I'm at it, going to do a vacuum leak check, just to be sure. And some reading in the manual...might have to look a jets.

Originally tried setting mixture with a tach, but didn't get much change there...that's why I just used a basic 1 1/2 adjustment on the mixtures. Proved too rich.

Tinker, tinker...still liking the way it runs!!

Even though you have carbs adjusted the same they could be "off" a tad due to differences in compression of cylinders, valve adjustment and basic manifold design. You are probably really close, i know when I made my sync carb hat the float was off thus requiring me to adjust one carb more than the other. Like others have mentioned get timing set my motor likes about 18 initial and 32 all in by 2800rpm but again all motors are a tad different , cam, compression, carbs etc. Another thing to look out for is porosity of intake manifold itself. Kinda late now for you, but I had a couple of oem intakes stage 2 and 3 where I made block off plates for carbs and intake opening and pressurized intake to about 20 psi and I sprayed soapy water and sure enough I had pin hole leaks in metal underneath and on top. I used gylptal paint to seal underneath and primed and painted top side. Repressurized and no more leaks. Just trying to ensure tunability without chasing my tail anymore than is necessary.

 

[oldbee]

It’s only 100miles, but a little lean to me. 1/4 turn out on mix screws?

 

[miller]

It’s only 100miles, but a little lean to me.

A little lean? Yeah, oldbee, it was a 1/4 turn 'in' I did, to kill the over-rich I had. I'll keep a close eye on it, maybe back out 1/8 turn. My fault, waiting to 500 miles to check things...but, between the over-heating radiator thing, no soot until 400 miles, and the engine actually running pretty strong...well, you get the idea.

 

[miller]

Even though you have carbs adjusted the same they could be "off" a tad due to differences in compression of cylinders, valve adjustment and basic manifold design.

Yes, sir, have considered, and understand the possibilities of what your saying. Looks like an old dog, can learn new tricks! Between dual fours, and the crossram, it's all pretty new stuff for me. (Having a blast tinkering!)

For the manifold, I wound up making gaskets for it, adding stainless block off plates at the crossovers. Acts like their holding up good. Cam not that much, a bump more than a magnum, good idle.

Like others have mentioned get timing set my motor likes about 18 initial and 32 all in by 2800rpm but again all motors are a tad different , cam, compression, carbs etc.

Just going by my old school ways, the plug reading tells the true results. Times have changed! Could very easily be flat wrong, though, my motor 'seems' to like the timing I have. I need more plug reading, to decide which way is needed.
I will have to play with it though, it looks like, because of the signs I'm getting in the plugs. The exhaust soot wasn't helping. Guessing a slow build-up, through the miles...it is clearing up, now.
I'll have to check which springs I have, and how they do with more throttle, as you mentioned. Dang, all this reminds me of my old super-tuning days!

Thanks a bunch, for all the leads!!

 

[coloradodave]

Here's a post I made about 4 years ago on how to make your own carburetor synching tool:
https://www.forbbodiesonly.com/mopa...etor-synchronizer-cheap.75710/#post-910102411

 

[miller]

Thank you, Dave!

 

[miller]

Had to straighten my act up, and get #s right...said carbs are 1405s.
Jets - mains .100, sec .095
Rods - 070 x 047
Springs - pink 5"Hg

How many miles on a set of plugs, with this gas, before I can get a decent read? Any thoughts?

Back to the books, looking at timing, and the newish plug reads.
Besides the manifold w/dual fours, and the Crower 32241 cam, engine is fairly stock. So, nothing too wild.

 

[miller]

Well, well, well...what's that old saying...'if it ain't broke, don't fix it!'

I tried, re-setting the initial timing, using the vacuum gauge. Found the high mark, backed it off 2"Hg, timing around 20. Remember, original initial I had at 14 degrees. Went for a drive...engine running a little hotter, got to a good straightaway, and hit it. All I heard was a line of high pitched pings, until I backed off, fairly soon. Real disappointing. Pull wasn't as good, either.

At 14 initial, when I hammer it, all I get is the sound of air getting into those eight wide-open barrels. For now, once it cools down, I'll go back to 14 degrees, and NOT worry where the dang markings are at, on the plug straps.

No truer words, every engine is different. Tinker, tinker...