302 V-8 running improvements

[gbritnell]

Hi Gents, I have an update on the 302 engine.
Prior to the last video I had redesigned the distributor thinking I had a great idea to operate the points. It worked but very intermittently. I then went modern and replaced everything with a Hall trigger. The magnet is on a stationary post and the timer is similar to full sized automotive practice, it has windows around the perimeter of a drum. I have been playing with it and I think this is going to be the answer. It turns out that all the carb problems were actually ignition problems as you can see by the video. I want to remake the carb to look more like the full sized version but I won't have time before the NAMES show so I'll have to bring it like it is. For anyone considering using a hall trigger, go for it. This seems to be working great.
George
[ame]http://www.youtube.com/watch?v=O_vQp0gevh0[/ame]

 

[arnoldb]

George, that hall trigger does work great; Wonderful sound track ;D

Kind regards, Arnold

 

[Noitoen]

Nice engine . You could build a "make believe" carb around the one you have. With a scale air filter it would hide the working one and look good ;D

 

[stevehuckss396]

Awesome G!

I love the sound of a mini V8!

 

[kustomkb]

Looks and sounds awesome.

Very nice!

 

[Stan]

I think most members on this board would agree with me that we stand in awe of your ability. Congratulations on a job well done. Stan

 

[slick95]

George,

I keep watching the video over and over...Super Sweet Sound

Jeff

 

[putputman]

Looking forward to seeing your engines a NAMES.

I don't quite understand your distributor. The magnet is stationary and the Hall effect rotates? Maybe you can explain it to me at the show.

 

[gbritnell]

Hi Arv,
The magnet is stationery inside the distributor. It's mounted on a small angle plate so that it faces horizontally. The magnet is .125 diameter and .062 thick. To mount the Hall transistor first I cut a window in the side of the distributor body, then I made an aluminum mount to hold the Hall transistor and epoxied it in place. I calculated the depth when I made the mount so the Hall transistor would be flush with the inside diameter of the distributor body. My triggering device is like an upside down pot, for want of a better description, and in the side wall are cut eight little windows. The OD of the 'pot' has about .006 clearance to the inside of the distributor body. It's mounted to the distributor shaft by a 2-56 set screw so I can adjust the timing. It also has 2 pie shaped windows in the top so I can adjust the position of the magnet as close to the inside of the 'pot' as possible without touching it. The wall thickness of the 'pot' is .030 so this gives me about .006+.030+.011=.047 distance between the Hall and the magnet. I have found by experimentation that these powerful little magnets will work up to about .07 away from the Hall transistor. I'm fairly familiar with electricity and how it works but it still amazes me that this thing will switch on and off so many times per second. I took the engine over to my buddies place this morning to run it for him and we put a tach on it. I can get the idle down to about 6-700 rpm and it looks like it will go to a little above 7000 on the high end, so if you figure 7000 rpm divided by 2 (cam speed) gives 3500 rpm. Multiply this times 8 triggers per revolution and you get 28,000 cycles per minute divided by 60 and you get 466 per second. Amazing!! In the future I won't build anything with mechanical points again.
When you get to NAMES I'll open it up and show you what I have.
George

 

[MakMov]

That is a cool little engine I always liked SBF, but that sure does seem like an awfull lot of timing advance.

 

[Noitoen]

I'm planning to construct a CDI double coil 4 cyl for my little Samurai Jeep and my hall device is like those slit opto sensors, only instead of a led it has a magnet. When a metal vane goes through the slit, it detects.

 

[cidrontmg]

"all the carb problems were actually ignition problems"
heh, another confirmation to the old saw: "Most carburetor problems are electric"... ;D