top fuel distributors

[karll]

why do top fuel dragsters have two distributors on them. they're only 8 cylinders right? and each distributor covers 8 cylinders, so why have two distributors covering 16 cylinders? does each cylinder have two spark plugs or somethin? is the second one a backup? just curious, this has always puzzled me.

[500]

Each cyl has two sparkplugs.

[karll]

are both plugs firing, or is one just a back up for the other.

[500]

Both are firing. There is so much fuel going through a fuel motor that it is hard to keep the fire lit with only one plug. Also if there was only one plug it would be offset to the back or front of the bore depending on which side of the motor . This means that the flame front is uneven and more advance would be required to burn the fuel all the way over by the opposite cyl wall.. By having 2 plugs the burn pattern is much better, more of the fuel is burned and less advance is required.

[karll]

ahh, it all makes sense now. thanks 500, i appreciate it.

[Erik412]

Since there are two distributors, do they both have their own location in the block or is there a special gear box that runs both at the same time?

Thanks
Erik

[karll]

from what i have seen they are mounted on the front left section of the block. i think there is a special gear system running them, because they are at an angle. you can see 'em in this pic to the left of the driver's head. two read cylindrical things. i dont really know any of this for sure, but it makes sense to me. lol.

[Erik412]

Originally Posted by karll

i think there is a special gear system running them, because they are at an angle.

During the race this weekend at Bristol, they showed a closeup of the distributors and they are run through a gear box that sits above the block. I also noticed that they are all made by MSD Ignition. I checked their website to see what they were like, but they didn't have any listed.

Erik

[500]

The 426 Hemi's { and all big block Mopars } have the distributor mounted at an angle on the rt front of the block. The oil pump is external at the lower left front of the block. Do a www search on street hemi to find out more. Mopar Performance may have a site with pics.

[victimizati0n]

They arent distributers, they are megnetos.

Thats why there is no battery, or alternator on top fuel cars.

And they run hemis, so that is why they are up front, and on a slant like that.

The main reason for having 2 plugs per cylinder, is because if you only had 1, and the cylinder fills up with fuel, the plug isnt gonna fire, but with 2, there is double the chance.

[karll]

so its a magneto like on a tiller or somethin to that effect? if its a magneto on a 502 shouldn't it be big and shit? or are they small? are the red things the magnetos? do i have any idea what im talkin about? no. what does the fact that its a hemi have to do with the fact that they're mounted on a slant? yea, i dont know shit.

[500]

http://www.msdpromag.com/

http://www.allpar.com/mopar/hemi/hemi.html

There is a world of information available in that little search box on your homepage.

[victimizati0n]

Originally Posted by karll

so its a magneto like on a tiller or somethin to that effect? if its a magneto on a 502 shouldn't it be big and shit? or are they small? are the red things the magnetos? do i have any idea what im talkin about? no. what does the fact that its a hemi have to do with the fact that they're mounted on a slant? yea, i dont know shit.

Yes, that is exactly what it is like. Top fuel run 500 CI engines if im not mistaken. The red part is the distrib. cap, and the magneto is all under it.

[86MonteSS]

Top Fuel have 490 to 510 ci......they would put 8 mags on the on the motor if the rules would let them. At least thats what i read in an nhra drag racing book

[victimizati0n]

putting 8 magnetos on an engine wolnt do anything, ecept put more weight on it.

How do you expect them to put 8 spark plugs in each cylinder?