do i need a mag?
 

BBC427, methanol injected, nat asp. 1/4 mile drag,

do i need a magneto? :wink:

Nope you need a MSD unit with, anything from a 6AL to a 7AL3 box. More fire power and less HP drain than a Mag.

JMO

Zip.

do you run methanol and a MSD unit? which box? no problems?

I run a 7AL2 with a pro power coil on a 15:1 alky injected 434. On a couple of occasions it has fired a 15% tip of the can without issues.

what sparkplugs? how much gap?

With my 582 and alky injection, I ran a 6al, 7al2,7al3 and 7530t digital. No difference in et with any and they all did just fine.

thanks David....thats the kind of info i was looking for! gonna get my box checked out...

NGK 8's set @ .024 gap, with a 6AL, same setting with 7AL2. I've never ran a 7AL3, so i don't know the difference.

Zip.

I run an autolite AR3934 @ .030

AR3910s gapped at 30, Extended tip plugs, A lot of engines miss without them.

why is that they miss without the extended tip plugs?

Because the non ext-tip doesnt burn as well with alky causing a slight miss.

wonder if the 3910's plugs would fit my engine? steel 990's with big dome piston to get some compression. present plugs are autolite 145's, have gapped them from .018" to .035" without success. big difference in reach between the two plugs.. :?:

I also run Autolite 3923 in my small blk. they are exteded tip, don't know if they will work with a b/blk, i have to index them with my 14 to 1 pistons, just a suggestion.

Zip.

thanks for the tip, Zip! i have some leads to follow up on...won't get out again this year. it's a long off season up North :wink:

Also a decent ext tip plug, last sunday a guy at the tracks with 565 18 degree big duke engine had a slight miss they'd been looking for. I looked it over for them, and tested a few things but I kept going back to the 3923 although a ext tip, still do have a miss issue in certain combos do to the difference in the stap on the plugs. I found a set of plugs, replaced them and he went on to 2 finals that day, miss free. Although big dukes are a different animal, I feel the strap on the 3923 can cause a issue vs the 3910, on certain combos. If I get some time, I'll shot a few pics to show the difference.

I'd index them and roll the engine over by hand and see if they hit, if not id give them a try.

thanks David, pics would be great!

the standard plug reach is .460" and is flush with the chamber. do i need to get the tip into the combustion chamber as far as possible? change up to .750" reach and extended tip if it will fit?

which way do i index the ground strap? did that many many years ago with a small block dodge, made no difference in that instance.

Wooh !!, you can't use a .750 reach plug if you are inside the chamber @ .460, but you can still use and extended tip plug, but a short reach. This now becomes a whole new ball game. I don't personally have any heads that use the short reach heads, so i'll leave it to someone who does.

Zip.

I also do not have a head that uses a short reach, mine are all good with the ext tip. Like zip said you can not use the long reach plug, but will need a ext tip, and at that point my knowledge runs out with the plugs as I do not know which plug to suggest.

OK, just the extended tip if they will fit?

For anyone that's never used a plug that must be indexed so the piston does not hit it,be sure the motor is not at tdc,90,180,or 270 degrees befor you put them in or take them out.The strap might hit the pistons that are at the top when you turn the plug.Bill.

?
 

Bill,
THAT is EXCELLANT INFO!Because Screwing the Plug in,if the Piston is in the Wrong Area,could Cause a Severe GAP LOSS!
Also Wanted to Say the Max is Getting CONFUSED w/Extended Tip,and Reach.

Later
G 8)

Re: ?
 

X3! excellent info! have never tried anything other than the standard plug so i have no idea how much room i have.

reach= length from tapered seat to base of threads

extended tip= ground strap and center electrode protrude into chamber further from base of threads

MSD called, 7al2 box is 100% :o

update,

5 rounds Sat, i am King :lol:

According to all that I've read and practiced, all plugs should be indexed to the particular combustion chamber. Not just for piston to electrode strap clearance but to provide best ignition and create a positive flame front for maximum expansion of the fuel/air compound when it ignites . . And each Combustion Chamber is a little different, so to speak.

It's basically the physics of the internal combustion engine and what works best. Higher compressions create problems with ignition, and when we use higher octane (less volatile) fuels, getting the fire started in the right place is what it's all about . .

You must start your plug search with the head on a bench. You can't discern much (except by hit and miss) if you're trying to figure out where the electrode is in the combustion chamber while it's on the engine . . Once you know the reach, and the direction of firing, then you put the head on and start looking at clearances in actual conditions and head gasket dimensions . .

According to most builders and tuners, a plug needs one thread into the combustion chamber. Any more (or less) than that and you're beating a dead horse. Then you must find a plug with the proper electrode reach. Far enough into the chamber to ignite the fresh charge from squish to open . . but not far enough to kill a piston or the plug . .

To some of you, this isn't anything new, to others, helpful I hope . .

New plug technology being used by NASCAR (for the most part, as far as I know) is a plug that's flush with the combustion chamber, with a fixed gap electrode. Instead of a strap they have a "disc" with a hole in it that the positive electrode comes through and is flush with the ground "disc" . . All the Gen II, III, and IV GM engines use them and when they switched over to Ethanol it didn't seem to necessitate a plug design change . . A friend of mine has a Gen II in his Bonneville car and I've tried to get the plugs he uses in it for our big block, but so far . . no luck . . And Champion (the manufacturer) doesn't even list them in their exotic racing plug catalog . . Knowing someone at Childress might be helpful, heh, heh . .

-my mistake, listening to an internet keyboard cowboy! (located in Oregon)

-fuel system was not plumbed correctly

-got hooked up with someone that actually KNOWS what they are talking about

-now runs to the hundredth...

-talk to Casey Smith at GoodVibrations :wink: