5.9 magnum flywheel

Where in heck can i find an external bal flywheel for
a magnum engine..??

stock 143 tooth - Rockauto

130 tooth - mancini

I've got one you can have for $5 plus the ride.

So i have a 1978 casting 360
I thought it was a magnum because of the vertical
intake bolts - i guess it was in between LA and Magnum
But Im thinking it is externally balanced - which means you
need ext bal flexplate , too . If goin automatic
Im just running it on a test stand to see if she is junk or not .
Im bummed its not a real magnum . But oh well .
Next issue - will available flywheels fit my BH .

Was gonna use it to test carbs , distributors , etc . And make
noise in shop in winter .

If I can get a six pack intake that bolts up - would be great
Didn t realize heads needed re drilled

Oh well jbc if thats the flywheel I need thats weighted -
Itd be worth it - otherwise its just junk cast iron .
Thanks, Andy

A cheap modman intake on needed list too . Lol

Don't think those are 78 360 heads either.

I see no air injection ports below the exhaust ports. You might have a 78 360 short block with magnum heads. If it has stud mount rockers that's a clue.

I do not think you can see anything port wise with the gasket in place. As far as magnum goes the valve covers should be 8 bolt as far as I know.

I just remembered something on the valve covers that the LA style will bolt on a magnum head. With the intake bolts being vertical one would have to think they are magnum. Pulling a valve cover will tell the story.

All interesting !
Thanks for input .
I have a hodge podge.! I wonder whats inside !

10 bolt valve covers and the heads with air injection have an extra boss below the exhaust port that is noticeable, it is not there on the OP's heads.

Here's a pic of me cleaning out that air injection port on a 79 360

I realize that but I believe his picture has the gasket covering them up.

Im gonna pull the gasket and see whats up
Was wondering why they were weird shaped ..

Figures the valve covers are glued on and I didn’t wanna mess with them
But - I didn’t see any air smog holes on the head

Rockers are definitely studded d on

Not sure on the exhaust air injection holes but studs on the rockers and vertical intake bolts along with the magnum style head bolts lean towards magnum. Like I said the earlier 5 bolt cover can bolt on a magnum with the 8 hole gasket. It could be glued ti insure it does not leak. Looking at those exhaust ports has me thinking the magnum did not have the injection holes. Also that head had many other identifiable casting features that tell me it is not a pre 92 casting.

If the engine is external balance there is a old TSB or factory bulletin that shows taking a internal balance 318 flywheel and drilling it to make it balance correctly. The bulletin showed a templet and instructions on how to exactly do it. Not knowing whats inside you might pull the pan and see what casting numbers are on the crank. What balancer does it have?

No they do not. The exhaust manifold gasket is substantially different if you have air injection ports. All that machined surface you see where I am drilling is covered by exhaust manifold gasket and there's be a big hole around the air injection port. A non-air injection gasket would not even cover where the holes are.

There is no "lean". The Magnum head is the only factory head for the small block that has stud mounted rockers. Period.

Vertical intake bolts can be added to an LA head if someone had a reason to run a Magnum intake on one. A simple matter of drill and threading holes. So stud mounted rockers are the visual indicator here, the casting number will be a double check.

As far as getting a flywheel, your problems have just begun, lol. You may, or may not, have and LA rotating assembly, or a Magnum one. We already know someone put a Magnum top end on, it's not out of the realm of possibility that it also has a Magnum rotating assembly, which means different flywheel balance. Heck, I guess it could be internally balanced as well.

Casting numbers on the crank and rods will tell you your answer on LA or Magnum, added balance material in the crank will answer the internally balanced or not question. LA rods have a wider small end that will not fit in a Magnum piston without machine work.

I agree they are magnum. It was his first picture not being real clear that you could not see if there were holes. All other evidence said they were magnum. I have seen other gaskets that can cover the hole. Here is an example. Will they cover completely I do not know or care just an example. We should be more interested as to what he can do for a flywheel.

What size flywheel are you looking for? How many teeth? RockAuto has 143 tooth flywheels for pickups with 360 Magnum and LA for about $100. If you need a smaller one, you could have a 318 flywheel drilled according to the M.P. engine book. The info should be available online. I had a flywheel done for an LA 360 25 years ago, cost me $65.00 back then. I would guess it's $100 - $125 to do that today.

130 tooth to use my BH
Balancer looks balanced to me ..

That is a 360 external balance damper.

If all you want to do is start it to see how it sounds you can use the 318 flywheel. It will have a vibration however just to run it to see what it sounds like it will not hurt anything.

Found One on Facebook
Cant believe it popped up out of thin Air

By looking at the guys profile he goes fast so it probably is in balance.

The magnum balancer is about 1/4" or so thinner than the LA. The hub itself is still in the same plane as the LA however so the pulleys would all line up if you swapped the timing cover/ water pump/serpentine drive and all. Magnum heads have 10 bolt valve covers but the LA covers will bolt on them. I have LA covers on my magnum heads as well as all the front drive system on my LA block. The magnum flywheel would have 8 notches on the back side for the crank sensor to read, the LA flywheel does not. Magnum heads also use the 5/8 hex spark plugs where the LA uses 13/16 hex. Also the bolt bosses at the ends of the heads are not the same so you may need to fabricate a little if you want to run all the LA accessories with the magnum heads. Putting the magnum accessory drive system on an LA headed engine is not feasable.

The down and dirty way to make a 318 crank work on a 360, is to tack weld the balance weight off of a 360 torque converter onto the flywheel. Run it and see if your vibration is gone, then weld it on better. Did it dozens of time with cast cranks when we were circle tracking. never had one fly off. Jim