302 V8 crankshaft/flywheel bolt centres?

[Robin Little]

I am about to send an Essex V6 flywheel to the machine shop to get it redrilled for the V8 crank, The machinist has asked if I have co-ordinates for the CNC machine to machine the new holes, can anybody help with this and what are they referenced to? eg where in relationship are they to the external balance on a v6 flywheel.

Thanks in anticipation of your help.

 

[Steve26]

Robin,
first you will need to know what your engine balance is? It will be 50oz or 28 oz if it is a 302. You will need to know where the balance is in relation to the hole pattern on your crank and make sure it's in the right spot or you will vibrate your bearings to death! I would think there is someone here on the forum that has done this and can tell you how to do it if you first tell them whether you are 50oz or 28oz. The hole pattern is realy the least of your worries, it's much more important where the balance point is.
Steve26

 

[DARREN]

I have the drawings for the pre and post 85 crank bolt hole positions, but, no details on the relation to the weight though.

Happy to send you the drawings that i have, but, is there anyone who can help locate the weight?

D.

 

[Mike Huddart]

Robin,
first thing to say is don't do it.

One, you don't know if your engine is 28 or 50 oz balance.

Two, the Essex V6 flywheel is neither of those so even if you got the balance weight in the right place it's going to be wrong.

Three, have you ever actually seen a GTD, type, modified V6 flywheel ? Twelve holes instead of six, a blanking plug because two overlap and an adapter ring because the crank register is too big, all on a cast iron flywheel that's probably 25 years old.

We refuse to build any engine that has one of those flywheels let alone stand next to one on the dyno!
Save yourself the grief and have a word with Mick Sollis at Southern GT or have your chap with his CNC jobby make you one out of steel. (with only six crank bolts )
Mike

 

[flatchat(Chris)]

Looking at the clutch face 60°, 60°, 60°, 60°, 56°, 64° -- 7/16"dia on 3" PCD
The weight is ~ on the off set hole pos.(56°) Centre bore is 1.75" dia.
The weight is a complicated formula --best to match balance the new FW with the OEM one

And, I agree with Mike --a good custom made steel FW would probably cost less than modifying those old POS in the long run

 

[Dave Bilyk]

mmm,
when I took my flywheel off, this is what I found!
It is a steel one, but why butcher it like that when a proper weight could have been fitted?
Mine is a 50 oz (really 50 oz.in) balance, and just to put it into perspective, at 6000rpm, this moment gives a rotating force of 3196 lb acting on the crankshaft end - external balancing seems pretty scary from that perspective.
The other picture shows what happens when you mess with flywheels, oww!

Dave

 

[Robin Little]

I take your point with the redrilling of the bolt holes, it will be very weak around that area and dont like the fact of having to make a spacer/spigot to centralise the flywheel , does anybody have any photos of the standard Flywheel , Mine will need the 50oz balance, With regards to having one made is there any spec of material which I should use? Will have a read up on how the balance weight is achieved to try and create a drawing for the cnc guy. I realise that I could purchase directly but half the experience is learning exactly how the balance is achieved and having one made locally.

GTS Tuning if you have a CAD Drawing of the bolt holes it would be appreciated. I use Autocad LT if it is compatible. Or copy of handdrawing if that is what you have.

Thanks again.

 

[Al Snow]

I went down the route on my 302 of buying a flywheel and Renault bellhousing off Mick at Southern GT and then have had everything balanced professionally. I may be telling trying to tell Grandmothers how to suck eggs but I would recommend a full balance to anyone as beyond just getting in the ballpark and satisfactory, as there are real performance gains in a spot on balance done by craftsman with the kit to work up everything together (flywheel, clutch plate, clutch housing, crank, damper, rods, pistons, etc). Respect to you though if you can get it right. It was beyond me, but much is. cheers alan

 

[flatchat(Chris)]

A 1045 steel is the best for run of the mill flywheels -tough and durable.
4140 or Cr Mo --prone to hot spotting / heat checking etc.
Cast iron is the best for clutches --but prone to cracking and exploding in Hi Po applications (its brittle)

 

[DARREN]

Hopefully attached is a PDF file with pre and post 85 302 mount hole details.

Perhaps you'll be kind enough to the community to post any drawings you do for your flywheel for future reference.

D.

 

[flatchat(Chris)]

Mmmm, not sure about your post '85 dwg ...... Chev ??

 

[DARREN]

They are both redrawn from original GTD drawings according to those originals they are both for Ford, but, i have no definitive way of checking at the moment.

I thought the post 85 drawing looked like my 5.0 litre Mustang engine i have here, more so than the pre-85 anyway but not checked it out yet.

D.