Milling 289 Head Limits

[Paul Keller]

Has anyone determined the "limits' of milling a 289 head? Need to make up for some combustion chamber work to get the comp. ratio back to 8.75:1 and believe that 0.060" mill is about right. Anyone cut through the face at this amount? Has anyone cut through any amount? Realize that there is a difference in casting thickness, but would be nice to know of limits before starting.

Thanks a lot, Paul Keller

[Mike Van Veghten]

I know one guy said he went .125". I wouldn't go that far...but.

And as you note, how far have they been cut in the past..?
I don't recall the dimention, but I believe someone on the racing board had the actual drawing thickness of the head with the drawing tolerance. I'll look around a little, see if I can find it.

Now, on one hand, I'd say yea, .060" is plenty doable. On the other, this messes with the rocker geometry, and the fitup of the intake manifold. The manifold has two locations this screws with. The port top and bottom and the angle of the manifold to head gasket surface.
That said...using thicker gasket material, would fix both of these problems.
But...if you are out for notable power gains, depending on the head gasket thickness plus you're -.060" head cut, you may need shorter pushrods to keep the rocker geometry anywhere near correct.

MANY people overlook this. With the tiny Stude cams, you (we) need everything the cams have to offer.

Check the rocker geometry..........

Mike

[PackardV8]

[Chicken Hawk]

Has anyone determined the "limits' of milling a 289 head? Need to make up for some combustion chamber work to get the comp. ratio back to 8.75:1 and believe that 0.060" mill is about right. Anyone cut through the face at this amount? Has anyone cut through any amount? Realize that there is a difference in casting thickness, but would be nice to know of limits before starting.

Thanks a lot, Paul Keller

About 45 years ago I milled a set of heads .125". I used thicker intake gaskets and had no problems other than had to elongate the top water manifold bolt holes to get the bolts in. The original thickness of the heads is 3.563" so you can measure and see if they have been milled before.

Also I've found milling .010" will reduce the cc's about 1.5 so milling .060" would reduce the cc's about 9.

Ted

[sals54]

Yeah, I was the one who wrote about having cut my heads .125". In fact it was Ted's experience with having his heads cut .125" that gave me the confidence to cut mine. They worked GREAT ! ! ! ! They end up having combustion chambers that look much like closed chamber Chevy heads. Nice "kidney bean" shape with a large quench area. I coupled that with a Chevy valve conversion using Manley Pro Flows with undercut stems... 1.88 intakes and 1.5 exhausts with Z-28 springs. I also used the thin head gaskets. Never had detonation problems which I attributed to the excellent quench properties. That's just my guess, based on some of the writings back in the day in Hot Rod magazine. I seem to recall that we ended up with over 11:1 compession. It sure drove like it. I had those heads on a 259 and flat top pistons. It ran like a scalded dog.

[Mike Van Veghten]

Hey Sal -

Yep...you are the one I was refering to...!
How ya been ?

Mike

[sals54]

Hey Mike, Doing well and barely surviving this CA economy, but getting by. How are your projects? I have an M90 Eaton supercharger that I've been playing with. I'm trying to adapt it to a 259. We'll see how that goes.

[PackardV8]

Hi, Sal,

Getting OT here, but I've had an Eaton on the shelf for several years now. Adapting it to the Stude manifold is no problem. It's trying to decide whether to use a carb without it ending up looking positively weird or stay with the EFI and all its' attendant CASO challenges. That, plus it gets really crowded back by the distributor. Let's start another thread on this and share ideas.

jack vines

[sals54]

Sure Jack,
I'm planning to use a carb in a draw through configuration. I'm almost ready for some measurements to find out if I can keep it all under a Lark hood. I doubt that I'll be able to manage a setup suitable for a C/K though, but ya never know.

[PackardV8]

Sidedraft Weber or Solex 2-bbl would work perfectly.

I've done some preliminary measurements and I believe it could fit under a Hawk/C/K/Avanti hood.

jack vines

[sals54]

I'll go ahead and start the new thread. I will call it M90 Supercharger. I'll get some pictures started tomorrow.

[Paul Keller]

Thanks for the great info. The intake matching and piston-to-head issues are being addressed and dfoublr/triple checked.
The valve geaometry was not considered - Always better to check something rather than find out the hard way (have done enough of that). It was suggested that if the geometry/valve tip contact is not satisfactory. that the rocker shaft stands can be shimmed or cut as needed. Is this a correction anyone has tried??
Also, have been trying to run down Urethane "A" Arm bushings from a supplier in Australia, Noltec (previously noted in the forum). Seems they have new owners who are NOT listing the Stude' application (this accoding to Geelong Brake-Clutch, a Noltec distributor, also of Australia - There are no known US distributors). looks like another dead end. Has anyone contacted the main US suppliers (P-S-T or Energy Suspension)??
Thanks again for everyones help, Paul Keller

[Mike Van Veghten]

Paul -

No....the only time you want to mess with the rocker shaft stands is if you use long or short valves (stems). If you only tried this method, the geometry would only get worse in the "head height" circumstance.

Decking the block and or heads requires a change in pushrod length.
Like the engine I am building, I had the blocked decked to zero the block deck to the piston and .040" from the head. I "will" be shortening the pushrod length...to correct the geometry !

If you don't do this, (as noted above), you will loose precious lift figures, and there ain't much lift that anyone would want to loose... It's like gold to a Stude fan.!

Mike

[Paul Keller]

Can the present push rods be shortened (I'll need 0.060" mod) or is it necessary to get custom made??
Paul K

[PackardV8]

Yes, Paul, the OEM pushrods can be shortened. I've seen it done by yanking out the tips with vise grips and cutting the pushrods with a hacksaw and with a tubing cutter. That's shadetree engineering at its' finest. Smith Brothers will make new ones for around $125 last I checked.

jack vines