One of the problems with porting those older heads is insuring you are working on a good pair of castings.  Internal rust is just one of the problems that can crop up only after the heads have been ported and put on an engine.  Just a light deburring or smoothing of the internal surfaces does go a long way towards improving the head flow which can be done by the first time porter.  Slow and easy is the main thing to consider here.  While eighty percent of any flow improvement can be done in about twenty percent of the time that it takes to fully port a set of those heads, it’s that last twenty percent of flow improvement that’s tough to get.

 

Using ½” head bolts will allow for an increase in head bolt torque but 20+ lbs of boost is going to require some special thought towards copper head gaskets and O rings.  And then water leaks associated with the copper gaskets will come to the forefront.

Lorena, Texas (South of Waco)

I was tired of replacing head gaskets with 65 lb/ft of torque.  Every time I would hit 6500 rpm (naturally aspirated) under load gasket would go.  I didn't like the ARP 62 lb/ft torque spec.  I tightened down to were I thought either the thread would pull from the head or my gasket is going to hold.  Been working great for about thousand miles under boost.

Hutz: There's been one or two articles in YBM in the past, on engines with heavy duty supercharging. You're looking for big trouble! At the very least you need to follow the advice to go to 1/2 inch head bolts. Likely consider O ringing the heads too. And what's with throwing out the torque wrench?!

Paul

you could dual stage them like the tractor pullers do?????????????

 lincoln/merc. y-blocks &mel's                                                               bucyrus, ohio.

I have been running a steady 8-10 psi right now with my heads that I posted myself.  I haven't had any trouble so far but I also threw the torque out the window and just cranked the heads down.  I think they might have a chance at 20psi.  We are going to build are own manifolds and run twins on this now.  Once I get my dished pistons and new heads we will start building everything and I will try to post the progress as good as I can.  Two turbos aren't necessarily better than one good one but we have the room and it will look badass!!  On the other hand maybe two is better than one

P.S.  Has anyone tried up to 20psi yet by chance?  Just wondering if they have how it went......

I know John can't change the head bolt spacing (not really sure that's an issue)but I'm sure he has beefed up the quench area and where the gasket seals.  I don't doubt that his heads are superior to the cast iron ones.

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

I wonder if the aluminum heads address that.


Lawrenceville, GA

I don't think it's the four bolts vs. four bolts, it's the way the heads is cast.  The newer small engines have material in the right places and the bolts spaced evenly.  The problem with the Y is the quench area is not supported all that well even with "posting".  Although they were more than adequate for natural aspiration and a small amount of boost (5psi) I'm afraid 20 psi will just lift the roof.

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

I notice that a lot of newer engines use only 4 bolts per cylinder. Is it a difference in the casting that makes them better suited for boost? He can drill and tap for 1/2" bolts. If that doesn't work, maybe some sort of turn buckle system can be used for additional tension, using the side mounts that are not used to mount the engine in a truck.


Lawrenceville, GA

Good luck holding the head down with 20 psi.  I've seen a lot of these import engines at Elmo and Bonneville that make un-believable HP and MPH, I love the Y-Block but these newer engines do have some engineering advantages.

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias