Picked up my "G" heads yesterday from Windy City Engineering (Chicago). Great people (Dale especially) to deal with, and they have the tooling/experience (30 yrs.) to accomplish the highest quality headwork.

They replaced all 16 poorly installed hard seats, cut them to a minimal/uniform depth (within a few thousands, so rocker geometry can be precise), smoothed the throats, did a 3 angle valve job and lapped them in, milled the intake surfaces level, milled the rocker stand pedestals level/equidistant to the deck, honed out the bronze guide inserts to proper clearance, ground the spring seats uniform, and tested/measured/fitted/shimmed/labeled my new springs/retainers/keepers so open/closed specs. would be exact regardless of installed height, and printed out a comprehensive invoice that detailed all final specs. They even delivered them to a much more convenient location for pick-up, which cut my travel time in half. $250 well spent!



P.S. Dale showed me the custom (?) caliper tool he uses to measure installed ht. with retainers/keepers assembled. Since I never got around to mastering the forum photo posting process, I emailed a pic to Ted. Maybe he will post it?

6 VOLTS/POS. GRD. NW INDIANA

Dan you had a lot of work done for $250.  I just had 7 hardened seats removed, replaced, precisely ground for a predetermined spring height.  Plus head milling.  Nothing else.  Cost was $200.

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

Problem is, I now have to cc the chambers again and see how much higher the new seats are. While the added compression is certainly welcomed, my zero-decked short block with the higher lift cam, 5:4 rockers & long pushrods, plus the head milling done earlier may now dictate clay testing a couple cylinders at least just to be safe?

6 VOLTS/POS. GRD. NW INDIANA

Here’s the pic forwarded by Daniel of a valve spring height gauge that uses a dial caliper as its basis.

 

And here’s some links to instructions for posting pictures.

http://www.y-blocksforever.com/forums/Topic7693-6-1.aspx

http://www.y-blocksforever.com/forums/Topic6165-6-1.aspx

http://www.y-blocksforever.com/forums/Topic3361-3-1.aspx

Lorena, Texas (South of Waco)

Rather than clay testing, install one head and valves, with a very weak spring, only enough to keep the valve closed.  Then place a dial gauge on the retainer, square and plumb, rotate cam for max. lobe lift.  Manually depress valve and spring while watching needle gauge for clearance.

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

Actually you should check, using the above method, for several degrees of crank rotation, with the timing chain on and in time.  Just after TDC, the exhaust valve on some performance cammed engines accelerates faster than the piston at TDC and can actually "catch up" with it just aqfter TDC.  Minimum clearance is not necessarily at TDC is what I'm trying to say.  The clay method will compensate for this since you turn the engine to get impressions from both valves.

John in Selma, IN

John - "The Hoosier Hurricane"

Daniel,

Just wondering what was "poor" about the first install on your seats, off center, too deep, or just bad seats?

   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

John is absolutely right in that valve to piston clearances must be checked with the timing chain installed and preferably with the camshaft degreed in.  If the camshaft is being advanced, then the intake valve will be closer to the piston and likewise, if the camshaft is being retarded, the exhaust valve will be moved closer to the piston.  For the amount one valve moves closer to the piston, then the other valve will move a like amount away from the piston.  Rule of thumb for a flat tappet camshaft is for each 4° the camshaft is advanced or retarded, the valves will move 0.025” closer and away from the pistons depending upon if advancing or retarding the cam.  But as John mentions, the camshaft profile itself will vary this value so it’s always recommended to do a physical check.  The clay method is reasonably foolproof but be sure to spray some WD40 or other lubricant on the clay so the clay itself does not stick to the valves.

Lorena, Texas (South of Waco)

Hey Dan, I have another check to make too (like in valve clearance)!

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

Tim,



Some seats were too deep, and most were cocked enough to warrant replacing all and starting fresh.



Funny thing, I checked with a cheap hole gauge and digital caliper to re-measure guide clearance. Though they said that the bronze inserts had been honed out wider, I'll be damned if I can detect it. While a half thousandth increase COULD be hard to nail down with my tools (.0015"-.0020" range), I'm starting to wonder if maybe the inserts were pre-sized, and the alloy is just too hard and elastic to hone much? Or, is it another case of being led down the proverbial "garden path" by machinists who think they know better than their customers? When I mentioned my fear of exhaust valve seizure during cam/engine break-in/overheating, he flippantly commented..."not with bronze guides".



P.S. Instead of clay, wouldn't it be easier to just install a few weak springs and measure the piston-valve clearance at various points of crank degree by pushing on the valves with a dial indicator? You could check after final assembly and merely reinstall the springs with air pressure.

Or, if both heads AND deck were level, and acceptable clearance was similar to gasket thickness, would you need to torque the heads to check clearance?

6 VOLTS/POS. GRD. NW INDIANA