Jughead

I found this listing of a cast iron cylinder head in the GM hiperformance parts book


6260482 - Open Chamber Cylinder Head (Cast Iron) 1968-90


This is Chevrolet's best cast iron cylinder head for high-performance big-block V8s. It offers exceptional power at an economical price. This casting has 118cc open combustion chambers that reduce shrouding at high valve lift and improve engine airflow. The seats are ground for large 2.19" diameter intake valves and 1.88" exhausts. This high-performance head has rectangular intake ports and square exhaust ports. It is machined for 7/16" screw-in studs and guideplates (not supplied).
Technical Notes: (see "Technical Notes" at the beginning of the Cylinder Head Group section for important information) This head was installed on LS-6 engine assembly P/N 366250 and LS-7 engine assembly P/N 3965774. It can be used with both closed and open chamber pistons to produce various compression ratios. Casting number 14096188 or 6272990. Cannot be used on Gen V engines because of upper water hole alignment. Open Chamber Design.


At $371 each that'd be a great alternative to the $$ aluminums.

They spec with 325 intake volume, 2.19I and 1.88E valves, 118cc chamber and have rec intake ports. It's listed as a service replacement. I'm gonna run the numbers thru the desktop dyno later.

Good? Or Pass?

GregP

I have them on the boat motors. They are reported as the best factory heads (like if your running in SS classes), but I don't consider them competative with more modern heads, iron or aluminum. You can get the flow numbers for them for the dyno programs (I have them, got them from Super Chevy magazine). If you compare them to the modern aluminum offerings you'll see quite a difference. I've "heard" the difference can be an easy 50-100 HP upgrade to a "typical" 500HP marine engine, but just couldn't afford them (got to buy two of everything) when I was putting the boat motors back together. Desktop dyno says my motors should pull 500 HP. Backing out HP from speed using Mercury's formulas I get more like 475 HP.

-Greg

427Hotrod

Those are the basic GM rectangular port head that up until the last 5-10 years was about the best deal out there. They can make lots of power, but as was mentioned there are better designs available. I believe that is a bare price, so if you compare it to a Merlin iron head they are pretty close in price, but with the Merlin making lots more power.

All of them are going to need at a minimum a basic port and bowl clean up because they are all pretty ragged out of the box.

By the time you get them assembled with valves, springs, retainers, seals, keepers, studs and guide plates you are going to not be too far off Aluminum prices.

Heads $742
Valves- mid range=$176
Springs=$125
retainers=75
keepers= 31.99
guideplates= 36.00 ( not sure if thats for one head or two)
studs=44.99

You're in the $1200+ range already. You might use cheaper parts and get it down, but not too much!


Jim

GregP

My motors have fairly mild cams (.553/.571 lift), but still were stretching the "stock" valves. After being lucky enough to catch it before one actually broke I now run nothing but Severe Duty valves. A few bucks more ... until the cheaper one breaks.

-Greg

clem zahrobsky

greg,if you mean the valve lash was closing up,that is caused by detonation tuliping the intakes up into the intake port. i had that happen to a boat engine. :chevy

GregP

No, these were stretching at the retainer end in the area with the reduced diameter for the keeper. The machinist found it when we pulled the heads apart for cleaning (one got dropped in the mud in the bottom of the river getting it from the boat to the dock, funny story but not fun at the time, it's a bitch swimming down and then trying to swim back up carrying a BB head). Went and pulled the heads off the other (still running at the time, a rareity) motor to check them and found the same thing. The motors had about 20 hours on them at the time.

-Greg