9/28/2026
GOOD NEWS 
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CYLINDER HEADS

- - - - - GOOD NEWS - - - -

SEPTEMBER 28/2026
ALL HEADS ARE CAST & CLEANED UP (REALLY NICE).
FIRST TEST HEAD AND NEW CNC SCANS ARE DONE (PERFECT).
I TRAVELED TO THE MACHINE SHOP TO DOUBLE CHECK THE WORKMANSHIP.

DATE FOR ME TO PICK UP THE HEADS IS ABOUT OCTOBER 12TH.
THEN WE HAVE TO PACK THEM & SHIP.

IT IS TIME TO SEND OUT INVOICES 

TO ALL THAT HAVE NOT PAID IN FULL.
INVOICES WILL MAIL THIS WEEK. 
PAY BY CHECK OR M.O. AND SAVE 6%
NOTE:
1: WE WILL NOT BE SELLING HEAD GASKETS.
I RECOMMEND THE "BEST" #573-G GASKET
FROM MOST DEALERS.

2: THE FOUR (4) SPARK PLUG SEALS (BELOW) ARE
SHIPPING WITH ALL HEADS
FREE OF CHARGE 
TO SAY THANKS FOR WAITING.

3: WE DO HAVE TO CHARGE FOR SHIPPING THE HEADS.
-CHARLIE-

The Rocket-428 High Compression Cylinder head
Cast Aluminum 356-T6,
7:1 Compression Ratio (140-cc)
All Heads Are Dual Plug.
This head wins hill climbs! 
Casting and machining time is usually about 4-5 months.

 SOLD OUT - SOLD OUT
$xxxxxx
IF PAID BY CHECK
All costs and time suggestions are approximate
and could change as we move forward.
ESTIMATED DELIVERY IS JUNE-ISH (+-)


YAPP STUDIOS INC.
3860 Cain Run Rd
Batavia OH 45103

     

513-724-9000
[email protected]

ROCKET-428 CYLINDER HEAD
356-T6 Aluminum, 7:1 CR

all castings are 8 Spark plugs

FOR THOSE NEEDING A FOUR (4) PLUG HEAD
WE HAVE OPTIONAL
"PLUG-SEALS"

The Rocket's combustion chambers are a match of our very successful
Lion Speed Head III & IV.
The extra thick walls hold heat steady for even firing and extra metal is available to those that want to reshape to their own designs. The spark plug positions are designed for maximum flame front and have proven power on the dyno.
Plugs on the driver's side have more power.
All of Charlie Yapp's cylinder heads are custom tested designs.
 The foundry and machine shop helping me produce this 2026 production run are the same who have done our Rocket-428 in the last run. They know my need for precision and have proven to me that they will do a fantastic Made-In-USA-job.
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