[DeTomaso] Cleveland "Tunnel Port" Heads on ebay

[Daniel C Jones]

> Ford tried tunnel port heads on 289 hi-po engines but found there was no
> advantage over simply putting bigger valves in a std head.

The 289/302 tunnel ports were the result of a rapid development program
to increase the flow of the SBF head for Trans Am racing.  The tunnel
port allowed a large area straight intake port that didn't have to bend
around the pushrod. 2.12" diameter intake and 1.54" exhaust valves were
used compared to 1.78" and 1.45" for the standard SBF head.  They made
more power and were an advantage over standard SBF heads but the engines
had reliability problems at the RPM they needed (tunnel port engines
used an 8500 RPM rev limit).  One weak point was the the shaft mount
rocker system borrowed from the Y-block.  Special connecting rods, a
4 bolt main, screw-in freeze plug, block and a forged steel crank were
developed to help the tunnel port engines live and were carried over
to the Boss 302 program which added the Cleveland canted valve heads.
With the Boss 302's, reliability greatly improved and the rev limit
raised to 9000 RPM.

> These are likely salvaged experimental castings,

The ones for sale were originally acquired from Junior Johnson who
developed the tunnel port heads for Ford and are an early set that
were used for valvetrain mock up on either a Fontana or Motorsport
block (not the matching T-351 block).  Custom Jesel rocker arms were
used.  Chad Decatur said the heads were ported by Diamond-Elkins and
flowed 350 CFM on the intake side using 2.14" and 1.65" diameter
valves. They were intended for Casey Luna's WOO sprint car but never
raced.  A production batch was subsequently made and I've seen (in
person) boxes and boxes of the heads and intakes, but not the matching
blocks.  At one time, RDI was sitting on nearly the entire production
run.  Dick Trickle won an Arca race at Daytona or Talledega with a
pair, after which they were promptly banned.

Dan Jones