bence13_33

I'm thinking about getting a set of #6272990 Rectangular Port Heads w/ 2.19/1.88 Valves. What do you guys think, these will be a cheaper alternative to purchasing the $1300 Merlin Heads.

How well do you think these will work with my setup? If I'm not mistaken, weren't these heads used on the LS6 454s?

Thanks.

RatRacer

It's hard to beat brand new Merlins' for $1300. Once I installed larger valves, new springs, retainers, locks, seals, new bronze guides, hardened valve seats and pocket ported my stock oval port heads I had about $1000 in them.

Go with the new stuff. Merlin oval port heads are very good. The rectangular port heads only perform better above 5500rpm. Street races are won with midrange power, not high rpm peak horsepower.

fireball

I'm running these heads. Supposedly GM's finest. Here's some data I've collected on them...

Description Open Chamber LS-6 & LS-7 Service Head, 425hp, approx $700
Casting # 6272990 (equiv 14096188, 6260482, 366250, 3965774)
intake / exh valves: 2.19" / 1.88"
Material Cast Iron
Combustion Chamber Open 118cc
Intake Runner 325cc
Intake Port Type Rectangular
Exhaust Port Type Square
Flow: valve lift Intake Exhaust
.05 32 24
.10 69 53
.20 125 103
.30 183 140
.40 233 176
.50 264 198
.60 292 204
.70 - 207


[Modified by fireball, 4:27 PM 11/30/2001]

mountainmotor

My 2 cents is the the factory exhaust flow fizzles out at around .590 lift.The Merlin has a raised exhaust port that will help flow substancially.A set of the Merlin oval ports and .250 long rods used on a 468 with good compression and an open plenum intake manifold makes for a sweet street engine with 3.73 gears and 4 spd.