Open deck vs closed deck

[omcforever]

I am dab ling in loopers nowadays and starting to get away from crossflow. What is the difference between open and closed deck motors and when where they produced and are there any models or years that are bad or preferable. Thanks

[aj06bolt12r]

I am dab ling in loopers nowadays and starting to get away from crossflow. What is the difference between open and closed deck motors and when where they produced and are there any models or years that are bad or preferable. Thanks

I can tell you that the open deck looper blocks were much higher quality castings.. Less casting flash and port misalignment with the sleeves than with the closed deck blocks. The open deck blocks also had much higher flowing exhaust chests or manifolds which is a big deal if you are trying to make power at like 9000 RPM.

I don't know the exact year.. But I think they switched from open deck to closed deck in the very early 90's... Like 91 or 92 ish.

That said it is possible to make plenty of power for a hotrod lake motor using a closed deck block... I really think the late 90's early 2000's ocean pro 3.0 liter loopers are a hell of a bargain as a platform to make a lake hotrod from...

If you are going racing or really trying to wind one to the moon and actually make torque at those very high RPMs then you are for sure money ahead to start with an open deck...

[sharpeye Mike]

I ask Gordon from Monty racing and he told me 88 to 92 made the best power.

[racer]

88 to 92 is the 3.0 open deck. 93 on 3.0 is the closed deck. The closed deck came with finger ports, lower exhaust port and smaller exhaust runners. The later open deck had bosses in the block for finger ports but the production ones you have to cut the finger ports into them. I agree with Gordon on power but for most that have not ground on a lot of these they will not notice a big difference, especially at 7500 or less.