Engine with gas ported pistons no power

[dirtman45]

Just built a new engine for a street stock in Wissota land. Runs ok but doesn't seem to have the power of the old engine that had regular pistons. Won't even turn the same RPM on the same track. New cam was exactly the same, swapped the old heads on this new short block. Pistons are down in the hole the same as the old one, used the same head gasket #. Just doesn't have decent power, should have had more than last year..

Any ideas out there?

Thanks/

[stockcar5]

Just built a new engine for a street stock in Wissota land. Runs ok but doesn't seem to have the power of the old engine that had regular pistons. Won't even turn the same RPM on the same track. New cam was exactly the same, swapped the old heads on this new short block. Pistons are down in the hole the same as the old one, used the same head gasket #. Just doesn't have decent power, should have had more than last year..

Any ideas out there?

Thanks/

how much less hp did it make?

[dirtman45]

Wasn't dyno'd so we don't know.

[perfconn]

Gas ports are not the reason.Look somewhere else.

[joeltjen]

"wapped the old heads on this new short block.".......theres your problem.....get some new valve springs!!!!!

[dirtman45]

"wapped the old heads on this new short block.".......theres your problem.....get some new valve springs!!!!!

Heads were gone through before putting them on. The only thing used over were the Manley race flow valves. Has Crane springs, retainers and locks. The springs are the same part number that were on there before.

[tutt71]

It's not the gas ports.

[speedbuggy]

Might want to try a compression test to see if it's one or two holes or all.

I agree...not the pistons.

[LateModel B23]

What about the cam? Was it degreed in right?

[fast_crew]

Maybe bores were not finished properly? Maybe cam timing as mentioned? Is the rod length the same? Same bore/stroke?