Iron head choices, performance upgrade or not

[Paul G]

Will switching from 346 heads to 452 heads be a performance upgrade?

I am getting some exhaust smoke on start up, worn valve guide seals I would guess. I have a pair of take off 78 452 heads with about 50K miles on them.

The engine is a good running 68 383, 346 heads, with a mild Crane cam HMV 278-2, 222/234, 467/494, LSA 114. Performer 383 intake, long tube headers with short exhaust that dumps under the car right now. 

Is the head swap worth the small cost and big effort?

[Challenger340]

Nope... same Head, 452's are basically just the hardened Exhaust Seat version for the most part, Flow exactly the same.

[BSB67]

How long has it been smoking at start up?  Is this recent, or go a long time?

[cdr]

Smell the oil for gasoline, when the map sensor went bad it could have washed fuel past the rings, an oil change might take care of it

[Paul G]

Smell the oil for gasoline, when the map sensor went bad it could have washed fuel past the rings, an oil change might take care of it

I will do that.