early 348 engine

[Sal58]

I have a 1958 Impala with a 348 engine, the heads are the early heads (791 casting I believe) ,can I replace these heads with the 333 409 heads and a 409 truck intake?

 

[boxerdog]

The truck intakes are all small port and will work fine. The 333 heads will require plugging the spark plug cooling holes.

 

[oldskydog]

If your block is an 872 casting with a date of late Feb or later it should have the cooling jacket and would only require drilling out the dimpled pads to use later heads.

 

[Sal58]

stamped code is T320G, March 20 1958, so the spot on the block that needs to be drilled is easy to locate?

 

[1958 delivery]

You need to look at the block, it may or may not have the area for the cooling holes

 

[oldskydog]

Look at Figures #1 and 2 and note the pads just above the spark plug holes. If you have those then locate the dimples and drill there.


http://www.348-409.com/forum/threads/spark-plug-cooling-tsb.21411/

 

[427John]

Also if you look at the thread 348 Tripower build gone wrong post #1 picture #17 or 18 it shows a good view of that area of the block deck,while the dimple isn't very visible (this block may have been decked) you can clearly see a stain where the cooling passage hole was in the head gasket.

 

[boxerdog]

Look at Figures #1 and 2 and note the pads just above the spark plug holes. If you have those then locate the dimples and drill there.

...or not. If the pads are there, you are good whether you drill them or not, the heads shouldn't leak. If the pads are not there, it's obvious and you will have to block the hole in the 333s you plan to use. Do you need the holes? Not sure that question ever got answered, kinda like steam holes in SBC 400s, depends who you ask!