I have to agree..Although i don't have the exact answer as someone already pointed out there seem's to be many reason's, i can't imagine with the amount of block's that have the X cast that they would all be replacements..
The X casting came out in mid 62 and kept on until the end of production of both OEM and replacement blocks. I've got six 409's from 62 to 65 all with the X. One replacement block and five OEM blocks. Max
I just purchased a 59 el Camino with a 348 engine & 3 spd stick. I am trying to figure out what year the engine is and if it is correct for this truck. The original data plate has been replaced by DMV. The block number at right hand head is T0707H. Where are casting numbers that might be helpful. Thanks
Rumors were, the factory guys got more HP out of a 348 when equipped with a 4 bbl intake and carb from a 340 hp 409 than with tri carbs. Marketing guys could sell more hp cars with tri carbs than with one large 4bbl.
Tman, Been there, done that. I put some Silver Seal in the radiator and it sealed up the holes just fine. Had to be sure I wasn't circulating water throught the heater so it wouldn't plug up my heater core. It didn't but a couple of minutes for the water to stop running.
crank flange on 348 round,409 bell shaped,unmolested 409 pass dipstick on pass side,small heads and intake have bolt holes between ports,low compression pistons have pent roof pistons,hi comp have angle on one side of piston only,and could have valve reliefs,notches in block none high comp,one notch less, 2 notches lesser..rivey409@yahoo.com,348 and 409 engines since 1958,mich.early 58 blocks,and heads, no plug cooling holes,uses 3/8 sparkplugs,later blocks and heads cooling holes use 3/4 reach plugs, don't weld tap and plug. brought to you by POISON IVY
Have read this thread and really learned a lot. I know that what I have done with mine would make most of you puke. I picked up a '61 348 from a farm truck. Run absolutly wonderful. Couldn't believe the size of the bell housing and flywheel. This engine was destined for a repop altered. I attended a swap meet at the Detroit fairgrounds and picked up a 409 snowflake intake for next to nothing... hooray. Now when I get the intake off my engine (having no idea what I'm doing) I'm looking at intake ports about 1" x 1 1/2" on the block, and about twice that on the intake. Drats, and I picked up two edelbrock carbs at the same meet. Double drats. After this project set for a while I ran into a fellow that told me how to make "em fit. Like I said, somebody's gonna puke. I cut off a couple of bolts, screwed 'em into the block with lok tite, bondoed over the dimples, sanded it smooth. slightly rounded off the ports in the block, gooped up my gaskets and squished everything together. Musta been at least .040 of gasket between things. Oh well, It's been on the road for three years and hasn't done anything stupid yet. I was thinking that two edelbrock 650's would drown it out, but to my surprise it runs very good, with extremly quick throttle response. Only ignition change was to get the governed distributor out and replace it with a stock points type. So far The only problem was a failed condenser, other than that....Yee- hahh. Norm
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