348 block question

[jm32409]

Hey Guys,

I recently purchased a complete 409 motor but after further inspection it happens to be a 348 block#3857655. What puzzles me about it that it has a 409 oil pan with dipstick on the right and also is has a 305 hp highrise 4bl 348 intake on it. The block has an X cast on the front so am I correct in assuming this is a 348 truck motor? All of the parts appear to have been on the engine quite awhile. Also there are no numbers stamped on the deck, was that common with the replacement blocks? I have not pulled the valve covers off yet to see what the heads are as I just got it home tonight, but any help in identifying this block would be appreciated. Thanks in advance for your help, and keep up the good work!!

Thanks again,

Jeff

[Mr Goodwrench]

sounds just like mine... 348 truck bet it's got 333 heads on it.

[Phil Reed]

Jeff...that is a 348 truck engine....they made them up thru 1965., I believe. I'm home now and my parts books are at the shop but I believe I'm correct with that. Not sure what heads would be on it though. Please post the numbers as I am curious!!

[Fran Preve]

Phil: yes they made 348 truck replacements at least thru 1965, I'd have to check for '66.

[jm32409]

Thanks for the reply guys, sorry I did not have any time today to pull the valve covers, I had to go the Atlanta Motor Speedway and watch the race today!

Ed409 made a good point that those blocks are thick walled and can easily be bored to 409 specs. Is the block the same as a 409 just a smaller bore?

Thanks for all your help,

Jeff

[64ss409]

I had to go the Atlanta Motor Speedway and watch the race today!
Sure, you would have to mention that! The best I could do was "Crank it up". When I do that, the wife leaves and heads for the kitchen for a while.:rolleyes:

Junior made a comeback from last week!:)

Sorry, I got off the 348/409 subject.

Ron

[ed409chevy]

Originally posted by jm32409
Thanks for the reply guys, sorry I did not have any time today to pull the valve covers, I had to go the Atlanta Motor Speedway and watch the race today!

Ed409 made a good point that those blocks are thick walled and can easily be bored to 409 specs. Is the block the same as a 409 just a smaller bore?

Thanks for all your help,

Jeff

Jeff, I really think they cast all the X blocks the same, then bored them to the desired size. The 409 blocks had a 656 casting number and the 348 had a 655 number, probably so they could keep track of which was which. This is just my theory, since I haven't declaired myself as an expert just yet. Good luck on your project. Ed409chevy

[348NUT]

Some of the truck engines used the #3770083 intake which codes out for a 305hp car intake but the truck version does not have the water pump by-pass nipple in the front. It could be drilled or you can T into the heater outlet or just cap off the nipple on the water pump. NUT :)

[59elcooldsuv]

I was wondering about that valve relief in the top of the cylinder. I keep reading stuff that says "the truck blocks had a relief milled in for the exhaust valves..." but never mention that relief in pass car blocks.

My block has that relief, but the casting number and the stamping on the deck all indicate pass car.

Is this normal?

[348NUT]

348 Car blocks had one relief. Trucks had two large reliefs. They were to drop compression, not for valves. NUT:)