348 truck motor

what is the difference between a 348 truck motor or a 348 car motor? i know that the 409 had a relief cut in the cylinder is that the same with the 348?

 

in the early 60's my buddy got a 348 truck motor. the problem with it was the large combustion chamber. I think we put 10 to 1 pistons in it, which gave it about 8 to 1 compression. maybe with todays gas that might not be to bad.
The engine ran good, but probably didn't make the HP that a high perfomance car 348 would.

 

The truck motor had lower compression and not as much cam. I think that there were some differences on the ports as well. But the truck motor may have just had the low performance car heads.

I have had one apart and don't recall there being a relief in the cylinder but its been quite awhile since then so you can't place much stock in that answer.

 

Haven't seen it personally but I believe there are notches out of the cylinder. They stll run good but not a whole lot of power. Fine for an "A" or somthing light but anything heavier I would look into putting some good parts in it.

 

They have relief cut in the cylinders as the 409 truck, and the 333 heads.

 

I have one out of a truck.It has the notches in the cylinders.W motor guys tell me that it helps give valve clearance if you put bigger valves in it and it improves the breathing so it isn't really a detriment to a modified engine.Mine also came with a huge honkin' water pump that won't clear in a car and a distributor with a governor on it to keep the rpms down. I replaced those with parts off of a car engine.I don't know if all trucks had the bad distributor and huge water pump or not.

 

thanks for all the help.

what kind of compression did the trucks start with?

 

I've also heard that the truck motors have the dipstick on the opposite side that the cars do, leading a lot of people to think that it's a 409, which had the dipstick on the side that the truck engines do. (does that make sense?)

My 348 decoded as a '61 tri-power car block, but it had the notches in the cylinders too. It came with the big valve heads, the optional performance ones, maybe those cars got notched walls too. Supposedly the big valve 348 heads are the same as the low horse 409 heads, so maybe you could use 340hp 409 heads on a 348 truck block.

 

They all had the combustion chamber in the block, with flat heads. The trucks just had larger chambers. The Heads made no difference in Compression ratio, but had better porting (airflow)

 

I had a friend that said they made great blower motors. He built one with a 6:71 in a 33 Plymouth roadster it was under driven for the street but it was a monster.

 

Can anyone confirm this? The common wisdom is that the dipstick location is a pretty good indicator of which displacement it is.

 

I'm not sure about the 348, but the 409 truck engines do have a slight "combustion chamber" in the head and reliefs cut at the top of the bore in the cylinders. If you use a truck engine as a basis you lose a little compression, between .5 and 1 compression point. It's still plenty if you run hipo pistons.
I don't like to depend on the dip stick location for reference, since the 409 pan bolts on the 348 with no modifications.
Larry T

Ya might look at this, these guys are usually pretty sharp.
http://www.348-409.com/forum/showthread.php?t=21149&highlight=348+truck

 

dip stick not real important just want to make sure i can get at least 9.5 to 1 compression. so if i change the pistons i should be ok? how much is to much to pay?

 

348 truck dipstick = right side as the 409 car and 409 truck. The original compression is about 7,5-8 to 1, here you have everything you need for your rebuildt.
http://www.bruneauperformance.ca/
http://www.show-cars.com/

 

Fits my memory that the truck block is a different deck height than the passenger car block. Anybody remember?

 

That's in the 366-427 big block truck engines not the W-Motors