I've seen ads from people wanting 409 engines & some say no truck motors---just wondering what is the difference -inside the eng or outside & are there a difference in the 348s just wondering thanks
Take a look at this thread. It has a lot of info on the 348 and 409 engines http://www.jalopyjournal.com/forum/showthread.php?t=250849
Personally I would prefer a truck engine for a driver. Lower compression and will run on regular unleaded. One draw back is the heads. Smaller valves and ports. Bassically the same as the 348 heads.
Some of the truck motors have two notches cut out of the bore and that results in a low compression. But not all trucks have 2 notches. I have a truck block that only has one, just like the 1959 car block that I have.
The truck heads have a notch at the top of the cylinder to lower the compression approx 1 point. These truck heads are just fine to use to build a very nice engine. All you need to do is install pistons that are approx 1 point higher than the compression you are wanting to run. Example: if you want to run 9.5-1 compression then install 10.5-1 pistons. Heads also make a diffrence....but as far as the block is concerned it is really a simple solution.
Heads dont have a notch or a combustion chamber. 348 and 409 heads are dead flat. Notch is in the wedge shaped combustion chamber created in the top of the cylinder by the odd ball deck angle on the block. I ran a 1/4" stroker crank in an '09 back in the 70's and we machined 1/8" off of the top side of the piston that faces the head.
I think the 333 truck heads have a little recess in them. Some of the truck blocks have an extra notch that kills a little compression but improves flow. Between the recess in the head and the notch in the block you loose a little compression (off the top of my head a little more than .5 point), but the pistons are responsible for most of the lower compression in a truck block.
All the heads are flat, even the 333 truck heads. It's in the block only. We built a 409 using the truck block and 333 heads with stock valve size, opened the intake port to the big port 690 head size to run a factory dual quad, running a hyd roller version of the 425hp cam with shitty stock exh manifolds(2.5 outlets) ...it's in a '61 Chevy with a 4spd and that thing is FUN with 3.36 gears. No, you cannot use the top 2 bolts on the intake above the runners, but seals just fine. Get a set of Bob Walla's aluminum heads if you want to scream ...
This is from the 348-409 website (about truck and marine engines). "A: They share alot of the same parts like crank and rods but the heads and block are different between them. The truck and marine blocks have a cut out area in each cylinder that helps lowers the compression to 7.75:1 The notch in the block is not responsible for all the compression loss however. The truck and marine heads (333) have a combustion chamber and shorter pistons which are responsible for the largest amount of the compression loss. On a positive note, the notch in the block also allows more room around the exhaust valve thereby enhancing the air flow." This is an engine I built using a truck block and 333 heads (with combustion chambers) for a customer. And this is how much I had to cut out of the heads to match them to a stock 2X4 intake.
Here is a photo of the cylinder side of the 333 heads. Note the relief in the deck around the valves. The passenger car 348/409 heads don't have this feature. All truck blocks, 348 and 409 have at least one notch in the cylinder around the exhaust valve. Earlier 348 truck blocks have an additional notch (2 per cylinder); these blocks should be avoided.
"...... Earlier 348 truck blocks have an additional notch (2 per cylinder); these blocks should be avoided. " - UMM I'll take those ones then thanks! Nothing wrong with those early double notch 348s- I have un uncracked standard bore in my garage and I plan on buiding it. 11:1 pistons, pass cylinder heads, and steel head gaskets will work just fine.<!-- / message --><!-- attachments -->
333 and other truck casting cylinder heads -I can't quite remember the #'s - 702 rings a bell DO have a small combustion chamber but for arguments sake they are "flat"- with 90% of the combustion chamber in the cylinder. -Regarding the notch in the top of the cyinder on blocks. ALL 348 blocks are the SAME both PASS and TRUCK they all have a notch at the top of the cylinder. This notch is NOT as large as a 409 truck block notch-at this point in time who cares if its a car or truck engine. Most guys looking at it don't know sheep shit from cherry stones anyway so find the nicest most complete one you can for cheap. ALL 409 TRUCK blocks have a notch at the top of the cylinder. This notch is LARGER than the notch in a 348. NO passenger car blocks have this notch. The notch drops the compression ratio about a quarter to half a point so ya it has little to no effect. It DOES NOT drop the compression ratio 1 point like a lot of guys think. Just count your lucky stars that you have found an UN cracked 348 or 409. Finally the confusion with 65 blocks. YES the last 3 digits of the very common "656" TRUCK 409 is shared with the very rare PASSENGER car block in 1965 -also ending in "656". The only way to tell is read the suffix code on the front pad if no one has machined it completely off like I do sometimes OR pull the heads. W engines are a strange animal -be careful!
Even with the 11:1 pistons and passenger car heads you'll still wind up with a rather low compression ratio. But, hey, if you're just wanting a cool looking engine then I guess they're OK. I wouldn't spend the $$$ on rebuilding one given the availability of the non-double notch blocks, though.
Exactly... I used a truck block & car heads for my stroker motor years ago. 14 years later still running great....
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