Thread: 348 or 409

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I'm going to replace my 305 with either a 348 or 409(same block) and was wondering if anyone has done this switch before? Want to know if I can get an adapter for my 350 tranny and what other problems will I run into.

Haven't worked on one of those in a while, but if memory serves it's the same mounting flange as the small block, so your trans should bolt right up.

Hey Chevy 37!

How much power are you planning on getting? I still have my 305, and i also got a 350...i just want the most power for the street and MAYBE once in a while strip.

Let me know!

Have both a 60 chevy 348 stock that put out 335 HP, and I have a 409 stock that put out 340HP. I have a friend whos an engine builder and between both of us he says we can make 500HP easy with the same amount of torque

Bob Thanks for the info. I has asked streetsome time ago if it would hook up and I'm pretty sure he said the same.

I've had a number of High performance 409s, and they were very different from the 340 hp engine. Much bigger heads, radical flat tappet cam, two Carter AFBs, 11.5 to 1 compression, and some free flow exhaust manifolds. The factory rating was 425 HP.

If you want to find out actual horsepower, NHRA used to factor engines in Stock classes. Maybe you can find out what their "actual horsepower" rating was. Just for example, the 426 Hemi was rated at 550 HP, so I doubt that a 340 horse 409 is capable of those kinds of numbers.

I think you will find that it will bolt to your trans, but may have problems with the fit, due to the width of the engine. It is also much heavier than the smallbock, so you will lose some performance there, too.

I would put my money into a 400 smallblock, which is nearly a bolt-in, and you will be able to buy anything you want for the project, such as pistons, headers, cams, etc. I had a friend with a 406 in a '68 Camaro that ran consistant 10s with a Powerglide.

Hotrodpaint. Thanks for the info. If we take the 340-409 we would use better heads and go with some deep dish pistons and probably with a more agressive cam. Should be able to get 500Hp. as far as width, your right on that and my 37 engine bay is not that big, but I have 2" of clearence on both sides, not much but enough. The only problem is, I'm concerned about is the heat buildup. On the 400 block, to be honest I've never worked with one and heard that they overheated because of the piston location. True or not?

I haven't heard of major heating problems on the 400. Chevy probably made a few million, so I would guess they work just fine, unless there is a malfunction of some sort.

I think you will have trouble buying a lot of HiPo parts for the '09. The supply of parts was drying up when I stopped buying in the late '80s.

The one good thing about the '09, is the fact you will have something unusual under the hood. They ran good, but the bigblock and smallblock Chevies were superior in several ways, so just remeber that Chevy replaced it for a reason.

Problems they had were too much rod angle, causing the pistons to rock in the bore. The pistons were too heavy. Even the HiPo rods were weak compared to the standard 396 rod. They had a habit of yanking the rocker studs, so you'll need to pin those. They had a poor combustion chamber shape, and you'll have to be careful with cam lift if you have the big '62-early'63 heads. I was busting moly push rods regularly, using a Z-11 cam in a '62 motor. The only thing I will say in it's favor was "it didn't run very often, but when it did run, it would leave tire tracks to 100 MPH!"

http://www.flatlanderracing.com:/
Chevy 409 Pistons
10.5 to 1 Comp Ratio
Features/Description:
Ross 409 Chevrolet pistons are ideal for street/strip applications and are suitable for nitrous systems of 250 HP or less.
Pins included are .990 dia., 2.930 length, .150 wall, 149 gram weight, aircraft quality, and are retained by double spiro lox or can be press fitted in rods.
Ring grooves are 5/64, 5/64, 3/16.

give Belmont's a call, they have all sorts of old speed stuff...
http://www.belmontsrodandcustom.com/

chevy 37
I ran a basically stock 400 in a '62 pickup with a stock radiator and never had an overheating problem. I did run a 160 thermostat in the summer and a 180 in the winter with I beieve an 11 pound cap. The 409 sounds sweet though.

The 348 and 409 are an absolute bolt in replacement for BBC and SBC in regards to the trans, flywheel(s) block-mounted starter(s) and side engine mounts. Those engines only came in big cars, though, so there weren't any stock rear dump exhaust manifolds made. I had a 60 El camino with a 348 and t-400 and it barked the tires when it shifted. The third link bracket actually peeled the axle housing metal!
Also had a flatbottom with a 348...great ski-boat motor!

Again Thanks for all your advice. Sure is nice to have knowledgeable people around.

I think using a 348 would be unique and very cool in your truck. I have on built up for my 59 Impala. Its bored 60 over forged pistons, high peroformance camshaft and some other goodies. I cant wait to fire it up . Just have to wait to win the lottery lol so I can buy the rest of the things it needs. One thing to consider is like Hotrodpaint pointed out its a huge block and weighs a ton. You also might even have to do some suspension uprades to make up for the weight ? I actully had my cherry picker bend when I pulled the original 348 from my Impala! The cast iron powerglide that was attatched to it probally had a little to do with that also lol.

Yes, if you look up "boat anchor" in the dictionary....there's a picture of a Chevy "W-block" engine.