Thread: 350 chev vs. 400 chev

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Thanks, I think I will just scrap the 400 along with the rest of the truck and stick with the 350

FWIW, a few years ago I pulled a 400 out of a wagon and stuck it in a 621/2 ton. I hooked up a 3 speed using a 454 flywheel. When a cam lobe wore out I replaced the cam with a 64 edition Isky 30-30 cam, Offy 360º intake, Holley 650dp and a cheap set of Hedman headers. I used the stock 283 bellhousing with hydraulic clutch and had a 3100lb pressure plate built locally and the best clutch disc they had. My only problem was keeping rear ends under it and at the time it made a few believers out on the street especially a guy in a 455 Bonneville amongst others. Never had a over heating problem running the stock radiator and the clutch fan that came with the engine and no shroud. It pulled a 16 ft camper trailer like it wasn't even there. I quit driving it when I busted a valve spring grabbing a few too many R's. It still sets in my garage and if I ever rebuild it it will go in my 76 Vette, same cam and with a Offy 360º dual quad intake.

double post

Originally Posted by racemaster

Thanks, I think I will just scrap the 400 along with the rest of the truck and stick with the 350

DO NOT SCRAP it! Circle track guys will buy it from you and pay decent money for it as long as it is a good core and not cracked. I'd look into that. Keep in mind the 400 crank is used for 383 builds in 350's. You have to have the mains turned down, but it is an option. Don't just scrap it.

Heck no, don't scrap it!!!!! If it is a 509 two bolt main block, it is a good foundation for a nice engine. It would be best if the block can be cleaned up with a .030 overbore. Lots of potential here with this engine. Don't be too concerned with a small base circle cam. The big end of the rods can be clearanced to get around this.

NOooooo!! No, no - don't scrap it! It is very salable, and if you just don't want to bother with it, I need a (looong) day trip, I'll drive over and take it off your hands.

If you are contemplating a rebuild, before you buy any parts, have the block magnafluxed. 400 blocks are more susceptible to cracking than other blocks. It is getting harder and harder to find a good 400 block.

Originally Posted by racemaster

Reduced base circle cams? By that you mean there are special cams for the 400? I have a retro-fit roller cam for a 350, but if I cant use it then the price of improvement just went up. I have read of cracking problems with the stock heads but I also have some good 350 heads, should I put them on instead? How about you stop beating around the bush?

400's used a 5.565" center-to-center connecting rod, which cleared the camshaft lobes. When you build a 400, you would normally use a 5.7" or 6.000" connecting rod because there are more piston choices with those rods. Problem is, these 5.7" and 6.000" rods will interfere with the lobes of the cam. Aftermarket rod makers, such as Scat, make rods that will clear the cam or you can use a cam with a smaller diameter base circle to clear the rods.

A 400 bored to 406 and with the right cam and a good set of aftermarket aluminum heads will easily make 500 hp. Any head used on a 400 needs to be drilled for steam holes if the motor is to be operated at street rpm's. 400's used for racing would make enough rpm's to keep the steam pockets in the block flushed out without using steam holes in the heads.
Technical Articles at Greg's Engine & Machine

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Before you give up or get too far along, drop by Anderson Machining on 1st street - across from the main NAPA warehouse. Talk to them for the straight skinny on what both rebuilds will take and get an estimate of how much. They also will be able to speak to modifications for more power. Excellent shop with good work ethic.

Stock 400's are torquers! Of the 9 engines I put in my '72 El Camino in 450 thousand miles, two were 400's. They lasted as long as any 350 hand grenade, ans smoked the hides a lot better. Short on RPM, but you can't have everything in this world, I guess.

Well, I pulled a valve cover and everything looked clean. So I pulled the intake and boy howdy, looks like new lifters. Looking down the distributor hole I could see what looked like new bearings. From the other end I could see a double roller chain. At that point I am thinking this motor was recently rebuilt. So I crossed my fingers and put it in the broncamaro. Would not start. Pulled the plugs and two center plugs on driver side came out wet with water in the oil. Started thinking "great, cracked head". So I pulled the one head and the head gasket was ripped, Im guessing during installation. Also some of the head bolts were not torqued. Cylinders still showed cross-hatch. All valves were a bit loose. Had 3 head gaskets hangin on the wall, drilled one for steam holes and put the head back on. Once I got the timing right it started right up. Changed oil and filter. My freinds, I believe this motor has less than 1000 miles.

My offer still stands ---- just in case you get dis-enchanted.

Rrumbler, you are welcome anytime.