Does anyone sell or make a stroker kit for a 400? my father(58) remembers when they stroked a 400 to a 454. but this was a long time ago. anybody have any clue? and would it really be worth it to run in my camaro with an LT1 intake setup and edelbrock heads?

 

Yes their a few options you have with a 400 block. Bored .030 over you'll have a 407 with stock 3.75 stroke. If you don't deck your block you can run same pistons and rods and run a 3.80 stroke for a 412. This is what I'm thinking off, for a forged crank it doesn't cost anymore, but my block may have already been decked.

The next step up is 3.875, you'll need custom pistons and a small base circle cam. This bumps it up to a 4.20. also you must clearance the block, I've heard varied opinions as to how much.

For a 434 you need a 4.0 stroke, a few companies make pistons but I think they're all domed so you'll have you get custom pistons, get the domes milled off off the shelf ones, or run race gas. Also once again small base circle cam, and more block clearancing, I've heard people say you''ll have to use block filler, because you have to grind so much, and others say it doesn't take much.

it is possible to make a 454 with a small block but as far as i know it is only possible on a aftermarket blcok. There are two routes, 4.125 bore and 4.25 stroke and 4.25 bore and 4.0 stroke. Either one would require an aftermarket block.

I'd really like to hear somebody who's actaully built one of these engines just to get this info first hand, not a friend of a friend said that his cousin had to...

Check ebay there are a few people selling kits, also check out http://www.ohiocrank.com/, its a little more than chinesium, but the parts are made in the USA.

 

most likely these kits are really expensive as well. so tons of block work, i knew about the clearanceing the block but, i dont know maybe just the 30 over 400 will be fine for me. lol

 

I just built a 434: BowTie block bored 4.155, 4" forged, internally balanced crank, 6" Carillo rods, JE forged dished pistons, 15 Degree Brodix heads, small base circle mechanical roller cam, etc.

Clearancing the block was relatively easy; much the same as when I did the 415 (+.030 400 block) that's in my car now. In the 415, I used 5.7" Chevy small journal rods with the 2" big end bore and a standard base circle hydraulic roller. Offset ground crank at 3.825; forged flat top TRWs.

Never did a 454 though. I suspect that to get the add'l .125 clearance needed at the oil pan rails, you'd need to fill the stock block in that area in order not to hit water. Aftermarket blocks and GM performance blocks have revised coolant passages to eliminate that problem though. Custom pistons will be called for too.

Jake

 

What about destroking a larger block? I don't know much about big blocks - possible? Or would you get something like a 477 (still very cool) ???

 

Thats completly against the point. A big inch small block is a way to get Big block horsepower and torque numbers without the extra weight. Nothing like beating rats with a mouse. Not to mention you can just tell every ones its just 350...

Jake jr. how similar are the bow tie and stock 400 blocks in terms of clearance? How much did it cost you for the offset grinding and does TRW make off the shelf pistons for a 3.825 stroke? Part #'s? If i go custom pistons I might as go with the a 420. Right now I can't decide between a budget roller 4-bolt 383, budget 407, or save up and build the 400 the way i want to first time for big cubes, and a blower

 

Big small bloacks can get expensive in a hurry.

The Bow Tie block is nothing like a stock 400. The cylinder walls are a lot thicker, and the pan rail design is revised. Also, the bulkheads are thicker and the casting is beefed up in critical areas like the main webs to support a lot more power.

To get a 454 you need an aftermarket block that will accept a 4.250" bore. Otherwise the pan rails need to be clearanced excessively and the block will start to lose strength. Plus, with that much stroke the cam base circle becomes very small, and the chance of snapping a cam with high pressure valvesprings increases dramatically.

With a production 400 block the best you can hope for is around a 430 by using a slight overbore (.030) and a longer stroke crank as mentioned. You really have to be careful when boring this block more than .040, because they are notorious for core shift, and most won't tolerate a .060 cut without excessively thin cylinder walls. Sonic check before spending money on boring one. The deck surface on the 400 is also pretty thin and flexible. You can have some of the offending collant passages tapped and plugged with 3/4" pipe plugs and then milled into the deck. This will stabilize it a bit, but with high cylinder pressures the chance of kicking out a head gasket or cracking the block is an ever present danger, even with head studs. I would consider about 550HP the practical limit of a stock 400 block regardless of the way it is prepped.

I would suggest building a 377 is you want a good race motor. The short stroke, big bore combo builds power like none other. Most of the factory powerhouses used this combo (427, 302, ect). It also allows you to run long rods without cam and piston hassles. Just my 2 cents.

 

Both blocks needed clearancing at the oil pan rails. The BowTie block because of the Carillo rods' big ends and the 400 block because of the longer stroke and NON 400 length rods.

The BowTie block is visually different (externally) so you'd never be able to pass it off as a 350 block to anyone with more than a mild knowledge of blocks. Some 400 blocks with 2 freeze plugs may be able to squeak by except for the really sharp eyed block gurus.

The 400 block clears a stock base circle cam, while the longer stroked BowTie block needed a reduced base circle cam.

Offset grinding cost $250, but the rod journals were also reduced for the 2" small journal SB rods in that cost. Of course there was a lot more done to the crank which caused the total cost to rise.

The TRW pistons are off the shelf, but the part number is buried in the paperwork that I haven't come across in years. They have only two valve notches per piston, full length skirts, pressed pins and I opted for 5/64ths rings rather than 1/16ths. If you plan to rev above 6500 rpms, 1/16th rings are the way to go. I built my engine for low rpm torque.

One of the mags had two engines built as identically as possible. One was a 377 and the other a 383. Both were tuned and dynoed. The numbers and conclusion of the author was that the 383 is the better of the two due to the higher torque. The 377 did make slightly more HP, but only at the very top of the rpm band. Choose your poison.

My advice to you, build the engine as big as you can without exceeding the block's capability.

Jake

 

[QUOTE]Originally posted by TKOPerformance
I would consider about 550HP the practical limit of a stock 400 block regardless of the way it is prepped.
I would suggest building a 377 is you want a good race motor. The short stroke, big bore combo builds power like none other. Most of the factory powerhouses used this combo (427, 302, ect). It also allows you to run long rods without cam and piston hassles. Just my 2 cents. [/QUOTE

I can agree with you on all but the last two points. 550hp being the practical limit, I sure hope not! I know there are people running 400 blocks in the power adder boards, so why would it not hold up for n/a? Just punching some numbers into desktop dyno, a healthy solid roller 407 should be able to make well over 550 hp with open exhaust. I’m thinking of saving my 400 block for a blower or turbo motor. Hopefully if I can afford the blower by then I can afford to sink some major money into a shorblock to take the abuse. If your so worried about cracking the block at least stud the mains, and if you can afford it go all out with splayed mains.

As for a 377, the RPM's where the shorter stroke would be necessary would be beyond where a street car is ever going to live. A 407 is going to be able to make more hp, idle better, and have more torque. I think the only place where a 377 has its claim to fame is when you want a budget build and you have a quality 350 rotating assembly lying around. There are people out there that rev the crap out big stroke motors with quality components. I think if you’ve got the money to build the motor to take the abuse a 400 block is the best way to go.

 

Well, the reason I said that is experience. A good friend of mine was running a 409 small block for the past coule of years in his race car. The engine had splayed mains, main studs, and head studs. It was also running iron heads. The car is a '92 Firebird door car (tube chassis). It weighs about 2,250 pounds minus the driver. The 409 was good enough to propel the car to a best of 8.90 in the 1/4 mile on alcohol. I figure that based on his ET and MPH the engine was making about 650-700 HP. It held together fairly well like this for a couple of seasons of moderate use (a trip to the track a month during the good season, some bracket racing). So, under limited use situations the 400 can live for several years at over the 550 level, but I wouldn't want to depend on one making more power than that on a daily basis. Just because other people are doing it doesn't mean that it's a good idea. Insert rhetorical bridge jumping question here.

This past year it finally let go. The deck surface cracked between the head stud holes and water passages in five different locations. Three of the cylinders were full of water when we tore it down. The block was toast. Luckily nothing major was damaged, but the potential for serious damage was there. He'll just upgrade to a Bow Tie block or a Mowtown block now and reuse all of his internals, but he was very lucky. It could easily have hydrolocked the motor and bent rods, ruined pistons, or snapped the crank if he has been on a run when it sprung those leaks. Fortunately he was just putzing around the Hooters car show.

The 400 makes a great street motor, but I think it leaves a lot to be desired in a race engine. People used to run them because they provide big cubes for cheap, but the problem is that the block really isn't all that well suited to racing. A 350 block is considerably stronger. The 400 has a weaker deck, thinner cylinder walls, and thinner main webs. The siamesed cylinders are an asset to strength, but they also make the engine more detonation prone (hot spots). The 400 was never designed as a performance motor, and there was never a factory variant that could have been called a "high performance" engine. It was designed to provide good low end torque to move land barges, while getting better gas mileage that a big block. It was never intended for high RPM or high power levels.

By building a 383 or a 377 you get a combination that will live longer and still provide good power. The 383 is the torque king on the street, and is a better street motor. The 377 is a track engine. It makes power at high RPM, which loads the block gradually, instead of shock loading it with low end torque. This allows the 400 to make some serious top end power while still holding together.

Another point worth mentionign is that 400 blocks are becoming increasingly rare. Most often you will pay a hefty preium for a 400 over a 350, which as far as stock blocks go makes the 350 a lot more appealing to me. If you're going for an aftermarket block up front them by all means get the one with 400 bores. I'd stick with 350 sized mains and rods though. Less weight and less friction.

 

http://www.speedomotive.com/PONTIAC%...RANK%20KIT.htm

Here is a website that offers a 400 stroker kit for a pretty good darn price. I managed to buy a pontiac 400 and th350 Tranny out of a 78 TA for $100 off this dude. So when it comes time I know for sure I'll be stroking this engine.

http://www.speedomotive.com/PONTIAC%20400-467%20STROKER%20CRANK%20KIT.htm

 

old post. but im not talking about a pontiac motor. id ditch the 400 but you probably are going for a nastalgic car...pontiac car, pontiac motor, i get it. good luck with it

 

Well, the difference between the stock 400 block and the BowTie block is pretty dramatic. The BowTie blocks is CNC'd, so everthying is square. It has thicker cylinder walls, revised oiling (priority main) and revised cooling system passages, correctly indexed lifter bores, equal deck hieghts, etc., just to name a few.

For instance, in the stock 400 block, there are coolant passes at the bottom of the cylinder bores RIGHT WHERE you need to do the grinding to clear a stroker crank. The BowTie block is solid in those areas, so grinding for clearance is a snap.

If running a stock 400 crank, offset grinding of the crank to get that extra little bit of stroke is simple (for the machinist - not for me, LOL) to do.

Because we went with a 4' stroke crank AND 6" rods, the BowTie block had to be clearanced just a little at the bottom of each bore. This is something you can do yourself during mock-up.

My pistons are off the shelf, forged, two valve relief TRW's. Unfortunately I don't have the part # because the short block was originally bought by a friend. I got the short block from him in exchange for building the 434, so I don't have any of the short block paper work. You can call Speed-O-Motive for any of that kind of info.

Using a stock 400 block, a .030 over-bore is as big as you want to go. Sure there are those who have gone .040 or even .060, but before going that route you should DEFINITELY have the bores sonic tested to determine their thickness.

My thinking is you need at least .200 wall thickness ON THE THRUST WALLS, after all maching operations are completed. Core shift can cause one or more of the walls to fall below that on a .060 over-bore.

Most BBs can take a .060 over-bore, but I've had ONE that had core shift and one bore cracked at the bottom of the bore in a location that ruled out a sleeve. That's when I learned to sonic test all blocks, both SB and BB when going more that .030.

Going on .030 may also allow you room for another over-bore should you happen the hurt the engine somehow. If you go .060, you'd be looking for another block if you hurt the .060 over one.

On last but of advice: If you opt to go the stroker route, BE SURE to select a maching shop that specalizes in RACE ENGINES! Not just a shop that does dealership work as their main income source. RACE ENGINE shops hold much tighter tolerances and their reputation (which translates into whether they stay in business or not) depends on the quality of their work.

They have the most up-to-date machines, keep them calibrated better and are more meticulous. You'll be glad you did.

Hope this helps.

Jake

 

There's all kinds of good information and advice in what was said above.

If you want the engine a certain way just build it like that the first time. Ultimately you'll be much happier you did. The cost difference between building the engine you want and the one you could live with is probably fairly small when you stop to consider it. Finance that difference out as credit card debt for a year or two and it looks even less significant.

If you're planning a blower you can easily get by with less cubic inches. When boost enters the equation it's usually cheaper to just add more boost than it is to add more cubes. Even an 8:1 350 is still going to make good low end torque and won't be too soggy on the bottom end on the street. If you've using a roots style blower the low end isn't even that important, because the boost is nearly instantaneous. Centrifugals take a little longer to build boost, but still produce a healthy dose at low RPM. Turbos take time to spool, which can translate to lag, especially with a really big turbo. You can solve that problem with twin turbos, a shot of nitrous, or a bigger cube motor that inherently makes better low end torque.

If I were going to build a brutal street/strip small block I'd opt for a stock bore/stroke 400 with stock length rods. I'd use a Bow Tie or Motown block, a fully forged 4340 rotating assembly and Mahle forged pistons. I'd have the 350 sized mains though (less mass). I'd use splayed mains, and studs in everything. I'd top it off with AFR heads, a custom ground roller cam, some form of aftermarket EFI, and a PT88, or even a slightly smaller turbo. That combo would be quite streetable with a motor of that size, yet could easily push the car deep into the 9 second zone with nothing more than a revised tune up in the computer and some race gas in the tank. You'd probably have roughly $13,000 tied up in the engine if you did all thw work yourself, but you'd be making an easy 850+ HP. Thats only $15 per pony, that'll even make nitrous blush.

 

Summit sells motown blocks that already come clearenced for 4" cranks and can be bored up 4.25". They go for about ~$2200. If youre feelin froggy, you can get an is all aluminum version for about $3500. The associated rotating assemblies are about $1900 for a 427.

Please tell me a TPI is not going on top of this engine.

 

A 4.25" bore with a 4" stroke would be 454 cubes, not 427. It's the same bore/stroke as a 454 BBC. A 427 uses a slightly shorter stroke. A 427 BBC uses the same crank as a 396, but with the bigger 4.25" bore. For the dimensions it doesn't mater whether or not it's a BBC or an SBC, I just noted those examples fro point of comparison.

With a big stroker like this I'd probably just buy a shortblock from Bill Mitchell. You can get them assembled from Summit too. Then you get a warranty on all those expensive components. They're selling complete engines carb to pan for less than $9,000 now for a 530 horse engine.

 

I meant the block has the ability to be bored up to 4.25".
The World rotating assembly for a 427 has pistons for a 4.125" bore with a 4" crank.

 

Oh, that makes sense then. You wouldn't want to punch it out all the way up front anyway, or at least I wouldn't. You always want to leave some meat for a future rebuild. The great thing about this block is that even at 4.25" it's still got 0.2+" of material inthe cylinder walls. The only thing that limits it is that the bores are ready to collide at 4.25" There's very little meat between the cylinders. They do offer a crate 454 SBC too. There are rumors that there will a fuel injected crate engine of 427-454 cubes soon too that will come ready to run. Expect about 530 horses and enough torque to make a Diesel blush.