Would this block and crank combo work?

[Gordz32]

I've been kickin around some Ideas for a new engine for the chevelle. This one hit me hard. Is it possible to have a 400 block with a 327 crank, has it been done, any problems you can think of, Any info would be great fellas. THanks, Chris

I'm re-thinking this for the future: How do you guys think this combo will work for a turbo motor, Quick revving, high revving, with an aprropriate sized turbo and a blow threw carb

Speedomotive sells a destroke kit exactly what i'm looking for:http://www.speedomotive.com/p-60-chevy-400-to-350-with-6250-long-rods-destroker-kit.aspx

I'd probably start with a new sportsman block

[Norwoodx55]

You would need a large journal 327 crank, main journal spacers(typical of a 377"), and possibly some custom pistons. Should end up at 350" or a little more. Would be a revvin' motor.

[LowBuckX]

Here is an old article that one of the mags put out. Called "The 350 Chevy should have built" They use 6.200 ford IL6 Rods but you can find this size on the market now. Also a few companys offer pistons for this too. Read this article http://purplesagetradingpost.com/sumner/techinfo/350%20chevy%20engine.html

[Kenova]

Use 6.250" rods and you should be able to use 400/406 pistons ment for 6.00" rods. To eliminate the bearing spacers, you could have a custom crank ground. It would add some cost to the project, but I think it would be worth the extra peace of mind.You could probably get away with going to small rod journals (2.00') too.
That old Hot Rod article is one of the few engine stories that have really stuck in my head. I've spent way too much time thinking about it.
Ken

[LowBuckX]

I know the feeling . Large bore,,short stroke,,, Long rods... whats not to love :seizure:

[USAZR1]

Yep,a 348" sbc that would kick butt.

[Gordz32]

Just wanted to say thanks guys, I'm going to continue my research, anybody know about the potential over heating and cracking problems associated with the 4oo blocks, I hear the 2bolt is less prone thant the 4 bolt but I want the obvious added strength of the 4 bolt. Any more infor is greatly appreciated thanks!

[Kenova]

The factory 4-bolt 400 blocks are the ones prone to cracking. The holes and threads break through near the bottom of the cylinders. This is where the cracks start. A 2-bolt block with aftermarket splayed 4-bolt caps is supposed to be much stronger. With a shorter stroke and longer rods, there will be less side loading of the cylinder walls.
The only time I ever had trouble with overheating was with my first 400. It replaced a 283 which was still running a 6 cyl. rad. I didn't replace the rad :pat: , so of course it overheated :slap: . After putting a bigger rad in the car, I had absolutely no problems. Keep in mind that it may be a 400 block, but the engine will only displace 350 ci. (less heat). It's also a good idea to drill the extra steam holes in the cylinder heads. Some say it's not necessary, but why take the chance?
Ken

[LowBuckX]

A studded 2 bolt 400 bottom end would be fine for up to 500 or more HP with the short stroke combo.

On the Speed-o-motive kit it sounds good but Id opt for the $400 upgrade to the 4340 crank.

[SStrokerAce]

A studded 2 bolt 400 bottom end would be fine for up to 500 or more HP with the short stroke combo.

On the Speed-o-motive kit it sounds good but Id opt for the $400 upgrade to the 4340 crank.

dont want to step on any toes but...

All depends on the RPM level and the mass of the rest of the parts. With carefull parts selection a street type motor can go to 7000rpm and stress the crank the same as a 6000rpm stock bottom end 350.

In the case here the piston speed is going to be very low but the piston mass is going to be higher due to the larger bore.

FWIW I'm building a 355 right now that's in the high 500hp range, has a bobweight of 1593g (vs. 1850g stock) and with a little help of some physics and math the force acting on the crank at 7000rpm is the same as the stock 350 at 6000rpm, therefore a new cast steel crank will be more than adequit for the job. I could have reused a stock crank but I would rather have zero fatigue in the crank to start with and have the crank come with a radius in the edge of the journals to start rather than have to grind one in.

I like the big bore, short stroke idea, but in reality a 350 stroke or 383 stroke is a better idea since you are not limited by a cube rule. A 377 or 406 would make for more fun on the track or street.

Bret

[Gordz32]

btt for a newer idea!

[Twins Fan]

Your signature says you ahve a 540 in the Chevelle. Why are you worried about building a small block, is it for another car?

It would be an interesting and different combo though, and it would rev to the moon.

[Lowend]

I guess it's time for me to repost this again....



Speed-O-Motive may be the worst engine builer in the country... awful reputation that they have earned.

I'm gonna give my engine building speech (again)...

All machine shops pay about the same for engine components. Because of the market, there is virutally no profit margin (3% to 20%) to be had on any engine components.
So using this logic, if any one is selling a shortblock for signifigantly less than every other shop they are either
1) cutting corners on the machine work
or
2) using substandard parts somewhere

[6'9"Witha69]

I guess it's time for me to repost this again....I knew someone who worked there (Speed-O-Motive) years ago. Assembled a "blueprinted" big block in 3 hours so the customer could pick it up. They didn't cut corners on machine work, but the assemblers were knuckleheads. Don't know how different it may be now.

[Gordz32]

Yes the chevelle has a 540, but this idea is for something else, As for speedomotive, I'm not looking to have them build the motor, just saw that they have the rotating assembly. I too have heard terrible stories about them. Just wanted info or ideas on a turboed, 400 de stroked to a 350.:yeah:

[Lowend]

If you are going turbo'd (considering the power and RPM levels you have to be looking at) I would be looking at Crower for the rotating assy. Light and strong.

[MonzaRacer]

OK as for a "blueprint " engine all of the blue print is done before assembly.
I generally have my engine aprts ready to go and can assemble and engine in 2 to 4 hours.
as for Speed o motive being a bad palce well I have bought parts from a lot of places and they are one of them.
As for parts prices well that where your wrong. If you buy 100 cranks from a company they can and will sell you the 100 lot cheaper.
I used to buy 500 and 1000 count Z28 spec SBC valve springs for super cheap over buying them 16 at a time.
I still buy them by the box but not as big a box and get a great price.
Lot buys are much cheaper and if you buy several lots you get even bigger savings.
But as for the rotating assembly I built one of these with a cast 307 crank and some spacers(lookup 377 spacers) nad it turned 7000 with out a hitch. I built a similar one but we used and old 302 large journal crank and it really was an rpm monster. Pistons are a fun task as back whne I did them they were VERY expensive. I really like Wiesco but ross,Venolia, SRP, and other can make you a great piston but try to keep your rod to stroke ratio right around 1.82 to 1.85 too long a rod kills the curve. We even used some heads that were found to be a little choked off for a 406 or 377. These things rock for winding engines.
Good luck

[sumfuncomet]

For anyone out there thinking about speedomotive....STOP!!! It would be the same as digging a hole in your backyard and burying your hard earned dough.These people are inept and dishonest Contact me and I will tell you my horror story

[wendell]

Pushing a Chevelle with a short arm 358 isn't going to be fun unless you have the money and gear to spin it to 8500+. Remember folks only race 5.0Ls, 310s, 358s, 360s, 410s... ect because the rules make them. You'll also notice that when given these displacement limits, they build motors exactly at the limit. There's no sense spending a bunch of money on a fancy little engine just to get smoked by a crate 383. If you've got a 400 block us it to it's full potential with a 3.85+" crank. especially with a heavy car.