[70 nova]

What is the strock and bore on a 427 small block. what do i need to build one.

[78SilverShark]

I don't have the exact specifications of a 427 (they are most certainly in the Knowledge Base, and there is a recent thread..in the last day or two..that somebody listed them all out), but the 427 is certainly not a small block. It's a big block.

Good luck with the engine!

78SilverShark

[corenele]

i think u can get a sb427 from a 4.250 bore and a 4 inch stroke but u need a after market block to do it$$$$$$$$$$

[Mikey123]

4.125 bore x 4.00 stroke = 427 inches in sbc, 4.185 bore x 3.875 stroke = 427sbc, 4.250 bore x 3.750 stroke = 427 bbc, 4.250 bore x 4.00 stroke = 454 bbc ???

[chevy302dz]

A 427sb is going to be a expensive bulidup for starters your going to need a aftermarket block and a set of heads that can flow enough for those kind of cubes

[Forsaken502]

are you talking about a sbc or a sbf? I know the ford 351 (not sure which designation, windsor, michigan/modified/clevland) can be made into a 427. I read the article in a mag, I'll see if I can find it later.

[Sandflea427SS]

I think one of the easiest ways to do a 427 Small Chev is with a World Mo-town block. Bill Mitchell just went to a 454 with the same block. It turns out he was waiting for Fel-pro to make some good head gaskets. The walls are reaaallly getting thin at 454 by the way! The block is a bigger deal than the heads. You can buy cnc ported heads that will flow enough.
Check out the Bill Mitchell 600 horse 454 crate engine

http://www.theengineshop.com/newstuff8.shtml

and the Bill Mitchel 427 crate engine

http://www.worldcastings.com/littleblock.shtml

[78 monte]

To me getting into exotic large cubic inch small blocks is kinda a waste.Cause a 427/454 BBC has way better head options as compared to anything availible for a SBC.Buy the time you get done buying a World block,special crank,rods,pistons and super heads.You coulda spent less into a BBl shortblock and spent more time on there better larger port heads.
Just my opinion.

[1BAD80]

You do NOT need another new block to build a 427 small block motor. You can build up to a 434 with a old style 400 block.
It's very expensive and a lot of block work and planning.
First thing you do NOT need a after market block.
I have built one and its in my Vette. No matter how you want to build it or buy one complete your talking between $7 to $10K if you want to build it correctly and depends on the quality of the parts, you get what you pay for. I advise unless your pockets are large and have the time to build it your-self, I recommend you build a good strong 406 motor.
With good heads, some flow very close to BB heads.
I have the use of the machine shop on the dragster that I pit crew on and do my own work, and know the right person to get the parts from.
I have over $6k in parts alone and stopped counting. But I like small blocks better than BB for the street and weight. Then you have to think of all the chassis upgrades to take the HP.
With the new style of cam location in the Rocket blocks from GM you can build a 504 small block (they use sleeve's) no worry about to thin on the bore, Sonny Leonard built one, runs on 93 octane dynoed at 1020 HP, 875 ft.lb. torque. The GM blocks have most of the clearance's already machined. Along with their connecting rods ground for clearing the cam.
George

[rick458]

Has anybody built one on the World Motown block?
It says you can go to 414 without any further machining

[Mad Maggot]

I know World sells a crate engine 454 smallblock, called the Hardcore 454, it has the same bore/stroke as a big block 454 (4.250 bore, 4.000 stroke). Shafiroff also sells a 454 cube small block, and also a 472 small block, both as crate engines. All of these motors use the World Motown block, which is great because it is dimensionally the same as a stock SBC, making for better parts compatibility. If you are serious about building a big inch small block, it would probably be easiest with this World block. Just don't use boost or nitrous with it, the walls and head gasket will not take it.

[firestone]

If you have the money to do it, and build it strong, here is an idea for parts.

Engine shop short block $4600 assembeled.
http://www.theengineshop.com/sbkits3.shtml

AFR 210 comp $2000 or street $1300 ported heads
Comp:
http://www.jegs.com/cgi-bin/ncommerc...47&prmenbr=361

Street:
http://www.jegs.com/cgi-bin/ncommerc...60&prmenbr=361

Victor jr intake:$219
http://www.jegs.com/cgi-bin/ncommerc...61&prmenbr=361

Comp cam:314HR cam (252 252 @.050 .600 .600 lift) ~ $600 with lifters
http://www.compcams.com/Technical/Cu...ML/128-169.asp

This motor would have a powerband of around 2700-6700 RPM and depending on which heads you use make between 575 and 625 hp. If you wanted to use a mech roller cam you would be looking at 600-650 hp.

Good luck
Adam

[Rick WI]

Originally posted by 70 nova
What is the strock and bore on a 427 small block. what do i need to build one.

Mickey gave you the answers on the bore stroke question. As to what you need there are a ton of options. A stock 400 block will work but you must sonic check the bock and I would recommend a short fill of hard rock. The downside is you are limited on the stroke and with these big small blocks I like to have a big stroke for a street application. That builds torque down low. If you want to do it better than I recommend the Dart block. The Dart block is setup with spread rails and a raised cam location. It's available in multiple deck heights and offers tons of options for the build up. The main benefit is being able to fit in up to a 4.250 crank with very little grinding. Keeping the stroke up allows you to start off with moderate bores allowing for a lot of rebuilds over the future. Going with a World block your at the end of the rope almost before you start, due to the huge bore and thin walls. Bottom line I'd prefer to see a Dart block with a 4" stroke. Your initial bore will be 4.125 and you'll have overbores up to 4.20 or so.

These blocks can take silly amounts of nitrous, but you need to run an MLS gasket for sure on the World if you do (if they are available). On the Dart either an MLS, Fel Pro or Corteco White Seal will work fine and are all available.

Heads are very important with these small motors. They can consume huge amounts of air. For heads you want at least a 220 runner and I'd suggest a Victor E intake. The Victor Jr is too small. The Super Vic is even worse (no plenum volume). That should make power up to about 6000 before falling off. Seen and done lots of real dyno pulls on theses motors. Cylinder heads should flow over 300 on the intake and over 200 on the exhaust if you want it to breath and make HP upstairs. A 434 with AFR 220 heads and a camshaft in the 260 range will make a bit over 600 HP and be done in the 6000 to 6500 range at most.

We dynoed a 434 last week with ported to the max World Products Sportsman heads that flowed in the 270 range and 13:1 compression for a dirt car in a restricted class. It only made a tad over 500HP. With the heads stock it made 450. Point being old tech type heads are not a good match for these motors, unless you are restricted by a racing class.

Bottom line is you'll be spending some money on heads. It is difficult to get too big of a head with a small block this size or too much plenum volume. The last dyno runs I made on my 454 small block it made over 500 ft/lb of torque at 3000 at the rear wheels with a 240+cc runner and makes power to 6500, so big heads will not kill the torque on these motors.

You will want to run a carb in the 850 to 950 range. Camshaft can be in the 240-249 range @ .050 and still be very streetable. You will also want big headers, at least 1 7/8. Three inch exhaust is a must.

Crank and rods, your not going to want to run the cheap eagle or cast Scat stuff with something like this. You want a good forged crank and a quality set of rods. Likewise with the pistons. Everything will need to be balanced and should be internally done.

[firestone]

I agree that the 220's would be a better match, but if you use the 220's you have to use a shaft mount rocker, and I thought the 227's may be a little much for the combo. I think the best way to match the parts would be to buy parts based on their recommended powerbands. Having a big motor like this would be would bring the powerband down alot, but the parts would still be matched. Rick, it sounds like you have some experience with large motors like this. I was just kind of curious what you think about my reasoning about the parts I listed for it. I choose them based on their recommended power bands, do you think that is a good idea? If so, if he went with a 220 runner head, a cam with a 240-249 2 .050 duration would be a mismatch of powerband by around 2000 RPM. Is it wrong to have this assumption? Here are the powerbands of the parts I listed, tell me what you think.

AFR 210cc heads 3000-7500
victor jr intake 3500-8000
314HR 3500-6500

It seems to me that these parts would act well togather although only making power to around 6000 RPM, because of the cubic inches.

Here is the recommended powerbands of the parts you listed

AFR 220 heads 4500-8500
Victor E intake 4500-8500
a cam with .244 @.050 duration ~ 3000-6000 RPM (304HR)

I agree that the 220s and the larger intake would make better high end power, but I would think you would have to run a cam in the 260-270 @ .050 duration range to make it match the rest of the parts. Am I mistaken?

Thanks
Adam

[Rick WI]

Adam, I do have lots of experience with big small blocks and have run a 454 small block in my Camaro for over 3 years now. Before they were known about in the mags. The shop I have my dyno in also does a lot of big small block builds up for the dirt car guys and we just did one for a buddy of mine.

You can't really look at the catalog specs on camshafts and intakes and apply to a motor like this. You have to take into consideration that they are more like big blocks. So you pretty much throw that stuff out the window. Like us guys the big small blocks like lots of head. With the bigger bore and stroke your going to get velocity through a bigger intake and runner that you won't have on a 350 or 383. If you have too small of a head and intkake you'll shear the mixture due to too high a velocity and it will die on the top end due to poor mixture quality and not enough volume in the intake plenum. Keep in mind a big block head with 300cc runners is not a big head these days. An AFR 210 head is not going to make power to 7500 on a 427 small block.

Here are the thoughts on the components. Unless you go with a cylinder head such as an 18x Brodix or All Pro 17 degree with a runner volume in the 250-260 range your not going to get a big small block to rev to the moon with a reasonable duration camshaft. On a 427 if you crutch a small head with a huge by large camshaft (like 260-270 @ .050) to get the motor to rev you'll ruin the powerband below the peak and it will be hard to live with day to day. It also is not going to make that much more power on top. So, for a motor that will see street driving put a head on it that will feed it some air along with an itake with some plenum volume and cam it reasonable. Let the heads do the work on the top, which will be around 6000 or so with 220's, and with the reasonable duration you will build tons of torque down low and it will still make power on top in a reasonable RPM range.

For my application I am running All Pro 22 degree raised runner heads with about 240cc runners. They flow 340 on the intake and 240 on the exhaust. My cam is a 260/265 @.050 and lift is .704I and .669E on a 114 LDA. I run 12:1 compression and also spray it will nitrous. I have about 12" of vacuum with these specs.

My intake is a very worked over Super Vic set up for fuel injection with a 1500 cfm two blade throttle body. Both the runners and plenum are paper thin trying to make this intake work. I have spent a considerable amount of time trying to "free" this motor up on the top end this past winter with head tweaks and intake tweaks, and minor cam timing changes. Even wtih all these tweaks this past winter I doubt it will still be building power at 7000. I'll be happy if it builds strong to 6500. I'll know this coming week as it's going on the dyno for pulls.

We did a 421 this past summer for someone. Due to it going in a vette we were stuck right off the bat with a performer intake due to hood clearane issues. The customer will also be auto-xing the car a lot so this isn't all that bad. That motor got a set of ported Edelbrock E-Tec heads. Those runners came in right around 210 after porting. We did put that motor on the dyno but never were able to get numbers on it due to lightning damage, from a storm, on the data aquisition system. I suspect that motor will be all done by 5500 at most but it will make a boatload of torque.

What is really surprising to folks when we do a dyno pull is how in most cases the motors stop making power much lower than what the customer, or in some cases us, would have expected. Even if the motor was in a car prior and just got freshened the customer would swear it still pulled to say 6500 but in reality it dies at 6000 and stopped making power in the 5500 to 5600 range. What is also surprising for folks is how much power they don't make as well.