74 vert

Is anyone running a 427 small block. What block should I use to punch it out to a 427? I would like to be able to use hooker side pipes with a 427 small block setup. Any ideas or suggestions and can I make this work in my 74 vert? :smash:

PatsLs1vette

4.00 stroke in a 400 block should be somewhere around there.

[Modified by patsnitrovette, 7:47 PM 2/26/2003]


[Modified by patsnitrovette, 7:50 PM 2/26/2003]

Pete79L82

To build a 427 SBC you will need a standard bore (4.125) block with a 4.0" crank. You can use a stock 400 block but you will have to make sure it is a really good one to take that much arm. You would be better off to start with a World Product Mo-Town, Dart Little M, or a GM Bowtie block. Which one depends on if you want to use a 350 (2.45") or a 400 (2.65") main journal crank.

You will be able to run your sidepipes if you stay with a standard configuration (non-raised exhaust port) head.


[Modified by Pete79L82, 6:57 PM 2/26/2003]

Aaron76

There is a company that has re enginered the small block adn they claim to get the dispalcement over 427ci


this is the website. http://www.theengineshop.com/engine.shtml

Corey_68

You can even make a 454SB, but will cost some serious $$$. Cheaper to build a REAL Big Block and make more power doing so.

But what a sleeper a 454 small block would be! :eek:

Pete79L82

I hope you can get more than 427 CI out of that block as it is a picture of a big block! :rofl:

Bill Mitchell is one of the owners of World Products so that is a picture of a Merlin big block.

Actually 427 CI in a small block is kind of small by todays standards. All of the blocks I listed above can go as big as 468 if you get the raised cam versions.

427V8

Been there done that have the bill for it. :smash:

I wouldn't recommend it.
Why?
There's no point.
You can build a 406 to just about the same power levels.
The pistons arn't custom.
You don't have to gring into the side of the block so the rods don't hit.
No one believes you anyway.
You have a limited choice of heads, since you need big chambers.

Unless you have too much money to throw at it just build a nice 406, it will do anything the 427 can do unless you want to make it an all out unlimited class car. ( but then put in a big block )

74 vert

ok, thanks, the 406 seems more common.

gdh

It seems that once you get over a 406 the laws of diminishing returns really start to kick in when you factor in the cost/add'n hp. I never knew that one could go up to a 468 sb. What advantages would a 468 sb have over a 454 bb, this is not a flame type of question - I am just interested in the adv. and disadv. of this. :cheers:

Corey_68

The only advantages are room and weight. The BB will make more power because they have larger heads and can accompany larger valves. To my knowledge there is no 345cfm 118cc 2.30 valve head for a small block. So you are really limited on heads/air flow.

Pete79L82

To build a very potent big inch small block does take a lot of money. The last 462 ci that I built put out just over 800 HP but cost just under $30.000 complete. When you get to that size everything has to be a special item. Raised cam, spread rail blocks, rolled over cylinder heads, special oil pans, shaft mounted rocker, offset lifters, wide intake manifolds, custom pistons and a TON of machine work to make everything fit.

As for Corey's comment about cylinder flow, Brodix makes a -12 series head that flows over 400 CFM while still keeping good velocity. Plus they have a very small chamber so you can get good compression without having to fight a piston dome like with a big block chamber. That is one of the things that make a small block so throttle responsive.

The biggest advantage to big inch small blocks over a big block is rotating mass. By having a lighter crank, rods, pistons, and valve train a small block will accelerate faster than a big block, just a fact of the laws of physics.


Taking a small block and a big block of equal cubic inch and of equal horsepower the small block will out accelerate the big block every time. The disadvantage is it is going to take a lot more dollars to make the small block equal in cubic inches and equal in horsepower.

If you ever have the opportunity to drive a high HP big inch small block don't pass it up. Only then will you know that if dollars are not a consideration and you want to cubic inches under 468 you would always choose the small block.

But for most peoples budget it is wiser to build a medium inch big block at a fraction of the cost.





[Modified by Pete79L82, 8:24 PM 2/26/2003]

74 vert

(Pete79l82), very good reply. Man, I'm learnin' all sorts of stuff here. :flag

LT1driver

what combo makes a 406 and what is the ave cost if you have the block already (350 block??? :confused:

Fevre

Pete

Hate to diff with ya but if you are doing a low buck build up the bb is a better value and faster in the 1/4.

http://www.chevyhiperformance.com/te...30/index4.html

I have to say that I don't think the comparison is apples to apples and think that if done right the sb could have been much better. I am a sb fan so I don't take this the wrong way.

:cheers:

Pete79L82

As I said to build a good BIG inch small block is not cheap. In the artical they spent $850.00 more on the big block to give it a 41 HP advantage. If they would have spent 850.00 over the price of the Dart II heads on the small block they would have been more equal in HP and the outcome would have been completely different.


A 406 is a 400 block bored .030 over (4.155") with a 3.75" stroke. In that combination you cannot use a 350 block.

A common configuration with the 350 block is a .030 bore (4.030") with a 3.75" stroke giving you 383ci. (reasonably priced)

Or use the .030 350 block (4.030") and use a 4.00" crank giving you 408ci. (more expensive)

If you do a search there should be plenty of threads on the cost of a 383 combination.



[Modified by Pete79L82, 9:45 PM 2/26/2003]

Russ Bellinis

If you live in California, and have a car newer than 1975, you can't legally use a big block in it and still register it for the street. A small block looks the same from the outside regardless of internal discplacement, so it will get by the visual inspection so all you would have to do is make it run clean enough to pass the sniffer. The only way to get a big block past the visual inspection is to find a smog tech who can't tell the difference between a small block and a big block by looking at it.

MotorHead

I have a 400 block in the basement right now and went through all the combinations 406, 427, 434 etc. but I tink it is going to be a 406 because you don't need any exotic parts and no extra machining is required that keeps the price down and I would imagine the power difference is not going to be that great either once I get through with it.

I like the comment above for reasons why not to build a 427 " No one will believe you anyway " now that's my kind of humour :D

73 LS-4

Pete, there's parts of your argument that I don't get, maybe you can clear them up for me.[QUOTE]


1. As for Corey's comment about cylinder flow, Brodix makes a -12 series head that flows over 400 CFM while still keeping good velocity. Plus they have a very small chamber so you can get good compression without having to fight a piston dome like with a big block chamber. That is one of the things that make a small block so throttle responsive.

Granted there are some very good flowing smallblock chevy heads out there now, but there basic valvetrain layout restricts their maximum flow, Rats with their canted valve heads normally have an advantage and we all know there are some huge flowing BBC heads out there. The BBC's biggest asset is in it's head design. For comparison try and find a stock production smallblock chevy head that will outflow my LS-4's 049 heads, which is just a large oval port head not even a rectangular port.

2. The biggest advantage to big inch small blocks over a big block is rotating mass. By having a lighter crank, rods, pistons, and valve train a small block will accelerate faster than a big block, just a fact of the laws of physics.

True, but a lot depends on the parts used. I doubt a 427 SB's internals weigh a whole lot less then a 427 BB's internals given the same alloys used in both. Given equal displacement I'd think the 427BB would accelerate better becouse it has a shorter stroke then a 427 SB. As we all have seen the best revving engines have always been large bore small stroke engines. The 427BB is no exception to this rule and was known for it's high rpm ability.

3. Taking a small block and a big block of equal cubic inch and of equal horsepower the small block will out accelerate the big block every time. The disadvantage is it is going to take a lot more dollars to make the small block equal in cubic inches and equal in horsepower.

Should quantify this as well, should say equal hp and equal torque. given equal hp and equal vehicle weight the one with the most torque wins. Given equal hp between a SB and a BB, you normally see the BB with the torque advantage but not always.

4. If you ever have the opportunity to drive a high HP big inch small block don't pass it up. Only then will you know that if dollars are not a consideration and you want to cubic inches under 468 you would always choose the small block.

Haven't had the chance to drive one, but if someone wants to volanteer one I'd be more then happy to take it for a spin.

5. But for most peoples budget it is wiser to build a medium inch big block at a fraction of the cost.

Don't get me wrong here, it must sound like I don't like SB's but that couldn't be farther from the truth. I do however find the biggest advantage to a SB chevy is in it's power to weight ratio. Normally your talking 200lbs less weight in a SB, that's .2 in the 1/4 from weight alone, even more of an advantage if you road race or autocross (less weight to turn and stop and better weight balance). For pure power potential, it's hard to beat the BBC with it's canted valve heads and large bore potential.



:cheers:
Pat Kunz

8T1-7T9 BIONIC VETTE

I hope no one takes this wrong.....however I'm very curious to see some BB Corvette quarter mile times.....Maybe I'm not very observant and missed some posted times of the big blocks through the quarter mile......
I've always been partial to the chevy small blocks since they seem to perform well out on the street and on the track....
So if some of you guys with big blocks can post some times and speed through the quarter I guess this would sort of answer the question......Should I buy a BB or a SB? Thanks for the replies..... :seeya Cappy

Pete79L82

Don't get me wrong, If you are going to build a engine on a budget and use stock production parts you don't want to build a big inch small block.

1. Granted there are some very good flowing smallblock chevy heads out there now, but there basic valvetrain layout restricts their maximum flow, Rats with their canted valve heads normally have an advantage and we all know there are some huge flowing BBC heads out there. The BBC's biggest asset is in it's head design. For comparison try and find a stock production smallblock chevy head that will outflow my LS-4's 049 heads, which is just a large oval port head not even a rectangular port.

BBC heads are not an asset in anything other than drag racing. In any form of racing that you have to get on and off of the throttle the BBC head is very weak. Even in drag racing the trend is to smaller ports on a big block. Rehr-Morrison and Sonny Leonard are even going back to oval ports on there top end motors.

2. True, but a lot depends on the parts used. I doubt a 427 SB's internals weigh a whole lot less then a 427 BB's internals given the same alloys used in both. Given equal displacement I'd think the 427BB would accelerate better becouse it has a shorter stroke then a 427 SB. As we all have seen the best revving engines have always been large bore small stroke engines. The 427BB is no exception to this rule and was known for it's high rpm ability.

You will not find BBC cranks under 41# and good BBC steel rods under 500 grams or SS valves under 110 grams. Even with the longer stroke a 427 SBC will out accelerate a 427BBC with everything else being equal. The key word here is EQUAL.

3. Should quantify this as well, should say equal hp and equal torque. given equal hp and equal vehicle weight the one with the most torque wins. Given equal hp between a SB and a BB, you normally see the BB with the torque advantage but not always.

If you look at the artical that Fevre posted you will see that the SBC made more torque that the BBC up untill 3800 RPM so it is a misconception that a BBC will have more torque than a SBC.

4 and 5 are subjective.


As I said earlier, If you are on a budget or are using stock componets then it is more realistic to build a big block.
If you are going to build a big inch small block there is nothing you can use from any production car and get good power. Everything is special items. Ask 427V8 or Monty what it cost to build a big inch small block. They are not cheap or for the faint of heart.

Pete