big block rpm? [Archive] - Chevy Nova Forum

: big block rpm?


Shauns BB70
10th-February-2012, 06:22 PM
my car has a 1970 396 (402) not sure if its a 4 bolt main or 2. My question is how many rpm can a stock 2 blot main big block handle. The guy who built the engine said the cam should make power to 6500 rpm. I shift at 5300 cause im not sure if the bottom end will handle 6500. I cant remember if he said it was a 4 bolt or two. I know its a cast crank. Also I have a steel crank from a 427. can I make this work in the 396? Thanks guys!

MANGOPUPPY
10th-February-2012, 06:35 PM
my car has a 1970 396 (402) not sure if its a 4 bolt main or 2. My question is how many rpm can a stock 2 blot main big block handle. The guy who built the engine said the cam should make power to 6500 rpm. I shift at 5300 cause im not sure if the bottom end will handle 6500. I cant remember if he said it was a 4 bolt or two. I know its a cast crank. Also I have a steel crank from a 427. can I make this work in the 396? Thanks guys!
396/427 strokes are the same. I have a "STOCK" 2 bolt block (454) that I have no problem twisting to 7200. There are many more important parts giving the ability to get there. A steel crank is a good idea. You may never need to wind it up to the redline, but the dyno will tell no lies (well, sometimes). That would be a good place to start anyway.
In short, yes it will go there. Many folks get the wrong idea about 4 bolts vs 2 bolts. If I happen to get a deal on one, great. If not, great. Machine work quality is key. What type of cam is it? I'm assuming it is hydraulic.
oh yeah, I'm pretty sure its not a fourbolt. That's not too common..

koreyss
10th-February-2012, 07:04 PM
for a stock bbc 5,400 rpm would be the max I would go...if you want more ya gonna have to pay more...:yes: Crank, rods, push rods, etc... I would be glad to help but together a nice "Rat" !! Depends on your budget! but its soo easy to get power out of a BBC!!!:yes:

taz3
10th-February-2012, 07:55 PM
I twist my 402 2 bolt, cast crank to 7500 rpm!:yes:

rhorne12
10th-February-2012, 08:00 PM
If you have just stock but good condition parts and proper assembly, 6500 should be no problem at all. Valve springs would be my only reservation and if they are correct for the cam, you should be good to go.
I have done many, many BBCs and even 496 with stock two bolt mains have gone 7000+ with never any main or block issues. Not even mild supercharged.

taz3
10th-February-2012, 08:19 PM
If you have just stock but good condition parts and proper assembly, 6500 should be no problem at all. Valve springs would be my only reservation and if they are correct for the cam, you should be good to go.
I have done many, many BBCs and even 496 with stock two bolt mains have gone 7000+ with never any main or block issues. Not even mild supercharged.

^^X2^^:yes: That's where I spent money knowing the bottom end was solid.:yes:

levisnteeshirt
10th-February-2012, 08:32 PM
a 396, 427 ,,, 7500 used to be the standard rpm for 'em ,,lol ,,, a 2 bolt with a 4 speed i'd kinda worry about ,,, many many old write ups of tests with BBC's with 2 bolts going to 7500

one i remember the most was a stock 396 PHR mag built ,, they went stock everything , then they put a Lunati 268 @ .050 solid cam in it , a scorpion intake and a 850 and made 501 hp ,,, then they put a 125 NO2 kit on it ,, 2 bolt main ,, then they put a tunnel ram and 2 750 DPs on it ,,, winding it to 7500 ,, 538 gear in a Vega with 14 x 32 slicks ,, old school :)

koreyss
10th-February-2012, 08:35 PM
I don't know guys 6500 and 7,500 rpms is kind of pushing it with those skinny stock push rods and stock everything...High rpms and sinking hp and tq, the dyno will show...

Tommy
10th-February-2012, 08:37 PM
I twist my 402 2 bolt, cast crank to 7500 rpm!:yes:


Hey Paul,open your tach up and switch it to 8 cylinder.....


http://images.thetruthaboutcars.com/2011/06/VanTach-4-550x412.jpg :):)





Tommy :)

koreyss
10th-February-2012, 08:41 PM
Hope you got a backup motor!! LOL these guys are pushing you!!! if you hear a loud pop!! call a tow truck!! LOL!!

nukledragger
10th-February-2012, 08:47 PM
I twist my 402 2 bolt, cast crank to 7500 rpm!:yes:
Wow! Really? Then I bet Grumpy hates that he did all that research and development on steel cranks!!

taz3
10th-February-2012, 09:07 PM
Hey Paul,open your tach up and switch it to 8 cylinder.....


http://images.thetruthaboutcars.com/2011/06/VanTach-4-550x412.jpg :):)





Tommy :)
Come up, and you can reset it while I shift!!:devil:

Wow! Really? Then I bet Grumpy hates that he did all that research and development on steel cranks!!

I knew an engine builder up here that was light years ahead of his time, he set an NHRA record in an Pontiac Astro. He used to do all my BB's and man did he know his stuff!:yes:
I love the look from passengers, when they see the tach at 7-7500 as I grab the next gear, it's like :eek: :D

Tommy
10th-February-2012, 09:33 PM
Come up, and you can reset it while I shift!!:devil


That would be easy if your still trying to shift with that muncie shifter.... I'll fix your tach while your under the car getting the trans back out of gear :poke::doh:


Tommy :)

Tommy
10th-February-2012, 09:37 PM
I love the look from passengers, when they see the tach at 7-7500 as I grab the next gear, it's like :eek: :D


You really need to fix that tach Paul.... :moped:



Tommy :)

taz3
10th-February-2012, 09:39 PM
That would be easy if your still trying to shift with that muncie shifter.... I'll fix your tach while your under the car getting the trans back out of gear :poke::doh:


Tommy :)

The secret is I'm not racing when I'm shifting that high, so it don't have to power shift it. 2 ways to break a Muncie, hard launches and 7000+ rpm power shifts.

You really need to fix that tach Paul.... :moped:



Tommy :)

Nope, go big or go home!!:yes::thumbsup:

nukledragger
10th-February-2012, 09:46 PM
I knew an engine builder up here that was light years ahead of his time, he set an NHRA record in an Pontiac Astro. He used to do all my BB's and man did he know his stuff!:yes:
I love the look from passengers, when they see the tach at 7-7500 as I grab the next gear, it's like :eek: :D
Everyone knows someone that was "the best engine builder no one knew about". You're overstating the facts which may lead this poor guy to break his motor. Please allow someone with machine shop high performance experience to answer the original posters question.
Cast 402's WILL rev to 7500, and Muncies WILL shift at 7500.....about three times. Then they spit chunks all over the street.
My advice to the original poster, ask your machine shop these questions. They actually build engines! This is probably not the information you want to learn on a "chat board" where no one is invested financially in your engine.
JMHO

taz3
10th-February-2012, 09:55 PM
Not quite, his credentials speak for themselves on both sides of the boarder and he was also employed through GM. He passed away a few years ago, but as I mentioned, all his accomplishments still stand, this is not my opinion of him, it's actually who he was, a well respected engine builder up here in Southern Ontario. Any one who is affiliated with drag racing up here, is well aware of who he is.

Since his passing, I am now the only person, who can prove a true 69 SS Nova without paper work, so it's not another "I know someone story" just because he didn't make the big headlines. He as well known up here as Grumpy is down there!

nukledragger
10th-February-2012, 10:01 PM
Since his passing, I am now the only person, who can prove a true 69 SS Nova without paper work, so it's not another "I know someone story" just because he didn't make the big headlines.
Assuming what you say about his accoplishments is true (which i question because you dont reveal this master engine builders name), you are not him. Therfore, not being a machinist, you can not accurately answer the question.
If you truely follow the creed "Nova People Helping Nova People", you will let this poor guy seek advice from those whom have first hand (not second hand) knowledge of the subject.

taz3
10th-February-2012, 10:07 PM
Assuming what you say about his accoplishments is true (which i question because you dont reveal this master engine builders name), you are not him. Therfore, not being a machinist, you can not accurately answer the question.
If you truely follow the creed "Nova People Helping Nova People", you will let this poor guy seek advice from those whom have first hand (not second hand) knowledge of the subject.

Well, first off he's dead now, so I can't really hook him up any more!:rolleyes:

I've never lost the bottom end from any BB he built for me, so....

Number 690 on the list Llyod Ulmer, not quite an everyday joe accomplishment.
http://www.draglist.com/lists/lpsq32.txt

Tommy
10th-February-2012, 10:11 PM
Since his passing, I am now the only person, who can prove a true 69 SS Nova without paper work, so it's not another "I know someone story" just because he didn't make the big headlines. He as well known up here as Grumpy is down there!


What? Are you serious Paul? You really believe that don't you..... That's one of the funniest and saddest things I have heard today....



Tommy :)

nukledragger
10th-February-2012, 10:18 PM
Exactly how many big blocks is that? And how many drag strip passes did you make? Im assuming you raced in a super stock or stock eliminator class?
And if he in fact was the greatest engine builder who ever lived; him being deceased means he can no longer build an engine for the poor guy that you're telling to shift his motor at 7500rpm.
So that being said, lets participate in that "creed", and let him check with a reputable engine builder for advice :), as opposed to someone he doesnt know who has bunches of big blocks built by a guy that no longer is above ground.

taz3
11th-February-2012, 12:06 AM
Exactly how many big blocks is that? And how many drag strip passes did you make? Im assuming you raced in a super stock or stock eliminator class?
And if he in fact was the greatest engine builder who ever lived; him being deceased means he can no longer build an engine for the poor guy that you're telling to shift his motor at 7500rpm.
So that being said, lets participate in that "creed", and let him check with a reputable engine builder for advice :), as opposed to someone he doesnt know who has bunches of big blocks built by a guy that no longer is above ground.

When did I post he was the greatest and where is it posted, that I told anyone to shift at 7500rpm?:confused:

I posted I twist my 402 2 bolt, cast crank to 7500 rpm! you're implying something else.

Reread the original question before you start bashing my response, that is nothing what you are implying.

taz3
11th-February-2012, 12:10 AM
What? Are you serious Paul? You really believe that don't you..... That's one of the funniest and saddest things I have heard today....



Tommy :)

Not at all, it was simply to entertain you for the day Tommy!:)

nukledragger
11th-February-2012, 01:38 AM
I posted [B]I twist my 402 2 bolt, cast crank to 7500 rpm!/B] you're implying something else.

Reread the original question before you start bashing my response, that is nothing what you are implying.

Paul, go easy there fellow Nova fan. No one is bashing, that wouldn't be polite. When YOU make a statement like "I shift my cast 402 at 7500 rpm" in a thread where a gentleman has asked about the RPM potentional of a big block, you Sir have in fact implied (ie given the impression) that these motors can easily handle it. If you were simply touting the strength of your specific motor, then your original statement should have been followed by, "however, not all cast big blocks were built to the extent of mine". If you were actually NOT implying anything, then the statement had no business being in the thread, because now the original poster may think he can go wing the guts out of his motor.

Regarding your statement about being the only person who can identify '69 SS cars; I thinks that's outsanding. As a matter of fact, I would like to formally invite you over to the Yenko site to share this expertise, or at least offer the service (for a fee obviously) to those folks to "certify" their cars for them. I'm sure they would be excited to have iron clad confirmation of their cars. After all, we're all in this hobby to share...aren't we??? I can't imagine that someone focused on NPHNP would want to keep that informatio to themself....

Shauns BB70
11th-February-2012, 01:53 AM
Well I know im just a shade tree mechanic and have alot to learn but im sure even if it will hold at 7500rpm, its not making power any longer. Thats ok though, im only looking for 6000 to 6500 frequently. thats really why i asked about the steel crank. I really need to get to the dyno and see for myself what she is pullin instead of taking the builders word for it. that way i can see if she even will make power at 6500 like he claims. If i short shift at 3500 she really blows the tires off which makes me think 3500is where my torque peak is, and if my torque peak is at 3500 im kinda thinkin max hp is somewhere in the neighborhood of 5500 give or take. Am i thinking right? really wish i knew what cam was in it. i really appreciate the input guys please keep em coming!

asteeler4life
11th-February-2012, 02:02 AM
FOR ME IT'S WHAT YOU WANNA DO WITH IT, IF YOU WANNABE THAT SLUGRUNNIN' AROUND TOWN WITHA BIG MOTOR WITH NO GUTS, DO SO, I'LL SEE YOU SOON, :yes:
BUT IF YOU'RE REAL WITH IT, DO THE FULL WORK ON IT.

MANGOPUPPY
11th-February-2012, 05:37 AM
Hey Paul,open your tach up and switch it to 8 cylinder.....


http://images.thetruthaboutcars.com/2011/06/VanTach-4-550x412.jpg :):)





Tommy :)
Holy s***, that's the funniest thing I've heard all day!!!

65 Post
11th-February-2012, 07:52 AM
I've run 396/402/427's for over 30 years and one of the best engines I've raced was a cast crank, 2-bolt, 402 with 12 1/2-1 compression. That engine ran 72-7500 every pass and I NEVER had a crank problem. Yes I run a steel crank now, but that what was more available back then. Engines will naturally live longer at a lower rpm if it's built for it. But something else to consider in his combo is, what heads and cam is he running? If it's a hydraulic cam and oval port heads, he'll be limited to around 6500rpms. Not saying it can't go higher, but that's about it for making power. I've never driven over a cast or steel crank in a two bolt block. And if I remember correctly, red line on a SS396 car with a 325/350hp combo with hydraulic cam was around 6000 from the factory. The 375 horse engine was higher with a solid cam. Dave

taz3
11th-February-2012, 08:12 AM
Paul, go easy there fellow Nova fan. No one is bashing, that wouldn't be polite. When YOU make a statement like "I shift my cast 402 at 7500 rpm" in a thread where a gentleman has asked about the RPM potentional of a big block, you Sir have in fact implied (ie given the impression) that these motors can easily handle it. If you were simply touting the strength of your specific motor, then your original statement should have been followed by, "however, not all cast big blocks were built to the extent of mine". If you were actually NOT implying anything, then the statement had no business being in the thread, because now the original poster may think he can go wing the guts out of his motor. A steel crank would be a better option an open chambered heads breathe better than closed too.

Regarding your statement about being the only person who can identify '69 SS cars; I thinks that's outsanding. As a matter of fact, I would like to formally invite you over to the Yenko site to share this expertise, or at least offer the service (for a fee obviously) to those folks to "certify" their cars for them. I'm sure they would be excited to have iron clad confirmation of their cars. After all, we're all in this hobby to share...aren't we??? I can't imagine that someone focused on NPHNP would want to keep that informatio to themself....

My intentions were not to miss lead you, but simply to inform you, it is possible to do.:yes:
As Nuckledragger mentioned many things need to be in place to achieve 7500 rpm, as my engine does. My response was nothing more than to inform you that it can be done. You'll really need to know your valve train specs to understand why your engine is falling flat after 5500 rpm. I would certainly think a reputable engine builder, should be able to assemble a cast crank, 2 bolt and the correct valve train assembly, that would be capable of 6000-6500 rpm safely.

As for the Yenko members, the last time I spoke some of them restoring a Yenko Nova at a US show, and offered them some information on textured painted dashes, they told me no, it was factory over spray, not textured paint. Yet, oddly enough there is an unaccounted digit, on the trim tag to support it, PPG paint codes for it, and people like Jerry MacNeish who are aware of option and paint. While the Yenko folks could really benefit, so can people wanting to clone these cars for profit, it's the only reason I don't publicly post it. That's why I've remained here were NPHNP is exercised.

Sorry for the high jack.:(

65novaken
11th-February-2012, 08:16 AM
i would like to see the parts list and builders assurance and dino results before i ran my BB at 7500. forums give out a lot of great info dont get me wrong but like mentioned earlier it is the net and everythings true on the net isnt it?:rolleyes:.rember......theres alotta over reved BBs used as boat anchors.
jmo.

taz3
11th-February-2012, 08:48 AM
i would like to see the parts list and builders assurance and dino results before i ran my BB at 7500. forums give out a lot of great info dont get me wrong but like mentioned earlier it is the net and everythings true on the net isnt it?:rolleyes:.rember......theres alotta over reved BBs used as boat anchors.
jmo.

Great point, you need to know your builder, my father grew up with my builder, so I've known him my whole life and spent plenty of time at the track with him. I was lucky, because he was a person family friend. I don't think I would walk into any builder and request this build with no background information.:no:

koreyss
11th-February-2012, 11:05 AM
Well I know im just a shade tree mechanic and have alot to learn but im sure even if it will hold at 7500rpm, its not making power any longer. Thats ok though, im only looking for 6000 to 6500 frequently. thats really why i asked about the steel crank. I really need to get to the dyno and see for myself what she is pullin instead of taking the builders word for it. that way i can see if she even will make power at 6500 like he claims. If i short shift at 3500 she really blows the tires off which makes me think 3500is where my torque peak is, and if my torque peak is at 3500 im kinda thinkin max hp is somewhere in the neighborhood of 5500 give or take. Am i thinking right? really wish i knew what cam was in it. i really appreciate the input guys please keep em coming!

Until you go threw that motor yourself and know whats in it!! I would advise staying away from those high revs...the motor has to be built to handle high rpms safely..Besides bbc's or "RATS" make plenty of street power in the lower rpms any way! RIGHT!! Imagine you shifting a built BBC at 8,000 rpm on the street!! YOU will go to jail and lose your car....hopefully thats all...:yes:

Good luck man!!!

ChrisL66
11th-February-2012, 11:48 AM
We ran a 427 with a stock crank and rods (balanced though). We launched at 5500 rpm, shifted at 7000 and went through the lights at about 7200. It was raced every weekend for several years until it eventually blew up :D

Chris.

taz3
11th-February-2012, 11:57 AM
. Also I have a steel crank from a 427. can I make this work in the 396? Thanks guys!

I do believe the 427 cranks can be used in a 396, hopefully an engine builder will chime in to verify this.:yes:

levisnteeshirt
11th-February-2012, 01:01 PM
i think the nah sayers in this thread have read too many magazine articles , with hyd cams on a 114 LSA :: gag :: ,, and EFI :: PUKE :: ,,, and 496's that only wind to 6000 :sleep: ,,,, a 396 or 427 used to be built to wind around 8500 ,, with the right stuff of course ,, but they will wind and they can last ,,,

with a 2 bolt i'd get main studs , and maybe gets straps for the center 3 mains ,, a BBC will stand way more than most will think

Tommy
11th-February-2012, 01:05 PM
Both 396 and 427 are internally balanced engines and cranks are 3.76 stroke. they come in cast iron and forged steel. The low performance engines came with the cast crank and high horse engines were a forged unit. I'm no guru nor am I a Nova Czar.


Tommy :)

levisnteeshirt
11th-February-2012, 01:49 PM
back in the 70's ,, a 427 bbc gear was a 557 with a 32 in tire ,, they'll wind ,,, they really pull hard at those high RPM's with the right cam ,, thats where the square port heads shine on a 427 ,, they're evil ,,, my neighbors 435 tripower vette was amazing ,, the tach would sweep past 7000 like a rocket ,,, it had been balanced and had hooker side pipes on it ,, and had the vacume linkage took off the front and back 2 barrels and a mechanical linkage installed ,,, roar just isn't the word when all three were wide open ,,, i still find it hard to believe they released these cars to the general public ,,lol,,,

Baddbob
11th-February-2012, 10:06 PM
A friend of mine drag raced a two bolt 468 with a cast crank and 3/8" truck rods for quite a few years shifted at 7K and it never did break, it was replaced with a 540 and is collecting dust in the shop awaiting street duty now. I think the 2 bolt blocks and cast BB cranks are underrated by many.

Carl Stevenson
11th-February-2012, 10:14 PM
my car has a 1970 396 (402) not sure if its a 4 bolt main or 2. My question is how many rpm can a stock 2 blot main big block handle. The guy who built the engine said the cam should make power to 6500 rpm. I shift at 5300 cause im not sure if the bottom end will handle 6500. I cant remember if he said it was a 4 bolt or two. I know its a cast crank. Also I have a steel crank from a 427. can I make this work in the 396? Thanks guys!

If you want it to last, 5000-5500 and it will last forever. If you want to take chances, shoot for the moon and don't come back here whining if it blows up!!!

Paul Wright
11th-February-2012, 10:32 PM
Let's keep the "bench racing" civil, guys.

My only comment is one person's anecdotal evidence isn't proof that everyone's results will be the same. Excessive rpm can ruin an engine. I would never assume that all 402's can rev to 8,000 with no ill effects.

Shauns BB70
11th-February-2012, 10:38 PM
If you want it to last, 5000-5500 and it will last forever. If you want to take chances, shoot for the moon and don't come back here whining if it blows up!!!

Im asking for advise from you guys. I am very conservative with what i do to my engine. kind of a poor boy here so i cant afford to tear a big block up. thats why I asked what would be safe for the stock bottom end. I wouldnt blame what ever happens to my engine on anyone but me. You wont hear me whining because of advise i asked for. Thanks for your input anyway.

koreyss
12th-February-2012, 12:00 AM
@Shauns BB70

Will I hope somewhere along the comments you got a little more info on rpms on a stock BBC!!! you definately got a pretty good BBC in your Nova.. Don't blow your motor up!! You have to know whats in it before you even go to a machine shop..Fact! they, he are going to ask. what crank, rods, etc..what the motor has in it.. but I would just Shift at a safe rpm or get it dynoed.. Then when you decide you wanna hold that pedal down and shift a little later. Tear the motor down and build it stronger....:yes: Rember you got a "RAT" and the power and torque come in at the lower rpms.. :yes:

Shauns BB70
12th-February-2012, 05:50 AM
@Shauns BB70

Will I hope somewhere along the comments you got a little more info on rpms on a stock BBC!!! you definitely got a pretty good BBC in your Nova.. Don't blow your motor up!! You have to know whats in it before you even go to a machine shop..Fact! they, he are going to ask. what crank, rods, etc..what the motor has in it.. but I would just Shift at a safe rpm or get it dynoed.. Then when you decide you wanna hold that pedal down and shift a little later. Tear the motor down and build it stronger....:yes: Rember you got a "RAT" and the power and torque come in at the lower rpms.. :yes:

Thanks man, that's probably what I'm gonna do. Might just build a different BB while still running the 396. If I can find a good block for a decent price that is.

OldGuy 71Acadian
12th-February-2012, 11:27 AM
[QUOTE=Shauns BB70;1783384]I am very conservative with what i do to my engine. kind of a poor boy here so i cant afford to tear a big block up.[QUOTE]

Shaun, I think you answered your own question here. There is no guarranty here. Longevity usually comes with conservative driving, but even that, is not the case with many daily drivers. Anytime a person pull gears hard, there is a risk of breakage. While aftermarket parts are designed to be an improvement over stock parts, again, any new part could fail. No matter how many people in this thread give their personal experience with a stock BBC, your experience may be completely different.:yes:
eg. I've had to heat aluminum parts many times in my life, usually with good results, but, every now and then i get carried away and hold the heat on too long. Result: one minute the aluminum part is there and then poof it's gone.:eek::eek::eek: Many people told me that aluminum can take lots of heat. Honest, they've done it a million times.:turn::devil::devil::rolleyes::D

Shauns BB70
12th-February-2012, 11:47 AM
Man, I love this site. So much knowledge around here and everyone willing to help. I dont think i have conversed with anyone that has their nose in the air!

OldGuy 71Acadian
12th-February-2012, 11:53 AM
Man, I love this site. So much knowledge around here and everyone willing to help. I dont think i have conversed with anyone that has their nose in the air!

I do, right before I sneeze.:eek::devil::devil::rolleyes::D:D:D