Conv389drv

Assuming the valvetrain can handle it, what is the RPM limit of the 350 shortblock itself? (gen 1 small blocks in this case).

Are there different limits on 350s of the 70s versus 350s of the 80s years and so on?

SWCDuke

Depends. The LT-1s got forged cranks and higher quality rods that were produced from the production forgings.

Basic 350s won't rev beyond 5500 due to induction and exhaust limitations, but they should be reliable to 6000 as long as you don't run them out of oil.

Oil starvation is probaby what initiates most catastrophic bottom end failures, not a rod or crank breaking.

Duke

Vetterodder

Depends upon the components within the shortblock and their condition. A properly built 350 bottom end should be reliable to in excess of 7k. At the same time, a poorly built or worn 350 could grenade at 4k. Race 350's have exceeded 10k but we're talking high $$ engines that get high $$ rebuilds after every race.

LD85

I know of and have seen a 355CI, 4-bolt, short stroke engine that shifts at 7800-RPM

Conv389drv

I've seen some articles in the past where they take a junkyard 350 out of a 70s car, a basic smog motor / two bolt main, and dyno it with new top end parts. They were making pulls up to 5800 I believe.

In another article, they bought a rebuilt 2 bolt shortblock, and were spinning that one to 6000.

I wanted to get some real opinions from experienced guys, without the magazine bs, because the mag guys won't mention that the engine blew up going down the road three months later

tsw71

The two bolt block will live as will the cast crank. My only concern would be with the rods. My 355 in my 71 is making 308rwhp on the stock rods, and until I installed a rev limiter recently, I was frequently turning 6400 rpm. I now limit it to 6000 for "peace of mind". I did use ARP rod bolts which I would consider a must for anything over 5500.

I will also mention I have a street rod that i built when i was a kid. It's a 4 bolt 350 with cast crank and stock GM rods out of a truck and ARP rod bolts. This one turns 7500+. I replaced the stock cast pistons with forged years ago due to cracking on ever one of them, so the cast pistons deffinately don't like high RPM

I would feel better having better parts in both of these motors. BUT with decades of abuse on both of them, I think it's safe to say that you can get by with the stock stuff if needed.

vettedave

Hmmm so far I'd say about 10,000 rpm. + (Nascar)
You did say the valve train could handle it. Well the bottom end if built right with a dry sump can handle it if your talking racing engine.

Now if you are talkin bone stock... (year? size?) heavy cast pistons and
a stock ignition gets pretty lazy past 6000 anyway but if the valve train (and ign.) is up to it ... were talkin 7000 easy. Doesn't the LT4 redline at 6500 or 6800? ('69 302 from the factory 7000). Just don't throw it around a corner while your doin' it........BANG!

KyRP2NITe Corvette

The funny thing about what the limit to RPM in a motor is.....
You never really know until you find it and that usually sucks

terry82

in 1973 i found the limit to be right around 7 to 7500 rpm when i missed a shift from 2- 3 but i did have that vette beat .

Yellow73SB

my uncle runs around 7k in his race ar with hydrolic lifters

SHAKERATTLEROLL

Hmmmmm now dont free rev the motor bad bad bad. But in gear keep the foot on the floor till it stops pulling then change gears. Actually you should change gears if the next gear will pull harder or with the same amount of pull as the previous gear. Hope that makes sense.

Conv389drv

Heh heh heh, My dad tells me that back in the '60s a lot of guys blew up their 283 engines because they kept on pulling strong all the way up to the point of the explosion

REDC4CORVETTE

11,500 rpm's under load,not free wheeling.
Small block 350 315 ci destroked.
16 holes around the ring land for compression.
Joe hunt mag.
1050 holley dominator.
High volum oil pump low presure.
Engine builder Mike Hays in 1969 Huntington Beach California.
Ran 10.50's in 3400 lb nova.
Howard alum rods brooks pistons.
Lockerman heads.
Good for 50 runs.
Engines were built for 10,000 and guaranteed to run your car on the record for your class,or your money back.
Only one was ever returned from florida.
The end of that storie.
Person brought car from Florida on trailor.
Rented track for the day,first run in his chevelle 10.43 ,he said it would only run 11's.
He had to pay for the track and the tow to California and back to Florida.
To look up info See Drag Scoop mag in 68 and 69.Pictures of the Drag Scoop Nova.

The car also held the IHRA record for d hotrod 1 and c hotrod 2

Allthrottleandsomebottle

I got a nice little 327 4 bolt main punched to 331 cid.............very mild build with OEM crank/valve train/Rhoads Lifters /steel 2.02 double hump heads and been up to many 7K revs since 1985. Still goin strong in my 68' Camaro with 30K miles

chuntington101

SHAKERATTLEROLL your right there mate. its why WRC cars change early (about 5K i think) coz the restrictors mean the motors make big torque but low BHP. i think some teams actualy dyno the cars to see when the in gear torque curves overlap (ie when the next gear makes more WTQ than the one your in). now thats serious stuff!

TwoFast4Lv

LT1s seem good to 7,000 with a good valve train

most all SBC stuff should go 6,000 with good valve train parts.

It is usually the valve train that lets go

Russ Bellinis

It depends on what you have and what you want to do with it. A stock 350 with nodular iron crank, cast rods and cast pistons is probably good to 6000-6500 rpm at the drag strip where you only touch the high rpm and then upshift. If you are hot lapping Daytona, You would probably not want to use more than 5500 for sustained high speed. If you hav a zz4 with steel crank, forged rods and forged pistons, 7500 is probably ok. One thing to keep in mind is that a cam that works at high rpm (above 7000 rpm) won't make torque down low. You can build a small block to rev above 7000 safely, but you probably won't want to drive it on the street.

ALLT4

I had a 327 several years back I used in my race car. A 77 Monte Carlo, you know the land yacht Montes. I didn't have anything exotic in the motor at all just decent performance parts with an Isky circle track cam. Dart II heads 2.02 yada, yada... It sounded great and propelled the 3777 pound car to an even 14.00 ET

Could have went faster but I only had a 600cfm performer carb on top of an open plenum manifold.

That was one of those motors you wish you had back!

Russ Bellinis

I think the 327 was expected to rev higher than the 350s. I'm not sure, but I think the 327s had forged internals instead of cast.

JDRez42

I have a stock bottom end in my 80 107k and i did a vortec and cam swap. Better springs were needed in the vortecs to handle the lift but since the swap i have shifted at 6500 many times assuming my tach is right. I was surprised but it still feels strong so i just keep the pedal on the floor. If i blow the motor i'll just put all the gas money i'll be saving into the big block and get it done sooner.