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-   -   Is 5500 rpm pushing my luck ? (http://www.hotrodders.com/forum/5500-rpm-pushing-my-luck-182336.html)

adantessr 08-07-2010 07:20 AM

Is 5500 rpm pushing my luck ?
 
I have always assumed that a 5500 rpm redline was safe for a stock build 350 or 355 . Is this safe or am I pushing my luck ? I am not really hotrod savvy , I just have a real good knowledge of the basics .

454C10 08-07-2010 08:19 AM

I have no problem spinning a stock 350 block up to 6500 rpms for short burst. Even 7000 rpms.

Of course the cam and valve springs have a lot to do with how high the engine will rev.

A lot of times 5500 rpms seems like the engine is coming apart but that is due to the other stuff on the engine that is limiting the rpms (heads, exhaust, carb, intake, cam, valve springs, .......),

a friend of mine put an autozone 350 short block in his drag camaro with a good set of heads, intake, carb, 292H compcam, 3500 stall, 4.56 gear, and a 200 shot of N02. He ran it every weekend at the track for over 2 years and shifted between 6500 and 7000 rpm. the engine finally beat out a bearing but most likely due to the no2. I'm sure it would had lasted a lot longer with no n02 and a few less trips to the drags. and he drove that thing to work and street raced it during the week days. guy was crazy.

I had a similar experience with 350, 2 bolt, KB pistons, steel crank, arp rod bolts, and balanced. Nothing special but not stock. I tended to shift at valve float 7200 rpms. Used it in a 2600 pound car (240z), 3.90 gear, 5 speed trans (hit 7200 quickly). Ran it for 10 years and floated the valve every time I drove it. Also ran it at the track with N02.

So. I feel a stock 350 can handle a decent amount of rpm for short durations if the engine is in good condition. and the rest of the stuff on the engine is up to the task.

funny how a cam changes the feel of an engine. 4000 rpm feels very busy when the cam is small, but put in a big cam and 4000 rpms feels like the engine is barely revving.

simcros 08-07-2010 12:14 PM

Speaking of floating valves. What does that feel like. The reason I ask is I'm running 142 supercharger on a Chevrolet 350, edlebrock 600 Carb and a 700r4. When I'm running manually through the gears 2nd gear 5000 it acts like it limits out, like out of fuel. Could this be valve float or am I just under carbed?

eloc431962 08-07-2010 12:19 PM

Nothing wrong with going to 5500 rpm on a stock 350. JMO


Cole

eloc431962 08-07-2010 12:21 PM

Quote:

Originally Posted by simcros
Speaking of floating valves. What does that feel like. The reason I ask is I'm running 142 supercharger on a Chevrolet 350, edlebrock 600 Carb and a 700r4. When I'm running manually through the gears 2nd gear 5000 it acts like it limits out, like out of fuel. Could this be valve float or am I just under carbed?

What has all been done to the engine? Shouldn't be floating at 5000 rpm ,IMHO.
Probably the carb or in the timing JMO


Cole

simcros 08-07-2010 02:54 PM

I don't know the specs on the engine. Wasnt an issue until I installed the supercharger last winter

Rickracer 08-07-2010 06:10 PM

A supercharger will lower the rpm level where valve float occurs, you gotta remember, you now have positive pressure working against the valve springs, trying to push the valves open. ;)

adantessr 08-07-2010 06:27 PM

Quote:

Originally Posted by 454C10
I have no problem spinning a stock 350 block up to 6500 rpms for short burst. Even 7000 rpms.

Of course the cam and valve springs have a lot to do with how high the engine will rev.

A lot of times 5500 rpms seems like the engine is coming apart but that is due to the other stuff on the engine that is limiting the rpms (heads, exhaust, carb, intake, cam, valve springs, .......),

a friend of mine put an autozone 350 short block in his drag camaro with a good set of heads, intake, carb, 292H compcam, 3500 stall, 4.56 gear, and a 200 shot of N02. He ran it every weekend at the track for over 2 years and shifted between 6500 and 7000 rpm. the engine finally beat out a bearing but most likely due to the no2. I'm sure it would had lasted a lot longer with no n02 and a few less trips to the drags. and he drove that thing to work and street raced it during the week days. guy was crazy.

I had a similar experience with 350, 2 bolt, KB pistons, steel crank, arp rod bolts, and balanced. Nothing special but not stock. I tended to shift at valve float 7200 rpms. Used it in a 2600 pound car (240z), 3.90 gear, 5 speed trans (hit 7200 quickly). Ran it for 10 years and floated the valve every time I drove it. Also ran it at the track with N02.

So. I feel a stock 350 can handle a decent amount of rpm for short durations if the engine is in good condition. and the rest of the stuff on the engine is up to the task.

funny how a cam changes the feel of an engine. 4000 rpm feels very busy when the cam is small, but put in a big cam and 4000 rpms feels like the engine is barely revving.

Thanks for the reply . I am running my 355 with flat tops in an 1800 lb T-bucket with a turbo 350 and 3.08 gears and even with a stock grind sealed power camshaft it hits 5500 almost before I can think of grabbing 2nd with the B&M dual gate shifter . I was just wondering if I needed to watch the tach closer and less worrying about keeping it straight . LOL . It does fishtail alot on takeoff . Just about the time I get things straightened out and take a look at the tach it is at 5500 rpm. Thanks again .

TheMonster 08-08-2010 02:05 AM

Quote:

Originally Posted by simcros
Speaking of floating valves. What does that feel like. The reason I ask is I'm running 142 supercharger on a Chevrolet 350, edlebrock 600 Carb and a 700r4. When I'm running manually through the gears 2nd gear 5000 it acts like it limits out, like out of fuel. Could this be valve float or am I just under carbed?

Carb is way to small man. Get a QFT 750 or even 850cfm.

DoubleVision 08-08-2010 04:14 AM

We`ve tached stock 350`s to 6000 many a time and held it there over 15 seconds without any issues. Cool thing about small blocks tached that high is they sound really cool. In my tech college days my instructor told us about how he raced in the late 60`s. He had a tubbed 55 chevy, 283 bored to 4 inches, 3.00 inch stroke crank, a massive solid lifter cam, fully ported camel back heads, big valves, monster valve train, tunnel ram dual quad with twin 585 holley carbs, aftermarket rods and forged dome pistons. The rear had 5.13 gears and the tranny was a 3 speed GM. He`d pull up, do his burn out, then pull to the line, he`d push in the clutch and tach it to 9500 RPM, when the light went green he`d side step the clutch. His words on it were "If it didn`t break, you went fast" He said he never lost when it didn`t break, but it broke often. He showed me parts he still had. Twisted axles, grenaded tranmissions, exploded clutches, gutted differentials, splintered bell housings.
He said what he hated the most was when the clutch exploded it took off part of his toe and left a scar on his leg from a deep scratch. He said another time he was at the line tached to 9500 and the harmonic balancer came off. He said those engines had press fit only balancers, but there after he had the crank drilled to make sure it didn`t come off again. He said when the balancer hit the track at that speed it sounded like a bomb went off and pieces flew everywhere. Needless to say the track manager nicely asked him to leave lol.


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