Maximum rpm for SB

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jeeper

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What is the maximum rpm a stock small block can take?

Assuming I have a dead stock 318/360 what is the maximum rpm that is repeatable for say3-5K miles? In other words it does not need to last me for the rest of my life, but some street bashing and a bit of mild racing.

Thank you, ROB
 
Totally stock I'd be surprised if you didnt start hurting stuff at 6000ish, assuming you can get it that high on stock stuff.
 
my stock bottom, modded 360top 318 gets upt to about 5,700rpm daily and i do cruise at about 3,700rpm on the highway somewhat regularly. oil change interval is pretty high just for personal preference with shell rotella 15w-40 anda Napa (wix) filter.
 
I guess I should have clarified. I will likely be modifying the top end. The bottom will be stock with maybe an oil pump and windage tray.

My cruise RPM will be high due to my new 4.10's!

Thanks, ROB
 
The 17 year old (but only 3000 miles) rebuild on my 340 sees 8000 often. Balanced, polished stock rods, full roller (cam and valve train).
 
A stock 340 will take 6500rpms no problems. Mine saw 7400 on the dyno, stock crank, reworked stock rods and light pistons and pins.
 
Theres limiting factors to the engines max rpm.
Valve spring rotating mass cam profile.
Whats your plan?
 
I'm looking at a stock bottom end with a cam / intake etc.

I realize I may not have the top end to support 6500. My only question is do relatively stock engines have trouble hanging together to 6K? IE will the pistons and rods stay connected to the crank at that RPM etc?

The engine build is another thread for later once I get it home.

Thanks, ROB
 
OK, I wanna be in in this post as well. I'm curious how high a 360 will spin and last for a while. I want to race/street the car (73' Duster)70/30...60/40. But, I also don't want to rebuild the motor every season (year) Can I make 450/500 HP Reliably?
 
eleventy billion???

Nahh.

You want high revs? Go talk to Kyle Petty, etc.
ask what they do for the Coca Cola 600 race.

If you have not put 4.10's in the car yet,
i suggest 3.73 as a compromise. :)

Which cam do you plan on using?
 
It depends on a number of things. Remember a 360 has a cast crank wich isnt going to be a strong as a steel crank. Weight of the piston,pin and rod is going to have a lot to do with how long the crank lives at high rpms.

My motor had 120 passes on it when it was freshend. 340 steel crank, very light pistons ans pin (525gs) re worked stock rods. The crank was replwced because it was cracking fron stress. Peak power is at 6900rpms,(shift around 7200) just under 500 horse.

Valvetrain is another big factor. Dont exect to be pulling a Hyd cam up to 7000rpms. Lidters will pump up by then. You need a good solid cam, valve springs and retainer or a roller set up to be happy up tthere. Also weight is again a factor.

You'll need good heads, intake and carb aswell.

I would say a good street motor will take 5500-6500 rpms shifts for a long time aslong as its well built.
 
OK. I figured it was good for 5500 with an occasional 6000 burst for awhile.

I just remember my old 289 that I was always dealing with the small rod bolts and then the rail rockers that liked to pull studs.

That is one of my reasons for liking Mopar, shaft mounted rockers, 3/8" rod bolts etc. It is a far superior design.

Thank you guys, ROB
 
Lighten the car as much as possible to help take the stress load of the engine alittle.
Like Adam said. I agree.
 
I negotiated a manual box while out junk shopping yesterday. I have hoarded a few dippy aluminum master cylinders as well. I should get those on there

The only real option that my car has is PS. It is a manual disk, column shift car.

I have not decided what my weight loss strategy is at this point. In typical fashion it will likely include making lighter bumper brackets that type of thing. I really would rather not drill holes in every bracket, but I am willing to do what is reasonably easy to return to stock later.

Thanks, ROB
 
I've been wondering about this myself, because mine was rebuilt a few years ago before I got it and I don't know what's in it, parts-wise. It seems healthy and pulls strong up to about 5500, which is all the higher I've pushed it so far. Don't want to abuse it, 'cause it is mainly street-driven and I want it to last until I'm ready to put a big block in there.
 
This is what my experience has been.

With a 340, Ross lightweight pistons, stock steel crank and Eagle H beam rods. Assembly was balanced of course I twisted it to 8000 repeatedly. I screwed up and didn't check the babbit rod bearings soon enough and it spun a rod bearing. I previously had trimetal bearings in it without a problem for two seasons. The babbit lasted only 1.75 sesons. We were racing every weekend though then for eight months.

The current MP shortblock 360 with Hyperexplosive pistons, stock cast crank and stock rods with ARP bolts in it, not very well balanced at all sees 7200-7500. I checked the rod and main bearings after a year and a half and they were fine. Again trimetal bearings not babbit.
 
My 69 Swinger has a 340 that will Zing 9000,I do know it is a 340 with a pair of X heads and is a solid lift engine but other than that I know absolutely nothing,I have never even had a valve cover off of it. I am looking forward to tearing it apart one day to see just exactly what is inside. I do Think that the swinger will outrun my 67 chevelle SS and the SS has a built big block with about 450 HP or maybe even 500. Wish I would have had it dynoed when it was built and before it was put in the chevelle to be certain of the HP but with all it has and what was done it should be pushing around 500 HP.

Bobby Dodson
 
Kind of weird that I mentioned Ford in an earlier post. A pal of mine gave me an engine for my Bronco.

It was in pieces and had the rail rockers etc. When I brought it home the other day.

It looked like the rod bolts could be used to hold a hood scoop on.......

Sounds like a missed shift etc. shouldn't be a real problem with a mild engine.

Thanks, ROB
 
Ok does anyone know the redline on a 273 commando? I am scared to rev it up to much and it would be nice to know what the factory rpm limit is? Engine is basically all stock.
 
More importantly for every engine in this post, is "where does it make the most power". A stock cam and valvetrain just cant spin past around 4500 in the case of 318/273s. The cams and springs wont do it. the 340/360s can go a little over 5, but again, they will give float fairly low. If you change the cam and springs, you may raise it, but a street sized cam, isnt making power at 5800. So you dont need to rev it to there. The majority if dual purpose cars are being shifted too high anyway. Taje them to the track, and start with a shift point of say, 4500 and work up. As the times get faster, raise it, when they stop getting faster, you've reached you real shift point. RPM of valve float is the dead last thing you want to know. Because at that point, you already gone way over peak hp, and are in "possible damage" zone.
 
Okay now I got to tell you all that my little 318 that has been running for the last ten years has regularly seen 6500 rpm and on a few occasions over 7000. it has gasket matched heads with bowl work, 280 dur .480 lift comp cams cam w/springs, hypereutic pistons, ballanced and she still runs great, this winter I will be tearing her down for the first time to see what the damage is.
 
According To A Mopar Performance Manual From The 70's My Father Has.it Is A Big Blue Book Probably 3 In.thick Giving All Types Of Adjustements,suspension Mods,engine Specs Etc...
States The Stock Cast Crank In A Small Block Should Not Exceed 6800 Rpm.
 
mean318 said:
Okay now I got to tell you all that my little 318 that has been running for the last ten years has regularly seen 6500 rpm and on a few occasions over 7000. it has gasket matched heads with bowl work, 280 dur .480 lift comp cams cam w/springs, hypereutic pistons, ballanced and she still runs great, this winter I will be tearing her down for the first time to see what the damage is.


I dont quite understand why? I'm running the exact same cam in my 318 and it runs out of steam at about 5,700rpm. I have 2.02 J-heads. I see no reason for you to twist it up to 6500/7000, thats great it can. but i doubt you are making more power than around 5,800rpm...thats just the characteristics of a cam with those specs. So why twist it so high? i bet your power is dipping, ever run it down the 1/4 or on a dyno? i bet you'll see better results around ~5,700rpm as a redline/shiftpoint. just my .02cents.

You don't have a cam to support and make power at that high of rpm. And with what sounds like very basic head work, I doubt you have the heads that are made to flow decently at that rpm. Just because it will rev higher, doesnt mean its best to :scratch:
 
rpm?

eleventy billion, sounds familiar??

LOL< depends on cam, valve springs, and crank,{forged/cast}
as well as the quality of the balance,of the engines rebuild;
and the crank dampener/harmonic balancer.


5,500-6,200 I would say is the normal "street" limit.
The more cid,the less rpm, normally.

My 2 cents.
 
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