318 safe max RPM?

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604

604

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Any one have a recommendation on a relatively safe max RPM for a 318?
71 318 stock bottom end; stock cast crank; stock heavy floating rods (the 340 type) ; stock pistons.
New rings and barrings. This was a very low mile engine. I was thinking 6,000????
When I was a kid I know my 73 318 saw over 6,500 many many times. Not saying it was smart.

I know I have the top end and cam to pull it, gust do not want to go past what the bottom end can take. Thanks!
 
You problem is oil. The stock passages can not feed the engine much past 6500 RPM's in the best conditions. Your crank will suffer for going past this point.

RPM is controlled by the valve springs abilty to keep the valves from bouncing around and the valve train together, not separating, jumping around. Then it would be cam profile.
 
Like I said I am not to worried about the top end. It should be fine. 273 heads, extensively ported. 360 valves. And Edelbrock RPM springs. 273 adjustable rockers.

Just wondering,
If they have such oiling problems over 6,500 how did they spin those D-stock 273's so fast? I have read accounts of shifting at 7,000

Just wonder what mods they may have done to keep them together at that speed. As my next engine will be built to hopefully duplicate, or improve upon that.
 
as long as there is oil in it you will run out of power long before it will blow
 
I think the best thing to do is talk to a trusted engine builder. There's a method to get higher RPM's that has to be followed. Plus you'll waste a lot of them depending where your power band is. There's a reason that 5500-6000 is so very common because above that is going to be wasted unless you build it from the ground up to have the power band up in the higher RPM range. Read this page to see a 6500 RPM + Bulid in action. Oh and it peaked at 406 HP @ 6300 RPM
http://www.popularhotrodding.com/enginemasters/articles/mopar/0667em_mopar_318_engine/index.html
 
Just dynoed one wed. made good power. 318 +.060 peak power at 6700RPM

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"Spin" is a relative word. If you run down the highway with 4.56's at 4500 RPM or more for an extended period, you might just run out of oil in the pan

But quick revs are not going to hurt if you have a decent oil pump

When I had the 340 in the old Landcruiser, with a little reground solid tappet cam, that thing ROUTINELY saw 7000 or a "touch more" in mudholes and stuff like that

You SHOULD worry about your top end. A broken spring, sucked valve, etc can end and engine just as quick as failed oil supply. So check the spring seat pressure, installed height, quality of your retainers, look for coil and rocker bind, and not knowing what cam/ piston combo you have, you might want to take a look at piston/ valve clearance

If this is "occasional" trips into the higher RPM realm such as street use, and you have a good IE "high volume" pump, I wouldn't worry too much

The LAST part of the question is, NOT "how high is safe", but rather "where should I be shifting it" for max acceleration? This is best done with either a dyno curve, and you can calculate transmission gear ratios, or by the use of a dash mount accelerometers, like "G force" which can generate a hp/ acceleration curve

Depending on what you have for a cam, you might just find that you will never want to shift it that high
 
I used to rev mine until it would not rev anymore,did it all the time without any issues.I would not think twice on turning it 6500 or more,I turn my 383 6500 all the time.

Jim
 
oldstyle, that's a good running 318, nice flat tourqe band as well.
604, are you sure it has a cast crank in it? It should go 6500 -7000, all day long with good heads.
 
Thanks every one.
This is just a "first step" in this car. As it will end up a D/MP class recreation when I am done. I did put a new pump in it, windage tray, and NOS Milidon pan from the 70's (the one that looks like a cut up factory pan with a section welded in). I plan on shifting it where it likes it, if you will. Just do not want to hurt it as the car funds are about to dry up more or less for a while (will be having twins in a month or two).

I did check valve clearance and coil bind. And all was fine. Cam is a comp 20-223-3 so I am sure it will be done more or less by 6,500.

My permanent engine will be a 318 block, 273 foraged crank, scat rods, KB domed pistons, 360 heads, old school Offenhauser intake. Cam for that one is yet to be determined.

oldstyle,
That is one bad 318!!! Sure would like to know what is in that one!
 
Kinda off my original subject,
But has any one run top bearing haves on the top and bottom of the crank? I have read in allot of the old articles, and books to do that for improved oil flow. Makes sense to have the grove in the bottom to.
 
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