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Deleted member 36901
Guest
What is safe RPM to take 426 crate engines too. cast iron heads solid flat tappet cam stock rockers
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Staying safe, no more than 6k maybe 6500
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Deleted member 36901
Guest
I've been shifting at 6200 so I wanted some opinions on rpm
when it stops pullin no need to rev it past it's peak power .
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Deleted member 36901
Guest
It will pull more just didn't know if it was too high and unsafe
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Deleted member 36901
Guest
That's what I'm saying ha-ha don't need to be hurting it don't plan on shifting at 6200 everyday just if I take it out to the track on a Friday in a great while
Another way to look at this is it's "safe" 500 rpm past the point it stops pulling with authority, or as they say "when it lays down"
DrCharles
Well-Known Member
Rev it until it blows, then reduce 500 rpm 
Seriously, what does the manufacturer recommend? Or are they just keeping quiet?
Seriously, what does the manufacturer recommend? Or are they just keeping quiet?
Unconventional
Well-Known Member
Good money in keeping quiet from the manufacture end. I'm sure they would be happy to sell Dartkid another.
67Dart273
Well-Known Member
Why not do it right? You have the money, you spent enough on that great engine. Have it dynoed and generate a curve. Then plug in the curves that would be equivalent to the transmission ratios. You shift where either torque or HP crosses in the various gears
You can also do that with the various in-car performance monitors, you can do this from torque, acceleration (g's)
Here is a random example. You don't need to RUN the car in each gear, you just need a good clean curve in a known gear usually "straight through." Then you can plot the curves multiplied by the ratio of the gearing
You can also do that with the various in-car performance monitors, you can do this from torque, acceleration (g's)
Here is a random example. You don't need to RUN the car in each gear, you just need a good clean curve in a known gear usually "straight through." Then you can plot the curves multiplied by the ratio of the gearing
famous bob
mopar misfit
A little of it depends on ur gearing. I shifted my s/s type engines at 6200 too. Lasted 14 yrs, w/ a few minor problems. Was sold completely worn out.
How can you give a max safe RPM with no pertinent information? Who's crate engine? What solid flat tappet cam? What valves and valve springs? What engine internals? No dyno sheet? Let's all just keep guessing! After all, it isn't your engine!
x 2
Dartnut
Don't hate me because i'm beautiful
X3!
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Deleted member 36901
Guest
It's a Mopar 426 crate engine. Cast heads stainless valves 2.25 intake 1.94 exhaust . stock rockers it's a 9.1 motor Mopar dual plane intake forged crank and rods as well as pistons has a ray Barton solid lifter flat tappet cam that ray had bullet racing cams grind
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Deleted member 36901
Guest
The problem is that Mopar Performance had severe quality control issues with those crate engines. The last one I worked on was eating itself up internally even though it was brand new. The bore clearance was wrong, the pushrods were rubbing on the head gaskets, the ring gap wasn't set properly, etc.
If your engine is running good and there is no trash in the oil, lash is holding steady, plugs look clean, leak down is fine, compression is fine, etc. then let it eat. But personally I wouldn't trust one of those engines unless I had pulled it down and gone over it myself. The ones I've seen all had major internal problems.
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Deleted member 36901
Guest
That's why it has a different cam in it the hydraulic lifters wouldn't hold oil pressure so I changed cam and lifters and the cam bearings looked scary so ended up changing them to
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Deleted member 36901
Guest
I've heard allot of bad about them so I was just asking what everyone's opinion was on safe rpm
famous bob
mopar misfit
-I had that combo or close at one time on two diff street hemi engines, 6000 on both.
famous bob
mopar misfit
^^^^^^^^
Thank u on the complement, I resemble that remark > LOL
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