350 verse 400 SBC

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econo racer
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350 verse 400 SBC

Post by econo racer »

Years ago I built a 350 then a 400 sbc. I noticed that the 400 sbc revved much faster in park. Only major difference was the 350 had hyd cam with vortecs verses the 400 had a solid and 200 cc head. both stock cranks and rods with cast pistons if that matters. :shock: I was always under the impression that the smaller stroke engine revved faster. What is the deal with this. Oh both had pumping compression about 185 lbs.
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Re: 350 verse 400 SBC

Post by Dave Koehler »

You answered your own question. More power with the 400.
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Re: 350 verse 400 SBC

Post by mag2555 »

Surly you do not mean to make a flat out comparison between the two motors do you?
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Re: 350 verse 400 SBC

Post by plovett »

There are dozens of reasons one engine could rev faster in park than another. In my opinion there is absolutely no way to tell. It may not have, and probably does not have anything to do with 350 vs 400.

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Re: 350 verse 400 SBC

Post by econo racer »

So I am guessing it was because of the solid tappet cam.
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Re: 350 verse 400 SBC

Post by Monza355 »

What were the specs of the solid cam vs the hydraulic one in the 350 ?
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Re: 350 verse 400 SBC

Post by Ken_Parkman »

Weight of what is being revved is a big factor. A different torque converter could have a big effect.
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Re: 350 verse 400 SBC

Post by plovett »

ignition curve?.....all sorts of things.
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Re: 350 verse 400 SBC

Post by JoePorting »

The 400 rev'ed quicker because it was able to move the weight of all the internal parts quicker.
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Re: 350 verse 400 SBC

Post by cardo0 »

Reving an engine in neutral w/o load is not good for it. There's no counter torque on the rotating assembly and the valve train accelration/speed will be much greater.

Better comparison would be 20mph to 60mph.
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Re: 350 verse 400 SBC

Post by pamotorman »

if the intake ports were the same size the 400 had quicker throttle response because the air velocity thru the intake port was faster due to the larger cylinder displacement
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Re: 350 verse 400 SBC

Post by allencr267 »

acc. pump shot was too much for the 350. :wink:
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Re: 350 verse 400 SBC

Post by CGT »

We do have a resident "revs faster" expert....maybe he will chime in.
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Re: 350 verse 400 SBC

Post by BOOT »

plovett wrote: Fri Nov 16, 2018 8:54 am There are dozens of reasons one engine could rev faster in park than another. In my opinion there is absolutely no way to tell. It may not have, and probably does not have anything to do with 350 vs 400.

JMO,

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Re: 350 verse 400 SBC

Post by novadude »

cardo0 wrote: Fri Nov 16, 2018 1:17 pm Reving an engine in neutral w/o load is not good for it. There's no counter torque on the rotating assembly and the valve train accelration/speed will be much greater.

Better comparison would be 20mph to 60mph.
I always cringe when you see those dudes on youtube posting videos of themselves free-revving engines to 8000+ rpm with no load over and over again. :roll:
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