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I have a 1981 Camaro with a 267 small block and im trying to figure out if I should go with a 350 or just modify the 267. Which would be more bang for my buck, and how much power can you get from a 267? :confused: Does anyone know what I should do?
 

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The only reason to use smaller cubes to your advantage is if you're going to use it to make RPMs in an attempt to chase down HP or to conform to a race class that has cubic inch limits.

If you have a 350 that makes 300 hp compared to a 267 that makes 300 hp, the 350 will do it at a much lower RPM, make tons more torque, and be much cheaper to build.

Cubes are king.
 

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All other things being equal, always opt for a block with the largest bore you can find. The 267 uses a tiny little 3.500" bore. The 350 uses a 4.000" bore. The 400 uses a 4.125" bore. The larger the bore, the better the intake flow is as it goes past the valve. A small bore will shroud the valve and interrupt the flow "kernel" at the cylinder wall. Optimal distance between the edge of the intake valve and the bore is around 0.200"+.

Notice the valve sizes on the 350 L31 Vortec motor, 1.94"/1.50". This leaves a very nice margin between the edge of the intake valve and the 4.000" bore and probably contributes significantly to the excellent flow figures of the L31 heads. I don't know this from a scientific standpoint, it's just my opinion. It is my feeling that you can get a valve in the head that is TOO LARGE and will offer diminishing returns if there is insufficient margin.
 

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1cool81camaro said:
I realy want to keep the 267 with my all origanal camaro, but I want to know how can I get the most power out of a little 267? I realy dont want to swap motors or go any larger. Any advice?
If you wanna keep the 267, find a nice dual plane intake and a cam.
 

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1cool81camaro said:
I realy want to keep the 267 with my all origanal camaro, but I want to know how can I get the most power out of a little 267? I realy dont want to swap motors or go any larger. Any advice?
Not to be rude, but we've already BEEN THROUGH THIS w/you.

IMHO, it's a waste of time and money to do anything to the 267 beyond a good tune-up. Your "originality" kick also prevents you from installing headers. The stock exhaust system would be about the only thing that may be lacking, from a performance standpoint- even the carb and intake are sufficient for that lowly engine.

A cam may exist that will provide you w/some more power- I have no idea who makes one, or what the specs would be. There's NO support for this engine in the aftermarket- beyond the parts that fit because of the similarities between it and other SBC's.

Some power can be made by recurving the distributor to a better timing curve and such- even though changing engines to a 350 would be invisible from any one unless they ran casting numbers, etc.

You can put a lower (higher numerically) rear gear in it for better acceleration off the line. It might survive a 50 HP NO2 hit, but the originality thing again- all those non-stock hoses and wires, etc.
 

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Keep the 267. However, you`ll be disappointed to find a small RV cam such as the edelbrock performer cam that idles smooth in 350`s will make your 267 idle rough and the power band won`t start until 2500. The 267 was a experimental mistake by GM in order to save fuel and meet emission standards. The 267 is honestly good for nothing, A stock 4.3 V6 will eat it alive in performance. You can`t even run nitrous on a 267 because the small bore and long stroke equal to the cylinders running hotter. The intake on these engines were special, as were the heads, the intake and heads used real small runners in order to make high velocity just to give it some low end torque. This is due to the small bore so bolting on a aftermarket dual plane intake will take power away from the low end and add it to the high end. I`ve said it in the past, you can`t hot rod a 267 because it doesn`t have enough bore size to breathe. Unless your camaro is a RS or a Z28 it`s never going to be worth anything, numbers matching or not and if I recall correctly only the base camaro came with the 267.
 

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Not in a 267 block. The 267, 305 and 350 all share the same stroke depth of 3.480, the 267 has a 3.500 inch bore, the 305 has a 3.736 inch bore and a 350 has a 4 inch bore. You could use the 267 crankshaft in a 350 block, but you would need to have the crank balanced. The max overbore for the 267 is .030 which isn`t enough to help it any. The 305 can be bored .060 as can a 350. Finding a 350 block is easy and cheap.
 
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