Technical > Matt Shaff's Engine Shop

The Nostalgic 265 Engine Build

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bfalfa55:
I am interested in hearing why tou feel that would be the case. I am not arguing it, just gathering intelligent opinions.

Frontenginedragsters:
I based my opinion on the last of 3 camshafts you mentioned.

Matt

bfalfa55:
The RPM range I listed for the last cam came from talking with a Lunati rep. The actual range for a 350 chevy was 1,800-5,800, he said the smaller cubes would shift up 500 RPM. Did they give me miss information by telling me the RPM range would increase when it is actually going to decrease ? I have always been under the impression that the range has to increase to get more power out of a small cube engine. This engine will be just below 10.2:1, with the aluminum L98 heads, with 1.94/1.5 valves. With that cam and these heads, do you think it is going to choke cylinder flow by the time it is at 5,000 RPM ?

Roger:
Take a look at a dyno test performed on a Chevrolet 350ci/290hp crate engine as delivered from Chevy to Westech and modified with only a RPM manifold and headers, then draw your own conclusions. The crate engine had 8-1 compression and stock iron 76cc heads with 1.94-1.50 valves. The camshaft specs from Chevrolet are:
    222*/222* duration @ .050”, .450”/.460” lift. 114* LCA hydraulic flat tappet
This cam is somewhat similar to the last two you listed but unlike those you listed it has the disadvantage of being flat tappet.
 
I have to ask myself if a modified Chevy 350 with a somewhat similar cam to the ones you listed can make 330hp at 5500rpm, then why wouldn’t the two last cams you mentioned work as well in your engine and rpm even higher due to its smaller size and increased compression. Can’t help you with the x-pipe deal, I use zoomies.

   Chevy 350ci/290hp modified by
Westech with RPM intake & headers
Horse Power       Torque        RPM       
       100             270#          2000
       160             280#          2875     
       240             345#          3750
       305             340#          4625
       325             325#          5250
       330             315#          5500
     (Figures pulled from a graph)

Frontenginedragsters:
 I apologize for responding late to your posting.
Working at our shop by day and putting up a new building at night.
 Mine are only opinions because I have no dyno history with small bore engines.
I know we see improvement on air flow going from a 4.000" bore to a 4.060" bore and that adds power.
Your running an engine with a bore of 3.935". Reducing the 4.000" bore by .065" also would slightly reduce air flow.
Also the short stroke reduces the volume of air being pulled in.
If you lived a little closer I would cut you a deal on dyno time just to get the real answer.
Matt

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