Not Ranked
Roy,
I couldn't find a file to duplicate the GT-40 heads, so I used an AFR 185cc head with the same valve sizes as a GT-40. Maybe one of the other users can provide me with the correct file. I really don't know if this will affect the outcome or not...
Anyway,
With a 4.060" bore, and a 3.78" stroke, that's about 398ci. I used a 10:1 CR, a 750cfm carb (I forgot to ask what size carb you had), a dual plane intake manifold, and I looked up the cam that you had in the Summit Racing catalog....it's a split duration/lift cam.....with 204 and 214 degree durations with a .448/.472" lift. I input hydraulic solid lifters also.
Basically the cam and the heads are killing you. Based on the inputs that I gave it put out a max hp of 351 and max torque of 454. By just changing the cam alone, it raised the hp to 397 (same Comp Cam as I have in my 425ci stroker) and made the torque 431 lb-ft.
For this size of engine, it just needs to breathe better. I'll go ahead and give my disclaimer that I may not be the best Desktop Dyno operator out there...some of the others may wanna chip in here. But I input the specs as I could find them.
Like I said you might wanna go with a different cam at least...Even a single plane intake made the hp go to 420 with the cam I just mentioned.
Hope this helps. I'll be glad to help you any way I can.
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