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Original Message
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| RE: Offenhauser Port-O-Sonic Experience?!? |
| By Ross - 08/07/2001 12:50:05 AM; IP 12.75.102.147 |
I run an Offy P-sonic on my 427. Its a great manifold for mid-high range, however, it wont do much unless you have a good cam and heads ported to take advantage of it. WIth that being said, there is probably a lot you can do before buying a 300 dollar used intake. P-sonics arent cheap
The 390HP cam if you mean 390GT/CJ cam, is not that wild, and .050 numbers are extremely low compared to modern cams of the same adv duration. This leads to low-ish vacuum and not much power, where newer grinds make much more power and still hold good vacuum and low end. You can do much better and pull higher in the RPM scale. Remember though, without porting the heads, even with good valves you'll be done by 5700-6000 IMHO
Also, if your current manifold is an Edelbrock Performer, cut the middle plenum out under the carb and add a 1 inch open spacer, it'll add quite a bit of midrange, it wont be revolutionary, but you'll definitely feel it. If its an Edelbrock Streetmaster, open the plenum to the same shap as a standard Holley base gasket and add a 1 inch spacer (per Edelbrock in their original Streetmaster instructions for racing)
If you are spending money, I'd go with the Edelbrock RPM, you can buy it cheaper new than a used P-sonic and it will pull to 6000+, but do a cam change at the same time and you'll see the most gain.
Bottom line, first thing I'd do is a spacer and grind the plenum divider, then I'd go with more cam. If I had the cash during the cam swap, I'd buy an Edelbrock RPM.
You didnt mention headers, but for an FE they are almost a requirement to "run upstairs" |
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