400 mods
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400 mods
I just bought a 79 F150 with a 400 and a C6. I did this cause my other truck's transmission blew up, literally. The torque converter studs were sheared off, the bellhousing was in pieces, the tailshaft was broken off, and the case sat sidways under the truck.
Anyhow, I'm real satisfied with the 400, however, it feels a little gutless after about 3000 rpms. It's totally stock. I just got done puting bearings in the bottom end and plan on puting a 4bbl manifold on it with a Holley 600 vac secondary, and headers. What kind of gain can I expect? Also, I've heard that the 400 came from the factory with a cam retarded 6 degrees. Is this true?
Finally can someone clear up some exhaust questions for me? I've always heard that free breathing exhaust is better, but from experience I've found that that's only true to a certain extent. What exhaust size and muffler type would be most suited for this motor?
Erik
Anyhow, I'm real satisfied with the 400, however, it feels a little gutless after about 3000 rpms. It's totally stock. I just got done puting bearings in the bottom end and plan on puting a 4bbl manifold on it with a Holley 600 vac secondary, and headers. What kind of gain can I expect? Also, I've heard that the 400 came from the factory with a cam retarded 6 degrees. Is this true?
Finally can someone clear up some exhaust questions for me? I've always heard that free breathing exhaust is better, but from experience I've found that that's only true to a certain extent. What exhaust size and muffler type would be most suited for this motor?
Erik
Elder User
Joined: Jan 2004
Posts: 867
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From: Eastern Pa
First the mods you list are fine. The cam is retarded unless it is in a later 400 truck engine. Any how use a good double roller timing chain and while your at it why not stuff a cam in there. With the headers and intake you can easily utilize the benefits of a cam. As for the exhaust, for your purposes 2 1/4" would be fine. You could use 2 1/2" if you wanted. If you go to 3" with a mild engine you might add a little up top but lose it down low.
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