Im really happy!!!! I posted a question about re-plaicing head gaskets on a 360 and I got it all apart and the block inside says 352 so I wanted to find out what the really was becuase the guy who i bought it from said it was a 360, well I got to measuring the stroke and it truns out it's a 390 so im gonna re-build it and put a rv2 cam with a nice intake and carb on it!!!!! I was just kinda wondering what kind of HP will that put out?? Im probly gonna run a edelbrock intake and a 600cfm Rochester. Stock exhaust maniforlds for now but soon ill have headers and flowmasters.

 

Congratulations. The longer stroke makes a big torque difference.

In terms of HP, you can expect low 300s from a 390 with stock heads and exhaust, a decent 4v intake/carb setup, and moderate to hot street cam. Depending on the cam, you may see a gross HP number as high as 350-360 once you go to headers. A fully "built" 390 with big valves, ported heads, and a single plane intake can make 400+ hp.

 

What will headers really do for a 390. just a bit of performance? I read where many peop,e are having them installed but geesh they cost a good chuck of coin...I don't know if the cost over ride the bennies?

Lonallie@cs.com
lonnie.dotson@boeing.com

 

You can get a set of flowtech (Holley) headers at autozone for $100. They aren't coated or fancy but neither are your manifolds. They will make a noticeable difference on a 390.

 

I don't know anyone who has done any scientific testing of the difference that headers make on an FE, e.g., putting their truck on a chassis dyno with stock iron logs to get a baseline, then swappings the logs for headers and doing another dyno pull. What I do know is that lots of people really believe they work, performance engines always use headers, and computer simulations like Desktop Dyno always show significant performance gains from headers.

Headers can range from $100 for the cheapest plain steel set to $750 for a top quality set with a Jet-Hot or similar coating. I suspect that the performance is about the same. The extra money will get you a set that fits better, is less likely to leak, and lasts a lot longer (cheap ones will tend to rust out quickly). Jet-Hot and similar coatings, besides making headers last a long time, reportedly keep header surface temperatures (and, thus, engine compartment temps) considerably lower. That should make other items, like your starter, also last longer.

A cheap set of headers provides great bang for the buck in terms of performance gains, but they're not for me. I don't want to have to continually be replacing blown gaskets, fixing exhaust leaks, and battling to change heat-destroyed starters. I'd rather stick with the stock logs than use a cheap pair of uncoated headers.