head porting

[blh0007]

hey guys, i have read the basic head porting article in the tech library. I just was wanting to hear if anyone has found a decent power increase on a 4.0 v-6; was it worth the time and effort.

 

[Dweano]

I'm not talking from experience just what I heard but I think you'll get a small increase, but its a good supporting mod if you do like, exhaust intake cam tune etc

 

[Angie]

Hi, I can't say if there was a difference or not, I did a full rebuild and added the compcam 410. what I can say thou is that if you are going to try this home job, take your time!!! follow the directions. I went at this project slowly and it took about a week and a half for the heads. burned out a dremmel in the process. If you are going to do this I also would reccomend you reseal the valves and reseat. no since in going half assed at it.

 

[blh0007]

thanks for the feed back guys. hey angie, what kind of improvments did you see in your rebuild. my truck's engine is getting on up there in the mileage and i'm thinking of how i should approach a rebuild. thanks

 

[Angie]

Improvements? well with new stem seals it doesn't ahve that tiny puff of blue when it is started. the motor that i redid was out of my old running 91, and then placed the motor into a 92 that was in better shape. I am still on the fence as to what has been improved except I know it is strong and will last me years. I am waiting to get the motor/truck dynoed and Diablo Sport chipped to tune in the cam for it is burning excessive gas. Power is there however, after the tune I know it will be way better. hope this helps. for you were a bit vague

 

[James Denton]

There is a big differences a good head & porting job done right ---Will get you some more HP---better gas mileage--and run better---Take your time and work om them a little at a time.

 

[Bird]

OK - some facts about 4.0 OHV heads - they flat out suck in the flow department and it's 99% on the exhaust side. The intake ports on the 4.0 actually flow pretty decently - only require a little bowl cleanup and coarse sanding the port to remove casting imperfections. Opening up the intake port only hurts the flow. The exhaust side is where the power is made - it will take a lot of work on the bowl, guide, short side radius and port roof, but once done correctly, will greatly increase the flow and make some nice power. Add in a 410 cam/headers and you'll have an entirely different engine.

If you are only going to use a Dremel, don't expect much - it doesn't have the cutters / stones / sanding rolls available to reach down into the bowls and ports to be able to properly get the job done and takes forever to show any progress.

Also, there's 2 diferent style exhaust ports in the 4.0 - takes different work to get good flow out of each type...............

Bird