Just for full disclosure since you're new - Intense has had a lot of spectacular failures through the years and have cost multiple customers engines & transmissions. I bring this up because heads were one of their disasters:

-Valve seat recession. They were hogging out the valve seats to shove in giant valves. Problem is, they were grinding beyond the factory induction hardened seat area. This didn't matter for the drag cars, but was a big problem for the street guys that were racking up mileage. Basically the exhaust valve would slowly eat it's way into the head. This would screw with valve train geometry over time (as the stem height would grow and change the contact point of the rocker) and would eventually ruin the heads permanently. The "solution" - run lead substitute (used in the fuel of cars made before unleaded gas to allow them to work on modern fuel)

-Valve guide wear. For whatever reason, they chose to go with valves with a different than stock stem size. This forced them replace the valve guides and they did so with soft brass. Again, running a handful of quarter miles in a drag car was fine, but when you started racking up a bunch of street miles (especially for those with a really big cam), the valve would groove the brass and would allow valve slop and oil leakage (not that the valve guide is meant to stop oil, the seal does, but it makes any minor seal issue a big problem with a measurable gap past the valve). Not sure what their official "solution" ever was to this, initial reaction to the first few failures was just "better QC checks because something wasn't assembled right".


With that said, those issues popped up probably 15 years ago at this point, so hopefully theyve actually fixed both. My point is just before you spend $2k on heads, its worthwhile to do some serious searching for someone actually using current production stuff from them.

 

Got it, thanks for the heads up. Are there any more aftermarket 3800 distributors that I should look into?

 

I will saw DIY head porting is harder than it looks. The work and technique isnt hard, but doing it right and doing it exactly the same 6 times isnt easy. The 3800 is a bit harder in that its iron, so it's nice that a slight slip doesnt result in a giant gouge, but it does make it tougher going. Upside is it's almost 100% labor. You need some bits and an air die grinder and that's about it, so its almost free gains in terms of dollars spent.

I looked into it years ago before I bought ZZP S4s. Best advice I got - go down to a local junkyard, grab one 3800 head (NA or SC, doesn't matter, they're both basically the same) and try it on one port until you're happy. Then try and do exactly the same on the next port.

Lastly, take it to a local speed shop for a flow bench test and get results for all 3 cylinders (including the one left stock). Thatll let you know A) if your technique / changes made a usable improvement over stock (ie not at .700 lift) B) if you're able to keep consistent from one to the other. If both check out, let her rip on your real heads.

Personally, after jacking around with one, I decided it just wasn't for me. I could certainly see the reason most shops have switched to CNC nowadays. Biggest thing I've seen new people screw up doing this is they think bigger port = better, so they hog out the ports as much as possible. This kills velocity and often kills low lift flow too. Have to keep in mind this isnt some .850" lift monster, most of the valve's time will be spent well under .600".

 

ZZP used to be one of the other big ones. Not sure why they took their heads off the page. May be worth an email to see if they're still offered when you get closer. A lot of the record cars through the years have run ZZP ported stock heads.

 

I have almost all of the tools required already, as I planned to port my own heads a while back. But something came up and I never got around to it. I even went to the junkyard like you said, to pick up a practice LIM and head. I ended up only coming away with a LIM, cause the exhaust manifold bolts were so rusted, and I didn't have enough tools to get the job done. But nevertheless, I practiced on the part I had, and it went pretty well. Although, it would take me quite a while.

When researching the subject I found some videos. One I took as a more general porting technique guide. Some of the tips in this one likely wouldn't apply to our heads, but I still found it very informative.
The other is a three part series on specifically porting 3800 heads. Here's a link to the intake portion.

What do you think about relapping the valves while I'm in there?

 

Probably worthwhile to try a junkyard again, or even reach out on the 3800 FB page to see if someone has one laying around. It's a significantly different feeling from aluminum. Just would be nice to practice on something that's not the real thing.

I'd definitely lap the valves to make sure they seal up nice. Like the porting, its basically free, and itll give you a warm and fuzzy once you see that nice even band all around them.

 

When gasket matching, should I use a new, or used gasket?

 

Personally I'd use the new gasket you intend to run. As you're just using it to scribe / mark the surface, there's zero risk in damaging it as itll be removed for porting.

Reason I'd use the new is so itll be as close a match as possible. Certainly all replacement gaskets will be made to the same general specs, but there's always the chance that one brand of gasket wont exactly match the other (ie 15 year old OEM vs say some brand new Felpros ).

 

Agreed.

As long as you do the research on how it's done, and have a bit of money to get some heads from the junkyard, you might just find a new hobby.

 

After my third try at the junkyard, I finally managed to pull a head and take it home yesterday. Cost me 47$ and a sunburn from working in the Texas sun for about 4 hours. I'll be disassembling it and thoroughly cleaning it before I can start learning to port it. The intake runners were pretty grimy, the stems of the exhaust valves were white, and the tops of the intake valves were disgustingly caked in carbon. It'll take awhile to get all of it as clean as I want.