B3 Cylinder Head Cross Section [Pics]

[91_festy_Gl]

Sticky! I wonder if the B8 head is the same way? I have a spare you could cut!

[blkfordsedan]

I have an older Craftsman electric die grinder, kinda looks like a heavy duty Dremel. It has a cable attachment (like a dremel) that you can use to get into almost any port. It works good on aluminum but cast iron is a little tougher. I use it for the "fine tuning" as well. Nothin beats a good air grinder. I need some long shank bits like you got.

Got any Buddies with a flow bench? I'd love to get some actual flow numbers on a stock & ported B6 8V head.

[Zanzer]

Sticky! I wonder if the B8 head is the same way? I have a spare you could cut!

You'll be receiving a PM soon

Got any Buddies with a flow bench? I'd love to get some actual flow numbers on a stock & ported B6 8V head.

I have a friend who has one he uses for Harley heads. I thought about trying to borrow it. At some point I'm going to build my own but the flow meter is kinda pricey. Starts at $500

Too late now though, I got all the intake ports done today

[Zanzer]

As requested, here are some pics of the ports with the areas that need attention highlighted. I just used a Sharpie to highlight the edges. When porting I would remove alittle more than the shaded areas and flow them in.

Here's the intake halves.





And the exhaust halves.






I have some pics of a B6 head I'm currently doing that I'll post after I get them sorted out and uploaded.

[Zanzer]

I'm going to break this up into 2 posts because it's a lot of pics.

I'll start with the intake side because it needs less work. I like to "pick the low hanging fruit first" so I always start with the easiest port Plus it allows me to get back into the swing of porting. Typically the first one takes the longest because I work out what needs to be done while I'm working the port. After that I just try to make the others match the first one.

You'll also notice that I didn't do a lot of grinding on this port. This is for 2 reasons: 1 - Since it's an NA application I wanted to take out as little material as possible because I didn't want to kill air velocity in the port. Flow is good but not at the cost of velocity. If this was for a boosted application the port would look a good bit different. 2 - Since this is the intake side, it's actually better to leave some of the as cast roughness in the port because it helps atomize the air fuel mixture before it reaches the valve. You don't have to give the port an NHRA grade polishing. Smooth port walls only yield minimal gains.



From the combustion chamber side:

Before



After



From a different angle looking down the port

Before



After



And finally, looking into the port from the intake side

Before



After

[Zanzer]

As you can see from the previous pics, the exhaust side needs A LOT of work and modification. I had to remove a good bit of material to round off the short side radius but I didn't want to get too crazy because there is a water passage directly under it. The edges left from valve seat back cutting took a good bit to work out as well. You'll also notice in the pics that I polished the entire port. This wasn't done to improve flow, it was done to inhibit carbon buildup. The "as cast" port was extremely nasty and carbon is notoriously bad for building up inside the exhaust runners. When I was cleaning this head, the hardest areas to clean were the ones with the poorest quality in the casting. Now the port walls are fairly smooth and uniform so hopefully carbon will have a harder time finding a new home.

Here's the pics from the combustion chamber side

Before



After



From a slightly different angle so you can see some of the short side radius

Before



After



And here it is looking from the manifold side of the runner

Before



After

[sasquatch]

nice porting job looks awesome

[Occhty]

When we used to port and polish race bikes, there was a (Teflon coating like) treatment we would have done, can't remember the name of it though. But I never saw any carbon stick to that stuff. I think they used it on cylinder wall too. Not sure if it's still being done, just a thought, but the way that exaust port looks it might be worth checking into. Although I think you would have to be porting serious.

Awesome port job there Zanzer.

[Safety Guy]

Thanks for the magic marker & porting pics! It seems a lot clearer now, though I'll be very conservative with it!

I'll probably practice on my old '89L head first, then I'll do my Aspire head that will be going on my "MPG B3" when I put it all together.

Karl

[blkfordsedan]

Excellent Job, well done! A perfect example of a moderate street/pocket port that will improve flow and not hurt port velocity.

One thing to note for anyone trying this for the first time: When porting from the chamber side, be very careful to avoid contact with the valve seat. Especially if using a carbide cutting bit. If you nip the valve seat you'll be doing a valve job. Take your time and be patient.

Are you going to do port match or any chamber work, maybe just a polish?

[Zanzer]

^^ Good call on the valve seats! I forgot to add that Yes, a carbide bit will make quick work of a valve seat and has absolutely no conscience LOL

I did a very small port match on the intake side after I took the pics. It barely needed any as the intake port and gasket were almost a perfect match.


*Another note for first time porters, don't gasket match the exhaust runners. There is an intentional mismatch between the port and manifold. This creates a reversion dam that helps keep burnt gasses from re-entering the combustion chamber as exhaust pulses move back and forth in the exhaust system.*


I'm going to do some work to the combustion chambers as well. The casting looks pretty bad in 2 of them some I'm going to clean them up, remove some sharp edges, and try to un-shroud the valves a little. I always save the combustion chambers for last because no matter how hard you try, you always get a little nick here and there from the grinder chuck while working on the ports. By saving the chambers for last I can clean those up too

[thered56]

Thread rated. Rep added. Thanks for all the great tips. I'm looking forward to the B6 cross-section.

[link5186]

Thread rated. Rep added. Thanks for all the great tips. I'm looking forward to the B6 cross-section.

x2
Time to get some bits and start practicing. Definitely need to get that exhaust port right. I'm still not over that ridge!

Sent from the bathroom via crapatalk

[Grey Vw]

*Another note for first time porters, don't gasket match the exhaust runners. There is an intentional mismatch between the port and manifold. This creates a reversion dam that helps keep burnt gasses from re-entering the combustion chamber as exhaust pulses move back and forth in the exhaust system.*

Too late I think. Are you talking about gasket matching the head or the exhaust manifold?

[blkfordsedan]

Too late I think. Are you talking about gasket matching the head or the exhaust manifold?

LOL, both. The port openings on the exhaust manifold should be slightly larger than the port openings in the head. That will help keep the exhaust pulses from backing up from the manifold into the head. It's not that big of a deal if you already matched them to the same size. You can always enlarge the manifold ports....or just leave it. You just don't want the ports in the head to be bigger than those in the manifold. Get the idea?