[carbonmike]

I have a spare B18 head that I am thinking about have rebuilt. I plan on replacing the valves, guides and springs. I will have hardened seats installed, milled flat and at least a 3 angle valve job.


Are there any reasons not to use the stock valves, guides or springs? I see that some European sites offer upgraded single coil springs, I am guessing they are probably a stock spring from another application. Would there be any reason to upgrade from stock springs with a 6500 rpm rev limit and a D-Cam?

I think bronze valve guides could also be alternatively sourced and could be used with a guide seal. Any good reason to use these vs the stock B18 steel units sans seals?

 

[Phil Singher]

The stock valves, guides and springs are fine. Your machine shop can easily modify the guides to take stem seals.

 

[carbonmike]

So I finally got all my parts together. There are no machine shops in my town, so I called all the ones within an hour or two drive, only one guy called back. He has never seen an old volvo head before but I explained what I wanted and he seemed cool with it. The head I have is a spare one I picked up for cheap. It has already been milled 0.070" and gives me just about the chamber CC I am looking for. The exhaust seats were worn a fair bit.

I asked the guy to install hardened exhaust seats, new valves/springs, 3 angle valve job, skim-mill to flat, install new valve guides, light porting/bowl blending. My main goal is to bump the compression and get a little better flow.

When I dropped the head off the guy said he wasn't so sure about installing hardened seats since the head had such a short turn he wasn't comfortable with the amount of material there. At the time I just deferred to his experience. But now that I think about it, I think I need new valve seats. Not only is the question of unleaded fuel but I don't know how he can do a proper valve job with the currently worn seats. Isn't installing hardened seats on a B18 head a pretty standard practice?

I am thinking of pushing back on him in regards to the new seats. If he won't do it I guess I will have to drive farther to find another shop. Luckily I have a bit of time here as he will not be able to get to it until the end of the month.

 

[carbonmike]

Hello, Hello, is there anybody out there?

Considering my exhaust valve seat issue. I think going with a larger 37mm exhaust valve would allow a decent valve job without having to install hardened seats. Could there be any performance gains with a larger valve on a B18 head?

 

[dcthompson]

Don't even think of not installing hardened seats.

 

[carbonmike]

It took the machine shop 5 months to do a relatively simple amount of head work. I guess if you aren't one of his racing buddies you just get put on the bottom of the to do list. I had him machine the intake valve guides for proper valve stem seals. He didn't machine enough off to provide clearance with the valve spring retainers. Rather than waste more time I decided to buy the tool from comp cams and do it myself.

I figured while I was at it I would machine for double isky valves, (no pics).

Had the shop do some basic bowl blending. when I got it back I went a little wild and decided to do a little more work on the exhaust port around the guide.

Had about .080" milled off of the head, measured the combustion chamber to be at 44.5 CCs.

Installed the head over the weekend. I was tempted to install an Isky VV81 cam but thought it might be too much for a little B18. Measured valve cam and valve motion to make sure the D cam and followers I had in there were still in good shape. All valves had .285" of travel at the push rod, around .385" at the valve. I have a rather paltry 1.43:1 rocker arm ratio when you consider lash. I could probably use more valve lift, even with the small 40mm intake valves.

Anyway I couldn't be happier with the results. I have a lot more low end grunt. Engine used to run out of steam around 5800 rpm, now it pulls strong to the redline I have set at 6800 rpm. Using a GPS app on my phone 0 to 60 times used to come in at around 12.5 seconds. Managed to measure two pulls at 9.5 and 10.5 seconds with the worked head. On the 10.5 second run I bounced of the rev limiter in both 1st and 2nd.

 

[ScoopMan]

Nice! Can I send you my head too when I get around to this task? JK

Actually a bit surprised you had so much trouble finding a decent machine shop to do what you wanted.

 

[Phil Singher]

I find there's no benefit to larger valves, or at least not enough to be worth the bother. The best flow numbers I've ever gotten were on a B20B head with stock 42/35mm valves. B18 heads flow nearly as well with similar porting.

These heads don't respond to high valve lifts no matter what you do. I've never gotten exhaust flow to peak any higher than around .325", and some actually fall off at .400". The intake flow is slightly better at .450" than at .420", but just a little bit. What's important is how well the flow at mid-lift, because that's where the duration is.

Absolutely fit hard exhaust seat inserts. The intakes don't need them.

 

[carbonmike]

Do you ever open up the combustion chamber to de-shroud the valves? The combustion chambers don't provide the rule of thumb +20% diameter clearance.

 

[Phil Singher]

 

[carbonmike]

I noticed on the head I just removed that some of the carbon build up on the combustion wall was thinner/non-existent. I am assuming this is where flow is hitting the chamber wall. Interestingly it is towards the center of the chamber.

 

[NO_SPRK]

kinda off topic... do the FI b20 heads (like a 72 F head) have hard seats already?