michaelmount123

Here's a 4V head on the bench being prepared for a high RPM race application. It's got quite a few mods. If anyone's bored, and/or up for a challenge, try to identify all of them. I think there are seven, perhaps more. I'll identify the first one.
1. Intake ported
2.
3.
4.
5.
6.
7.
Any more?

PaulD_944S2

OK, I'll bite:

2. Adjustable cam gear
3. Camshaft bearing girdle (replaces camshaft caps)
4. Cam grind/reground
5. Dowel pins
6. Additional tensioner support on cylinder 3 by girdle
7. Cam cover bolt modifications because of girdle

Spark plug O-ring reliefs moved up to meet cam cover
There may be mods under the girdle to hold the cam cover on

Beautiful piece of workmanship!

Humboldtgrin

951and944S

Whoa...., you move fast, I just sent the head 2 days ago.....

Seriously though...., let's see.

Tensioner oil feed hole is plugged because hydraulic actuation feature will be deleted.

Don't know if this one counts but cams run full length of head and utilize +1 head/cam journal where the factory stops short of the #6 journal at the cylinder #4s second intake and exhaust valve.

What would be another difference is the intake is usually bolted but here you have studs but I assume it's just a convenience to hold the gasket on/off while porting.

Paul already got the obvious ones I see but I'd say that the area where the lobes pass towards the lifter have been clearanced for more valve lift.

T

V2Rocket

are those sharpied numbers valve lash?

951and944S

Being that there are lash caps on the bench next to the sharpie and offset feeler gauge....., I would say yes....

T

Droops83

That looks great. What sort of RPM/power range is expected?

I suppose that the camshafts need to be removed to change valve shims? (EDIT: I just noticed the lash caps/shims on the bench, and the answer is YES . Are said shims of a type that is commonly available? They look similar to Alfa shims.

Thanks for sharing.

V2Rocket

DOHC Subaru engines since '97 use 35mm shim-over-bucket design solid lifters, and there's like 40 different sizes of shim in tiny increments (i think 0.0005"?) you can get from the dealer about $8/ea.

i didn't measure the height/depth of my Subaru lifters to compare against Porsche, but it might be something to look into.

michaelmount123

You guys are pretty slick; slicker than I expected. Paul's got a keen eye and got most of what's going on. There are o-rings sealing the cam girdle to the head, and yes, the Porsche sealing rings fit against a valve cover machined to accommodate the girdle and seals. The cover uses all the original fasteners. The tensioner mount is reinforced by welding to adjacent lifter bores, and a bracket (not shown) supports the other end when bolted to the rear girdle. Terry picked up on the extended cam that supports the #4 end lobes to keep them more stable. He also noticed the plug in the oil feed for the oil fed tensioner. This head uses a mechanical tensioner (modified stock) to eliminate that potential failure point.

The cam is a custom billet piece, uses lightweight solid followers, and the lash caps fit over the 7mm valve stems. Yes, setting lash is a pain. The All the mods provide a stable valve train for 8000rpm shifts, and protect against damage from over-revs.

V2Rocket

would love any details on the mechanical chain tensioner.
assuming shims and springs inside in place of oil piston?

gruhsy

So what engine is that cylinder head going in?

PaulD_944S2

MINE!!!!!!

Sorry, I wish...................