OZ 250 advice

[ozconv]

I am a new member to the forum. I recently bought a rebuilt OZ250-2V head and intake off of eBay from Aus Ford Parts and was wondering if anyone has ever delt with them? My plan is to install the head on my '67 mustang convertible. I restored the car about 10 years ago and it is mostly stock except for a pertronix ignition and coil, 14x7 aftermarket rims with P235/60R14 Cooper Cobras, 4-lug power front disc brakes, and a unisteer manual steering rack. Except for the pertronix the engine is a basic bone stock rebuild with less than 10,000 miles on it. The car has a rebuilt C-4 automatic and the original 7.25" rear axle with a 2.83 gear ratio. I use the car primarily for cruise-ins and car shows with occassional pleasure cruising.

I have received the 250 head from Aus Ford Parts and done a preliminary examination. The casting code on the head is ARD10E 6048 AC. The head was rebuilt using the original valves. One of the exhaust valves shows some pitting. I removed one intake and exhaust valve to measure them. The stems measure 0.344" in diameter so according to the Falcon Six Performance Handbook they are non-US valves. The intake measures 1.770" and the exhaust measures 1.476". This is confusing to me beacuse the OZ-250 section of the FSPHB says that 1.75" intakes were the largest intakes offered. The measurements were taken with a pair of calipers. It looks to me like a 3-angle valve job was performed. Not sure if hardened exhaust seats were installed. The head does not have a port divider but it looks like it may have been ported as the bowls and runners have a smooth surface and the exhaust ports flare out a bit at the gasket surface. There are no cast circles in the exhaust port ceilings except for no. 3 and no. 4 which also are the only place in the runners to have a rough cast surface. The retainers are one piece and look very similar to the 260 V-8 retainers in the FSPHB. Not sure how to post pictures but once I figure it out, I will post some.

My plans are to measure the combustion chambers to determine how much it needs milled to get it to the 67 200's 52CC size. I also may weld in a port divider before taking the head to a machine shop to have it checked out along with milling it and facing the exhaust flange. I am not planning to replace the valves and springs at this time as they are pretty good sized. Because my engine is rebuilt with low miles and in the car, I am reluctant to do a cam swap. I am, however, seriously considering a set of 1.6 roller tip rockers to gain a little more valve lift with the stock cam and the ability to adjust the valve lash. For exhaust, I plan to get CLassic Inlines header and install 2" dual exhaust with Flow Master mufflers. Because I blew my budget on the head, I plan to rebuild an autolite 2100 2V that I have lying around. I need to check the size but it is for a '67 289 so I am guessing it is around 300CFM. I also have the load-o-matic distributor so to save money I was planning to rebuild a distributor from a '71 250 and convert it to a Pertronix ignition. Any advice concerning my plans would be appreciated.

 

[Vin Man]

Sounds like a familiar project to me.

Just a couple of things I'm going to throw out there for you.
I think upgrading the cam is worth it. If you are going with all those other upgrades, you will really appreciate the cam.
I went with Magna Flow Wide Opens instead of Flowmaster. I am extremely pleased with the Magna flows and would recommend them over the flowmaster.
I had a 2100 as well and it was a 1.08 venturi. No matter how hard I tried, I couldn't get it to run as well as I knew it could. Part of problem was it was too big. I wound up with a 1.06 from Pony Carbs and it was great.
Plan on a throttle cable set up.

Lots of great resources here on the board. Slade (cobrasix) is a especially helpful with his website.

 

[addo]

Seriously, think hard before going to the trouble of installing a port divider. There's still not much evidence of them helping in daily duties. Considering that Ford went to the trouble of designing both new exhaust ports and specifying a factory header for this engine, don't you think they'd have had the perfect chance to split the centre exhaust - if they felt it would assist?

Valve heads have evidently been upsized; Aussie valve stems were bigger to begin with so you may have local product (of ours) as a substitute.

I would regrind the existing cam slightly. This gets you two things - a better cam profile for mild performance, and no issues with distributor gear wear as with aftermarket cams. Plus it's cheaper than a new cam.

Would be surprised if you need to skim more than 30 thou off the head; it's likely had a slice or two already.

 

[ozconv]

Combustion chambers measure 54.5 CC. I am thinking of milling the head 0.015" to get it to 51.5 CC (stock for 67) plus another 0.010" to acount for part of the thicker aftermarket head gasket. This should get me to around 8.9:1. When I rebuild my spare short block later (maybe next year), I will have it 0 decked and that should take care of the other 0.020" of aftermarket head gasket thickness and get me back to the stock 9.2:1. As far as regrinding the stock cam, what should I ask for? The head currently has oversized valves (exhaust are nonmagnetic so I am assuming they are stainless) and appears to have had some porting and polishing as the header gasket matches and the exhaust ports are bigger than the stock 67 head I have for comparison. I plan to have the head checked out when I have them mill it and also have the intake valves backcut. I also plan to use 1.6 ratio roller tipped rockers that should give a little more lift and duration. Right now the cam is the big indecision point since I don't have the tools or experience to swap out the cam bearings (engine has less then 10,000 miles on the rebuild).