200 Log/250 Log

[xrwagon]

Is there any difference between the two, my 200 is a 1967, i have access to a 250 log but havent got it to compare or buy until i know maybe its interchangeable, i may be getting this head sliced and diced for a fabricated intake manifold, extensive porting and triple side draughts or triple Su’s. I have manifolds i can cut and shut available.

 

[CNC-Dude]

I think i've seen on the Classic Inlines site that the log volume is a little bigger on the 250 head. But if your going to chop it off and fab your own intake its really a moot point by then. Since your going to do all that, have you considered making an EFI intake.

 

[xrwagon]

It was mainly because i have this other head available, i wondered as to what other either smaller or larger log heads would do the 200, a bit like how the later 200 heads have the larger valve. Ideally i don’t want to muck up my original head and thought well, if i get the 250 head it wont matter if we make a meal off it. So many options for the carb or efi route, i looked at a custom 250 crossflow setup at the drags last weekend, he has the spun up bellmouths and throttle bodys, should have got a picture of it as it was super neat and very well done, performance wise this larger XE falcon went 7.4 in the eighth and has done 11.4 over quarter, aspirated.

 

[xctasy]

I use the earlier head because the chambe flows 20% more than the other lateropen chamber heads. The later large runner and bigger chamber 250 heads don't yield any extra cfm, because the chamber is not optimal with the 1.65 valve sizes the Aussie logs used from 1965 to 1976. After 1968,they didn't follow US valve materials, sizes, valve seats, yearly emission changers, pushrod type or port runner sizes, and hadinferior exhast flow

The earlier XR log heads follow 1965 to 1967 non emissions US heads, and have none of the Australian alterations to the sparking plugs, valve guide size up grade, different temperature sensors, front water snout which is bigger, and have the earlier 170 C1 heads 52 cc closed combustion chamber, which makes more power with the 1.65" intakes than the 59 to 62 cc open chamber even with the later US 1.75" valves. Intake volume is irrelvent, but the later bigger 1-bbl hole is important for head flow, and the earlier head has a smaller 1-bbl hole, and earlier reversed cup rocker and ball top pushrods like the earlier US engines. When the XT and XW got the 188 and 221medium deck engines with 5.38 and 5.14" rods and 8.425"deck, the pushrods and valve gear and head changed. By the time 1971 rolled around, the tall deck 9.38" Aussie Log 200 and 250 engine was found in 71 XY's.The similar 72-73 XA's and 73 to 76 XB's used the same good head, with bigger 1-bbl intake port, larger runners, US Maverick kickdown rod casting, better exhast header, better everything except for peak cfm flow. The larger valve guides and bigger intake runners didn't liberate extra power because the combustion chamber was now 10 cc's bigger to keep the compression ratio down to 9.2:1.

There were standard fuel and super fuel engines, with different pistons sizes too. The 250 head casting remained basically the same from xy-xa-xb, and so long as you can find some 186 Holden pushrods and yella terra roller rockers, you can plane it down 90 to 120 thou, drop in a US 22 to 25 thou steel head gasket, and perhaps some Ferra valves on smaller valve guides, and you'll be able to fiddle diddle dee till yer hap hap pee.
"

 

[xrwagon]

thanks mate, i knew i should have just asked you, i am buying the Ford Performance book for starters. i did read that shaving even 60 thou off achieves 10.5-1 comp but requires a different pushrod, as i am going to put a solid cam in this motor i would need adjustable rocker gear. The holden roller rockers up for this with a solid cam? rollers and pushrods from a holden, i need to work out a comp ratio, i will be running on E85, the head gasket i was think of was .050 or .053 so decking the head 90-120 make the comp a bit to high, not looking at importing parts like gaskets etc, postage is to much.

 

[xctasy]

The Americans used the 2V head on the US 200 engiines, and its just a 250 log head really. So if you talk to the us 2v swapers, there is even a 2v facebook page, and run the same lifters, pushrods and rocker gear, you'll be sweet.

Any time you plane the head, just add the same amount in washers to the rocker pedastools. So some 62.5 or two of them, and some head bolts that won't ground out on the water pump, and other block holes will work. ARP studs work well.

Just ask, and these guys will help out, the info on these old iron heads is unreal.

 

[xrwagon]

thanks mate, i am doing my head or another log head, but not the 2v, will be experimenting on another head first, my mate owns a machine shop, so he will point me in the right direction as far as cutting the log off and adapting a manifold, where i live we also have a specialist manifold maker 6 boost, he is in Toowoomba. Going to make tis happen soon, so will do a in depth thread.