200 Crossflow (cast iron) turbo

[Anonymous]

I put this post in "aussie sixes" no response. I realy could do with some advice.

I am organising the rebuild of my motor which has a holset turbo with a compressor similar to a TO4b S3 compressor(small for a TO4) cam is gas research stage 1, about .450 thou lift and around 260 degree. Straight LPG, very early model gas research 350 cfm mixer. Redline Torker manifold. Ford truck intercooler cut down to 100cm x32cm x4cm (it fits between the lights on an XB with the narow section of the truck end tanks, like it was designed for the job, very happy.)

I have the machining costed and most of the parts. I have questions about 2 things:

1. I will buy ACL's Race 9411 pistons (8.5cc) bowl giving about 8.3 to 1 with my 60 cc heads and zero deck. Bore is currently standard (worn) is 30 thou a safe overbore? The cylinder walls look pretty thin in these blocks.

2. Valve springs, I want the lightest springs that will control the stock valves up to 6000 or slightly beyond. Anyone got any experience?

 

[addo]

For the springs - what about the Crow singles? As to bore flex - who's game to give a rock-solid opinion. Get it ultrasounded if you're unsure how centred the bores are. 40 over on a 202 turbo is pushing your cards but the 173 block is a thickwall and can be bored to plus zero 186 specs no worries. We are not so lucky with the Ford sixes...

Lose that iron head and you can run less boost - not so much weight to move.

Cheers, Adam.

 

[Anonymous]

good to see ur keen to do it all mate.



have a read of these two threads, read my responses there, u may pick up a few things.

http://fordsix.com/forum/viewtopic.php?t=8653

http://fordsix.com/forum/viewtopic.php?t=8981


one thing tho.. the intercooler u spec wont be as good a good 600x300x76/90mm core.
u'll find that cos its so long you will get a pressure drop across the core, also how wide the thing is (only 40mm) is not good you'll most likley find it is a restriction. and also wont cool air as much as you think. then again, you can just try it ans see how it goes, if it woks well, well.... i'll shut then. lol

cheers.joe.

 

[xctasy]

The Ford blocks have thinner castings than the earlier Holden 179 cube engines. Those had upto 150 thou of wall thickness, so you could take 'em out to 60 thou over 202 pistons sizes, a massive 123 thou over bore!

Aussie tall deck 200's are still okay, especially if you are using the longer 200/3.3 post 1970 con-rods, and the large journal 200/3.3 crank. There would be much less side loading than with the 250/4.1 set up, great for high boost and revs.


The V8 guys say an engine running a static compression of 11:1 or so needs 120 thou piston wall thickness at the thrust faces. Stock, that's all the thin wall 3.68" bore 200 block had. With a 56 thou overbore, and 20 years of cast iron oxidisation, my 250 block had about 80 thou according to my old ultrasonic cover meter we used at the lab. It's nothing to loose a uniform slag of about 20 thou due to rust if no corrosion inhibitor is used. More of an issue is block porosity. Some American guys with short deck 200's have seen block colour and hardness change with over bores beyond 30 thou.

Some guys have claimed Chrysler Slant/ Hemi Six -style over bores of overbores of 120 thou (using Commodore V6 /GM 3800 pistons) but I can't vouch for that. With bore spacings claimed to be 4.08 by some sources, a 30 thou over bore would leave 370 thou between the cylinders, and should be very safe for a 100 thou thick thrust face, even if it has had a little block rust.

In most cases, the rate of cast iron rusting is very low if the water has been kept topped up.

 

[Anonymous]

Thanks. I think I will go 20 thou. If that doesnt clean the block up I will get another one. I have a spare early x-flow block but it has the larger boss for the points distributor.

Anybody know the rough cost of sleeving?

 

[Fingers]

The distributor is easily fixed, had a mate who works in a machine shop modify them before with a bush on the shaft. Cant help on pricing though as it was the standard carton of beer barter system

 

[addo]

That's cheap on the dizzy, Richard. I pay $150-odd with a recurve/full rebush with the shaft swap. They TIG a NOS XA type shaft onto the XE unit.

Adam.