Crank in a 200 X-Flow

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Two years ago, I had a 250 engine in my XF Falcon before I exchanged it for a re-conditioned one, and up until last week, I thought I had a 250, only to be told that I now had a 200! ...The bas***ds took my 250, and replaced it with a 200! :(

I also tried getting in touch with them, but they've recently gone under new managemet... how convenient!

Anyways, sorry about my life story... LOL!

How would I go about stroking my 200 up to a 250?

As far as I know, they've got the same bore diameter just different stroke length, right? ...which means just changing the crank and conrods would stroke it up? ...Correct me if I'm wrong guys.
 
Get yourself a 250 crank, XF model to get seal compatability.
Get some ACL pistons to suit a 250 with 200 rods (you have) and bung it together, Viola, 250 with long rods.
A7M
 
Are the oil seals between the XE and XF different? ...Cos I'm not too sure if they replaced mine with an XE or XF.

Also, why is it better to use longer rods? ...More power? or higher RPM??? ...Sorry, I'm still learning! :lol:
 
Rear oil seals are as follows...
rope type up to early 1984
one piece from '84 to 10/87, casting number on l/h/r of block starts with 84DA or 86DA
metric one piece seal from 10/87 onwards inc. OHC casting number on pushrod engines starts with 87DA and upwards.
The 87da blocks can use the EA onwards cranks.
 
Why are longer conrods better than shorter ones though???

Also, how hard is it to change a crank in those engines?
Would I have to take the engine out of my XF falcon to do it?
 
Yep, the engine will have to come out. It's not an afternoon job but an organised amateur "team" could do the swap in three days to turn key stage. You will have to investigate your oversizes first, to order the pistons/rings. Once you know exactly which bits you need, talk to Barry at Ryde Auto One. Ask for genuine ACL parts and push him for a good price.

The long rods are for better rod to stroke ratio. This enhances its life under stressed conditions...

Cheers, Adam.
 
Thanks Addo.

What else could I change while the bottom-end of the engine is out and apart to increase performance??? ...or are the ACL pistons with long 200 rods a good enough combo?
 
They're agood start, but it depends if you have surplus budget as to the rest of any buildup. Don't build a motor which chokes for lack of a you-beaut top end.

Rollmaster timing set, Crow cam if you've $600 extra to play with(14602 or 14776) and the bits to go with it, clean the block through all the oil galleries etc. You are basically reassembling a motor, so take the time to do the stuff quickie rebuilders don't bother with. From memory, pistons and rings should be about $450. Bearing set maybe $180 in ACL. I have some Jap rod bearings (std) for sale which are very nice, but haven't seen better than ACL for the mains.

Dial your cam and check the balancer's on the money. Check all the other clearances as you assemble.

Cheers, Adam.
 
I recently put in a new cam (lobes wore on old one)...

It's a "Heatseeker Stage 2 cam" - Part No: HS 20 D
I dunno if its any good or not, what do you reckon? Iv'e got the specification card here if you wanna know any specs?

I also put in a new Rollmaster timing set.

All this was done about 3 months ago, doing hardly any km's.

So do you reckon it's a good start, or is the cam not up to spec?
 
I had the US Heatseaker HS10E 252 Cam, a rather mild thing. The Stage 2 will be really good for your car.

You'll note that the 200 can really rev its ring out, unlike the 250. There's an extra 800 safe rpm with the 200 X-flow.

The shorter rods increase side loads, or thrust loads, on the cylinder bore, and increase friction. The ideal ratio is 1.8 inches of rod, for every 1 inch of stroke.

*The stock 200 has 2 inches of rod, for every inch of stroke (6.275" rods, divided by 3.126" stroke)

*The stock 250 has 1.505 inches of rod, for every inch of stroke (5.885" rods, divided by 3.910" stroke)

*The 1997 on Falcons have 242 cube engines, with 1.550 inches of rod, for every inch of stroke (6.060" rods, divided by 3.910" stroke).

What A7M is suggesting is the stock 250 crank with 1.605 inches of rod, for every inch of stroke (6.275" rods, divided by 3.910" stroke).

The longer you can make the rod, the more power and torque the engine will produce, but you only notice it at the higer end of the rev scale. You notice the benifit most on engines that have a poor ratio, and the 250 is the best engine around to do a rod, piston and crank change. It's cost effective.

What's not cost effective is to loose cubes.

Go do it, and keep the cam you have. It was designed for the 250 six, not the 200!
 
Cool!
So if I use the 250 crank, 250 ACL pistons with 200 rods, It'll safely rev out to 5300rpm?

Just one question, sorry if Its a stupid one though...
But if I use 200 rods, with 250 pistons, wouldnt the stroke be too long for the block because of the longer rods? Ie. Wouldnt it make contact with the valves??

Sorry about the ambush of questions, It's just that I'm still sorta learning about stroking up engines!
 
Bang on.

The block is about 9.48" tall. The tops of most pistons sit about 20 thou (0.020") below the block on cross-flows. When the rod gets longer, either the piston or stroke needs to change. Aside from the bowl in the piston, 3.3 and 4.1 pistons are the same. It's just different length rods. Classic ase of robbing peter to give to paul.

The 200 pistons and 250 crank with 200 rods would result in the pistons coming out of the block 0.392 inches, or half the differenec in stroke.

Draw it down on a piece of paper, and:-

add half the stroke (3.91" divided by two)
to the rod length (6.275")
and to the piston deck (1.620")

This lot adds up to 9.85", or about 0.370" above the block. Ouch!

Most ring lands are only 0.275" from the top of the block, so the rings would pop out, and there isn't enough meat in a cast piston to shave off 370 thou!

New pistons ACL shallow 1.163" deck psitons, or just pyke out and get 5.885" 4.1 rods and redo the head to lower the compression ratio.
 
Ahhh ok, bit complicated, but you explained urself well...
Thanks buddy :wink:

What sort of headwork would I be looking at to decrease the compression like you say to do?

What would you recommend (to increase performance) :-
* Fork out for 5.885 rods + headwork?... or;
* Fork out for the shallow deck ACL pistons?
 
Just buy the stubby pistons. Top notch gear, why not use it? :D The timing set is good; less to worry about now! If CR is still an issue, perhaps lay back the chamber walls near the valves if possible, or unshroud.

Adam.
 
Will do... stubbies it is! :wink:

What would be a good compression ratio to aim for?

Seeing that I'm gonna work the bottom end, and already have it cammed + new timing gear, I might aswell work the top end; The head has recently been reconditioned with new seals, seats, welding of water holes, etc... So it's in good nic...

After porting & polishing the head (which I'll do after the crank change), what else should I do to the head for a good performance increase?
 
hey bassfreak ,the number you want for your piston is 6mkry9412 + and then your oversize .They have a 8.6cc bowl so thay would give you about 10.0:1 comp ratio @77cc. The rear main seal could be 1 of 3 ,1 is a dog turd seal (2) is a 1 peice 90mm x108mmx9mm or (3) 95mm x 110mm x 9.5mm.If your buying a gasket set tell the guys what size seal you have as theres 3 differnt bottom sets .another question do you like loud music or catching those little green fish?
 
Ahhh, I didn't know the x-flows had 3 different rear main oil seals... something to look out for! Thanks for that :wink:

Aren't those anti-pump lifters really noisy?

Alright, so far, my list is:
* Standard 250 crank.
* 250 ACL Pistons - shallow 1.163" deck, with matching ACL bearings + rings.
* 200 rods (which I already have = less money to spend!! :D ).
* Rear main oil seal.

Loud music? LOL! Yeah, what gave you that impression... the nickname? :wink:
 
Ooooo, and maybe add roller-rockers to the list... Depending on how much they are! :wink:
 
anti pumps arent noisy ,its the solid ones that can be noisy.Anti pumps have a differnt bleed rate (faster) so they dont pump themselves up and stop your valve from closing all the way.Roller rockers are pretty expensive look for a set of 2nd hand cleveland ones ..same same.New in nz for a 6 cyl set (12) $450.00 + ,in the trade and exchange today a guy had a so called yella terra head with roller rockers for $300.00 ..

if your gunna rev it get the antipumps

cheers dave
 
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