250 2v XY

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Anonymous

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Hey Guys,

I need some quick help for getting my 250 2v done up to beat a VL commodore, with a mild RB30, the 3L nissan motor, NON turbo.

The engine will be a daily driver and i am thinking of converting to straight gas very soon, i want the most power i can get out of it with my budget of $900. The motor was reconditioned not long ago, so i just need to know what goes good with these 250 2v's.

At the moment i am thinking of a bigger cam, but not sure which brand and what specs, i want something that will give me good acceleration. do i need any new valve train with that?? Double valve springs?? Timing gear?

Also get the seats done for lpg, but drive on petrol for a few months, get new rings and bearings if i need them, and not sure what else.

It would be great if someone could make a list of what i need, thanks for taking the time to read this.
 
One of the limiting factors may be the present compression ratio, by virtue of piston dish size. Any idea what was used?
 
pretty sure they are .030" repco standard pistons, would i need higher compression pistons??
 
If you get a lab style measuring flask and some clear poly tube from Bunnings, you can make a wet measuring system using ATF. One millilitre is one cc.

You need to measure how much fluid at TDC, how much at BDC, and importantly, how much is in the poly tube (including how far the spark plug normally pokes into the chamber).

Then subtract the tube's amount from the other two figures, and you have the static compression ratio (divide BDC amount by TDC amount).

There are so many piston options, and I don't think (unless they're old stock) Repco pistons are made specifically for them - so the piston type has a good few possibles!
 
Your not gonna do it for 900 ping, and certainly not if duel fuel. It won't work. Two carbs create to flow drops, and the engine won't run properly on either.

Been there, done that.


Meantime, cost out the folowing.

Ditch the petrol carb, fuel pump and carry a small adaptor to a barbie bottle if your silly enough to ever run an LP gas car out of gas (I've never done it, but my mates LPG 350 One tonner was run dry twelve times, and then gotr towed by my LPG Falcon... :wink: )

I'd get a Impco CA 300 A-5 carb, it does 432 cfm at 2"Hg, and can do 270 hp or so. Link it to a 2-bbl 4412 carb base. I've got a design for one, used it first in 1997, and it was designed to fit a 2V 250. It fits under the bonnet, and replaces the top part of a 500 cfm Holley 2-bbl carb.

Then get an E-series converter with the ECI lean cruise module, and XE electronic 4.1 automatic ignition, and have the gear rebuilt to fit the earlier pilot size. Get some good headers, and finally, get Crow cams to make a custom dual pattern , wide lobe centre gas spec cam grind with no more than 210 deg duration at 50 thou on the exhast, ground to a precross flow pattern.


Don't run a C4 or BW 35 if you have an Impco carb with a upgraded cam, they don't suit unless you get a very specific torque converter. Use the wide ratio Single rail from a XC 4.9 sedan. Use a 3.23:1 diff.


The go hunt Commodores. The engine should yield 190 horsepower, or close to a stock 351 C with the torque of a 302C.

As for compresion, what Addo said. Stock pistons are 15 to 28 cc for the X-flow, while earlier non cross flow pistons are special order, and need to have about 6.5 to 13 cc of dish. On Propane with an iron head, use 9:1 compression. Heat kills the exhast valve seats, and iron heads don't like lots of compression, althoug the 2V is actually better than the X-flo head for detonation resistance. Since 1990, LP Gas has a much lower RON number, so its no different to 95 octane unleaded.
 
Your 250-2v should have stock 1v pistons which yield about 9.5:1 comp which although a bit high for unleaded will work just fine with LPG.
To eat the VL sixes will only need a good stock or an EFI crossflow cam ground onto your 250-2v, much bigger than that will hurt torque which is really what these things are about. A better idea might be a small mechanical cam which Im sure crow can provide a profile (645) which is 206 dgrees at 1.25mm. This should give about 5500rpm with the right springs etc kit (ht950).
As to the LPG fitup, there are several ways , the Impco as described will work fine, but there are others that will work just as well.
The 2v head will need exhaust seats for unleaded fuels, including LPG. Id divide the centre exhaust port and make a gasket to keep the headers divided into two completely separate pipes even right to the bumper, if you run a single system, make it no smaller than 60mm. twin 50 is ok.
Dont enlarge the inlet ports, there big enough as they are, the exhaust can do with a bit of help.
This should give a quite powerfull engine with about as good perfromance a 5litre V8 possibly more torque which coupled to a BW four speed, and Id find the version with the 3.06 first gear (V8 I think) I prefer toploaders, but there a littel hard to find these days. The C4 would work well and probably easier to fit, depending on what youve got now.
Dont worry about beating the VL six, theyre not fast by any means and a good 250-2v will give you quite a surpise.
A7M
 
thanks guys, really helpful!

atm i have a 250 1v engine, toploader, BW LSD 3.23:1

Ive been looking at wade cams and this one sounds alright.

Ex .297 In .296
79-32 38-72
222 222
Hyd Hyd
.446 .444
110
Midrange to top end power
needs springs, carbs, exhaust


I already have dual extractors and twin 2" exhaust, thinking about getting double valve springs, atm sticking with the double stromberg.

I will get all the valve seats done, so it can run on gas.

with the ports I will:
-Sandblast the inlet ports
-port and polish exhaust ports

No way am i going dual fuel, straight gas for sure. and i dont think im going to run out of lpg, i dont run out of petrol so i dont think running out of gas will be a problem.

ive thought about the 300a carb but the 425 is better for a mild 250, unless i have bonnet clearance issues?? I was thinking of getting b2 convertor, again im not much of a gas man.

XE ignition will be done after all this, but dont need it right at the moment.

I really dont like spending money on things i can modify or make myself, as i have lots of tools.

How does all this sound?
 
sounds like your car is screaming for a good carb setup.a 250 2v head should make a mile of difference straight up.bolt it on and throw on a 500 holley and your in business :)
 
i would use a 500 holley, but i cant find any adaptors or 4 barrell manifolds.

and also i have a reco ww stromberg anyway.
 
500 Holley #4412 IS a 2-bbl carb. The Ford 250 2v carb is a Stromberg WW 2-bbl, about 300 cfm of so. There is a specific Redline 12 mm thick adaptor which allows the 500 to bolt on without any hassel.

Hood space is really at a premium on these tall 250 engines in any X-shell Falcon from 1961 to 1993. The stock WW 2-bbl has a special 39 mm thick air cleaner, down from 51 mm in the stock 1-bbl log head 250. The 500 Holley will just fit if you modify the stock air cleaner. Or use a Ramflo air cleaner or the remote adaptor Does 10's uses on his Turbo 63 Falcon. The accelerator linkage has to follow the 2V one.

Get that right, and you'll get a good performance boost on petrol.


The CA 425 may just fit under the hood, and it fits to the 500 throttle body, so a gas dedicated option should work fine. 287 hp of carb there!
 
k thanks, i pulled the head off last night, and the pistons are standard 20 thou over
so they might stay, just need a decent crow cam, but to hard to decide.
 
Well I have a crow cam, not too big though because I drive my car every day and need the engine to last. I got a lower range cam to prevent myself from revving it too high as well, and I find the torque more drivable around town. All depends on what you want the car for.
 
Tom, still need to look at piston dish volume and deck height to know where you're coming from.
 
sorry i have no idea addo? all i know is it isnt stock deck height, and i still havent had a chance to test the cc of the pistons.

ive decded not to take the pistons out.
 
ok, can anyone tell me a approx. ammount of fly wheel hp, with this cam.

http://www.crowcams.com.au/templates/Ca ... flow.shtml

the cam with
IN.32/68
EX.72/28 280
280 214
214 .442"
.442" 1800
4800 K6301 Gives performance and driveability in street modified engines.

also can anyone tell me the specs for a stock log head cam, and a stock 2v cam?

thanks
 
2V cam is a standard cam. The whole bottom end was unchanged. I have not compared distributor codes, but that is the only possible variation.

To measure deck height turn the motor so the balancer notch lines up with zero on the timing scale. Lay a steel rule across the block face and measure the depth to top edge of #1 or #6 piston. It should be 0-15 thou.

If you measure the diameter of the dished section and its approximate depth (by use of the rule and stacked feeler gauges) we can work out its volume.

Without knowing stuff like this, HP guesses are just a waste of time.
 
hey thanks addo,

i will measure it up tomorow and let you know.

Does anyone know the stock cam specs for 250's?

and how do i make the accelerator linkage for the 2v, i have a 302 windsor linkage out of a fairlane, how do i modify it?

Thanks
Tom
 
Cam lift was 221 thou intake, 229 thou exhaust. I didn't measure duration. It'll be around 252-254 advertised, with pretty gentle ramps.
 
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