johnemms
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| posted on 22/11/13 at 11:51 AM |
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Crossflow Head Wanted
Hi Guys..
Now is the time to get the spanners out and Xmas wish list..
My cylinder head is Mk2 Escort 1600 standard on 711 block
so I fancy swapping it over for some extra bhp..
Looking for a gas flowed stage 3 X-flow head anyone?
Thanx
Jon
Own chassis & Build - First time pass!!
"7's" aren't really "cars", they are 'experiences"
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02GF74
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| posted on 22/11/13 at 06:55 PM |
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got 3 heads.
1. brand new never used
2. very port head but is chamber type with thin oversided valves
3. ported head but myextra diy porting broke through to the bolt hole between the two siamesed exhausts.
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Paul Turner
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| posted on 23/11/13 at 05:46 PM |
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Simply bolting a big valve stage 3 head on an otherwise unmodified or unmatched modified bottom end will achieve little, what it will do is rob you of
all your bottom end torque.
All the components in an engine need to be selected carefully to get the best out of each simply bolting on bits is a sure way to end up
disappointed.
Think carefully about how you use the car and what you want to achieve. A change of engine to a 2 litre Zetec will actually cost less than modifying a
x-flow even to a moderate 135 bhp and will give you more power, better driveability, better reliability and better fuel economy.
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johnemms
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| posted on 23/11/13 at 07:10 PM |
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711 block
+90 1300 pistons
BCF2 cam
light flywheel
twin 40's
Chopped sump
High Oil pump
3D mapped ignition
Standard Head
Only done about 4000 mile loads of life in it so just need to get it breathing better 
I Drive it like I stole it & do not pootle about..
[Edited on 23/11/13 by johnemms]
Own chassis & Build - First time pass!!
"7's" aren't really "cars", they are 'experiences"
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Paul Turner
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| posted on 24/11/13 at 11:24 AM |
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quote:
Originally posted by johnemms
711 block
+90 1300 pistons
BCF2 cam
light flywheel
twin 40's
Chopped sump
High Oil pump
3D mapped ignition
Standard Head
[Edited on 23/11/13 by johnemms]
To take your points one by one:
711M is the block used in probably 99% of x/flow builds. Its strong but its safe rebore limit is 83.5 mm. Some will go further but there is only one
way to find out. Other x/flows are built with the older Cortina block which had inferior main caps or the AX block which originates in South Africa.
The AX is the block of choice if you have loads of money but they were never fitted in any car sold in the UK thus they were all imported specifically
for racing. Will go to about 86 mm bore safely.
+90 1300 pistons have been the standard fit in a 1700 x/flow for decades. They give additional compression but there are issues. The valve cut outs
are way too small for high lift cams or heads with big valves. Yours will probably need machining to suit, even if they have been machined already the
cut outs will need checking against your new head. The pistons are also very heavy but quite weak, they tend to snap off where the oil scraper ring
fits due to the design. To keep the engine reliable you need to restrict your revs to 6500 which means that most of the advantages of a big valve head
cannot be utilised. 83.5 mm Forged pistons are the way forward for reliability plus because of their better design, lower friction and lighter weight
an increase of 5 to 10 bhp can be found with no other engine mods.
BCF2 cam is a good upgrade but a Kent 234 is far better. With the right pistons to allow the use of more revs go for a 244 cam.
A standard flywheel that has been lightened can be deadly, only use a steel flywheel from a reputable manufacturer. As standard a steel flywheel will
be lighter than a modified cast one, go for a slotted one with a racing clutch and teh difference is huge. Guess it depend how much you value your
legs. The flywheel will aso need doweling to crank and the who assembly balancing.
Twin 40's are fine up to 165 bhp with 36 mm chokes.
Chopped sump, that depend who chopped it and how good the baffles are. Get it wrong and it will cost you the engine.
High (capacity) oil pump, should be fine.
3D mapped ignition, will probably need remapping.
So with a good head, forged pistons, 244 cam and 36 mm chokes in your Webers you will have possibly as much as 150 bhp but probably nearer 145 bhp.
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johnemms
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| posted on 24/11/13 at 12:51 PM |
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Yep.. looks about right..
So a Zetec plus a load of work will get me 135
Which is what my crossflow puts out now.
A Zetec means an exhaust ..bonnet. .chop sump
Clutch new cams ..rolling road.. possible new fuel tank
The list goes on..
If I find a nice head to drop on and get on the rollers
I'll probably be ok..
Next year I gotta get the shocks dynoed n replaced..
Oh n 4 new yokos.. 
Own chassis & Build - First time pass!!
"7's" aren't really "cars", they are 'experiences"
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BaileyPerformance
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| posted on 24/11/13 at 01:37 PM |
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quote:
Originally posted by johnemms
Yep.. looks about right..
So a Zetec plus a load of work will get me 135
Which is what my crossflow puts out now.
A Zetec means an exhaust ..bonnet. .chop sump
Clutch new cams ..rolling road.. possible new fuel tank
The list goes on..
If I find a nice head to drop on and get on the rollers
I'll probably be ok..
Next year I gotta get the shocks dynoed n replaced..
Oh n 4 new yokos..
A standard 2.0 black to zetec will give you at the very least 160bhp on twin carbs, more like 175bhp on jenveys and megasquirt.
I love x flows, we have had a couple on the dyno but there's ya mo reason to use them when you can pickup a zetec for £150. If you don't
want fuel injection and done want twin webers there are inlets available to take a twin choke off a x flow it pinto, you will still see 140bhp.
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Paul Turner
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| posted on 24/11/13 at 01:54 PM |
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quote:
Originally posted by johnemms
So a Zetec plus a load of work will get me 135
Which is what my crossflow puts out now.
A Zetec means an exhaust ..bonnet. .chop sump
Clutch new cams ..rolling road.. possible new fuel tank
A totally standard 2 litre Silvertop Zetec on your 40's with your 3D ingnition modified to suit will give about 160 bhp, possibly 165 bhp if the
engine is really healthy. A Blacktop will give about 5 bhp more than a Silvertop.
You can use the standard 2 litre flywheel with a Focus 2 litre centre plate but its a boat anchor, a Silvertop 1800 flywheel is a cheap way of getting
the weight down.
You will need new exhaust headers but I know a couple of people who got a man who was handy with a tig to simply modify the x-flow ones. Ideally the
exhaust needs to be a bigger bore than the x-flow but that could be sorted later depending on funds. X-flow bonnet fits exactly the same, no mods
needed. Sump required, £250 from Scholar, £300 for a Blacktop.
Cams only needed if you want more power, rolling road tune will be need on x-flow if you mod it so forget that, fuel tank
mods or swirl pot only needed if you go injection.
Having been doing this for almost 25 years now I can guarantee that a modified x-flow will cost just as much as a fitting a Zetec but the Zetec can be
tuned further if you want more power and will be more reliable.
I can also guarantee you that your current 1700 x-flow with a BCF2 cam, +30 pistons and a standard head is not producing 135 bhp, possibly nearer 115
bhp (at the flywheel). Engine builders stretch the truth and not all dyno operators are honest. I had a 1700 x-flow with 244 cam, 45's, powermax
pistons, dry sump and a well flowed head with REC valves which produced 145 bhp on a genuine dyno.
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johnemms
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| posted on 24/11/13 at 02:37 PM |
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Yep .. I can see that..
However..
My engine is all good and paid for years ago and A1 condition ..
Just fancy getting it breathing better.
If it was to go tits up then yes i'd ebay it and go for a Zetec..
On the road it goes very well drifts and looses traction predictably.
Knowing I have a standard head is bugging me..
I could swap it over on a nice Sat morning
 
Description
 
Description
Own chassis & Build - First time pass!!
"7's" aren't really "cars", they are 'experiences"
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Paul Turner
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| posted on 24/11/13 at 05:44 PM |
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quote:
Originally posted by johnemms
I could swap it over on a nice Sat morning
You could providing as I said above the piston cutouts are big enough for the valves in the new head. If they are too small its probably goodbye
valves and goodbye pistons.
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rusty nuts
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| posted on 24/11/13 at 06:26 PM |
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Easy enough to check valve to piston clearance using plastecine or even a thick pice of soldering wire pushed through the plug hole. BCF2 cam and 1300
pistons don't always need valve pockets, mine didn't even with a large valve head.
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