XB Log motor rebuild tips

[Stevemack 122]

Yeah not bad, not sure if i could be bothered chasing the carbs etc though?

[Gav 616]

If you want to stay true to the XB theme...log motors are the go unfortunately. The induction side of things lets them down I feel. I'm by no means an engine guru...but feel its probably pointless doing much to an engine with such a compromised cylinder head design. If you were allowing yourself a degree of license....go the 2V head on the pre-cross flow block...it kinda/sorta belongs (on the previous model!). I feel a wee bit of a purist with the older x-series so no crossflows or OHC engines....okay!?! Chucked an XF alloy head in my XA in the late eighties and thought it was the ducks guts...but now feel kinda wierd about doing that sort of thing.... I've got a 2V-250 head...got it tested...needs a full reco but has no cracks....will cost about $1200 to bring it up to scratch - having already spent $300 havng it checked. What's your budget? If you decide on a 2V head...most of 'em are probably good for reco only and will set you back a G after what ever you paid for the purchase price...worth considering how much you're actually willing to spend...

[matt_lamb_160 252]

I assume you have looked here:

 

http://www.classicinlines.com/alumspecs.asp

[Stevemack 122]

I assume you have looked here:

 

http://www.classicinlines.com/alumspecs.asp

I have now! lol.  

Gav I feel the same kinda, especially with such a good car to start with.  If it was half stuffed i would'nt mind so much dropping an OHC or similar in. 

[RAWDEAL 222]

How long do you plan on having the car ? you could always drop a later model motor in , and when/if you want to sell it ect you can swap it back?

 

I know that. an OHC / 5 speed setup would be leaps and bounds better to drive an a prexflow 

 

I have now! lol.  

Gav I feel the same kinda, especially with such a good car to start with.  If it was half stuffed i would'nt mind so much dropping an OHC or similar in. 

[Stevemack 122]

Like all my cars, i plan to hand them on to my kids when i turn my toes up!! LOL  Decision still not firm.

[XrBill 0]

I put a 4.1 log motor into an xr then decided to give it some more grunt by fitting a 2v head to it. I purchased a 2v aluminium crossflow head online and found it to be about 30mm wider than my 4.1 head.

No doubt whoever reads this will roll their eyes and think I’m a dumb buggar, and they are correct.

Question. Will a 2v cast head and pre crossflow fit on a log block? I think my log block is 140mm wide and the later block from about xf onwards is 170mm wide. I understand there were 2 different 2v heads, 1 cast, 140mm wide and precrossflow and the other 170mm wide, alloy, crossflow and fits the later 4.1?

Be kind with your replies, I bought my first xr in 1969 so I’m old and going silly!

[bear351c 10,270]

Welcome mate, can't help with the answer, as all my cars have had 2 more cylinders, but, I'm sure someone here can help. 

Got any pics of the XR.? 

[Thom 6,650]

all the pre crossflow heads will interchange to a degree, in your case when looking for a 2v head if the intake and exhaust are on the same side it will fit your 250, if it's a crossflow head (exhaust and intake ports on opposite sides) it won't fit your block

[gerg 10,871]

Yeah luckily Ford Oz kept it pretty simple. Up to the end of XB (early 76) were all log blocks which could take the 2V head as an option. XC onwards (late76) were crossflow blocks and not easily interchangeable with log heads and vice-versa as you found out. Only thing that they have in common really is head bolt holes and bores. Everything else, including camshafts (inlet/exhaust sequencing) was different.

Sent from my CPH1903 using Tapatalk

[Loggerhead 10]

On 5/28/2019 at 8:33 PM, Thom said:

all the pre crossflow heads will interchange to a degree, in your case when looking for a 2v head if the intake and exhaust are on the same side it will fit your 250, if it's a crossflow head (exhaust and intake ports on opposite sides) it won't fit your block

To a degree....hmmmm please elaborate, could I use say a 144, 170, 221 head on my 200?.

Because of my No 5 exhaust port flange corrosion issue

[Thom 6,650]

To a degree....hmmmm please elaborate, could I use say a 144, 170, 221 head on my 200?.
Because of my No 5 exhaust port flange corrosion issue

The head will physically bolt on, but it will be a little anaemic, the 144/170/xp-xt 200 have smaller valve sizes, smaller combustion chamber (will raise compression) and a smaller carb flange, you could put one on to get by but you will need an earlier carb to suit the head, you can come into issues with pushrods though as most of the earlier engine have a solid cam not a hydraulic, you'd have to use you 250 rocker gear and maybe have to get aftermarket pushrods to suit, you will need the earlier rocker cover too, as far as I know 221 head is interchangeable with a xy-xb 200 & 250

[Loggerhead 10]

1 hour ago, Thom said:

On 11/15/2022 at 2:07 AM, Loggerhead said:

To a degree....hmmmm please elaborate, could I use say a 144, 170, 221 head on my 200?.
Because of my No 5 exhaust port flange corrosion issue

The head will physically bolt on, but it will be a little anaemic, the 144/170/xp-xt 200 have smaller valve sizes, smaller combustion chamber (will raise compression) and a smaller carb flange, you could put one on to get by but you will need an earlier carb to suit the head, you can come into issues with pushrods though as most of the earlier engine have a solid cam not a hydraulic, you'd have to use you 250 rocker gear and maybe have to get aftermarket pushrods to suit, you will need the earlier rocker cover too, as far as I know 221 head is interchangeable with a xy-xb 200 & 250

Thanks for the info.

Sounds like a can of worms that I hope can be avoided 

Repco has got me some HIGH TEMP JB WELD which I hope will do the trick.