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Identifying Kent X-flow engine

Paul Deslandes

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This is posted on behalf of Philip, a new member who is not yet able to post on here himself.

I wonder if someone can possibly can help me here to correctly identify the engine in a 1992 Q plate Caterham.

The engine in the car looks like a Kent X-flow with twin weber 40's. The block has the serial number EE KD2115/17 EE stamped on the boss, as picture below, at cylinder head level. The KD tells me that it's a Ford block cast in 1989, but the EE letters before and after have been added by whoever built the engine (I guess). Do you perhaps have any idea who 'EE' might refer to? I'm just trying to establish that it's a genuine 1700 super sprint engine, and not just a standard block with a Caterham rocker cover added on top.


This might be one for you Roger.

Thanks in advance


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Naaah, definitely not factory, that would be 2 letters (the last 2 letters from the original vehicle's VIN) to denote the year, eg NA = July 1973 followed by 5 numbers which would correspond to the 5 numbers of the VIN.  This one looks like a serial number of the bloke who did a rebuild, as soon as the block gets skimmed most of the numbers disappear so you can be creative with a set of punches to validate your engine as being pre '75, crucial for an IVA.

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This might be a red herring, but from that era “KDxxxx” was the engine number quoted on a Caterham-issued certificate of newness (which, given the Q-plate, this car may not have had have - though that doesn’t necessarily mean it wasn’t all-new. When did ‘Special Car Tax’ end? Certainly post-1990, since I coughed up for it around then. SCT could be avoided by going for a Q-plate, whether or not the car was all new).

This was when a chassis number (for a kit-built car, at least) would be, for example, KLDxxxxR,
where K=supplied as a kit; L=long cockpit**; D=de Dion; x=the digits, normally the same on the chassis plate used for the engine No., where chassis and engine were both Caterham-supplied; and R=right hand drive.

(** subsequently of course, all production de Dions would be long cockpit).

Obviously the engine wouldn’t know who assembled the car or what the cockpit arrangement was, I assume they used that format as a form of ‘matching numbers’ (so loved of historic car auctions…) regardless of what was already stamped/embossed on the original casting.

As per Robert's comment, my Caterham-supplied 1700 was an AX block.

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Thanks Jonathan. I copped the tail end of that...

(Although with hindsight, and the wisdom of age - and the knowledge that I'd never want to sell the car - I would probably have opted for a Q-plate and spent the money on upgrades/petrol/beer!)

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  • 11 months later...

I would like to piggy-back here.

I have a Caterham built AX 711M lump with a deck stamp of "SAMCOR RAK1192".

I believe it was a South African sourced equipment engine, one of the last.

The rocker cover is the familiar black cast alloy with "SUPER 7 SPRINT".

The engine is fitted with an Aldon distributor and Escort Mk1 4 spd and 4>2>1 exhaust.

I purchased the engine separately from the chassis, so there wouldn't be any relation to VIN.

What I would like to know is if I can identify the displacement and cam based on this spec?

I want to upgrade this motor but I need to know what I have first.



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The 711M is an excellent block and can be tuned right up to full race spec, but the AX is even better. You cannot take a 711M to 1800ccm, but as a general rule the AX will bore out that far; it is ESSENTIAL to check bore wall thickness before you try though because you will occasionally find a "rogue".

The AX is also slightly heavier and stiffer, but it is significantly smoother running as a result. You may well find that it liberates a couple of extra horsepower for the same reason. Finally, it appears to be cast from a different material because it suffers less bore wear than the 711M.

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I have a paper from when I took the casting notes. I definitely have "95 AX" on there, but I thought I had 711M as well. I didn't know there would be a discrepancy over the presence of both. I will have to look at my notes again to confirm and get back to you.  I am interested in converting to 1699cc because one of the cylinders has a rust ring from when previous owner let it sit and seized.  the cylinder was honed, but the ring is still evident.  Im not sure if it will affect tuning much and minor uneven throttles on one of my DCOEs is still an issue. 

The car is going to get a top to bottom "cleaning up" with a few upgrades. I would like the displacement at 1700, if parts are available, a 234 cam or mid-range streetable equivalent, T-9 box and Quaife ATB LSD in the Ital diff, to be in the works.  I recently read the refurb Itals for the scholarship cars have welded bearings to fix a wheel loss issue encountered in competition.  Fun. 

Who would be the go-to for the 1700 pistons and rings? 

I have the T-9 and bells, a Tilton roller rocker set, and shortened drive shaft.  I might have the clutch plate.

Thanks, you guys are great!


Houston, TX

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The link below shows where you can get them. 83.5mm will give 1700ccm and is just very slightly larger than the bore for the +.090" pistons that Caterham used which gave about 1690ccm.


Note that the standard +.090" pistons that Caterham used are nowhere near as good as the forgings from Accralite; these are much stronger, significantly lighter, and despite much lower friction from the rings they actually seal much better, though they do require a plateau honed bore finish.

Believe it or not, just changing to the Accralites will typically add around 10bhp to the top end of the power curve simply due to lower friction (you can actually feel the difference when you install them into the bores).

You may need to machine them to get the correct compression ratio and while most valves will suit the valve pockets, you need to check that you have adequate clearance.


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No, I never found the 711M cast.  It would have been easy enough to see, above the starter, based on a photo.  Im happy enough to have an AX lump. I think I want to build up the lower end to ensure it never grenades.  Not that I drive it hard or compete, I can only afford one seven.  I would be semi-aggressive street/road.  

Im not entirely sure if I want to overbore to 1700.  I would never be able to sell it to the vintage FF people, if it were to come to that.  It may be possible to come close to 1700 performance without the overbore?  I would remain less "square". 

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