MonkeyBoy Posted January 8, 2011 Share Posted January 8, 2011 Hi all, I'm rebuilding my 1700 x-flow after a minor disaster in France last year, i just wanted a sanity check to make sure i'm not doing anything silly! The engine blew a hose from the oil cooler whilst bombing down the motorway causing the engine to seize. I've stripped it down and you can see the big end bearings are pretty knackered: Bearing pic 1 Bearing pic 2 Bearing pic 3 Crank journal Measuring the bores doesn't seem like there is much wear, so should be good for rebuild without having to rebore. My aim is to rebuild to get back to what i had before ('fast road' and the odd track day), but at the same time if it's worth doing any mods while i'm there then i can. I'm trying to keep the costs down so i can spend money on the race car (Mk2 Golf GTi in case anyone's interested!), so i briefly looked at putting forged pistons in but at around £520 for a set is more than i want to spend. So the plan is: Get bores honed and block hot tanked (try and get rid of bearing swarf floating around the block) Get block head re-surfaced (it's been in a damp garage and got a bit of surface rust) De-coke pistons (i hear oven cleaner and nail brush is good) Replace piston rings New conrod bolts (ARP ?) New cam chain probably Get unleaded head conversion and very light skim (again, a bit of surface rust) New crank bearings, gasket set etc Install megajolt that has been kicking around on the shelf for ages New oil cooler hoses Replace clutch and gearbox oil As for the crank, i got one off ebay that i jut need to measure and double check its right and check if its been reground. Was wondering about crank / flywheel balance, and a crank journal polish too. That's about it, is there anything else that makes sense while i'm there ? Was wondering about the cam, AFAIK it has the std SuperSprint cam, but should i consider upgrading or am i asking for problems without uprating pistons / conrods ? Oh and before anyone says, i'm not upgrading to a Zetec! Cheers Alistair Edited by - Monkeyboy on 8 Jan 2011 20:29:17 Link to comment Share on other sites More sharing options...
CaterBram Posted January 8, 2011 Share Posted January 8, 2011 had the same dilema myself but I decided to go Zetec i'm afraid, Just in the last throughs or finishing off, all for under £1200, including megajolt, which I'd been planing on doing for the X/Flow anyway. As you've already got megajolt, you could probably do the zetec for less than the x/flow rebuild...... -----Q469 WET, 1990 Long Cockpit in Ali except for the red bits. Class 2 150 BHP Zetec. With a Dual Drive :-)CaterBram on Facebook Link to comment Share on other sites More sharing options...
LesG Posted January 8, 2011 Share Posted January 8, 2011 Hi Alistair, Ok here goes; Yes clean everything; Glaze-bust the bores; Re-ring the pistons; Have the block decked so your pistons are flush with the top when at the top of their bore (increases compression); Balance crank with flywheel and clutch cover; Convert head to unleaded and skim; Buy Cosworth rod bolts from your local Ford dealer (cheaper than ARP and just as good, I found out AFTER buying ARP!); New shells, gaskets, timing chain etc.; If you have the Kent 234 cam (Supersprint) keep it; Enjoy! Respect to a fellow Dubber! (I had to sell my VR6 racecar to fund my 7, life is tough sometimes) Link to comment Share on other sites More sharing options...
eric Posted January 9, 2011 Share Posted January 9, 2011 You change the chain and not the sprockets, the tensioner assembly and the tensioner pad ? I am on the point to rebuild my 1600 sprint eric Link to comment Share on other sites More sharing options...
Neal Worth Posted January 9, 2011 Share Posted January 9, 2011 If you're worried about swarf travelling round the engine, you should look at replacing the oil cooler too. The last thing you'd need is to rebuild the engine and whilst running it back in a piece of swarf from the cooler make it's way back into the oilways. Link to comment Share on other sites More sharing options...
eric Posted January 9, 2011 Share Posted January 9, 2011 a Caterham seven does not need an oil cooler, except to have hassle with it. Don't fit it ! If you deck the block, check the clearance with the valves and your compression ratio if too high your piston need to be machined ERIC Link to comment Share on other sites More sharing options...
6speedmanual Posted January 9, 2011 Share Posted January 9, 2011 Flush out the oil cooler by all means as cleanliness is paramount. However the oil cooler would normally be downstream of the filter so should not have any swarf in it. P BRAWNGP green SUPERLIGHT FCITW 2009 😬 Link to comment Share on other sites More sharing options...
Dee Pee Posted January 9, 2011 Share Posted January 9, 2011 Just finished a 1700 Xflow piston and head re build. Whilst honing the bores is best, if the bores are in good condition, the use of wet and dry in the bores is permissable (that'll cause a few comments!). Bores and bearings must be well protected though and a compressor is useful . Don't just re ring the pistons, as the pistons, unless they're forged will have worn at the lands between the rings. Buy a new set of AE cast pistons complete with fitted rings ang gudgeon pins, balance equally, and fit carefully into the bores. I've run mine in for 1000miles at not exceeding 3K RPM and it hasn't blown up yet! Link to comment Share on other sites More sharing options...
Griff Posted January 9, 2011 Share Posted January 9, 2011 If you or anyone else is interested I have a freshly ground crank plus full set of main/big-end/thrust bearings sitting in the cellar all wrapped and waiting for a project I'll probably never start. It would need balancing with your flywheel/clutch (I think I have a mildly lightened flywheel too). Also a Piper BP 300 cam with match followers (used but only for about 2000 miles so still fresh). If you're feeling brave I have a set of 85mm forged pistons (no rods) too. They are in nearly new condition but really suit an AX block and would be very marginal on a 711M block. Cheers, Mike Link to comment Share on other sites More sharing options...
OliverSedlacek Posted January 9, 2011 Share Posted January 9, 2011 Alastair, It sounds as if you are on the right track. I would check the ring lands on the pistons very carefully, and I would think hard about either keeping the rings or changing rings and pistons together. The standard pistons are one of the weakest parts of an XFlow. You must also double check valve to piston clearance, as a skim will reduce it. Link to comment Share on other sites More sharing options...
OliverSedlacek Posted January 9, 2011 Share Posted January 9, 2011 I forgot to say, why not upgrade to double roller chain. Link to comment Share on other sites More sharing options...
eric Posted January 11, 2011 Share Posted January 11, 2011 Alister To avoid any mistakes, you should show your engine block to know if it need to rebore or not to a professional. you should show him the pistons too to know if they can be re use ( same for the con rods and the crankshaft) and simply re ring. If you need to rebore, and you have an ax block you can do it to 1720 cc, if you have a 711, I don't know but if not, you could sleeve the block. The question of changing the pistons : the cast ones will give you a compression ratio between 9 to 10 ( 1300 pistons) if your block is not deck (more if it is) For a road going engine 11: 1 is for my point of view a maximum. The forged piston from Burton (accralites) will give you 12:1 compression ratio that is too high (and more if your block is skimmed), so they need to me machined.You need to calculate the volumes to low the ratio to an acceptable level. I hope it helps eric Link to comment Share on other sites More sharing options...
OliverSedlacek Posted January 13, 2011 Share Posted January 13, 2011 Forged pistons are an excellent upgrade and increase power. I was sceptical about power increases, but 10 bhp is realistic. The reduced mass and better ring design significantly reduce friction, so you get the improved power with an improvement in fuel consumption. Link to comment Share on other sites More sharing options...
Bio Posted January 13, 2011 Share Posted January 13, 2011 Did the shells rotate in the rods, they have got very hot and distorted 🤔 Check the rod contact area between big end and shell,if this is damaged new rods wil be required. John Link to comment Share on other sites More sharing options...
DaveMorris Posted January 14, 2011 Share Posted January 14, 2011 I've got a spare set of rods if you need them. Nothing special in terms of lightening - but balanced. Dave. Link to comment Share on other sites More sharing options...
MonkeyBoy Posted February 13, 2011 Author Share Posted February 13, 2011 Hi all, Many thanks for all your advice, sorry for the tardy reply but i've been looking at options (and been on a good holiday!) but now i need to get myself moving on this. So, my plan is to focus on a decent bottom end rebuild so i can do the other things at a later date like full head rebuild / upgrade, megajolt etc. the head is a bit tired but at this time i'm just going to get unleaded seats put in. So i plan on: Rebore the block to 84mm (takes it up to 1720) and fit Accralite forged pistons. The concern is the compression ratio (estimated at 12:1) will be too high for the road so i'm looking into getting the bowl machined further (think Burtons or Vulcan can do this) to get the compression ratio nearer 10.5-11:1. Going to be fun trying to work out how much they need to be machined, might have to get some advice. Even with this am i likely to need a better starter motor ? The pistons i'm looking at are here though the catalogue says they are handed 1&3, 2&4 - not sure what this means, the existing pistons don't seem to be handed they all look the same. Also i understand i need to ensure the engineering place doing the rebore can plateau hone the bores. Also looking at a duplex timing kit (assume this is direct swap), and stick with the existing cam (234 i think), wasn't going to bother with adjustable timing pully . Other bits are Ajusa head gasket, Cosworth conrod bolts, renew other bolts and new gaskets all round. Also considering a new oil and water pumps while i have it all apart but not sure if its really worth it, no problems with the old ones. Thanks again for any input, greatly appreciated Cheers Alistair Edited by - MonkeyBoy on 13 Feb 2011 18:17:46 Link to comment Share on other sites More sharing options...
OliverSedlacek Posted February 13, 2011 Share Posted February 13, 2011 The pistons are handed because the exhaust and inlet valve are alternate positions. The valve cutouts need to match up so that the big cutout is under the inlet valve. The only thing to note with the duplex chain is that you must discard the oil thrower which is the bit that looks like a big washer stuck between the crank and the sprocket. The cheap (and reliable) way to adjust the cam timing is by using offset dowels. You don't need to buy a fancy adjustable sprocket. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now