BKS974c

[bks974c]

Video from Berwick Classic Me at 7.40


The miss you can hear has been cured by changing the carbs although still 40 webers, something to do with fuel sloshing. It now means when you handbrake it and then apply power you can actually slide the car.

Scott

[Lotus-e-Clan]

It's good to be lucky. Every one deserves their fair share.

What kind of oil filter are you using?

[bks974c]

WAS using spin on filter actually the large Volvo type. Will be going back to cartridges as never had a problem and have close on 80 in stock.

Part of the problem may have been we had been sitting for quite a while waiting our turn and the temp will have dropped, we were commited to a have a good go - high revs coldish oil = high oil pressure which may be responsible for the partly blown out seal.

Scott

[Lotus-e-Clan]

Very useful info Scott for those using spin-ons.

IMO it's more evidence to support the unsuitability of the Volvo spin-on filter for the Imp engine.

I have a large diameter Volvo one on the Imp sport motor and it had very high cold oil pressure. Clearly, as discussed on other threads, the cold oil is bypassing the filter matrix via the internal "blocked filter" valve and apart from the resultant high systemic oil pressure's potential for blowing the seal, it's not good that some (or all) of the oil is bypassing the filter matrix when cold.

I reckon the original canister oil filter blocks will soon attract a premium on eBay!

[benwick3]

Out of interest, do you have an adjustable oil pressure relief valve? Why do I ask? If adjusted too high at high revs the original oil canister holding the paper element can be blown off its seat with subsequent oil loss. I would expect the same to happen to a canister type filter as well.

Pete Richards

[bks974c]

Yes it had an adjustable PRV but has not been adjusted in 6000 miles, but could be a factor as I've never adjusted the valve.

Scott

[Lotus-e-Clan]

So approximately what level of hot oil pressure have you been running for the past 6000 miles?

If your hot pressure is way too high then the adjustment is probably the issue.

But if you are in the range 60-75 psi when hot above 4000 rpm then I'd say the finger points back to the filter matrix not coping with cold 20/50 oil, rather than too high a setting on the PRV.

[bks974c]

Hot oil pressure was about 60 psi - however if that was the max pressure generated by the pump and the PRV was say 90 then how do we decide if the filter is also a problem

Never mind we have moved on - the cars running and got a few mile on it - any recommendations on running in new bearings - apart from dont rev it to 9500 immediately

The oil pressure is much more stable now - cold 52 psi mildly reved 60psi hot idle 45psi hot running 52psi so I guess the standard PRV is working correctly.
The last time it was rebuilt I reused the old oil pump as it checked out OK but I guess it wasn't as at idle it dropped to 20psi so although normal and acceptable the bottom end is now healthier than it was

Couple of worrying noises upon starting the engine - the first a metallic grinding noise - very worrying but turned out to be the Alternator when tightening the pivot bolt it was straining the casing and causing something to rub internally - sorted by loosening the rear mounting to block bolts then tightening it all up before the rear mounts.

The other a knock but using the old screwdriver stethoscope its not internal and besides it was there before so not important.

Tomorrow check it over and set it up properly and get a few more miles on it before the weekend. Oh and wire the ignition through the oil pressure sender Scott

[Lotus-e-Clan]

Hot oil pressure was about 60 psi - however if that was the max pressure generated by the pump and the PRV was say 90 then how do we decide if the filter is also a problem

Yes, it is a bit of a judgement call because there is the potential for more than one variable influencing the systemic oil pressure (oil temp, bearing condition, PRV operation, filter matrix pore size and blocked filter bypass valve operation).

Because you have re-built the engine it's difficult to directly compare the effect of the two filter blocks especially as you were running modified PRVs. Noddy however, did a straight filter block change (std PRVs) and it cured the very high cold oil pressure he was getting with the spin-on, so my questions were based on his direct evidence, plus mine and other folks high cold pressure issues with spin-ons.

To my mind as long as the PRV is working AND your bearings are (were) good, 60 psi HOT oil pressure is not the maximum pressure that your oil pump can deliver per se. You can be fairly certain that if you were getting a maximum of 60 psi hot all the way from 4000 rpm to 9000 rpm then the PRV IS working and set to (approx) 60 psi (assuming your bearings were not already knackered and acting as multiple pressure relief valves!).

If however, the HOT pressure is 60 psi @ 4k rpm but rises to 90 psi @ 9k rpm then I'd say the PRV setting is set to 90 psi (or higher) or was never going to open at all. ie You only see the max pressure that the pump can deliver when you get to maximum engine revs in the absence of pressure relief.

When the oil is cold, IF it is able to pass through the filter matrix, then the max cold pressure you SHOULD see is equivalent to the PRV setting. In the case of unmodified PRVs (Noddys and on my Sport engine) that should be about 55 psi. I was seeing 80-90 psi during winter cold starts with a std 55 psi PRV because it would seem that the cold oil bypassed the spin-on Volvo matrix and therefore bypassed the PRV too.

If you haven't adjusted the PRV in 6000 miles and the bearings were good at the time of adjustment, then I'd say that 60 psi hot should approximately represent the PRV setting and so the high cold pressures you were getting points to the blocked filter bypass valve opening.


BTW AFAIK bearings should not need to be run-in - they shouldn't be touching the crank!

[bks974c]

The bearings were new replaced in the last 1000miles so may have contributed to the story.

Can't tell you what the PRV was set at regards pressure but was set at 3 1/2 turns from contact with the spring maybe someone else has info they can relate this to.

Scott

[bks974c]

Well I've not been able to convince myself that the knock (maybe more of a tap) is insignificant and rather than risk the engine I'll be pulling it back out again and see whats up.

I'm fairly scunnered (look it up if don't know the meaning) and the car is now for sale at £7000 which will include the engine being sorted and a new MOT but not the reg - the Imp is fully sorted having made lots of changes to address issues that have arisen so if you fancy a competion IMP get in touch.

I'm not giving up on Imps need the time to sort the other projects and moving this car on will give me the time and money to do that.

Scott

[TJB69]

That's a pity Scott. Hope you change your mind. Watching it on video and it looks a quick wee car.

[bks974c]

Cheers Tom, if I get an offer for the asking price I'll let it go and rebuild the Clan as a trackday car as it will be quicker being lighter. If I had the budget to stage rally I have a 66 Chamois that I could build as a proper historic rally Imp so no shortage of options.

If I don't I'll mothball it - I recon the bits on the car are worth more than the asking price so not the end of the world if I have to keep it but I had already decided this was to be my last year of the rallying I have been doing.

Scott

[bks974c]

Got BKS Mot'd before pulling the engine back out, stripped it and nothing leapt at me but no. 3 rod felt a little tighter in some spots when assembled on the crank out of the engine, so dropped the crank and rods at the machine shop for proper checking. Will see what the story is when I get it back.

Had a look at the head and noted no.1 inlet was further into the head than the others and after removing the valve it appears that the seat is on the move as the top is no longer flush with the combustion chamber and there appears to be swarf at the base of seat so will need to be sent away and see what needs done.

Scott

[bks974c]

The machine shop found after polishing no 3 big end that it was undersize so crank was reground plus 10 and they resized no 2 & 3 rods once they were torqued to 30 lbf as per the current spec for ARP bolts.

Whether the resizing was necessary because of the ARP bolts and 30 lbf or a result of the bearing being run is debatable but 1 & 4 were OK so more likely a result of the former.

Engine has been rebuilt now after checking the clearances with pastigage and it now turns over beautifully smooth .

The head will be sent away to get a new seat and be checked over and will be reunited with the block when its back, although I'm thinking of changing the R17 for the R20.

Scott

[bks974c]

With the Gretham/Chessman on the back burner I turned my attention to the other 998 its short motor has already been rebuilt but the head still needed a little attention.

Its slightly unusual in that it has large ports with a fully reshaped chambers but running sport valves, I'll post up some pics later. The Chessman head has large valves but standard shape chamber and slightly smaller ports.

I ordered some new sport valves and after grinding them in, checked the combustion volume 18cc which probably would have been OK when it was running an R21 but as its now running the reprofiled sport high lift cam it will be too high a compression however as I'm not sure exactly the timing or duration to calculate the required volume.

Tomorrow will set up the valve clearances and order a degree wheel so I can find out the spec of the cam before opening up the chamber.

Scott

[bks974c]

See viewtopic.php?f=7&t=23127&p=216861&hili ... ng#p216861
for discussion on the timing of cam.

Its now been built with R20 as this will suit the head, as too revy for the events I do in the Imp its going in the Clan.

Scott

[TJB69]

Looking good Scott

[ImpManiac]

^^ As Tom says: looking good! Those exhaust ports in particular look huge! Are they the same size as the inlets?

IM

[bks974c]

Since its going to be a wee while before I get the Chessman head back (not even sent it away yet ) and reunite it with the now rebuilt short motor decided to fit one of the rebuilt ported L4 engines that I did earlier in the year. I chose the one that I built without the cam dowel and see how it fairs.

See viewtopic.php?f=7&t=20512&start=40 for discussion re not using the dowel.

Lovely day, sunny and warm in the sunshine to get on with reinstalling an engine in BKS - had to prepare the engine taking off the heater hose and bypass outlets and blanking them, fit clutch and ancillaries, had to sort out a Sport dizzy and weld up a Sport exhaust manifold.

Tomorrow I'll finish getting the exhaust system sorted, oil in and get it fired up hopefully.

Scott

[bks974c]

^^ As Tom says: looking good! Those exhaust ports in particular look huge! Are they the same size as the inlets?

IM

The exhaust ports are slightly smaller .9 in what's interesting is the finish on the inlet ports is particularly rough up to the guides and beyond a normal finish. Its obviously deliberate and I assume to do with turbulence and keeping the fuel/air mixed.

Its also interesting working with the various heads how the Sport valves "look" better particularly in a reshaped chamber to 1.4 valves as there is room around them for the fuel mixture to enter the cylinder rather than being squeezed to the side. Mind you that might help as its then entering in the centre of the cylinder, but what do I know.

Scott

[ImpManiac]

...but what do I know.

A great deal, my friend. A great deal.

You are right about valve shrouding by the cylinder wall. If I were commissioning a cylinder head for a 998 cc engine (72.5 mm bore), I might opt for 1.37" inlet valves rather than 1.4" ones. For a 1040 cc motor, though, I'd probably still go with the 1.4". I think I've got 1.34-inchers in my 930 cc engine. I've got the build sheet somewhere...

The roughness does indeed promote turbulence, tending to keep the fuel mist in suspension rather than allowing it to 'drop out' on to the cylinder walls.

IM

[Lotus-e-Clan]

Yes 1.4's are a bit tight even in a 1040 head.

They seem to work well enough though, even without de-shrouding ...

[bks974c]

A day of mix fortunes, finished the exhaust system off and went to start the engine - turned over but no spark
forgot to the connections back on the coil mind it only took abour 30 sec to realise the problem.

Try again, swinging the distributor while cranking it coughs but doesn't catch. Try again but the battery dies, get out a spare and jump leads turns over but still bit slow. Ok try jumping off the Skoda after an initial burst the starter motor makes some odd sounds.

Change the starter motor an easy job with no radiator or water pumps in the road and guess what YES its exactly the same -
the problem was with the jump leads. Take the Skoda battery out and connect direct to the Imp and it splutters in to life

Set the timing and start adjusting the carbs (twin strombergs) making progress when it goes off a bit. rev it and black smoke rechecked everything and it appears to be the needle valve has failed on the overhauled carbs

Oil on the ground below the drain plug - what do you think ? Plug loose/knackered washer NO crack in the brazing
that will be a job for tomorrow for the quick steel.

Start over again on the carbs and just about there when it dies, restart it and give it a rev and it dies again - run out of fuel

Tidy up that enough for today, leg starting to hurt - tripped over the engine thats waiting to be sent away and rattled my shin this morning and its swollen up nicely now.

Scott

[Lotus-e-Clan]

Just one of those days!

[Dave ' Linwood ' Lane]

Its nearly Halloween so if you believe in all this stuff (which I dont ) then things will just go wrong or make no sense whatsoever,

[ImpManiac]

Tough breaks, Scott. Another session and you'll get it there.

IM

[bks974c]

Tough breaks, Scott. Another session and you'll get it there.

IM

Its OK no breaks just bruised

Scott

[bks974c]

Yes I'm happy again - not that I was unhappy at an point

After 3 days trying to get the new engine to idle sweetly finally I'm there resorted to building a second set of carbs and fitting them.

Several issues firstly ignition scatter traced to wrong magnetic ring (loose) fitted to the dizzy - my fault as several electronic ignition types lying about.

Main problem on the carbs - there should be a little button on the bottom of the piston that hold it open very slightly and allow air to flow over the jet orifice at idle and pick up fuel but on one piston it had worn away and so was effectively closed, so it was impossible to get a smooth idle.

As soon as I put the other carbs even from base setting I new it was better, set up was going great until rear carb started pouring fuel out - sound familiar thats because I reused the ones that had failed previously at least I can throw it away knowing its definately dud

I also changed the oil due to fuel contamination.

Not able to try it out as currently on Sorn so trailer it to the PCT on Sunday but once round the car park it seems good.

Scott

[bks974c]

Woke to brilliant sunshine might have mentioned that elsewhere and set off to Forrestburn for the PCT - only about 15/20 mins away from me but as trailering the Imp found some of the access roads to the site were sheet ice making it interesting with the trailer but arrived safely.

The current engine seemed ideally suited to climbing the hills without having to resort to high revs, cleaned hills 2/3 all day and improved greatly on 1&2 in the afternoon when they altered them slightly as high penalties due to the difficulty of them. Achieved 1's on both which was equalled by the trials special but not beaten.



Video of the Imp on test 2 - gave the marshal a shot sorry about the quality.

Scott

[bks974c]

Put the Imp away after washing the mud and grass off.





Then put it in the Clans space



Couple of pics of the modified air filter box allowing use of the remote air filter with strombergs and the extended throttle cable using brake pipe so can be easily swapped whether using webbers or strombergs.





Still think the Clan would look good in yellow - got some wheels already







Scott

[ImpManiac]

Sounds like you had a fun day PCT'ing.

Yellow suits Clans. Just my opinion.

IM

[bks974c]

Not strictly BKS news but close enough

Got the rebuilt engine and CR gearbox back into the Clan and bolted up yesterday a relatively painless task as it turned out but missing a number of bits that were at home.

Today put most of the missing bits on and tried to fire it up - backfires indicated timing out - absolutely sure I had timed the cam in correctly not 180 degrees so rechecked the leads. I had cable tied the leads together to keep it tidy and what I thought was 2 & 3 were actually 3 & 2 so put little dots on the lead tops to prevent a reoccurence.

It then fired up probably easier than any rebuilt engine I can remember but then the carbs are the webers taken of the Greetham engine and are fully set up so one less variable. Not run it for any length of time as still to sort an alternator and filled the cooling but starts on the key, tomorrow fit the alternator and set the timing, flush the cooling system and take it for a test drive.

Scott

[GeoffFarthing]

When removing plug leads, take some poly bag wire ties. No.1 wraps once round the HT lead and twist, No.2 twice and No. 3, 3 times. There is only one plug left for the other one to go on.
Geoff F.

[Peter Hurst]

When removing plug leads, take some poly bag wire ties. No.1 wraps once round the HT lead and twist, No.2 twice and No. 3, 3 times. There is only one plug left for the other one to go on.
Geoff F.

Or even small cable ties like this for a permanent marker

SDC16162 (600x450).jpg

[bks974c]

Personally I like my tipex dots my problem was not knowing where they went 1-3-4-2 firmly etched in my my mind and the location of no 1 on the dizzy cap, rather because I had tied them together I was unable to accuately follow the leads.

Today fitted the alternator and filled the cooling system and fired it up and settled quickly to a smooth idle but charge light not going out since its running large pulleys I did not expect it to go out at idle but despite reving it only a vague flicker. Removed it and stripped out the brushes pack and regulator and one of the brushes looked quite worn so replaced it and refitted the alternator which sorted the problem although charge light still on at idle.

Took it round the shed a few times and very tractible more so than I was expecting with the R20 but thats the benefit of the Clans lack of weight, sounds very nice too.

Scott

[ImpManiac]

Great work, Scott!

IM

[bks974c]

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[bks974c]

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[bks974c]

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[bks974c]

Copied from the For sale Section


Have decided to sell my rally car as I've got 4 imps and a Clan that need work and need to finance some of that.

See viewtopic.php?f=33&t=13865&hilit=bks

Mot'd until September 2013 and ready to go.

Currently fitted with an L4 engine with lightly ported head, Sport dizzy with electronic ignition, twin carbs Sport exhaust all newly rebuilt.

7 gallon alloy fuel tank Twin electric fuel pumps with filter king filter/regulator.

Front Radiator with Craig Davis electric waterpump (new replacement fitted 2012) and digital controller. electric booster pump for heater circuit.
Uprated heater blower.

Strengthened Gearbox casing with standard gear set and quaiffe ATB diff recently rebuilt by Transimp with replacement crownwheel and pinion
This cost me £1650 not including the rebuild.

Sport Driveshafts with Lotus couplings N/S fully rebuilt with new Uj's and bearings.

Fully strengthened trailing arms and crossmember.

Fully strengthend and skidded wishbones.

5 Minilight style Alloys with Dunlop M+S tyres (Tyres past their best)

Brakes just overhauled Drum all round with lines inside and S/S flexis.

Heated front screen with timer relay.

Digital dash, Brantz trip and clock, internal strip light.

Lamp bracket with Cibie Super oscars and QR fittings

Fully strengthened shell with multipoint roll cage (overkill really) all steel panels with Unique lifting/removable rear.

Corbra Seats and Willians Harnesses.

Sure there will be things I've forgotten to mention so happy to answer any questions.

I'm looking for £6000 Car is located in Edinburgh.

Scott
Edit : Rac Springs all round with Konis on the rear and Adj platform on the front

Edit 2: Hi ratio steering rack with Fiesta TRE conversion

Edit 3 : Remote air filter (K&N) with scoop from rear quarter window
Fia batter master switch, Fire extinguisher

Edit 4: Rose jointed quick shift gear lever

Edit 5: Full length sumpguard (not fitted), twin exhaust system inc motorcycle across the back.

Edit 6. Twin speed wiper, Double washer jets, Alternator with correct bracket.

Edit 7: Pre-engaged Toyota Starter Motor (Eric- Pimpdriver supplied)

[bks974c]

Now thats a surprise exactly a year since last posted anything on BKS

While its fully on the road I've only done 200 miles in it in the last 12 months, since putting the rebuilt L4 engine with a slightly re worked head its proved a bit lack lustre more so when you compare it to Karen Sport which should have a similar performance. Always suspected it was down to too low a compression ratio so since I had robbed the carbs of it for Karen's car which had started to smell of petrol when left standing, I decided to pull off the head and see whats what.

Measured the chamber on BKS's head 20.5 cc so I measued a std mk 2 and L4 head and they were 20.5 cc however my understanding is a sport is 19cc to maintain the dynamic compression ratio due the different timing. On the current set up I calculate I'm running with static 9.27 : 1 and 8 : 1 dynamic so I dropped the head off today and asked if they could take 30 thou off. If my calcutation are correct I should then have a combustion volume of 18.5cc and a static CR of 9.95 :1 and dynamic of 8.58 : 1.

These are based on the gasket for classics head gasket with has a compressed thickness of 45 thou compared to the Reinz which was 35 thou and that accounts for a drop in CR of 0.4 - quite significant and a very large change to the squish area so think I'll be dragging out the last of my Reinz gaskets, so I should end up with 10.38 and 8.94.

We will see if this translates to an increase in performance, I was going to have the seats recut for sport valves but that would only add another variable so stick to one change at a time.

In the meantime I started to rebuilt Karen's carbs - they have been on the car for over 10 years and are in excellent internal condition due to the car being a daily drive but has taken it toll on some of the screws .

Scott

[Lotus-e-Clan]

Didn't realise mainstream std gasket thickness would vary that much!

I wonder how many are running the thicker gasket and are baffled by a loss of performance!

I assume the L4 motor is an 875?
That 18.5cc chamber on a 998 or a 1040 with the right cam would be a flyer - even with Sport valves (OK it's an L4 but it would take Sport valves without too much fuss)!

[bks974c]

Didn't realise mainstream std gasket thickness would vary that much!

Neither did I but measured the old gasket as part of the checks

I wonder how many are running the thicker gasket and are baffled by a loss of performance!

I assume the L4 motor is an 875? yes

That 18.5cc chamber on a 998 or a 1040 with the right cam would be a flyer - even with Sport valves (OK it's an L4 but it would take Sport valves without too much fuss)!

[bks974c]

Carbs rebuilt although couldn't see anything obviously at fault - o rings all looked fine and flexible but replaced them anyway with new viton ones from Club Spares that I had bought a while ago expecting problems with the bio fuels but to be honest so far no effect to be seen.

The Reinz gasket is not in good enough condition that I'd want to use it but measured it while it was out -45 thou uncompressed compared to the gaskets for classic 45 thou after compression. Considering most head will have been skimmed before fitting a new head gasket this probably won't be an issue for most cars but in my case I'm trying to get the compression ratio up.

Ordered some NOS aftermarket ones from ebay, so will measure them before deciding which one to fit.

Scott

[bks974c]

Got the cylinder head back today, I had them machine it canted over so most of the material was taken off the plug side as this is the deepest side of the combustion chamber so reduces the volume with the least material removed, so I now have a wedge head

Re-measured the combustion chambers and it appears I also have it wedged front to back there is a residual step from combustion chamber to squish area on 1 and they reduce until you get to 4 where there's none.

No. 1 & 2 19cc No 3 & 4 18.5cc some of it's down to the reshaping starting at no 1 by the time you get to 4 you've lost some interest so opened up 3 & 4 to 19cc
more than I was aiming for but spot on for the Sport cam.

It now been all clean ready for fitting and I also carried out the timing tensioner guide mod to keep tension on the chain since it's heavily skimmed.

One of the head gaskets arrived today and measured it at 59 thou that's 14 thou more than my Reinz gasket and a 0.4 reduction in CR so will wait for the other one to arrive and see how that measures up.

Scott

[Lotus-e-Clan]

I'm wondering if copper HGs are thinner or indeed thicker than normal?

Don't know if you can get 875 copper HGs mind...

Btw are the inlet valves flat or dished - might get some compression back if you changed from dished. Also for a Sport cam one doesn't need much piston cut-out depth-wise as long as they are clear for valve diameter.

[bks974c]

I'll check as I have a used copper head gasket - quite why I don't know

Inlet valves are dished, so yes -flat valves would reduce by 0.2 or so.

I'll be happy to see how the head performance with the sport sized chambers, its cost me next to nothing having been rebuilt from one of the spare engines I had lying about so its really about proving the theory.

Scott

[bks974c]

Miserable morning here today, couldn't get motivated to do much this morning so went and bought another car

That now 1x Skoda Octavia Estate
1xSkoda Octavia Scout
2xMX5's
1xImp Rally Car
1xClan
1xSinger Chamois
1xImp Saloon

and that just the ones in my name plus got the kids cars to look after too. I've got an appointment with the shrink on Monday

The Scout was bought to replace the estate because as I do a fair bit of towing the 4x4 will be a bit more useful getting into and out of some of the venues especially when the parking is on grass. I'm going to put the BKS reg (significant to me as my first car ever) on the Scout and after removing some of the trick and expensive bit try seriously to sell the rally car.

The MX5's will be up for sale shortly now Spring is on its way.

With these decisions made I went up to the shed and put the head back on using the Reinz gasket with red gasket sealant on the fire rings and around the damaged bit at the timing cover. A productive 3 hours later I had car running, fired up first time and sounds good. Next week I find some time to set up the carbs and timing and then see if it works as I hope.

Scott

[bks974c]

I'm wondering if copper HGs are thinner or indeed thicker than normal? 45thou compressed

Don't know if you can get 875 copper HGs mind...

Btw are the inlet valves flat or dished - might get some compression back if you changed from dished. Also for a Sport cam one doesn't need much piston cut-out depth-wise as long as they are clear for valve diameter.

Got a couple of gaskets of ebay - the NOS Payen is 45thou uncompressed, the other 59thou so we now have a choice for further builds

Scott