616 replies to this topic

[johnR]

Yes they're tight - we went round the running engine/carbs with copious amounts of WD40 to try to identify any leaks but nothing showed up - wish it had, then I could have fixed it.

[johnR]

I took the car (in pouring rain) to Tipton Garage in Devon this morning on a trailer. A quick investigation and use of a leak detector that injects smoke into the carbs showed the suspected airleak was between the inlet manifold and the heat deflector. As the inlet manifold is for either HS2 or HS4 carbs the most likely culprit are the top two redundant HS4 stud holes which may have penetrated into the manifold. Should be a quick fix! Much relieved. Once the rain stops I'll sort the issue and we should be cooking. Tipton garage offer rolling road tuning at £60 per hour if anyone is interested - the proprietor races an A40 and owns a 60's Cooper s and his father worked for Downton so very knowledgeable about classic car issues.  

[johnR]

The problem...the blackening wasn't showing before so there was no sign that these holes were the culprits. The lower HS4 holes are just through the flange so I assumed the upper ones were too.

The solution...

Now just need to bolt the carbs back on

Edited by johnR, 13 June 2019 - 04:12 PM.

[johnR]

A slight holdup - the thread on one of the block heater valve bolts has pulled through - I thought they were dodgy - helicoil kit ordered. 

[timmy850]

Good to find the problem after all those issues!

[johnR]

Yes, I feel an idiot for not spotting it sooner but we were concentrating on the head to inlet manifold join and the carbs so missed it.

[johnR]

Helicoil kit arrived - the 1/4" inch size coils were a pain to insert, they either distorted or the tang broke off at the slightest pressure but I got there in the end. Heater valve bolted on and 2nd head steady installed.

 

 The car started and idles much easier but with the reduced noise I noticed a clonking from the waterpump side of the engine. I checked the rocker cover and it looks as though one of the rockers is contacting the vent baffle and possibly valve springs are just touching either end of the cover which is a new one to me. I had a quick go with a bodywork hammer to dish the baffle and put a slight bulge in the ends of the cover but I think it needs a little more work, even with a new cork gasket. 

I've also noticed the fan belt is loose - it's at the limit of adjustment so I'll need a shorter one.

I might have known it would be too simple to block the rogue air intakes and everything would be fine!

Edited by johnR, 19 June 2019 - 08:02 PM.

[johnR]

A bit more work on the baffle seems to have sorted the clonking (I think the marks inside the ends are probably from contact as the cover has come off and on), I've changed the needles back to size M as the E2s were unsurprisingly running very sooty. Just need an 825mm fan belt and I can get back to balancing the carbs properly. (After I'd bought a new fanbelt I found it didn't need it - the original one was running between the pulley and the damper rather than on the pulley!)

Edited by johnR, 19 July 2019 - 03:26 PM.

[johnR]

The engine idles nicely now - I did a bit of balancing - one carb needed richening up a little. When I took it for a run it drove nicely for a bit, then the carbs seemed to bog, only clearing when I stopped so there is obviously still some work to do - much better though. 

I noticed that the heat in the engine bay is softening the tube I was using for vacuum for the brake servo, I thought the mesh in it would support it but I've now replaced it with a piece of thicker walled rubber pipe.

[imack]

You really need proper rubber servo vacuum hose.

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Edited by imack, 19 June 2019 - 08:24 PM.

[johnR]

The piece I've replaced the hose in the picture with is rigid enough for now - I may replace it with the proper stuff when I've decided how I want it to look finally.

[johnR]

I'm still getting intermittent issues with the carburation - it runs OK until it gets to about 50 mph then starts to run terribly. After slowing down it picks up and is OK again. I thought it might be a fuelling issue as it mostly happened on slopes or hills and I had run low on fuel, but I've now filled the tanks and the problem is still there. Another mystery.

In better news, it was slipping out of gears but following advice on here I cut a ridge off the bellows on the rod/gearbox join and that seems to have improved things. 

Edited by johnR, 21 June 2019 - 06:14 PM.

[johnR]

A few more runs today after fitting the AH2 needles, the problem persists - only apparent on slight hills!

[johnR]

Plugs are sooty after a run on the AH2s so now I'm back to the M needles I started with. The problems at 50mph still persists. I've noticed that the plastic fan is just touching one side of the radiator shroud and also the rad fins a tiny bit. I've tried opening the bolt holes on the top rad mount in the opposite direction but there's not much material to make enough difference so I may make my own to move the rad towards the wing and back towards the bulkhead a few millimetres thereby alleviating both issues. Cutting one ridge off the gearbox to rod boot has totally sorted the slipping out of gears problem but I still have problems selecting first - generally I can only get to it through second. I had the same problem with the 998 and that was a different gearbox so I'm suspecting the clutch master or worn bobbins on the gear lever housing?

[johnR]

I've made a new rad shroud top mount plate to shift the shroud over (so the fan sits more centrally) and a few mm further towards the wing. I tried fitting an old electric fuel pump to see if, as I suspect, fuelling is the issue but found I didn't have any 8mm ID pipe. The heater valve (less than 2 years old/ 250 - 300 miles)has failed - the second one in four years. So now tomorrow I need a new choke cable( the old one was too short as I had modified it to use with the original single carb on the 998 and also taking the carbs on and off multiple times to try to identify the air leak has caused the cable to fray so it sticks on)some fuel pipe - I may get a facet pump as well while I'm at it, and a blanking plate and gasket.
I took a mechanic friend out for a run in it this morning and he agrees that it seems more like fuel starvation than electrical, also the oil level seems to be going up which would suggest a failing diaphragm in the mechanical pump.