Getting back on the road

Demetris said:
It makes sense because a UK car that was not allowed to go over 70 mph in the motorway does not really need the engine oil cooler, while one that had to cruise often in unrestricted autobans would make a good use of it.
Click to expand...
The 70mph limit came in 1965. I think they used the oil cooler in countries they perceived as hot (USA, Australia, Greece?). Also, the original brief was a car that could transport 4 people in comfort at 100mph for an hour. So it makes sense they'd want to back that up. My guess is that the oil cooler was removed after BMC/BL got their hands on Rover and tried to cut costs.
 
Well, it was time to fix the inevitable oil passage o ring leak on the head gasket. It had been weeping since this winter, but was quite bad after the race weekend at Like Rock Park in May.

I’d pulled the camshaft recently to check for a broken valve spring (see concerns about mod at higher revs). I wonder if I made a mistake as I found evidence of a near failure by the fire ring of no. 4 cylinder (see pic).

I checked valve clearances before pulling the head and found a could have valves had settled around 0.001” to 0.002” off spec so fixed those before fitting the new head gasket.

It’s all back together and idling smoothly. Next will be tracking down that misfire if its still there.

IMG_1679.jpeg
 
Car runs and idles perfectly up until 5,000rpm. Then it won’t got any further. Last things on the list:

(1) Insufficient fuel supply, I redid my calculations from the mechanical pump. It was just about adequate, but only just.

(2) The coil has been swapped with a known good one. But I still wasn’t sure about the Magnetronic module inside the diff. So borrowed a fancy 123ignition dissy from the race mini. Ran a little stronger and smoother with it. But still the miss at high revs.

To address (1) I decided to fit a Hardi 4412 electric fuel pump. It’s rated at 100 liters/hr and has a pressure rating of 2-3psi. I mounted the pump to the battery tray side. With new hard plastic fuel lines running to the carbs and from the reserve tap via a filter. The nice thing about this arrangement is I can use 1/4” compression fittings as used by Rover all the way through. Nice solid connections that seal reliably and are easy to undo if the need arises. Here’s a couple of pics of the install.
IMG_1695.jpegIMG_1694.jpegIMG_1696.jpeg

Once I’d made up a small wiring loom with an inline fuse I ran the pump for 15 seconds and got around 410ml. That equals roughly 100 litres, so I’m calling it a good’un. One less question mark.

The only thing that’s left is something mechanical. When I did the head gasket last weekend I did visually check the valve springs, I’m now thinking that I’m experiencing valve float at higher revs. It’s about the only thing left. Weaker springs + higher lift cam + high revs = might equal what I’m seeing at high revs.

Plugs look perfect, there’s absolutely no blow by or low compression. No pinking or ignition timing issues left. Car idles very smoothly, pulls like a train up until the 5k mark. It’s all I can think of left! So, tomorrow morning I’ll call up Geoff and buy his NOS set of valve springs. Hey ho….
 
Might check with Geoff before you buy that the stock valve springs are not going to go coil bound with the higher lift cam.
Real steel sell valve springs with one less coil for use with higher lift cams on the V8.
 
cobraboy said:
Might check with Geoff before you buy that the stock valve springs are not going to go coil bound with the higher lift cam.
Real steel sell valve springs with one less coil for use with higher lift cams on the V8.
Click to expand...
That’s a good point. Although the same spring are on there at the moment (albeit probably weakened by age) and they’ve been fine. Extra lift is about 1mm (0.040” in black and white), so not a big different.
 
@cobraboy measured a set of springs I had sitting around and looked up specs in the Rover manual. These are the numbers found:


Outer coil wire dia. 0.1665” x 5.5 active coils= 0.91575
Fitted length 1.827” - 0.91575”‎ = 0.911”
Before coil bound

Inner coil wire dia. 0.11” x 6 active coils= 0.66”
Fitted length 1.44”-0.66”‎ = 0.78” before coil bound

Total compression from cam 0.407”

Those numbers give me a good safety margin I think.
 
Have you considered that something could have slipped in the cam timing front during the last head gasket change?
 
Found it! Broken inner spring on cyl no. 3 intake valve. I can poke at screwdriver through the outer a wiggle the inner spring sideways. Looks like my gut feeling was right.
 
Didn’t find a broken valve spring in the end. But the springs have certainly taken a set compared to the new old stock ones. The inner spring about 1/8” (3mm) shorter and feels lighter too. Valves had a light grinding while out, new seal o-rings
going into the valve guides too. Everything now nice and clean and ready for reassembly.
 

Attachments

  • IMG_1734.jpeg
    IMG_1734.jpeg
    144.7 KB · Views: 6
  • IMG_1735.jpeg
    IMG_1735.jpeg
    149.6 KB · Views: 6
  • IMG_1729.jpeg
    IMG_1729.jpeg
    163.2 KB · Views: 6
  • IMG_1730.jpeg
    IMG_1730.jpeg
    156.8 KB · Views: 6
Head back together with new guide o-rings and springs. Measured the old springs against the book free length specs. Some old springs were a good 5mm (0.2”) shorter than they should be from age. So fingers crossed we’re onto a winner. The new springs feel much stiffer than the old ones by my reckoning. Just waiting on the head gasket to arrive now :/ the US postal service seems to not want to give it up IMG_1742.jpeg
 
Last edited:
Back from the UK (complete with a new head gasket as carry on)

I think I’ve found that earlier tappets were actually chrome plated. I’d seen a little glitter in the oil when I stripped the head from the engine before I left. Looking at the tappets I noticed some discolouration on the top surfaces of some tappets. I wonder if the valve bounce from the soft valve springs caused the plating to start breaking down.

I had some NOS later tappets on the shelf (I should’ve used them when fitting the new cam shaft, doh!). And have fitted them today with shims used before, I’ve measured the gaps and will refit with correct shim stacks tomorrow. I’m a bit jet lagged and noticed I wasn’t getting consistent measurements due to tiredness.

I will run the engine at 2000rpm for 20 mins when back together to make sure they all mate correctly (along with extra zinc added to the oil).

Has anyone else noticed that early tappets have chrome plating?
 
After a family emergency taking me away for three weeks I’m finally reassembling the top end. I spent most of today dialling in the valve shims and have them all exactly within spec for the reground cam. The new buckets changed things +/- 0.002-0.003” each. I’d also done a light valve grind while the head was apart as there was a tiny amount of pitting on the exhaust valves. This has increased the contact band from about 0.040” to around 0.070” that should help with valve cooling I think.

IMG_1821.jpeg
Ready for the head. I used a drill bit wrapped in tape as an alignment dowel at the back. Keeps the gasket and o-ring in place too, which is helpful. O-ring has a little phylum blue to help it stay sealed.

IMG_1834.jpeg

Head back where it belongs after almost a month of waiting. Shims now set perfectly, so hopefully it’ll stay there for a while.

I’ll try and find an hour here and there to reassemble everything.
 
Finally got the engine buttoned up yesterday. I finally have all my rev range back! So I’m pretty sure the weak valve springs were the issue.

Unfortunately when I was refitting the head half way through torquing down the bolts I realised I’d left the chain tensioner out! Bugger. I took it off again, then back together. I have a slight rhythmic puffing of the exhaust note. So, yet another head gasket ordered.

Having said that, compression test on the hot engine shows 177-175-175-172 some I’m pretty happy with it. She also pulls like a train all the way up the rev range.
 
Little update. I guess I should try and do maths when jet lagged. Found no. 3 exhaust valve had only 0.002” of clearance! So rechecking and adjusting valve shims today. Fingers crossed that’ll be it.
 
sdibbers said:
Little update. I guess I should try and do maths when jet lagged. Found no. 3 exhaust valve had only 0.002” of clearance! So rechecking and adjusting valve shims today. Fingers crossed that’ll be it.
Click to expand...
Too much brake fluid mate, but nevermind you're in recovery now....... :LOL:
 
You must log in or register to reply here.
Back
Top