Story and pics by Dick Reynolds.
So we are all looking at isolation, can’t drive the car without a valid excuse and I’m on “Special Interest Plates”. Daryl, Shane and Jon increasingly monstering my efforts on track!
Thinks to self “rip the engine out and do that cam replacement you’ve been dreaming of for 10 years”.
And that is exactly what’s happened.
Here’s the timeline:
Checked valve to piston clearances roughly and selected a Cosworth A3 grind.
10mm lift at valve, 47/83 83/47 timing giving 310 deg. duration. Rev range 4000 to 8000.
All depends on what’s in the engine as to how effective this somewhat warm cam is!
Took the head off, oversize valves – like really oversize, double springs, beautifully ported. Tick.
Piston tops look like forged items and definitely 83.5mm bore. So solid 1700cc. Tick.
Took engine out, flipped over, bearings OK and rods 125 Twin Cam items. Tick.
Removed the flywheel, pressure plate and clutch – AP Racing clutch. Sadly decided to replace and had all manner of problems chasing bits. All set now with 170hp capability! Tick.
Removed old cam – BCF2 fast road cam badly timed! (110hp on a good day). Checks with Dyno Day 82.6hp at wheels.
Cam arrived, set up the dial gauge and found original TDC of crank out by about 2 to 4 degrees so couldn’t time A3 at the required .087” (2.21mm) lift at TDC.
Duplex cam chain with Vernier adjustment arrived and set cam up at the precise timing. Installed home-made front cover hatch to allow adjustment of cam timing should I get it wrong or want to change it!
Did a “dry” assembly to check valve to piston clearance – 4mm! Plenty and room for a wilder lift at some later date.
Solid front pulley also arrived. This prevents pulley flying apart at high revs and is smaller diameter to slow water pump and reduce cavitation.
All new gaskets and followed the Wallage Kent Xflow book closely to re-assemble.
Assuming better breathing, installed 34mm chokes, 140 mains and 180 airs in DCOE Weber carburettors.
Put the completed engine back in car and set the ignition timing, primed the dry sump oil pump and re-filled the coolant.
Next step terrifying! You need to run the engine at no less than 2000rpm for 20 minutes to run the cam and followers in. Luckily, all went well and it’s run in.
Took the car out for a run and it went very well, no revs over 4000. Appears the jetting won’t be too far out.
Days later and a few runs around chasing various odds and sods like shorter fan belt etc. turned right out of Cannon Hill shops instead of left, entered the Gateway Bypass on-ramp and floored the pedal in third gear. Moment later the engine all but stopped – oh no! Looked down at instruments and realised I had hit the rev limiter.
Think this thing might have some poke!
Spent the next week solving little niggles like oil and water leaks and electrical glitches.
Now I’m sorting the tuning myself. Bit of plug analysis and getting the thing running sweetly.
Returns a day or two later!
Number one valve has half the lift it should and there’s a big knock in the engine.
Looks like a second wave of repair.
Such is life.
I’ll keep you posted.
So in a couple of hours the engine is out and a bit later I’ve lifted the sump off to see what has happened! All single handed thanks to a borrowed “Endless Chain”.
It appears the follower or lobe – more than likely the follower – has failed, stopped rotating, lost hard face and begun to lose my much needed valve lift. Actually lift reduced from 10mm to 5mm in about 10 miles of driving! As an aside, the damn thing still seemed to pull like crazy!
Reason for the failure? Sadly I imagine a lack of pre-assembly lubrication on my part, and possibly not run in well enough. Could also be a fatigue crack in the follower – yeah right Dick!
So how to prevent a recurrence of this!
First off, get some good advice. Re-read the Bible (Wallage), spoke to various boffins – thank you Peter Bowl , Clive from Clive Cams, Daryl Jarvis, Greg and Paul at Taylor Street Mechanical, Steve Lennox and others.
Second off, take the bloody advice!
Strip the engine down and find out how far the bits of my “valve lift” went!
Oil filter, sump and bearing surfaces indicate the filter did its job perfectly.
Next, clean out the areas – bought a compressor and blew the thing clean.
Ordered some “Redline Assembly Lube” on the netty thing.
Chased up a valve spring compressor and took the inner of the double valve springs out. This reduced the pressure on the lobes by about 30%. Just have to work out how to put them back without taking the head off AGAIN! Post script, found a valve spring compressor that does this at Supercheap for $40!
Unfortunately Clive Cams are very busy and I have a 3 week wait for the replacement camshaft. Good chance to chase up a few annoying glitches in the car. Things like finding the ideal Allen Key to get to the dry sump pump bolts, the ideal bolt length to get to that terribly annoying centre bolt on the inlet manifold, perfect the sump gasket assembly process, etc. Post script – all done. And even stopped the head lights wobbling!
Cam arrived looking exactly like the last one, so began the re-assembly.
Steve Lennox turns up with a tube of angel dust! I’d tell you what it is but then I’d have to kill you – something about NASA or NSA or something! Suffice to say it protects – big time! Sorry for looking such a dill on the morning Steve – really shouldn’t try to set up a cam when “under the weather”. By lunch I was on the ball again and assembling away. Block and head positively dripping with $40 a microgram assembly lube!
Saturday night, minimal drink and early bed.
Sunday is move the engine out to the driveway and stick it in the car. With some invaluable help from my golfing nemesis Dan Hodder the engines back in by lunch.
Few glitches with wiring etc and it’s late in the day before I can start the thing.
You guessed it! Didn’t start.
Pulled the pin and got a good night sleep.
Monday after work I figure out we are one plug position out on the distributor. Quick twist of the dizzy (you Elise guys have no idea what I’m talking about – but that’s OK!) and it’s all go. Alive again! Oil pressure, no big leaks but the exhaust pipes are glowing red on idle. Seems I need the 50F9 idles! As an aside, the bible says idle new cam for 20 to 30 minutes at no less than 2000rpm. Can’t tell you how painful that is with a new engine, untested!
Did the 30 plus minutes cam run-in. Set the idle and went for a ten minute drive to see if all’s well. Yep, all’s well.
It’s now next weekend and I’ve set off for a two hour drive to run the cam in a bit more! Did a plug check at a Truck Stop and all looks OK.
All that’s left to do is put the inner valve springs back in, change the oil and re-torque the head then“give it one”, but I’m feeling a tad reticent!
Maybe a couple more hours at easy revs and we’ll see.
Well I’ve done the couple more hours, including an EMR to Mt Glorious, no revs over 5000 rpm.
Next day, devise a cunning plan to put double springs back on head. Most essential ingredient being Clothes Line cord – poke about 1.0m into spark plug hole to hold up valve!
Checked all, seemed OK and planned another run up the mountain.
Well, it seems the work has been well worthwhile.
Noosa Hillclimb next week, so we’ll see how it goes.