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Lord Gruntfuttock's 1971 XY Fairmont


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  • Lord Gruntfuttock

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  • 2 weeks later...

Haven’t done anything since my ‘drive’ the other weekend, so popped into the shed to tidy up some tools/escape family/gaze at things, and unscrewed the catch can while there, thinking there may be a few drips of oil after the 30-odd minutes of running she’s had. Fuck me – full, and chocka-block full at that…

Guess that means my attempt at using the factory rocker covers hasn’t worked, drilling bits out of the baffles appears to have created a passage for oil to spew straight out the PCV valve. Bugger, wasted effort…

So I bought some taller baffled alloy rocker covers, no big deal but I really wanted it to look as stock as poss at first glance, plus I reckon most aftermarket covers look a bit shit. (I’m not into blinging engines or advertising brand names, but needs must and all that). I did think of painting some 80’s factory Mustang alloys the same blue, but there’s no guarantee rocker clearance will be any better, and I’m over painting stuff to be honest.

On the way are a couple of alloy covers, a new PCV valve, gaskets and breather, will be a quick job to bung em on then I’ll set timing and give carby a tune. Still have to sand and paint grille but weather has been a bit shit for that. Sort of want things to get done as my bike projects are nagging me…

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  • 2 weeks later...
  • 2 weeks later...

Had a crack at tuning her up a bit, started with the basics:

  • Checked throttle blades were perpendicular with pedal fully depressed (noticed I need new throttle spring)
  • Float level - just used sight glass on primary, should prob remove screw on secondary side to check it's ok too
  • Accelerator pump linkage - set to have 0.015" free play

Then hooked up some gauges and timing light...
1mrqbeda.uvx.jpg

 

Timing for initial startup was set around 10 deg BTDC. gave total advance of 28 at 3000rpm (with vacuum advance plugged).
Loosened clamp and tried to rotate distributor, was stuck. Had to get strap and vice grips on it to move, bit of a concern as I'd oiled it on install. Anyways, set idle advance to 14 degrees, and now have total of 36, which seems around optimum for these things...
og41jz0u.ezv.jpg

 

And tuned carb idle mix via vacuum method. Connected cheap vac gauge to port on carb and tweaked idle screws together to get max vacuum. Bit tricky but have a base level now at around 18 inches mercury, which I think is pretty good for the cam (drops to around 14 in Park)...
gdhtq3fp.zh2.jpg

 

And it drives much nicer, smoother all round.

Only concern is the bloody catch can is still filling really rapidly. Noticed when tuning there were puffs of mist coming out the breather at low revs. I've ordered a compression test kit so that should say if excessive blowby is due to dodgy rings. Bit of a bugger as it seems to be driving well, we'll see what compression results are before panicking...

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Compression test kit arrived at work so shot home at lunchtime to give it a whirl. Torpedo 7 kit, looks pretty good and has adapters so I can do bikes etc..

ybtb1y0g.bww.jpg

Got the following results (warm engine and 5-6 compression strokes per cylinder):

#1 130

#2 120

#3 128

#4 148

#5 135

#6 136

#7 138

#8 140

A bit of variation and pretty low overall (cam overlap?) but nothing indicating rings are really buggered. I'll recheck them cold as it's possible I was a bit rushed and didn't have connection done up right. Cyl 2 seems an anomaly but the average is around 135psi...

5fe5ps43.uyw.jpg

Wondering if it's running way too rich though looking at the plugs...

g11fppoz.5a2.jpg

Very sooty...

b052n4yk.1zr.jpg

Hard to say as it hasn't had a decent run, and it was left idling to warm up while I made up the remote starter switch, and that blackens up plugs. There were some fuel leaks from carb on startup as it'd been sitting for years, but seems to have stopped and I was hoping seals/gaskets had swelled up and all was ok. Might pay to grab a kit and clean/rebuild carb. If the carb is amiss it could explain the fumes and catch can filling maybe. I'll get the list number and order a kit when I get home...

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Been thinkin.

Will prob pull engine and get bottom end looked at. Did cold compression test at lunchtime and couple of cylinders increased psi noticeably with a squirt of oil in em.

Bit of a bugger but took the gamble all was ok, and guess sitting so long didn't do the poor old girl any favours. Looks like rings gone = blowby.

Hopefully a hone/rings and bearings job. Just gotta figure out if I get it warranted and rego'd first. Will rekit carb and see how she runs.

I hate rework, but was worth a crack, and I'd rather have some confidence things have been checked, plus we're planning house reno's so this will be last chance to work on it for a while.

Ah well. :)

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So got the grille all fitted (apart from driving lights) and pulled carb apart while waiting on bits. Pretty basic old Holley 4160. List # 1850-3, 600cfm, vac secondaries. Think date stamp indicates 1989, as it's prior to the anti backfire check valve that came in around 92. Best thing on this one is the quick-change secondary spring system I fitted yonks ago, means you can swap springs to alter when the secondaries come in pretty quickly...

2mqrys0v.wyy.jpg

Came apart easy as I'd fitted non-stick blue gaskets last time I played with it. Power valve (65) and main jets, size 66 (Holleys give numbers in thousanths of an inch). Bit misleading after you've played with metric scooter jets... :)

kbihbjux.mtb.jpg

The 4160 is a budget but capable sort of carb, both bowls fed via connecting tube from single fuel inlet, and has a secondary metering plate rather than block and jets. Decoding the plate number gives equivalent secondary jet size as 64...

zmvf3gfh.kne.jpg

Cracks in plate bothered me though, front has circular pattern that could be casting issue...

wlk4v4ts.mp4.jpg

and looks worse at the back...

fg5h1wmv.1jk.jpg

I don't think these are causing my problems, but good excuse to pimp my carb, so ordered a conversion kit that adds a metering block to the secondary side, Means I can swap jets, and effectively converts 4160 to 4150 model. The kit comes with extra gasket and longer fuel tube to suit.

It's about now I realise I've misplaced the carb cleaning brushes I got a week or so ago (while I've got 2 carbs in pieces) so things on hold till I have a good sort out...

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  • 3 weeks later...
  • 3 weeks later...
  • 1 month later...

Still haven't pulled motor for bottom end check, and considering it's running and nearly xmas I'll prob use it as-is till next year. No fuel gauge is a pain in the arse tho so killed some lawn today popping the sender unit out...
tbsfb2sr.jdt.jpg

 

I'd assumed the rheostat was koozed but it checked out  fine, 10 to 100 ohms over full movement of the float, and all looked good...
0c2kaogo.1xp.jpg

 

Then I realised the float was bloody heavy, yep holed - and so full of fuel it didn't slosh when shook. Put the hot air gun on it and had a cool fine jet of fuel spray out the very tiny pinhole. I SO wanted to light this...  :-D

ecwsjyhw.vka.jpg

And rather than piss around all day trying to re-solder it I ordered a new one. Tried to find something I could rig at the wreckers but nothing really suitable.

I'm still gonna pull the gubbins out and sort a few issues and lower the front etc (found puddle of fluid under trans today) but if I have a working fuel gauge I can just keep an eye on the oil and use it for a while while weather is good...

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  • 2 months later...

So strip went well, much easier pulling them apart when you've used anti-seize on the threads, and the gaskets aren't decades old...

iu52maue.lyo.jpg

Disappointingly i didn't find obvious ring issues, so no wiser why it's so smoky. Pulled the piston on the lowest compression cylinder and the bearings, bore and rings look ok (as far as I know, not really sure what I'm looking for) so hopefully a hone and ring job may sort it. I'll check how the ring gap looks and try to take it into a machine shop this week to get it checked out...

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Looked at the ring gap at lunchtime - took the top ring off, levelled it down bore with a vernier, and measured, just looks too big...
nsg2x4eb.t2c.jpg

Bloody hell, kept sliding more feelers in...
mz413j13.d5p.jpg

So it's over 50 thou. I think at 4.030" bore diameter the top ring should be around  0.016 - 0.018" - so that may be where the problem lies.
wsxmzykf.0hy.jpg

Prob been like that for years, I just never picked up as never had a catch can telling me how misty the crankcase was.
I'll try to get block into machine shop this week and get it inspected, hopefully a hone, ring and bearing job will sort her out...

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