Project 1974 MGB GT - The Mustard (Mit) Mobility Scooter - 6yrs ownership & the end is potentially nigh!

[Guest Hooli]

 

 

Oh and carb balance is a balls ache to do properly, if it is running ok and economy is not bad then I might leave them alone. easy to make it 1,000,000 times worse if you dont understand what to do and "av a fiddle"

 

I've always found it really easy with just twin carbs. I tend to do it with a bit of hose held to my ear until both carbs sound the same. On a bike with four I use guages.

[SiC]

 

 

 

That's my engine, admittedly it's a shagged Triumph 1300 unit and not a B-Series but it's still a 1950s era pushrod lump. It mostly sounds like the engine's major components are trying to make their escape, however it's been like that for the last 5000+ miles. One day I'll rebuild it, one day...

 

First time today I've had a chance to watch your videos. Hearing it through the speakers on my phone, it does sound a lot like that.

 

 

make sure it is not a leaking exhaust manifold gasket

 

Can sound like rattly tappets and obviously will make a noise in time with the engine speed.

 

As shit warms up and expands the leak could well seal up.

 

Big End rattle you will NOT mistake when you hear it, sounds orrible and you can feel it through the floor. more of a bang thud than a rattle. and on over run or cold start up. if the big ends are gone or going it will knock on cold start and then on over run pretty much every time. More so when the engine is hot.

 

Definitely doesn't sound like that or anywhere near that bad! Sounds a bit like someone tapping a nail on a piece of metal.

 

Oh and carb balance is a balls ache to do properly, if it is running ok and economy is not bad then I might leave them alone. easy to make it 1,000,000 times worse if you dont understand what to do and "av a fiddle"

It's why I've not touched it yet! It will need sorting though as the revs are two high and there is a bit of a difference between the two carbs according to my airflow meter.

 

I'll have to watch a few more Johnathan Twist videos and the like on carb tuning. Could also do with taking the float chamber apart and ensure its clean.

[Noel Tidybeard]

 

That was the 1850's OHV engine, I think the main rattle was the timing chain, still sounds like a diesel at idle...

 

1850 OHV you say?

 

new slant-four 1854 cc engine, which mated an alloy OHC head to an iron block, providing 91 bhp (68 kW) which offered sprightly performance. This was a version of the engine that the company was already providing to Saab for use in their 99 model

[captain_70s]

Derp. Typo!

[SiC]

It's Sunday morning in a 2017 November. A 31 year old man has some free time while his (lovely) wife is busy cooking Sunday lunch. What should he do? Naturally the obvious answer is adjusting tappets on his funny coloured MGB GT.

 

Cover came off in nearly a blink of an eye. First time I've ever been this far in on a car engine. I've pulled model engines apart but they're cheaper and much simpler. Usually on cars I own, to get this far would be the best part of a morning removing pipes, manifolds and wiring.

 

Looks very clean under the cover.

 

 

 

 

I then spent a good hour fiddling with the tapets. All apart from number 1 had gaps too narrow to fit the feeler in. The only reason it took so long was because firstly I couldn't turn the engine over.

 

So removed all the plugs. But it was still incredibly hard to turn it... Aaaannnd then I remembered that the handbrake is off and gearbox in gear. D'oh!

 

Secondly, as usual with stuff I do, I triple check everything. Also I end up trying to get it too exactly right.

 

As they were out by a fair bit, I was hopeful that it'd make a big difference. Unfortunately it's still very tappy. I know it's a tappy engine but it sounds a lot noiser than I expected still.

 

Here are some videos of it cold and warm. Not sure how well the noise comes up though.

 

Cold:

[Video]

 

Warm:

[Video]

 

I still need to get the carbs tuned. Since changing the rotor arm, static timing and now tappets, the idle has raised to 1000rpm when cold and 1500rpm when warm. Which is ridiculously high! I think the more I drive it's the more it's rising too. I guess stuff is freeing up and moving easier.

 

Carb tuning looks to be the next immediate fiddle session. The front 2 plugs are all black, while the rears have a light brown finish to them. So I'm guessing it's all way out of whack.

 

I also need to make a decision and find something to put on and protect the underside bits asap. Probably my biggest fear in killing it/big bills it is from not sorting that underside quick enough.

[captain_70s]

Does the carb on these have an idle speed screw? The 1850 did, right on top with the carbs, great to mess about with and completely ruin the car. I swear it just chose a random idle speed every day regardless of my tinkering.

 

At least inside the rocker cover is all nice and clean and not full of gunk, it does look a bit on the dry side though. Was the car running before you took it off? I know that Triumph OHV engines can struggle to get a decent amount of oil to the top end which can make them wear prematurely and be more rattly, not sure if the B-Series suffers similar problems.

Might be worth checking for wear on the rocker arms where the sit on the shaft, on my Triumph they'd worn to a figure-8 shape and moved left and right on the shaft! It was VERY tappy until one snapped and it which it became MUCH MORE tappy and I drove it home on 3-cylinders. Whacked on a second hand set of rockers from Quillers for £25 and she is still going!

 

 

To be honest all old pushrod Brits sound a bit crap, fit a loud exhaust and forget about it is my advice. The noises don't seem to suggest any bottom end problems and the top end is unreasonably easy to take off and repair even if it does shit itself, not likely to do anything major like a drop a valve.

[SiC]

Funny enough I did notice that the rocker arms weren't dead square on top of the valves. Some were slightly to one side. I wonder if the rockers have worn down.

 

It was reasonably dry up there, but then the last time I started it was the other weekend. I have noticed it being very tappy noisy on startups until the oil pressure starts rising. The pushrod and rocker surfaces did have quite a bit of oil clinging onto them though.

 

It could be clean because the previous owner had the top off to replace the gasket. The original was leaking and became an advisory on the MOT. This car was supposed to have been serviced by the garage he uses, but given how far the tappets were off I don't think it was. At least not properly.

 

Before I started the engine again I did give a good squirting of oil all over the top end bits. This did make the startup a lot quieter.

 

Something else I noticed was this bit missing from the top. Any ideas of what could have caused that and why?

 

I did wonder if someone previous was just careless with their tools.

[Mally]

Damage to valve spring retainer possibly caused when using valve spring compressor.

If so head would be off so the bits should be on the bench rather than in the engine.

 

It is possible to change valve springs without taking the head off, which is more likely to damage the retainer, and the bits could have gone anywhere.

This method is a bodge, which I of course would never do or recommend

[SiC]

I wonder if this engine has been converted to unleaded in the past then?

 

I am reassured that if it's the top end rattling, I don't need to worry too much about driving with a rattle and risking terminal damage. I guess worse case it could be damaging the cams, but again I assume they're easy enough to change without having to drop the engine out?

 

Part of my problem is that I've spent a fair bit buying this and in parts too. So I'm in too much financially to be mentally prepared to ditch it cheap if it all goes bang horribly. If it was like a 1k quid classic, I'd be less worried. However likewise, I'd be less worried about buggering it up when fixing and more prepared for bigger jobs.

[plasticvandan]

Shame your down in Bristol (I'm up in Worcestershire) as I could sort carb and valves very quickly for you,having got these down to an art on a series and reliant engines.Best way on valves is to not use the guage,but maths.Feelers cannot account for the groove worn in the top of the valve by the rockers,so they always end up slack and rattly.There is another method using the pitch of the thread,so that if you screw in while rocking the rocker until it just stops,then back off 1/4 turn that is the correct clearance(12 thou iirc,may be wrong,been a while!)

Idle speed is 10 seconds with the idle speed and mixture screws.

[SiC]

Thanks for the offer. I need to throw it at my tame mechanics to get the fuel tank changed, so I may ask them to sort out the tappets too.

 

I've increased the idle speed already in my ownership. The last owner definitely had the carbs re-setup when he acquired the car earlier in the year as apparently it was running awful. However it was idling around 500rpm by the time I got it home. So I raised it a tad to 800rpm.

 

I suspect that the new rotor arm that he had put in is crap. The idle substantially increased and smoothened the running when I put one of these red rotor arms in.

 

Retuning the carbs is something I really want to do anyway. Plus I've splashed out on my airflow measuring foofum thing and need to justify its purchase.

 

If I cock it up, I'll get my tame mechanic to fix it again...

[Fabergé Greggs]

Adjusting carbs is one of those things that seems like black magic until you take your time to figure out the logic behind it- sounds like you’ll take to it and find it immmensly satisfying! Go for it!

[Mally]

It is possible to change the camshaft with the engine in, but I would take engine  out, with a view to doing crank, shells, rebore, unleaded head..............Not worth it for the mileage you will do.

Unlikely the cam is causing the noise I would have thought, more likely wear in the rocker arms and shaft.

It's easy to take the rocker shaft off to check , but personally I'd just live with it.

It's an engine, it's supposed to make noises.

Tune the carb then keep the bonnet closed for a few weeks.

[cort16]

Dude where’s my camshaft.

Do these oil the top end through the push rods ?

[SiC]

I have no idea! It was one thing I was wondering how oil got up there. I did see holes in the rockers so oil could get in those bits. I assumed oil went in there, not out.

[SiC]

This is the first car I think I've owned with pushrods. Infact apart from my model engines, the only other engine I've operated with pushrods is a lawn mower...

[cort16]

I know some American v8s have hollow pushrods that are used to oil the top end . Quite clever really but if there’s issues then the top end gets noisy . No idea if these are the same.

[Mally]

http://mgaguru.com/mgtech/engine/of101.htm

 

Camshaft in bottom of engine, above crank, plenty of oil splashing around there.

Camshaft driven by timing chain from crankshaft. Cam followers follow the lobes, the pushrods are dropped in them

Pushrods are solid. Oil feed up to rocker shaft, feeds rocker arms, leaks out at the sides and oil splash lubricates top end.

[SiC]

When hot cams are put on these engines, do people usually drop the engine out and do it? Or are they accessible by taking the sump off?

[Guest Hooli]

Carb tuning looks to be the next immediate fiddle session. The front 2 plugs are all black, while the rears have a light brown finish to them. So I'm guessing it's all way out of whack.

 

 

Exactly what my old Midget used to do. No idea why the front always goes right & the rear lean, but sounds like it's a common thing.

 

From memory it's two turns of the mixture bolt for the base setting. You wind them up & then back them out the right amount. Once I knew how mine run best & that it didn't vary over a year I popped the carbs off & threadlocked the mixture.

[Guest Hooli]

When hot cams are put on these engines, do people usually drop the engine out and do it? Or are they accessible by taking the sump off?

 

Rad out, timing chain etc off, get to the tappets via the side covers, rad out & slide the cam out the front.

[Isaac Hunt]

.

I've not owned a car this old and never something with a carburettor. So I don't quite know what I'm doing with a lot of this, and will have plenty of questions! Part of the reason why I bought it was so I had something that I could fiddle with and learn on. As the other thread got a bit long, I thought it would be a better idea to split and start here.

He fixes electrics in modern Goonas like it's a walk in the park, a couple of SU carbs is not going to put up much of a fight

[Noel Tidybeard]

sounds fairly normal to what a landcrab/marina/oxford/cambridge should like

 

black plugs = front carb too rich - lean it off a couple of flats and re-check after a hoon

biscuit coloured plugs = about right on rear carb- leave it be

[vulgalour]

Sounds normal to me, just a very high idle which will be making it sound more rattly.  Certainly doesn't sound like anything terminal has or is about to happen, just seems a bit overexcited.

[PhilA]

You've helpfully reminded me that I still need to re-torque the cam bearings on the GTA.

 

Most British engines of that era make noise. I think this is why during the seventies when the Japanese began introducing cars that people who bought British could afford, their engines were not deemed trustworthy. You couldn't hear them running.

 

This is possibly why Talbot/Simca tried to lever their engines on the UK, you could hear their valvetrain from Jupiter.

 

Doesn't sound too bad. Get it tuned up and go out and enjoy it!

 

Phil

 

 

Edit: Anecdotally, the MGB here (along with most classic British tin) is generally approved of by all but the most die-hard American muscle enthusiasts. There hasn't formed much of a hater society. But, then again, three wipers make everything better. Nowt wrong with a B.

[SiC]

Had a bit of a fiddle with the carbs today. Balanced the carbs and tweaked the mixture. Don't think I've got the mixture quite right yet though. Will probably get my mechanic to set it properly. Idle is much smoother now and the oil pressure is registering 35psi at around a 750rpm idle. A bit lumpy at idle but I'm being picky, considering its over 40yrs old and has a dizzy+carb. Still a bit tappy but just going to accept it as how it should be.

 

[Video]

[Fabergé Greggs]

Sounds hunky dory!

 

You should celebrate by downing tools for a bit and driving it loads and loads

[vulgalour]

That sounds much happier.

[SiC]

Just done what I said I would never do.

 

£756.61 in parts (I'm not breaking that down, otherwise it'll depress me more),

£196.40 in tyres (fitted),

£3500 for the car.

 

Which means I'm currently in at £4453.01. Probably other stuff I've forgotten, like oils and odd+sods.

 

Also bought tools but I won't count that. Still need to pay the garage to change the fuel tank, plus other assorted bits - diff oil, wheel bolt change and welding. Finally need to stock up on stuff to underseal that bottom so I can use it in all weathers.

 

Oops

[danthecapriman]

Yeah but having a cool car is much better than money in the bank. Isn't it?!