My Alfa Romeo 33 rebuild - FIRST TIMER

[Urbancamo]

Nice looking and tidy engine bay for sure!

[Brit01]

Oil and filter changed this morning. Managed to drain 4 litres, made the guys wait longer, as normally the garages try to do them as quick as possible and never drain them properly.

AFR is on the rich borderline, the boxer prefers a slightly richer mix and is always safer than being on the lean side as we know.

Reading 13.1 on the idle jets and about 13.8-14 on the mains.
Planning to increase the pump jets to 35, currently have 33 which are a little undersized.

Will drive another 200-300 kms or so and change to a more expensive Motul semi oil for the regular 3000-5000 km changes.

[Guy Croft]

Don't try tuning the IDLE mixtures by AFR, get yourself a Colortune,

G

[Brit01]

Yes I heard the carbtunes are ok for idling but the wideband bosch is great to see the AFR while driving and cruising on the idles or mains.
You can see how rich it goes when the pump jets shoot etc.

I adjusted the floats just a tad yesterday, they weren't quite vertical at 5-6 mm. 13 ish on the mains and now it is 13.8-14 ish. Much better for the boxer.

Carbtune has it's limitations. Also to be effective on the boxer you really need a carbtune for every cylinder running at the same time IMHO.

The flat four has a tendency to go back and forth, balance 1 side and the other goes out, takes some time and patience.
Also (factory recommendations to tune), to listen to the sound of the rpm. if it falls while turning in the screw (leaner) then you're going too lean. You want a nice medium in between, at the rpm peak, whilst keeping at 850 rpm.

The AFR gauge makes this an easier job to do for me. I can see if one is out as the value jumps when that cylinder fires, once it's stable then I'm happy.

Maybe whizzman's idea of using a heat sensor gun could be used also. Novel idea.
Lean = hotter

[Brit01]

well I failed miserably!

After 100 kms exactly the same ticking tappet noise returned at exactly the same location on piston 3!!!

So fustrated you don't imagine.

What next? I don't know what the issue is now. Maybe a knocking small end bearing? But it doesn't sound like a knocking.

Guess the head will need to come off again to see if it's the same tappet.
Maybe the tappet housing is just sligthly worn.

Came home extremely diappointed.

[WhizzMan]

Are you absolutely certain it's not a slight leak at the exhaust port where the manifold bolts on. This usually gives a "ticking" sound as well.

[Brit01]

whizzman.

I will check that but I did retorque them 2 times just to be on the safe side. Both are tight.
But it is a loud ticking noise the same place where the previous failed tappet was.
Could a leak here really give such a louding ticking noise (adn only when hot!).

Can a slightly bent valve or bad guide cause a tappet to fail?

(The only part I took to the mechanic was the head to check the valves and change the valve seal!!!!).

ALSO this was always the cylinder that had a slightly lower compression than the others, by about 8 psi before (now only about 2psi though). No leak down test done. Difficult to find here.
There was an occasional spitting through the carb from this cylinder also on warm up.

Thanks

[Guy Croft]

1. Valve hitting piston

- Only happens (normally) if the head has been heavily machined (or block) and valve to piston proximity has been radically reduced.
- Bends the valve(s) and the engine misfires at idle although it might feel normal under load.
- When valves are bent compressions drop to a very low level - yours have not

Conclusion: likely not the cause

2. Big end bearing failing
- if very badly damaged can show as low oil pressure when engine is hot
- very high level of gas coming out of the engine breather can show up result from a badly damaged bearing
- can sound like a loose or worn tappet
- there will be a lot of debris in the oil

Conclusion: possible cause: drain the oil with engine hot into a clean container and take a good look

3. Tappet/cam problem
- will be noisy if tappet too loose
- if tappet too tight will wear cam and noise will follow

Conclusion: Possible cause - take the cam covers off and run your finger over the cam lobes. They should have smooth arc. Check the clearances.

Hope that helps some, can't think of anything else at this time. Use of a stethoscope can sometimes pinpoint the place the noise is coming from. A metal rod with one end on the place you're looking and the other against your ear will also work quite well.

Readers, think hard and write only from personal experience OF FAILURES on this one, no reason to cause panic. Brit01 - whatever the cause, just take a deep breath and find-fix it, OK? These things happen.

G

[Urbancamo]

Personally i have located several fault points just with piece of steel bar and ear.

Valve and big end noises are easy to separate. Valve train spins only 50% speed of crankshaft. So noise frequency is much more fewer.

[Brit01]

Great response Guy. Many thanks. Unfortunately yes I was kind of panicking last night. Breathing deep and thinking logically.

Now the noise appeared after 100 kms of driving.
From the same place next to the oil filter nearer the cam box/head. The noise is not emanating from the crankshaft area but yes I will take a pipe or object to listen more carefully.

2. Big end bearing failing

Good pressure last night while driving. 87/88 psi when cold idling. 45-55 psi @ 3000 rpm when hot.
I drained a small amount of oil on Monday night as the level was just a little high. A tiny amount of debris initially came out. Inspected it closely and appeared to be just tiny soft loose flakes of rust(really small particles), probably from when the crankcase was left dry for a while after cleaning. Nothing shiny, nothing looking like bearing bits like before. First time I took it apart yes it had bits of lobe tappets fragments - this was unmistakable.
No knocking noise coming from crank.


If the pistons small end shell/rod is worn and has too much clearance could this be mistaken for a tappet ticking as it is nearer the cylinder head?

Conclusion: Possible cause - take the cam covers off and run your finger over the cam lobes.

Looks like I'll have to remove the left cylinder head and check the lobes/tappet.
Shame I can't remove the cam box/cover without the head though. Head gasket removal!!

If the lobes and tappet face looks good then maybe a loose tappet casing or small end shell bearing worn down?

Now regarding the head gasket. It has 100 kms on it. Due to the total unavailability of these in this country and shipping of 3-4 weeks from overseas would it be possible to use the same one? I know I shouldn't with an old one but this has only 100 kms. (Probably scream at me for asking this - sorry in advance)


Best regards (wife was understanding last night thankfully)
btw : The only thing I took to the mechanic was the cylinder head to replace the valve seals and check the valves.

Conclusion: likely not the cause

2. Big end bearing failing
- if very badly damaged can show as low oil pressure when engine is hot
- very high level of gas coming out of the engine breather can show up result from a badly damaged bearing
- can sound like a loose or worn tappet
- there will be a lot of debris in the oil

Conclusion: possible cause: drain the oil with engine hot into a clean container and take a good look

3. Tappet/cam problem
- will be noisy if tappet too loose
- if tappet too tight will wear cam and noise will follow

Conclusion: Possible cause - take the cam covers off and run your finger over the cam lobes. They should have smooth arc. Check the clearances.

Hope that helps some, can't think of anything else at this time. Use of a stethoscope can sometimes pinpoint the place the noise is coming from. A metal rod with one end on the place you're looking and the other against your ear will also work quite well.

Readers, think hard and write only from personal experience OF FAILURES on this one, no reason to cause panic. Brit01 - whatever the cause, just take a deep breath and find-fix it, OK? These things happen.

Valve and big end noises are easy to separate. Valve train spins only 50% speed of crankshaft. So noise frequency is much more fewer.

So if one tappet is ticking at idle speed the noise should be maybe once every second? Just trying to visualize the valve train spinning at 900 rpm.
But if it's coming from the piston rod it will be ticking twice as fast.
so 900 rpm lets say

960rpm / 60 seconds = 16
16 crank spins per second.
16 / 4 (pistons) = 4
each piston should fire 4 times per second?
Is my calculation correct?

If it's 1 tappet then it should make a ticking noise 2 times per second at 960 rpm?

[Guy Croft]

One other thing - you did tighten the FW properly didn't you?

Small end bush wear is not common - you would have felt the pin VERY loose if they were worn out.

I would not pull the head at this stage. My advice may seem odd but I would drive the car a lot more and see if the noise gets progressively worse before pulling bits off. Reason is whatever is wearing will be more obvious (you may have missed it during build) the more worn it is - cam/tappet.

G

[Brit01]

One other thing - you did tighten the FW properly didn't you?

Sorry but - FW??

My advice may seem odd but I would drive the car a lot more and see if the noise gets progressively worse before pulling bits off. Reason is whatever is wearing will be more obvious (you may have missed it during build) the more worn it is - cam/tappet.

This is what I'm afraid of doing as it's making the same amount of noise from the same spot as it did before the rebuild and finding the destroyed tappet and worn lobe.
I'm concerned about wearing down the new expensive lobes again.
How quickly can you destroy a lobe with a failed tappet?

remember this is what was left over before:

damaged tappet.JPG (2.78 KiB) Viewed 9195 times

flat lobe.JPG (3.1 KiB) Viewed 9195 times

Thank you

Valve and big end noises are easy to separate. Valve train spins only 50% speed of crankshaft. So noise frequency is much more fewer.

So if one tappet is ticking at idle speed the noise should be maybe once every second? Just trying to visualize the valve train spinning at 900 rpm.
But if it's coming from the piston rod it will be ticking twice as fast.
so 900 rpm lets say

960rpm / 60 seconds = 16
16 crank spins per second.
16 / 4 (pistons) = 4
each piston should fire 4 times per second?
Is my calculation correct?

If it's 1 tappet then it should make a ticking noise 2 times per second at 960 rpm?

[Guy Croft]

FW- flywheel.

Remind me exactly what you did with cams and tappets, eg: new/overhaul etc put in bullet-points please:

1.
2.
3.

G

[Brit01]

1. Removed heads/cam boxes ( along with all coolant systems, carbs, manifolds etc)
2. Removed pistons/rods
3. Heads/Cam boxes thoroughly cleaned - hot water detergent 2 times and then lots of carb cleaner/WD40 through the tappet passages until all clean. Lubricated after.
4. Valves checked, seats cleaned, seals changed (by mechanic)
5. New cams and tappets installed (molykote added)
6. New rings installed after claneing pistons/rods/bolts
7. New big rod end shells replaced (molykote added)
8. Pistons/rods installed
9. Heads fitted with new cams and tappets/gaskets
10. Broke in lobes/tappets (15 mins at 2500 rpm)
11. Re-torqued head bolts.
12. Drove 70 kms in 2 turns
13. Changed oil and filter
14. Drove 60 kms in 2 turns yesterday and last night arrived to hear same loud ticking noise (when hot again) on cylinder 3 next to filter around cambox.

ah one more thing remember compression after 9 kms was 180 psi on each cylinder.

Thanks very much

Flywheel of course! - yes tight.
What would be the consequences of a slightly loose FW? Bad I imagine.

[Guy Croft]

You'll - please - have to excuse my ignorance - are the tappets hydraulic?

If not what did you set the running clearances to (inlet/ex)?

G