1965 vauxhall victor low compression

[garagejunkie]

Hi guys, I have recently been recommissioning a 1965 victor fb. The car had been starting and running fine after renewing ignition components. After getting it out onto the road for the first time ( first time under load) there was an instant problem with shuddering, no power unless the clutch was in . Almost like fuel starvation( it's not) . White grey smoke from exhaust .

I managed to get the car home labouring in 4th . A compression test shows 25psi in all cylinders ( compression ratio should be 120psi when new) I then squirted some oil in the bores and tested again which raised the compression to around 50 psi . So there is leakage past the rings but I'm more concerned about where the other 60psi is going . I was also puzzled to why it was even wear.

Could this be a cylinder head / valve problem ?

I think it should be a leaded cylinder head an my thoughts are the valves and seats are nackered with wrong fuel possibly? I've no history for the car. But I do know the mileage is genuine at 63,000 .

any thoughts or procedures to try would be welcome . But I'm sure the head needs to come off ....

Any my help out there?

Thanks m

[crossy67]

Easy diy leak down test. Find a way of plumbing a compressor hose into your spark plug hole. Make sure both valves are closed and pressurise your cylinder. You will hear where the pressure is escaping.

[Wacky Racer]

How do you know the mileage is a "genuine" 63,000?...seems very low for a fifty year old car.

Anyhow, good luck, definitely sounds like a cylinder head problem.

(My first car was a 1967 Victor 1800OHC)

[garagejunkie]

crossy67 said:

Easy diy leak down test. Find a way of plumbing a compressor hose into your spark plug hole. Make sure both valves are closed and pressurise your cylinder. You will hear where the pressure is escaping.

Thanks crossy
If never done this before but sounds like something I need to do before diving in and stripping, what sort of pressure will I put into the head ? Would a foot pump do the job and use the gauge ?


Mileage is low as it was stored for a while and I have the original dealer service book / receipts / mots etc

[PositronicRay]

When you do a compression test the main thing is showing similar readings across cylinders. The actual PSI shown maybe down to a poor calibration of your tester.

Are you taking all the readings with the throttle wide open?

Edited by PositronicRay on Saturday 10th January 07:31

[crossy67]

PositronicRay said:

When you do a compression test the main thing is showing similar readings across cylinders. The actual PSI shown maybe down to a poor calibration of your tester.

Are you taking all the readings with the throttle wide open?

Edited by PositronicRay on Saturday 10th January 07:31

Easy to verify your tester, just check another known good running engine, if the readings are low your tester's duff. I never have noticed much difference with WOT of closed.

A foot pump won't give you enough air movement and how you going to run from exhaust tip to carb whilst pumping lol. Check valve clearances aren't too tight.

[peterperkins]

Back to basics IMO.

On an old car like that assuming the head gasket/spark plug is intact and no cracked head/block, then there are only two places the compressed mixture can escape.

1) Past the piston.
2) Past the valves.

Could be stuck rings, worn rings, worn bore, worn pistons etc etc
Could be stuck, partially closing valves, bad/rusted valves/seats etc etc

Repeat compression test using correct procedure and checked equipment.

[Pumaracing]

garagejunkie said:

A compression test shows 25psi in all cylinders...

No it doesn't. The engine wouldn't even run like that.

[S0 What]

Pumaracing said:

No it doesn't. The engine wouldn't even run like that.

Agreed.
Did you test the comp with all the plugs out and the throttle fully open?
TBH the fact they are all the same is a good thing (usually), are the bores clean or rusted to buggery, i've tested a few newly rebuilt engines and they are low on comp across the lot (not as low as your apparently is mind you), running in propperly soon reaises the comp and cleans the zorst up a treat.
It could be the rings are stuck? fill with diesel and leave for a few days, then drop the sump contents, refill with oil and try again.
Tappets been set right? had this on a crossflow before, all set to less than zero then it warms up and runs like ste (well even more ste than it did cold).

Edited by S0 What on Saturday 10th January 17:34

[garagejunkie]

I feel a it stupid , before I went to strip things to investigate I nipped up to screw fix and bought another compression tester , it now has 120psi ! It turned out to be a problem with the ignition . It was firing on all cylinders at idle and under load only 2 and 4 were continuing to spark . The points seem to have been sticking or welding them selfs . It's now re timed AND new points and it seems to be running well on the road except from a flat spot when pulling away from junctions . Thanks for all the help and sorry to waste people's time , but I will remember all the above info many thanks

[S0 What]

Alls well that ends well at least it runs
AND thanks for getting back to us , so many dont bother and leave us wondering

[kev b]

A common problem on Vauxhalls of old was poor quality distributors where the four lobes which open the points for firing each cylinder were not the same height.

This results in wildly different points gaps between cylinders either wide or narrow, depending on which lobe was used to set the gap, causing misfiring due to a weak spark.

The way around this is to measure the gap for all four cylinders and set the gap so all cylinders are somewhere near.

[garagejunkie]

kev b said:

A common problem on Vauxhalls of old was poor quality distributors where the four lobes which open the points for firing each cylinder were not the same height.

This results in wildly different points gaps between cylinders either wide or narrow, depending on which lobe was used to set the gap, causing misfiring due to a weak spark.

The way around this is to measure the gap for all four cylinders and set the gap so all cylinders are somewhere near.

Thanks for that info ! I have fitted a spare distributer that I had all set up ready to use (hands were to cold to fiddle with the one that was in it ) I suspect there was something faulty with the one I took out so I will do your described check tomorrow. I'd like to get to the bottom of what happened. I just thought it being strange how 4 and 2 were firing fine and 1 and 3 weren't under load . . . .

All i have really done is change the distributer / points and problem solved.

(Just glad it wasn't a compression problem)

Thanks again guys I'll remember the advice !

[PositronicRay]

Ignition electrics are peculiar some times. I fitted an electronic dizzy (recommend the 123 BTW)

The car started and idled fine, any load and it missed all over the place, new set of leads sorted it.

[kev b]

I am interested to learn if your removed distributor has the problem I described.. Back in time even brand new replacement Vauxhall Viva distributors could be way out, giving poor running and a lot of head scratching after replacing a faulty one.

Whilst you are in the garage it might be useful to check the ignition switch as an intermittent or poor contact was not unusual either.

I am not sure which carb you have but a quick check of the vacuum advance capsule and accelerator pump would be worthwhile.

As a previous poster has said it is good when a resolution is posted after people have bothered to reply.