Fuel and vacuum pressure gauge

[Iain T]

Another must have to calm my fears. Its a Sealey kit but as you can see the gauge needle is way off zero! The supplier is sending another for delivery tomorrow, they don't want this kit returned. Just another example of poor quality equipment. 

To be honest I plugged it in without noticing the problem and wondered why the pressure from the Huco electric pump was reading 0.5psi. It may be the pressure is low but I can't trust this kit! 

[Pete Lewis]

as the dont want it back can you get at the needle to reset the zero ??

if the replacement is better  you can compare the readings to get some faith in what is calibration is like 

I have a similar looking but Gunsons brand and there is no external zero adjustment which would make it easier 

Pete

[Colin Lindsay]

Maybe that's atmospheric pressure?

I'll get me coat....

[Pete Lewis]

if it is were in a Vacuum  , does that go with depression which seems the latest  Oh dear    problem  

Pete

[Iain T]

1 hour ago, Pete Lewis said:

the dont want it back can you get at the needle to reset the zero ??

if the replacement is better  you can compare the readings to get some faith in what is calibration is like 

Good idea I like twidlin an fiddlin.

 

1 hour ago, Colin Lindsay said:

Maybe that's atmospheric pressure?

I'm feeling under pressure, mainly due to trying to get the top rear corner of the flippin driver's door glass to move 10mm inboard! Spacers in the glass channel just ain't moving it🤬

48 minutes ago, Pete Lewis said:

does that go with depression which seems the latest  Oh dear    problem  

Pete

Yes my wife calls me Marvin (the paranoid Android)

To top it all were barely able to get in the front door today. Found out the builders had installed a too short door handle split centre bar and the grub screw had unclamped! Ordered one 20mm longer, idiots had used an internal door bar when the front door is much thicker. I give in.......

Iain

[Wagger]

I received that kit last week. The needle is on zero. It agrees with two other gauges at 4psi. Good enough for me right now. The vacuum side will be good for manifold checks, I hope.

As others have suggested, just set the needle yourself and check it with the next one.

[johny]

This has set me to wondering about the reliability of using one gauge to measure positive and negative pressures...

[Iain T]

Haven't used it to measure the inlet vacuum. Are there any specs or charts available? 

Iain 

[Pete Lewis]

in general  idle 18-21inhg   full throttle    zero    cruise   25     decelerating 28 -32 ins hg 

Pete

[NonMember]

8 minutes ago, Pete Lewis said:

decelerating 28 -32 ins hg

That's rather extreme deceleration, when you consider that atmospheric pressure is 29.9"Hg, so half that range is more vacuum than outer space!

[Iain T]

That's better, I bought from Folkestone Fixings excellent service. Now to do some fiddlin

 

[Iain T]

22 hours ago, Pete Lewis said:

the dont want it back can you get at the needle to reset the zero ??

Yes! Took the casing off and rotated the copper half tube and zero'd the needle. Compared results with the replacement and they are the same. Result....but I don't need two kits! 

Iain 

[Pete Lewis]

you cant have too many

so rig it up and give us the readings   

you often need a squeezed up pipe to damp induction vibrations shaking the needle so you cant see it 

Pete

[Iain T]

The fuel pressure is fine at 2psi, I'm waiting until it gets a bit warmer to check the vacuum🥶

 

[Iain T]

Time to  try the vacuum test and which hose to use, I'm thinking the snake like curly hose from the manifold to the pcv? I think one of the adaptors that came with the kit might push on at the manifold  but failing that on the hose at the pcv end. Another option might be the dizzy vacuum hose connector on the carb?

I want the engine to run evenly at idle to get a steady reading.

Iain

[NonMember]

The carb/dizzy advance pipe doesn't really tell you manifold pressure - it's too close to the throttle plate. If you have a servo tapping, that would be a good place to use, otherwise the S-shaped PCV hose would work.

[Iain T]

3 minutes ago, NonMember said:

otherwise the S-shaped PCV hose would work.

Thanks, is it better to try and use a Tee or is it OK to leave the pcv outlet open to atmosphere? 

I don't have a servo tapping. 

[daverclasper]

51 minutes ago, Iain T said:

Thanks, is it better to try and use a Tee or is it OK to leave the pcv outlet open to atmosphere? 

I don't have a servo tapping. 

Was wondering that myself?.

[NonMember]

No problem leaving the PCV open to atmosphere. Without any manifold vacuum it will remain fully open and give a clear breather to the rocker cover.

[Iain T]

10 minutes ago, NonMember said:

No problem leaving the PCV open to atmospher

Great, I thought it would be OK as my TR3A just vented the crank to atmosphere. 

I'll try it out tomorrow. 

Thanks for your help

Iain 

[Wagger]

On 05/03/2022 at 12:45, Iain T said:

Yes! Took the casing off and rotated the copper half tube and zero'd the needle. Compared results with the replacement and they are the same. Result....but I don't need two kits! 

Iain 

If you go to 'Meets' or put it in the Courier at a modest price, a fellow member may make you an offer.

[Iain T]

Just now, Wagger said:

you go to 'Meets' or put it in the Courier at a modest price, a fellow member may make you an offer.

I've given it to my friend who has helped me with bits on the Vitesse. He has a crazy Daimler special, an mgc and is currently building a Sebring mgb v8. One good turn deserves another. 

[Wagger]

1 minute ago, Iain T said:

I've given it to my friend who has helped me with bits on the Vitesse. He has a crazy Daimler special, an mgc and is currently building a Sebring mgb v8. One good turn deserves another. 

Good favour. I borrow and lend the 'Odd' spanner with the other three petrol heads in my close. Our skills overlap. brilliant set up. Moved into it last April and cannot believe my luck. The 'In between' neighbours are friendly too, but see us as total 'Nutters'.

[Iain T]

So todays fiddlin. I warmed up the engine and hooked up the gauge on the manifold vacuum hose (pcv end). It showed a low vacuum at 15-16 which on the gauge says late timing. I fitted a strobe and according to the indicators timing is 13 degrees. I advanced the timing and the revs increased until the gauge read 22. However the timing was probably 25 degrees....on the indicator! 

The engine is fully reconditioned with gas flowed head and only done 5-600 miles. I'm wondering if the timing marks are if fact correct? I've heard stories about the pulley moving. Camshaft out a cog? Any other suggestions? Check the tappet clearances? 

Iain 

[Pete Lewis]

a timing chain does get longer as the links and pivots wear , yes tooth timing is adjustable to 1/4 of th tooth   but you time the dizzy so they can all be  miles out but thespark can be set to the marks and  show as correct   its all in the life of wear and tear but at a few hundred miles most unlikely to be the problem  a check of tappets is always worthwhile    tight clearacnes affect the idle speed

yes the outer damper ring on the crank pulley can degrade the rubber bond breaks down and the timming ring rotates about the main pulley 

the only way to check that is really make a piston stop from an old and extended spark plug , fit it to no1  turn crank carefully  in both directions to meet the stop  mark the damper ring at each point   TDC is half way between the two marks ...does it tie up with the ring marks ???

22hg is a bit too high  i would drop it nearer 18

at 22 i would expect over advanced and pinking to occur .

lots of oter things can affect manifold depression  even the air filters  

on the vitesse you should not have temperature compensators  which can reduce the vac if they are open 

keep the idle as slow as 600     at  800 you will get too high readings 

just some waffling 

Pete