44 replies to this topic

[stuart bowes]

no I think they mean a leak down test as in, pump pressure into the cylinder with an air line, and measure how much leaks out via the rings, or valve seat, or whatever.  sort of the opposite of a compression test, you pump the pressure in, instead of using the piston movement to create pressure

 

the tool has a couple of gauges, one to measure the pressure put in and one to indicate the losses (or something along those lines, just google "leak down tester" and you'll find it, they're not hugely expensive bits of kit)

Edited by stuart bowes, 10 October 2024 - 06:49 PM.

[stuart bowes]

Related question because I've never done it, do you have to make sure each piston is at bdc when you do that or is the pressure not enough to make it move

[timmy850]

Related question because I've never done it, do you have to make sure each piston is at bdc when you do that or is the pressure not enough to make it move

When doing it leakdown test you have to turn it over so both the valves are closed and the piston is at TDC

[timmy850]

Has the static compression ratio changed? Has the cam or cam timing changed? Was the engine run in properly with the carb tuned lean?

The engine with its new camshaft (Sw5), and double Hs2 (adjusted mixture) runs well.
I have never exceeded 3000 rpm (I don't want to force it. It seems that when it gets there it doesn't want to go any further. Kms done so far; 800). And it throws oil as I already said. Possibly U shapep sael, incorrectly fitted.

A camshaft with longer duration will typically close the valves later and give a lower compression test reading
Additionally if the cam timing is set later there will be less effective pressure as the valve closes later

It seems pointless to me to install a better camshaft like an SW5 and not rev it. I also can hardly believe you could drive a mini anywhere under 3000rpm. It should keep pulling cleanly to at least 5500 rpm

[PACINO]

Has the static compression ratio changed? Has the cam or cam timing changed? Was the engine run in properly with the carb tuned lean?

The engine with its new camshaft (Sw5), and double Hs2 (adjusted mixture) runs well.
I have never exceeded 3000 rpm (I don't want to force it. It seems that when it gets there it doesn't want to go any further. Kms done so far; 800). And it throws oil as I already said. Possibly U shapep sael, incorrectly fitted.

A camshaft with longer duration will typically close the valves later and give a lower compression test reading
Additionally if the cam timing is set later there will be less effective pressure as the valve closes later

It seems pointless to me to install a better camshaft like an SW5 and not rev it. I also can hardly believe you could drive a mini anywhere under 3000rpm. It should keep pulling cleanly to at least 5500 rpm

Hello Timmy! Very interesting what you say about longer more crossed camshaft.

As for the engine, it should be able to stretch cleanly up to 5000 revolutions..... I'll tell you that I've only done 700km since I rebuild it. I don't go over 3000 rpm (80km/h) because from there you feel like it doesn't want to go any further. So I think of two reasons:

- It's difficult to stretch more and go over 3000rpm because the engine is new.
- It doesn't go beyond that because something was done wrong such as the engine's initial timing degrees or the dizzy is incorrectly adjusted.

Regards
Luis

Edited by PACINO, 11 October 2024 - 08:28 AM.

[timmy850]

Mine hit the rpm limiter at 5500rpm the first time around the block with a freshly rebuilt engine & it is very happy to rev up. If yours isn't happy to rev it sounds like you have a very poor tune, which should be sorted before driving any more

[Lplus]

 

 

 

Has the static compression ratio changed? Has the cam or cam timing changed? Was the engine run in properly with the carb tuned lean?

The engine with its new camshaft (Sw5), and double Hs2 (adjusted mixture) runs well.
I have never exceeded 3000 rpm (I don't want to force it. It seems that when it gets there it doesn't want to go any further. Kms done so far; 800). And it throws oil as I already said. Possibly U shapep sael, incorrectly fitted.

A camshaft with longer duration will typically close the valves later and give a lower compression test reading
Additionally if the cam timing is set later there will be less effective pressure as the valve closes later

It seems pointless to me to install a better camshaft like an SW5 and not rev it. I also can hardly believe you could drive a mini anywhere under 3000rpm. It should keep pulling cleanly to at least 5500 rpm

Hello Timmy! Very interesting what you say about longer more crossed camshaft.

As for the engine, it should be able to stretch cleanly up to 5000 revolutions..... I'll tell you that I've only done 700km since I rebuild it. I don't go over 3000 rpm (80km/h) because from there you feel like it doesn't want to go any further. So I think of two reasons:

- It's difficult to stretch more and go over 3000rpm because the engine is new.
- It doesn't go beyond that because something was done wrong such as the engine's initial timing degrees or the dizzy is incorrectly adjusted.

Regards
Luis

 

The SW5 doesn't have really wild timing, but even then 150 psi on all cylinders is within the green band on my compression tester guage and thus no cause for concern - especially with a new engine.

 

 

Either it will rev to 5000+ or it won't.  You thinking it isn't happy above 3000 isn't any sort of definitive reason to condemn it.  All new engines need to be eased up to the maximum gently, but that means pushing them a little more each time as the run in progresses.  On the other hand, if it won't exceed 3000 rpm even with your foot flat on the floor, then there's a more significant problem somewhere than just being new.

 

My latest build has reached about 350 miles now and it'll go to 5000 no problem but I'll not hold that for more than an instant.

[PACINO]

Thanks both! I'll do a video from the ignition, acceleration and driving on the road so you can see how this car goes.

[Earwax]

Hi Louis    

 

I too am concerned that you say your engine hasn't been taken to 5000rpm. For two reasons below:

 

1. As mentioned above - without flogging it, just about every 'engine running in ' procedure asks for engines to be put under varying loads - and usually progressing up into the higher end of the revs. The SW5 cam will certainly continue to give more power up to mid 5000 revs. A lot of people ( including me) would be finding those revs a lot earlier in the running in process.

 

2. Even if only with engine unloaded, your timing checks should know if the engine easily rises through 3000 to at least 4000 revs- and if with no load it is fine BUT when actually driving the engine then actually is slower to pick up- then you can explore the reasons.

 

Please note - I would be probably be holding second to pull through 5000 rpm then be more sedate through third to fourth. ( this will keep you in the legal road limits  -  but I wouldn't just sit on say 3700rpm in fourth to long periods of time. I would also let the speed drop off so that car is managing to hold fourth but not by much ( if you were in a hurry you would change down to third) - and then slowly build revs and speed a few times in a row

 

With your engine build specs - doing that a few times should put a big smile on your face as you listen to the engine - 

[PACINO]

Thank you very much Earwax! I'm not totally convinced with this dizzy and its curve (123Ignition. Curve B) after several years of use. I want to try the original distributor again to see how the engine responds. It is true that now that with its powerful coil the engine always starts well, but there are many people who do not like 123Ignition electronic item. For example Keith Calver.

Regards
Luis

[PACINO]

Has the static compression ratio changed? Has the cam or cam timing changed? Was the engine run in properly with the carb tuned lean?

The engine with its new camshaft (Sw5), and double Hs2 (adjusted mixture) runs well.
I have never exceeded 3000 rpm (I don't want to force it. It seems that when it gets there it doesn't want to go any further. Kms done so far; 800). And it throws oil as I already said. Possibly U shapep sael, incorrectly fitted.

A camshaft with longer duration will typically close the valves later and give a lower compression test reading
Additionally if the cam timing is set later there will be less effective pressure as the valve closes later

It seems pointless to me to install a better camshaft like an SW5 and not rev it. I also can hardly believe you could drive a mini anywhere under 3000rpm. It should keep pulling cleanly to at least 5500 rpm

Hello Timmy! Very interesting what you say about longer more crossed camshaft.

As for the engine, it should be able to stretch cleanly up to 5000 revolutions..... I'll tell you that I've only done 700km since I rebuild it. I don't go over 3000 rpm (80km/h) because from there you feel like it doesn't want to go any further. So I think of two reasons:

- It's difficult to stretch more and go over 3000rpm because the engine is new.
- It doesn't go beyond that because something was done wrong such as the engine's initial timing degrees or the dizzy is incorrectly adjusted.

Regards
Luis

The SW5 doesn't have really wild timing, but even then 150 psi on all cylinders is within the green band on my compression tester guage and thus no cause for concern - especially with a new engine.
 
 
Either it will rev to 5000+ or it won't.  You thinking it isn't happy above 3000 isn't any sort of definitive reason to condemn it.  All new engines need to be eased up to the maximum gently, but that means pushing them a little more each time as the run in progresses.  On the other hand, if it won't exceed 3000 rpm even with your foot flat on the floor, then there's a more significant problem somewhere than just being new.
 
My latest build has reached about 350 miles now and it'll go to 5000 no problem but I'll not hold that for more than an instant.

Cheers Lplus!

[PACINO]

https://youtu.be/Pew...vtYX5etLPCVJecR

Hi guys! It's difficult to make a video and drive it, so it's not the best video, but you can see that normally when I leave the city and take the open road it's difficult to go above 3000rpm (80 kms per hour). In the last section of the video, uphill, I put the pedal to the metal, the car responded and reached 4000rpm.

I don't know your opinion.

Luis

[PACINO]

[84 City E]

I'm no expert but after watching the video, I'd say your ignition advance isn't working properly. Has it still got the 123 ignition fitted?

 

If it were a normal distributor I'd guess the advance weights were maybe seized

[Lplus]

The last clip when you went to 4000 sounded just fine and didn't misfire as you accelerated.  It also seemed quite willing to speed up.  When you were driving in traffic and got to 3000 it seemed to "gurgle" slightly and you didn't go higher, but that's more likely to be induction related.

 

If it were mine I would be to get it out in the country and run it up through the gears the way you did in the last bit.