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 Engine Compression 
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Firing on two.

Joined: April 22nd, 2009, 11:06 pm
Posts: 3684
Location: Ecosse
Post Re: Engine Compression
Quote:

You're going to have a busy weekend doing all these cars Sean, what with the whole team consisting of you and two drivers. :D


Multi meter - tippex and strobe points changed, set and timed -10mins?

But therin lies the plan......they will owe me big time than ill have a posse of bitches to send to the pump , shops, pit wall etc....


i mean ill have some valued helpers :lol:

back up to full quota of drivers, cars assembled and will be on my way this afternoon its the dream team of Me an Ron and for the last few years we have spent more time on other cars rather than on our own.

Its our year for calamity :? lets hope our Formula beetle drivers are sympathetic to the machine and are not "rumble strip warriors" good position in the 24hrs is about keeping out of trouble as much as it is about speed

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"Any advice of a technical nature is given on the understanding that I've actually done this shit, not just read about it in D*lly club mag some time ago.


August 25th, 2011, 9:23 am
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Firing on two.

Joined: July 26th, 2009, 3:36 pm
Posts: 1019
Post Re: Engine Compression
I - **cough** - knew that my slightly contentious post would get some serious answers going on this thread... :P


August 25th, 2011, 2:16 pm
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Firing on two.
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Joined: March 10th, 2010, 12:37 am
Posts: 1927
Location: Alone in my polytunnel with my pitiful competition onions
Post Re: Engine Compression
Sean wrote:
Rhythm Thief wrote:

It might be that your advance weights are worn. I usually check them when I'm doing the points on an engine for the first time. They do wear and new ones (under £30 from the usual place) make a big difference.


which bits wear, what do you look for, how do you test them and what's an acceptable state?

just to keep the whole thing mechanical rather than conjecture ;)

we had been doing some stuff on bob weights and how the different makes affect the advance curve and what modifications did what to the engine.

there was no conclusive outcome ........mainly because the dyno broke. :lol:


The weights themselves wear. I don't know what each side should weigh or how much wear is within tolerances, but I do know that they're one of those bits which many people never ever check and that when I changed the points on my old Charleston for the first time, I had a look at the weights and one was missing a fairly hefty chunk of metal where it had worn away. Once i replaced them with a new set, the timing problems disappeared.

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August 25th, 2011, 3:11 pm
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Firing on two.

Joined: April 22nd, 2009, 11:06 pm
Posts: 3684
Location: Ecosse
Post Re: Engine Compression
Rhythm Thief wrote:
Sean wrote:
james2cv wrote:
p.s. I proper need to learn to do all this shizz myself.


garage 5/6 :lol:


You're going to have a busy weekend doing all these cars Sean, what with the whole team consisting of you and two drivers. :D


relatively quiet in the end

Christian Callander and I built the College boys a new engine from the pile of shrapnel they had created.

turned out to be their fastest engine despite shimming the barrels with old oil controll rings and giving them a 2minute guarantee :lol:

then they welded it in as they couldnt work out how to fit front mount bolts or lost them ...one way street that was !

still they finished despite the chaos they had brought upon themselves

Us? we broke a shock( again! avo is not on xmas card list any more), had manifold problems which we managed the whole race, lost a wing and sheared a throttle pedal pivot, replacement unscrewed at start of last hour luckily driver knew what was happening and got it back.

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"Any advice of a technical nature is given on the understanding that I've actually done this shit, not just read about it in D*lly club mag some time ago.


August 30th, 2011, 2:22 pm
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Firing on two.
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Joined: November 29th, 2008, 10:05 pm
Posts: 9259
Location: West Sussex, U.K.
Post Re: Engine Compression
Were you on a Weber? I noticed that there's not enough travel in the cable to fully open a Weber and the last few mm was coming from the 'cable saving' spring on the bulkhead clip. Part of our initial troubles with the second engine in testing were due to a stretched cable which I can only assume was because it was constantly being subjected to a lot of stress. We also suffered a bent throttle pedal towards the end which I assume was down to the same problem. I wonder of that was part of the cause of your broken pedal pivot?

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August 30th, 2011, 7:21 pm
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Joined: February 8th, 2009, 12:07 am
Posts: 2357
Post Re: Engine Compression
Dont tell everyone, and just shorten the cable outer, more speed less troubles, better position. :lol: :lol:


August 30th, 2011, 7:29 pm
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Firing on two.

Joined: April 22nd, 2009, 11:06 pm
Posts: 3684
Location: Ecosse
Post Re: Engine Compression
nope solex

broke because its been used for too long and thread stripped nut end

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"Any advice of a technical nature is given on the understanding that I've actually done this shit, not just read about it in D*lly club mag some time ago.


August 30th, 2011, 7:49 pm
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Firing on two.
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Joined: February 11th, 2009, 12:32 am
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Location: Chichester, West Sussex
Post Re: Engine Compression
Ok so tested the compression on Hetty. Bare in mind this is a 1969 spec M4 - I got 160psi from one side and 170psi from the other. I thought that was quite good.

Should I worry about the 10psi difference?


September 6th, 2011, 12:27 am
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Agony Aunt - You have a car problem? Speak to Ken

Joined: March 6th, 2009, 1:40 am
Posts: 3675
Post Re: Engine Compression
Sounds quite good for such an oldtimer.

Not too sure about the use of 'bare', mind you... :lol: :

ken




samfieldhouse wrote:
Ok so tested the compression on Hetty. Bare in mind this is a 1969 spec M4 - I got 160psi from one side and 170psi from the other. I thought that was quite good.

Should I worry about the 10psi difference?

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September 6th, 2011, 2:00 am
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Firing on two.
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Joined: February 11th, 2009, 12:32 am
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Location: Chichester, West Sussex
Post Re: Engine Compression
:lol: right - the post of proof reader is yours ken!

I too was impressed - I thought I'd got the reading wrong! Thinking about it - I should have done a 'wet' test as suggested earlier in this thread. I'm hoping this indicates that the piston rings are ok-ish and the problem lies with the valve stems/guides.

Its such an easy test, it would be great to have a 'compression results' thread to compare between different engines. Although that would probably result in compression related hypochondria!


September 6th, 2011, 3:22 am
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