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435cc engine - compression
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Author:  Will2cv [ April 21st, 2011, 11:23 am ]
Post subject:  435cc engine - compression
Hi

Just a quick one - what should a reasonable amount of compression be for a 435cc engine?

It is part of an investigation into a hot start issue with the van - it starts from cold and runs fine apart from restarting when hot. Then it spins over and refuses to even fire once, and I have tried a number of different coils with the same result. (Maybe it is simply that all my spares are duff!)

Cheers
Will
Author:  ken [ April 21st, 2011, 2:37 pm ]
Post subject:  Re: 435cc engine - compression
Will,
a 435 engine has a C.R. of 8.5:1, the same as a standard 2CV engine, so you should be looking at around 150psi, with engine hot and throttle wide open.

How are your valve clearances? Not too tight? ;)
ken



Will2cv wrote:
Hi

Just a quick one - what should a reasonable amount of compression be for a 435cc engine?

It is part of an investigation into a hot start issue with the van - it starts from cold and runs fine apart from restarting when hot. Then it spins over and refuses to even fire once, and I have tried a number of different coils with the same result. (Maybe it is simply that all my spares are duff!)

Cheers
Will
Author:  Will2cv [ April 21st, 2011, 3:31 pm ]
Post subject:  Re: 435cc engine - compression
Thanks Ken. I'll get my compression tester out later and have a look.

Yep I set the valve clearances properly when the engine went in about 1000 miles ago. Changing the old coil for a fresh one gets it going again from hot but it is a bit strange that three coils in a row have failed to start it after a run.

Some weekend investigation is needed I think!

Will
Author:  lpgo [ April 21st, 2011, 6:41 pm ]
Post subject:  Re: 435cc engine - compression
1. Do you crank with full throttle when hot? That is what Citroen advises......

2. Maybe your fuell is vaporising when engine is hot!! Look at your fuellines/carburator

3. Are your breaker points and condensator in good condition, is your ignition timing right

4. I don't know anymore.
Author:  lpgo [ April 21st, 2011, 6:43 pm ]
Post subject:  Re: 435cc engine - compression
4. Change the leads to your coil, left to right / right to left it can be a reason
Author:  Rumble602 [ April 21st, 2011, 9:06 pm ]
Post subject:  Re: 435cc engine - compression
If all else fails, we'll get bump starting down to fine art on the way to Salbris!
Author:  Will2cv [ April 26th, 2011, 1:09 pm ]
Post subject:  Re: 435cc engine - compression
Thanks for the input guys.

An update - have checked compression and it is healthily above 150psi both sides.
Re-gapped points and set timing properly
Re-set valve clearances, they were set to 0.25 but did them again anyway!
Changed coil for known good one (starts Evie from hot every time)
New plugs and leads
Checked and set float level

After a good run up to and around the Easter camp the van is still reluctant to fire up from hot, this is with foot to floor as per the recommended hot-start procedure.

The only thing now to suspect I guess is fuel pump and carb itself as maybe it is a fuel vapourisation/starvation problem.

Apart from that, the engine runs beautifully. I love the sound and feel of a 435 8-)

Will
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