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Post by Deleted on Jun 20, 2008 13:32:18 GMT
Despite lots of attempts at getting my ' 71 P5B to fire up it still won't start. It seems to be that the engine turns over too slow to pump the gas in. I've put loads of oil down the plugs etc. I was told by a local that what it needs is 24 volts rather than my current battery at 13.5 volts. Question is, would this blow up my expensive new Mallory electronic ignition.
Any replies appreciated, Oliver
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Post by Smallfry on Jun 20, 2008 19:34:50 GMT
He is talking out of his ar5e.
If you do that you will wave goodbye to your alternator, your ignition, and anything else electronic.
The starter will endure it for a while, but not for long.
The fuel pump either works..............or it doesn't, and thats that. I have never ever heard of a mechanical pump not turning fast enough to pump.
If you have a low cranking speed problem..............which will not spin the engine fast enough to start it, it is either the starter motor, the battery, faulty or corroded connections or wires, or a faulty earth.
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Post by Phil Nottingham on Jun 20, 2008 20:01:19 GMT
I too agree - if it will not start then the motor is shot/bad connections or the engine stiff. 24v would probably ruin the electronics. refit the points!!
However I used to run 3 Cylinder 2 stroke Auto-Union DKW's which had 6v Bosch electrics - jump starting from 12v onto the 6v battery always started it fast! Its an old timer trick!!
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Post by harvey on Jun 20, 2008 20:18:20 GMT
If you convert 6v cars to 12v the starter moter will quite happily carry on.
As for putting 24v through your car forget it, it will blow the ign and alternator.
If you really wanted to do it though you could disconnect the main supply from the startermotor and add a separate 24v supply and use the 12v supply from the car to run the car and operate the solenoid.
Best to sort out the reason why it's turning over slowly in the first place.....................
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Post by johnwp5bcoupe on Jun 20, 2008 21:08:36 GMT
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Post by Warwick on Jun 21, 2008 1:18:50 GMT
I suspect he was just suggesting that you give the starter a dose of 24v to determine if it just needs a bit of a hurry-up to start. If it then did start and run okay you would know that the problem lay solely with the starter motor or its supply.
But to suggest this without making it clear that you need to first disconnect the starter motor from the rest of the electrical system, and just assume that you would know, was not very clever.
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Post by johnwp5bcoupe on Jun 21, 2008 5:58:17 GMT
Oliver you have been struggling so long now on this slow turn over  take the plugs out and turn the engine from the nut on the front pulley and see if it turns ok first as I think you said at one time the engine was tight? it should be no problem for a standard starter to turn the lump without 24v who ever told you that dont ask his advice again  |
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Post by Deleted on Jun 21, 2008 11:12:53 GMT
Thanks for the warnings. I did suspect it wasn't a clever thing to do. The engine turns , but still feels a bit stiff without plugs, and squeaks a bit as different pistons turn around. However, the starter seems to turn at a reasonable rate or at least compared with other cars I've had, and if the engines set up right it should just fire.
After having turned the motor over for quite a time the plugs have no sign of petrol. Next job rebuild the carbs.
Oliver
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Post by Warwick on Jun 21, 2008 11:28:20 GMT
I don't like that squeaking sound you mentioned, Oliver. It should just turn over with a bit of chuffing as air rushes in and out of the open spark plug holes.
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Post by Phil Nottingham on Jun 21, 2008 11:40:05 GMT
Not good - the bores may have dried up - poor some oil down the bores or even try some WD40 first
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Post by johnwp5bcoupe on Jun 21, 2008 12:01:12 GMT
As Warwick says there should be no squeaks I have lost the scenario behind this problem now did you prime the engine first? as Phil says get some lube down the bores it should fly over with no plugs |
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Post by Deleted on Jun 21, 2008 20:47:38 GMT
After having removed the rocker covers again, it seems oil is coming out the rocker shafts. I've put loads more oil down the plug holes, and loads of WD40 around the valves. Now no squeaks, but still a slight creaking noise ,seems to come from camshaft area. With no plugs in, the starter spins quite fast. All that needs doing is replacing carbs which on dismantling only the right (drivers side) had a spring on the jet/tube. The left carb is loose. Is this how my '71 model, theft-proof coil,AED etc. was designed, or has it been bodged ?
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Post by Phil Nottingham on Jun 21, 2008 21:23:09 GMT
Bodged - AED equiped cars had both the jets locked - you will probably find more evidence..
The thiefproof coil is also a very poor idea and gives a lot of trouble when it gets on in years
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Post by johnwp5bcoupe on Jun 22, 2008 5:58:06 GMT
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Post by Deleted on Jun 22, 2008 21:45:55 GMT
I've just done a compression test on the car. I know that the engine should be warm, but obviously mine not starting is cold, despite summer heat. I've got readings of between 14 to 8 psi on most cylinders, however on cylinders 4 &6 right-hand it's only 3 or 4. Should I take readings done when cold as significant, also how the hell do you get easy access to the plug behind the manifold tube going to the AED unit?
regards, Oliver.
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Post by Smallfry on Jun 22, 2008 22:47:20 GMT
With these readings, I would say that you have forgotten to install the pistons ?
This test should be done with ALL the spark plugs removed and most importantly...........the throttle must be wide open.
If you do not do this, the engine cannot draw much air to compress, especially when cold.
If you are doing this correctly, and the engine is turning briskly on the starter, you have a serious problem.
If you can't figure it out, if you can wait a couple of weeks, I will come and look at it with you.
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Post by Warwick on Jun 23, 2008 0:40:32 GMT
If the squeaking is coming from the camshaft, I wonder if there is a blocked oilway or 2 and the camshaft is running dry somewhere?
Shouldn't the SU pistons be held up too when compression testing?
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Post by johnwp5bcoupe on Jun 23, 2008 5:59:39 GMT
At those PSI readings on every cylinder even with the carbs closed sounds strange are you reading the meter correctly? is it working as it should? the plug behind the AED pipe is no problem to remove Oliver the pipe shouldn't be in the way |
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Post by Deleted on Jun 23, 2008 15:25:13 GMT
I should have said "bar" rather than "psi".This still translates into a low compression, about 150 on the good ones. I've just put a load of oil down the plugs which were low compression, and retested,one proved o.k which points to piston rings, the other didn't change, maybe a valve.
Engine, despite all the oil & wd40 squirted everywhere still makes a creaking noise on certain valve openings.
Next job, remove the inlet manifold and checkout the cam etc.
Has anyone got good reports about the Webber 500 carb & manifold
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Post by johnwp5bcoupe on Jun 23, 2008 16:18:22 GMT
I should have said "bar" rather than "psi".This still translates into a low compression, about 150 on the good ones. I've just put a load of oil down the plugs which were low compression, and retested,one proved o.k which points to piston rings, the other didn't change, maybe a valve. Engine, despite all the oil & wd40 squirted everywhere still makes a creaking noise on certain valve openings. Next job, remove the inlet manifold and checkout the cam etc. Has anyone got good reports about the Webber 500 carb & manifold Oliver I think you need to remove the rocker covers first and have a good look to see what is moving ( part open stuck valve not seating ) dry followers, camshaft etc then if need be dig deaper  your pressures at the Bar ratings given are 116-203 PSI  |
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Post by Smallfry on Jun 23, 2008 23:07:02 GMT
If that is in bar, then there is enough compression to start it, provided cam and ignition timing are about right, even if it runs unevenly.
Edelbrock Performer / Weber 500 is an excellent carb. Manifold choice depends on what you want from it. I would suggest the Edelbrock Performer 180 degree manifold because it gives much better low and mid range torque compared to the Offenhauser ones, which is what you need on the street, and the Rover is a heavy car.
The Offenhauser ones are OK if you have light sports car, and although the top end power is better, there is a very noticable loss at the low end.
The "Dual port" manifold does not offer any noticable gains either.
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Post by Deleted on Jun 27, 2008 17:42:20 GMT
Thanks for the replies, this weekend I'll get stuck into whatever is going on. I like to think I'm not daft, but perhaps I'm not as smart as I'd like to be. I'm sure this is a common problem.
Oliver
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Post by johnwp5bcoupe on Jun 27, 2008 18:06:21 GMT
Thanks for the replies, this weekend I'll get stuck into whatever is going on. I like to think I'm not daft, but perhaps I'm not as smart as I'd like to be. I'm sure this is a common problem. Oliver Someone who tries should have respect and help  Good Luck keep at it  |
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Good Luck keep at it 