bumpy
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| posted on 28/1/16 at 03:02 PM |
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Ignition connundrum
I have a long standing issue with the ignition timing on my 2 litre Pinto engine which I am inspired to cure as soon as I get on the road this
Spring.
In short
The engine is totally standard in all respects - Weber carb, standard exhaust, standard camshaft etc etc
If I set the timing according to the book (say 8-10 degrees), it starts fine but seems like I only have a 500cc engine on board, completely
gutless.
If I stop during my ride and advance the ignition timing incrementally up to say 15 - 18 degrees BTDC, the power gradually comes in and it becomes a
nice energetic engine. There is no great evidence of pinking, but in an open top car its generally less easy to hear. The engine stops and starts
without drama.
I park up happily for the night, but next morning the car refuses to turn over to start. I can sense the pistons coming to the top of their stroke and
being pushed back. For me this is displaying all the symptoms of an ignition that is too far advanced . When I retard the ignition again it starts
fine, but the cycle begins again.
The battery takes a good charge and shows the normal voltage of a good battery. The ignition is measured using a powered timing light and with vacuum
detached.
Any guidance would be welcomed.
Thanks
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nick205
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| posted on 28/1/16 at 03:12 PM |
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When you say the engine is standard, is it using all the same parts as when in the donor car?
I put a 2.0 Pinto in my MK Indy a few years ago and had to change from a Ford to Weber carb. In getting the car running right I took it to a rolling
road and the Weber carb had to be re-jetted to deliver fuel correctly through the rev range - it made quite a difference to the way the car drove and
may be worth checking on your engine/carb.
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gremlin1234
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| posted on 28/1/16 at 03:22 PM |
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distributors usually have weights in to give a mechanical 'advance'
my guess is these have seized, or the springs broken.
striping and rebuilding a mechanical distributer is not too difficult
see also
https://en.wikipedia.org/wiki/Ignition_timing
edit sp.
[Edited on 28/1/16 by gremlin1234]
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FuryRebuild
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| posted on 28/1/16 at 03:37 PM |
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It does sound like the dizzy
Pintos like advance. On my race engine, I was running up to 32 degrees, and it was a pig to start but ran like a beast. Then I moved over to an MSD 6A
ignition which retards the ignition 20 degrees on startup, and it started marvellously every time.
I threw the chokes away, and it would light up first turn of the crank. It was on a pair of twin 45 dellortos which are pretty reliable. They were
properly setup, choked and jetted by bogg-brothers.
When all you have is a hammer, everything around you is a nail.
www.furyrebuild.co.uk
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bumpy
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| posted on 28/1/16 at 03:46 PM |
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Thanks so far guys. I have been fettling with this engine for quite a while, so have already covered a fair bit of ground.
The engine is as taken out of the donor car.
The carb has been stripped and all jets marry up to the book values.
The bob weights are free and the vacuum advance works fine, indeed I substituted in another distributor and that gave exactly the same
characteristics. but, I will strip and investigate both.
To FuryRebuild.
That 32 deg timing, was that set at tickover or at elevated revs. I will have a read up about the MSD 6A ignition system.
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mcerd1
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| posted on 28/1/16 at 03:51 PM |
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This might sound stupid, but have you verified that TDC is where you think it is ?
Which type of crank pulley have you got?
What kind of coil have you got ? (9v or 12v)
Also were abouts in the country are you?
[Edited on 28/1/2016 by mcerd1]
[Edited on 28/1/2016 by mcerd1]
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FuryRebuild
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| posted on 28/1/16 at 03:53 PM |
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The 32 degrees was set at full chat and load - you want it accurate when you want the power. I think it was timed at about 4800 RPM when my cams came
fully on (stage 3 tarmac). The timing is a combination of carb setup (new jets and chokes), cam requirements, valves (I had wahoosive valves in
there), fuel quality (optimal and Aldon) and tractability. I could get away with a really hairy cam because my car was relatively light - it was still
drivable around town in much the same way as an RS2000 wouldn't be.
The MSD also gives a massive belt of a spark, which contributes to it. You need more spark to light up a high-compression mixture. You can open the
plugs a little wider to get a better burn. It's all a closed system that sits in a balance.
It's definitely a rolling road job. There's no way would I have the skills to set that up myself.
Keep an eye out on eBay for the MSD ignitions. They surface now and again at good money. I sold mine for something like £60, and bought it for
similar. They're £300 new.
[Edited on 28/1/16 by FuryRebuild]
When all you have is a hammer, everything around you is a nail.
www.furyrebuild.co.uk
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snapper
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| posted on 28/1/16 at 04:13 PM |
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Idle for Pinto is usually 10-12 degrees then ramps to 34 to 36 at 3,600rpm flat after that
The vac advance is for part throttle
You should mark the pulley so you can see 8,10,12,14,16 degrees then 30,32,34,36,38
You can then set idle to something comfortable and use a strobe to view what is actually happening
Get a mate to gently increase rpm from idle noting the approximate spark advance
you should see about 10 degrees per 1000rpm to 3600rpm 36 degrees
Try this with and without vac advance
If vac is already disconected the vac advance plate may be swinging on its own thus pushing you spark advance all over the place
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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coozer
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| posted on 28/1/16 at 04:18 PM |
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Put a trigger wheel and coil pack on it..
1972 V8 Jago
1980 Z750
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bumpy
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| posted on 28/1/16 at 04:21 PM |
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quote:
Originally posted by mcerd1
This might sound stupid, but have you verified that TDC is where you think it is ?
Which type of crank pulley have you got?
What kind of coil have you got ? (9v or 12v)
Also were abouts in the country are you?
[Edited on 28/1/2016 by mcerd1]
[Edited on 28/1/2016 by mcerd1]
The crank pulley is standard, with standard marks. I haven't checked it against a measured TDC and perhaps that's something to do, but I
would be very surprised if its more than a degree or two out, given that its on a keyway.
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mcerd1
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| posted on 28/1/16 at 04:30 PM |
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^^^ the reason I asked about the pulley is there are several types of OE ones...
The later ones have a 2 part design with a rubber isolator between them and although I've never heard of it on a pinto it is possible that the
rubber slips and effective offsets the marks relative to the keyway (this is apparently quite common on some old yank v8's that use similar
pulley designs)
If you are near this part of the world I've got various spare bits you'd be welcome to have / borrow to get to the bottom of this..
[Edited on 28/1/2016 by mcerd1]
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bumpy
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| posted on 28/1/16 at 04:37 PM |
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quote:
Originally posted by snapper
Idle for Pinto is usually 10-12 degrees then ramps to 34 to 36 at 3,600rpm flat after that
The vac advance is for part throttle
You should mark the pulley so you can see 8,10,12,14,16 degrees then 30,32,34,36,38
You can then set idle to something comfortable and use a strobe to view what is actually happening
Get a mate to gently increase rpm from idle noting the approximate spark advance
you should see about 10 degrees per 1000rpm to 3600rpm 36 degrees
Try this with and without vac advance
If vac is already disconected the vac advance plate may be swinging on its own thus pushing you spark advance all over the place
That sounds like a plan
Under normal driving the vacuum is attached.
I am using the following timing light so I can measure any level of advance by electronically trimming it to 'TDC' using the adjustment
wheel and reading off the degrees from the dial.
I guess if I turn the distributor to get 36 degrees of advance at 3600rpm that should be perfect for power delivery. After that I can measure it at
tickover and decide if it starts or not and then tackle that end of the rev range.
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bumpy
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| posted on 28/1/16 at 04:40 PM |
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quote:
Originally posted by mcerd1
^^^ the reason I asked about the pulley is there are several types of OE ones...
The later ones have a 2 part design with a rubber isolator between them and although I've never heard of it on a pinto it is possible that the
rubber slips and effective offsets the marks relative to the keyway (this is apparently quite common on some old yank v8's that use similar
pulley designs)
If you are near this part of the world I've got various spare bits you'd be welcome to have / borrow to get to the bottom of this..
[Edited on 28/1/2016 by mcerd1]
Thanks for that offer, but I'm nearly the length of England away from you. I have checked the pulley against one I have my spare engine and
they're identical
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mcerd1
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| posted on 28/1/16 at 04:41 PM |
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Which version of the dizzy do you have ?
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bumpy
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| posted on 28/1/16 at 04:51 PM |
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Both dizzys I tried were Bosch. I also tried a substitute ignition ECU without any benefits.
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gremlin1234
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| posted on 28/1/16 at 05:03 PM |
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is this the same engine as
http://www.locostbuilders.co.uk/forum/9/viewthread.php?tid=194506
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mcerd1
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| posted on 28/1/16 at 05:04 PM |
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So they are all the electronic type then - I'd try the ignition module next if 2 dizzys gave the same results
I don't suppose you have a points based one to swap ?
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rusty nuts
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| posted on 28/1/16 at 08:00 PM |
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My guess even though you say you have checked them would be sticking Bob weights or weak springs causing the Bob weights to advance the timing even
though the engine speed is low . You have the right type of timing light to check the timing advance.
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BaileyPerformance
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| posted on 28/1/16 at 08:36 PM |
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Have you chk'd the cam timing?
As already been said, pintos do like a quick advance curve, idle 16, total 32-36 all in by 4000rpm ish.
MSD6A won't retard timing during starting unless you buy an MSD starter saver to go with it.
Some pinto dizzy's are abit odd, very little timing in the dizzy, sometimes they rely on the vac advance to top up the advance. The vac
connection to the engine is important, if a weber there is a port on the side of the carb that still has a vacuum signal with WOT.
I suggest you chk the total advance (with vac off) you should have about 34deg at 4000rpm
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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bumpy
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| posted on 28/1/16 at 09:35 PM |
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quote:
Originally posted by gremlin1234
is this the same engine as
http://www.locostbuilders.co.uk/forum/9/viewthread.php?tid=194506
Yes it is. The engine performance (assembled by someone else) was compromised in a number of ways when I purchased the car, and it has been like
peeling back the layers of an onion, solve one problem and reveal another.
Problem 1 was that the car would hesitate and needed lots of revs to pull out at junctions - solved with new fuel pump
Problem 2 was that the throttle cable assembly was not operating fully to open the second of the progressive chokes - solved with a bit of
re-engineering
Problem 3 was that the tick-over was very erratic - solved by replacing a GT camshaft of unknown origin with a standard camshaft.
Problem 4 is to optimise the ignition timing - work in progress
I am nothing if nor persistent 
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bumpy
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| posted on 28/1/16 at 09:36 PM |
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quote:
Originally posted by mcerd1
So they are all the electronic type then - I'd try the ignition module next if 2 dizzys gave the same results
I don't suppose you have a points based one to swap ?
You might have missed it but I have tried a second ignition module without improvement.
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bumpy
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| posted on 28/1/16 at 09:40 PM |
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Out of interest is it possible to buy bob-weight springs of different 'strengths'
If I decide to treat my car to a new distributor they seem quite reasonable at about £60. The two main manufacturers seem to be Powerspark and
Accuspark. Is either of these preferred?
[Edited on 28/1/16 by bumpy]
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gremlin1234
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| posted on 28/1/16 at 10:07 PM |
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quote:
Originally posted by bumpy
Out of interest is it possible to buy bob-weight springs of different 'strengths'
If I decide to treat my car to a new distributor they seem quite reasonable at about £60. The two main manufacturers seem to be Powerspark and
Accuspark. Is either of these preferred?
[Edited on 28/1/16 by bumpy]
certainly is
a very quick search found
http://www.distributordoctor.com/distributor_advance_springs.html
also, I did get a distributor from powerspark, - it just works, (but that was for a vw polo! )
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snapper
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| posted on 29/1/16 at 06:27 AM |
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I have fitted Megajolt to several Pintos
It gives you total spark control
From reading all your thread I can see that you changed the camshaft from a lumpy one to standard
My first thoughts are
Did you re time the new cam?
Did you change valve springs to match cam?
Did you change carb jets to match standard cam?
What spark plugs are you running? May be the ones for the GT cam are wrong for standard cam.
What is the compression ratio of the engine? If this was higher than standard for the GT cam you may now have detonation due to even higher combustion
pressure due to much reduced standard cam overlap.
I'm getting the feeling the problems started after GT cam was changed for standard one.
FR32 is a good road cam easy idle that is very street drivable
RL31 is the max for road with a lumpy idle and sharp on cam power at 3500rpm
I think you engine was set up for something like an RL31 and by changing to a standard cam you have a huge miss match of settings, the ignition
problem may only be part of the issue.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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bumpy
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| posted on 29/1/16 at 09:44 AM |
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quote:
Originally posted by snapper
I have fitted Megajolt to several Pintos
It gives you total spark control
From reading all your thread I can see that you changed the camshaft from a lumpy one to standard
My first thoughts are
Did you re time the new cam?
Did you change valve springs to match cam?
Did you change carb jets to match standard cam?
What spark plugs are you running? May be the ones for the GT cam are wrong for standard cam.
What is the compression ratio of the engine? If this was higher than standard for the GT cam you may now have detonation due to even higher combustion
pressure due to much reduced standard cam overlap.
I'm getting the feeling the problems started after GT cam was changed for standard one.
FR32 is a good road cam easy idle that is very street drivable
RL31 is the max for road with a lumpy idle and sharp on cam power at 3500rpm
I think you engine was set up for something like an RL31 and by changing to a standard cam you have a huge miss match of settings, the ignition
problem may only be part of the issue.
Its an interesting thought, but my engine had a GT cam of unknown origin and all other parts were standard - carb jets, valve timing, springs etc
which is probably why it ran so erratically!
My target has always been to restore the engine to standard specs, so I am not at the mercy of someone who thought they knew how to tune it. So
everything is now at standard spec including the camshaft, springs and followers from Burton, spark plugs etc.
The builder assured me that the engine had had a re-bore, new 'standard' pistons and a very mild head 'skim' to ensure no
distortion, so I would think the engine is at pretty much standard compression.
At no time since I have owned it has it ever suggested to me (during driving at any revs) that it is anything more than a standard lump.
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