Printable Version | Subscribe | Add to Favourites
<<  1    2  >>
New Topic New Poll New Reply
Author: Subject: Ignition connundrum
bumpy

posted on 28/1/16 at 03:02 PM Reply With Quote
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

View User's Profile View All Posts By User U2U Member
nick205

posted on 28/1/16 at 03:12 PM Reply With Quote
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.






View User's Profile Visit User's Homepage View All Posts By User U2U Member
gremlin1234

posted on 28/1/16 at 03:22 PM Reply With Quote
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]

View User's Profile View All Posts By User U2U Member
FuryRebuild

posted on 28/1/16 at 03:37 PM Reply With Quote
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

View User's Profile Visit User's Homepage View All Posts By User U2U Member
bumpy

posted on 28/1/16 at 03:46 PM Reply With Quote
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.

View User's Profile View All Posts By User U2U Member
mcerd1

posted on 28/1/16 at 03:51 PM Reply With Quote
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]





- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

View User's Profile View All Posts By User U2U Member
FuryRebuild

posted on 28/1/16 at 03:53 PM Reply With Quote
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

View User's Profile Visit User's Homepage View All Posts By User U2U Member
snapper

posted on 28/1/16 at 04:13 PM Reply With Quote
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)

View User's Profile View All Posts By User U2U Member
coozer

posted on 28/1/16 at 04:18 PM Reply With Quote
Put a trigger wheel and coil pack on it..





1972 V8 Jago

1980 Z750

View User's Profile Visit User's Homepage View All Posts By User U2U Member
bumpy

posted on 28/1/16 at 04:21 PM Reply With Quote
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.

View User's Profile View All Posts By User U2U Member
mcerd1

posted on 28/1/16 at 04:30 PM Reply With Quote
^^^ 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]





- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

View User's Profile View All Posts By User U2U Member
bumpy

posted on 28/1/16 at 04:37 PM Reply With Quote
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.

View User's Profile View All Posts By User U2U Member
bumpy

posted on 28/1/16 at 04:40 PM Reply With Quote
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

View User's Profile View All Posts By User U2U Member
mcerd1

posted on 28/1/16 at 04:41 PM Reply With Quote
Which version of the dizzy do you have ?





- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

View User's Profile View All Posts By User U2U Member
bumpy

posted on 28/1/16 at 04:51 PM Reply With Quote
Both dizzys I tried were Bosch. I also tried a substitute ignition ECU without any benefits.
View User's Profile View All Posts By User U2U Member
gremlin1234

posted on 28/1/16 at 05:03 PM Reply With Quote
is this the same engine as
http://www.locostbuilders.co.uk/forum/9/viewthread.php?tid=194506

View User's Profile View All Posts By User U2U Member
mcerd1

posted on 28/1/16 at 05:04 PM Reply With Quote
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 ?





- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

View User's Profile View All Posts By User U2U Member
rusty nuts

posted on 28/1/16 at 08:00 PM Reply With Quote
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.
View User's Profile View All Posts By User U2U Member
BaileyPerformance

posted on 28/1/16 at 08:36 PM Reply With Quote
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

NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
View User's Profile E-Mail User Visit User's Homepage View All Posts By User U2U Member
bumpy

posted on 28/1/16 at 09:35 PM Reply With Quote
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

View User's Profile View All Posts By User U2U Member
bumpy

posted on 28/1/16 at 09:36 PM Reply With Quote
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.

View User's Profile View All Posts By User U2U Member
bumpy

posted on 28/1/16 at 09:40 PM Reply With Quote
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]

View User's Profile View All Posts By User U2U Member
gremlin1234

posted on 28/1/16 at 10:07 PM Reply With Quote
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! )

View User's Profile View All Posts By User U2U Member
snapper

posted on 29/1/16 at 06:27 AM Reply With Quote
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)

View User's Profile View All Posts By User U2U Member
bumpy

posted on 29/1/16 at 09:44 AM Reply With Quote
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.

View User's Profile View All Posts By User U2U Member
<<  1    2  >>
New Topic New Poll New Reply


go to top






Website design and SEO by Studio Montage

All content 2001-16 LocostBuilders. Reproduction prohibited
Opinions expressed in public posts are those of the author and do not necessarily represent
the views of other users or any member of the LocostBuilders team.
Running XMB 1.8 Partagium [ 2002 XMB Group] on Apache under CentOS Linux
Founded, built and operated by ChrisW.