
After spending a whole week trying to tune my 2ltr Pinto, with DHLA40's and a 300deg Cam. I eventually came to the conclusion that I dont quite
understand what I am doing.
Timing facts
1. Piston goes up and down
2. Cam does round and round
3. Dizzy induces spark at correct moment
When we talk about static advance needing to be between 16 and 18 degrees, is this for all 3 components?
Before I start twisting the dizzy to get the right spark point, how do I know that 1 and 2 are timed correctly? i.e. When the Cam is at TDC, what
should the Crank marks be set to (TDC as well?? or 16-18 deg)?
My engine runs but I get excessive spitting back through both carbs. Indicating either a lean mixture or hopelessly retarded timing. The engine also
runs very fast and loud..
Any help in laymens terms would be much appreciated
Rob
I think from memory on a 2ltr pinto ignition timing should be at 4 degs (pre 85) and 6 degs (post 85).
So:-
Align the cam pointer with the mark on the head, put the bottom pulley pointing at TDC and fit cam belt. (making sure they don't move)
Mark the bottom pulley with a white marker or summat at on of the two figures above (which ever relates to yours).
Start up engine and adjust timing with strobe/dizzy to get the white mark to line up with the crank pointer.
Hope that helps
Thanks, I think the key point there being setting both markers to TDC, before refittig the belt. I had been setting the crank pointer to 16degrees,
then playing around with the dizzy.
I like it when the answers are simple!
Ta
Rob
You mention its a 300 Deg cam,
I presume this is a lot wilder than standard cam?
In which case u'll need a Vernier cam pully and a timeing disk (for the crank) to set it up properly as there are no marks on the vernier to line
up with the marks on the head.
quote:
Originally posted by RobBrown
Thanks, I think the key point there being setting both markers to TDC, before refittig the belt. I had been setting the crank pointer to 16degrees, then playing around with the dizzy.
I like it when the answers are simple!
Ta
Rob
To use a 300 degree cam, you'll need some vernier pulleys. You'll never get the timing right with the standard pulleys, as they only allow adjustment by a tooth on the belt, whilst you need a much finer adjustment to utilise the cam(s) fully.
I only recently became aware of the tdc mark on the dizzy housing. It might have been from a previouly posted topic here.
My mistake was trying to set the advance using the crank pully markings.
There are no vernier pulley's on ebay at the moment, although I have seen them before for around the £45 mark.
Burton want £70+
Ralley des want £65
Any recommendations for getting hold of a cheaper one.
Thanks
They seem to be one of those bits which everyone needs. Once the cams are timed correctly you can then easily sort the dizzy and away you go. You'd be amazed at the difference 2-3 degress on the cam can make on power/running.
Vernier win my vote for the cam, this needs around 5 degrees advance to retrieve some mid range.
Also are your carbs bolted tightly, they should 'float' on the rubbers. You use special spring washers and just nip them up. overtighten and
they will dribble and leak as the fuel froths in the bowls.
Regards Mark
As you don't seem too certain of the method to set cam timing, is it fair to assume you did not build the engine. If not I would speak to the
builder before going any further. Contrary to popular belief just changing a cam does not mean you require a vernier pulley. The cam timing will need
to be measured first to verify what you have. Then you have options of 1) Leave it as it is 2) Fit offset dowels to adjust to your preference 3) fit a
vernier and dial in as required.
There will also be differing opinions on the preference for cam timing. Some will say advance it, some willl say retard it. The outcome will always be
a compromise so it depends how you intend to drive it. A good day on a roiling road will pay dividends on playing with cam timing.
As has been said, there is a notch in the dizzy to help set static ignition timing but this really needs to be done running to fine tune. With the
engine at TDC on the crank pulley with both valves closed on cylinder no.1 the rotor arm should be pointing somewhere back towards your passenger door
in line with the small notch out of the dizzy body.
Don't you just love cars!!!
quote:
Originally posted by RobBrown
There are no vernier pulley's on ebay at the moment, although I have seen them before for around the £45 mark.
quote:
Contrary to popular belief just changing a cam does not mean you require a vernier pulley
Got one...
I think the best 60 quid I've spent in a long time. The ease of adjustment is phenomenal. Took 20 minutes to adjust instead of all day(and still
not get anywhere).
I was contemplating taking the engine to a rolling road or specialist to get the carbs and cam timed correctly.£££££
£££££
I managed to get the engine timed and running without the vernier pulley, but found that the response was a bit sluggish.
With the vernier fitted I was able to adjust the cam timing to the best position then adjust the dizzy. The response is now fantastic.
That's the extra motivation I need to get this baby through SVA
I now can't stop smiling. The buzz is back
Well done that man! See told you it was worth buying one.