ignition
H&H made my ignition setup on the info given to me by the head builder. Working on a 10.8-11.1 ratio.
12 degrees advance at idle
38 degrees at 3500prm and something else I can't remember. Lol
I've always had it set this way as I wasn't aware I had a low compression engine. So it would have probably been wrong before, and should be right now.
We will try a few degrees either side of its setting on the dyno.
38 degrees @3500 is a lot, definatly wants checking on the rollers
Don't quote me. I am fool who knows nothing and going on memory, which is probably wrong.
It made peak power last time on the low compression engine at 12 degrees idle. Will check this one on the rollers.
How did the head guy get to those compression figures? Just wondering, since the old 'How to power tune SOHC Pinto' book mentioned about 10.2:1 (if I recall, it's been a long time since I read it!) with high compression flat top pistons and a -60 head skim. Has the head had any other work done to raise the CR?
The truth is I'm not sure. It started when my original heat valve seats burnt out. I was looking at getting them done and I had a chat with Eric from JEM engines who built and sold me a big valve ported and polished head. He suggested the cam to use, machines the valve Spring seats to suit etc...
He told me that his head running on a standard pinto bottom end should be around 10.8-11.1 compression ratio. Maybe it to do with the CC chamber of the head?
I'm not engine builder. This is the first time I've ever opened an to do more than change a bit of oil so it's all a learning curve.
He gave me a list of figures to send to h and h for a custom electronic ignition. I'm just trusting his expertise as I defiantly have none.
No problem, was just interested that's all. Probably decreased the combustion chamber capacity as you say.
Maybe but I've got a different theory round these high numbers. I don't think the lead will make such a big difference. For sure it could stand 38° easy without pinking but those day's they also thought max power was as close as possible to pinking. So they set advance until pinking and than back off a little. Today we should all know this is not the case. We talk about MBT (or minimum best timing).
I've regular been using AVGAS. Full of lead and never saw an other advance needed to make full power. So no prove to me it is burning slower (maybe commercial fuel was little different ). I still think the big numbers are from the way they tested advance.
I remember we did the same, increasing jet's until the engine stopped performing and fitted one jet smaller, advance until pinking and back of. This was the best tuning I could do on my first Capri and later Escort rally-Cross car back in 1988. Dyno sir? what's a dyno?
yes your not wrong, i remember jetting carbs was simply a matter of going up until it was clearly pretty rich and coming back a bit, we didnt know much about reading mixtures back then
Reading mixtures??? There was black smoke or no black smoke. I guess all engines where running very rich (an other reason why we probably needed more advance?? And why we needed high CR). This all in combination with a way to long duration cam?? More advance sir?
I remember we where always so worried about going lean and melt a piston. So we needed black smoke to be safe.
I know for sure, all Pinto's build today should end up between 28 an 32°. 28° for a good one. If you need more, check your build.
lol, i remember racing against a couple of cosworths with "safe" maps in the ecu, and struggling to see through the black smoke! safe? well they were never going to melt a piston, rings wouldnt last 10mins, niether were the bearing with a sump full of fuel but they wre "safe" lol!
From 8 - 12° idle up to 28° is correct to start with.
3rd time lucky?
Okay so, after the latest session this is what we have. The new bottom end defiantly helping power now. Torque is still lower than with the bike carbs low down. But doesn't feel uncomfortable to drive. I'm pretty happy with it for now. I've spent enough money on RR sessions to warrant changing the chokes to 34mm to see if there is any benefits.
Wheel bhp as usual
Ive spent too much on setups now. I'm happy with how it is for now...
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