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Re: another Alfa Romeo conversion
Posted: Sat Oct 22, 2011 7:52 pm
by delcowizzid
how many slots you got in that balancer LOL
Re: another Alfa Romeo conversion
Posted: Sat Oct 22, 2011 7:53 pm
by Jayme
id swap the leads over and try it, it can only go 2 ways

we fluked the datto dfi's on the first go

Re: another Alfa Romeo conversion
Posted: Sun Oct 23, 2011 10:09 am
by antus
@delcowizzid: the 4 cyl dfi uses 6+1 notches, so that looks correct
Re: another Alfa Romeo conversion
Posted: Sun Oct 23, 2011 10:45 am
by festy
I tried swapping the coil leads over, no firing at all that way.
So checked the cam timing at TDC - looks ok except the inlet is half a tooth retarded.

- inlet_cam.jpg (61.26 KiB) Viewed 4349 times
But I have a nasty feeling I've got a pair of exhaust cams in the engine - no wonder it won't run, check out the valve overlap!

- cams.jpg (69.7 KiB) Viewed 4349 times
Re: another Alfa Romeo conversion
Posted: Sun Oct 23, 2011 11:12 am
by VL400

That aint going to be helping things

On a side note, thats some serious valve angle. A bit like the old Toyota 18RG design.
Re: another Alfa Romeo conversion
Posted: Sun Oct 23, 2011 11:55 am
by festy
80 degree angle apparently, the engine remained essentially the same from the 50s to the 90s. It was pretty advanced in it's day.
Here's what the front cam lobe positions *should* be:

- lobe_diagram.jpg (13.98 KiB) Viewed 4338 times
As soon as i took he cam cover off this morning I knew something wasn't right, but as the cam markings lined up I wasn't so sure - it didn't occur to me that I might have put the wrong cam in until I was thinking about it later

Re: another Alfa Romeo conversion
Posted: Sun Oct 23, 2011 4:24 pm
by delcowizzid
just turn the exhaust cam 180 degrees

a lot of the twin cam exhaust cams have a more aggressive lobe profile and people use 2 exhausts or mix and match to get there desired cam profile
Re: another Alfa Romeo conversion
Posted: Sun Oct 23, 2011 4:51 pm
by festy
The factory inlet and exhaust cams are both identical so I just turned it round. I'd forgotten that they had timing marks on both sides - it's been years since I've played with these engines.
Timing light confirmed it's firing on TDC, I'll shift the crank sensor to give it about 7 deg advance and see how that goes.
Re: another Alfa Romeo conversion
Posted: Wed Oct 26, 2011 5:32 pm
by festy
Re: another Alfa Romeo conversion
Posted: Wed Oct 26, 2011 6:24 pm
by VL400
Good stuff

hopefully no more manifold busting backfires
