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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 :P we fluked the datto dfi's on the first go :D

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
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! :oops:
cams.jpg
cams.jpg (69.7 KiB) Viewed 4349 times

Re: another Alfa Romeo conversion

Posted: Sun Oct 23, 2011 11:12 am
by VL400
:wtf: That aint going to be helping things :wall: 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
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 :wtf:

Re: another Alfa Romeo conversion

Posted: Sun Oct 23, 2011 4:24 pm
by delcowizzid
just turn the exhaust cam 180 degrees :P 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
Somehow, installing the inlet cam upside down didn't bend any valves :D
I added about 7 degrees of advance by modifying the crank sensor bracket, opened the plug gaps right up, and changed the ref angle in the cal to 70, and kicked it over.















And it started.
:mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen:

Still so much to do, but gotta say i'm pretty happy.

Re: another Alfa Romeo conversion

Posted: Wed Oct 26, 2011 6:24 pm
by VL400
Good stuff :punk: hopefully no more manifold busting backfires :lol: