Smallport ignition timing problems

[4AGE Sedan]

Hi Toymodders,

I'm having a strange problem with my ignition timing on my smallport 4age after a rebuild. Standard crank and rods, new BHJ harmonic balancer, new .25mm o/s pistons and rings, HKS 264/264 8.1mm cams, uprated valvesprings and retainers, stock valves.

Basically, I cannot get the ignition timing set correctly. Following the BGB, I aligned the balancer notch on the "0" timing mark on the lower timing cover, made sure the cams and cam gears line up properly with the marks, and that #1 cyl is actually on tdc of the compression stroke. On first start I quickly realised that I had the distributor out by one tooth or so, as it was idling at 35° without the diagnostic connected bridged, but with the distributor body fully retarded. This is where things start to get strange; When I bridged Te1 and E1, it wouldn't start. With the connector still bridged, moving the dissy to it's full range either way didn't make any difference.

So I put the engine back on tdc, and retarded the dissy by one tooth and tried again. Now it idles smoother and better, but with the dissy body is fully advanced, the timing light shows 5° btdc. When I bridge Te1 & E1, the engine doesn't start, and the timing light shows 5° atdc.

Interestingly on both times it ran, (with diag connector not bridged) the timing would retard every time I gave it some revs.

I've had the dissy in and out multiple times now, and am certain that I'm only moving it one tooth on the dissy shaft each time.

Getting to my wits end here, any suggestions?

[sprinter86]

I am not sure if my experience is of any help,
But when I fitted my 264/264 cams, i had a similar issue where is seemed the dizzy could not be put on any tooth that would work.

I decided to use a dial indicator on the cam buckets in order to dial them in to the HKS specification on the cam card,
because the distributor runs off the exhaust cam, adjusting the lobe position via the adjusting cam gear you are also changing the
ignition timing of the engine via the distributers position.
Once is was dialled correctly, it fixed the problem of not being able get the dizzy onto the 'right' tooth.

May or may not be the issue your seeing.....but seemed relevant!

some HKS cam cards in this thread if you dont already have one
http://www.aeu86.org/forum/Thread-An...types-for-4age

[jondee86]

Bridging TE1 and E1 should put the ECU into diagnostic mode if the required conditions are met. When the ECU is in diagnostic mode you set the base timing to 10deg BTDC by doing whatever it takes. When the base timing is set, remove the bridging wire and the timing should jump to around 16deg BTDC.

Inverse procedure... without putting the ECU into diagnostic mode, set the timing to 16deg BTDC. Then, when the ECU is put into diagnostic mode, the timing shoud drop to 10deg BTDC.

When the engine is idling (not in diagnostic mode) and you blip the throttle, the timing will at first retard momentarily, and then advance. Perhaps this is what you are noting ?

Cheers... jondee86

[Starfire]

Also, don't forget that if you have shaved your head, decked your block or fitted a different thickness head gasket, you will have also changed your static cam timing, if using the standard timing marks. If you are using aftermarket cams, you really should be using adjustable cam wheels. Given that there are many options on this front for the 4AG, you really have no excuse not to fit them.

It also sounds like you're running a factory ecu with aftermarket cams. As the 264s aren't too crazy compared to the factory ones, you should be able to get away with it, but to get the best out of your engine, you really should consider an aftermarket ECU with a custom tune.

Cheers,
Terry

[4AGE Sedan]

I am not sure if my experience is of any help,
But when I fitted my 264/264 cams, i had a similar issue where is seemed the dizzy could not be put on any tooth that would work.

I decided to use a dial indicator on the cam buckets in order to dial them in to the HKS specification on the cam card,
because the distributor runs off the exhaust cam, adjusting the lobe position via the adjusting cam gear you are also changing the
ignition timing of the engine via the distributers position.
Once is was dialled correctly, it fixed the problem of not being able get the dizzy onto the 'right' tooth.

May or may not be the issue your seeing.....but seemed relevant!

So after consulting the cam cards I had when I bought the camshafts, I realised that I had not set the cams to the required specs. I simply dropped them in as per the service manual and hoped they would go.

After buying a dial gauge, and making up a crank degree wheel, I set the cams to their recommended specs and re-did the timing. Now it's properly set at 10deg BTDC with the diag connector bridged, and 16-ish deg BTDC without.

What surprised me, was that I had to retard the intake cam by 16deg at the crank (8deg on the cam), and retard the exhaust cam by 6deg crank (3deg on the cam). Thanks to all that helped