PorKen

This is a little confusing because of the changes with the V2 tool. With the V1 tool, the 'zero' is usually 1°R/2°L cold, measured with the dial indicator. With the auto, a few more degrees works well. Malcom is using 6° (8° hole on the V1 tool) which I think is the max which doesn't take away too much HP on top.

The 7/8 was cool around town, but on the dyno it took about 20HP off the table on my '86.

the flyin' scotsman

The cam drive and hub can be somewhat 'fused' together after being bolted tight for ~20 yesrs hence my suggestion of lube before attempting to adjust the cam timing. I ended up where I did as the cam was reluctant to move and when it finally broke the bond it moved a little further that originally intended. Fortunately the setting was where I had finalised going so it was left.

I'm going back in there shortly for a new t.belt and Ken's new tensioner project and may consider adjusting again if I can get sufficient seat time with the present set up - it's friggin snowing again.

sharkmeister85

Any thoughts as to how increasing cam advance effects ones ability to pass emissions testing requirements?
Glenn

sharkmeister85

Ken, could you elaborate on "0 degrees"? Cam degrees? Crank? Both cylinder banks at 0 degrees?
Glenn

PorKen

Glenn,

Advancing will probably raise NOx, as the dynamic compression ratio is raised.

0° with engine warm, both sides. On the V1 tool, that would be usually be one hole CCW. When cold, it would be 0°L/-1°R.

Louie reckons I might be able to get over 300RWHP with a little retard, as the HP is almost flat from 5500-6200, with a slight drop after 6000.

sharkmeister85

Ken,
Gotcha. Am I right in concluding then that all previous talk of using 8 degrees advance would mainly be of advantage to those with an auto box then? With a 5- spd, maybe I should just stick to the stock 2L/1R timing as near optimum? Thoughts or opinions?
Glenn

the flyin' scotsman

IIRC the advance cam timing changes are most advantaegous with auto boxes. When I drove the car Sat morning I could break the back end loose at will where it would never do before.

My question is, as the rotor is bolted to the cam hub how is the ignition timing change affecting the performance? Advanced cam and ignition appear to be good results...........long term effects?

PorKen

It depends how you drive, I reckon. I'm such a died-in-the-wool auto driver that driving a GT makes me uncomfortable, rev'ving up to 4000rpm to shift seems so foreign. If you do most of your driving in the city, and/or you want to have more grunt off the line, without having to dump the clutch, then some advance wouldn't hurt.

The ignition trigger is taken from the crank, so it doesn't change. The ignition rotor has a broad tip to match the range of the adjustable cam gears.