Surfaced Head and Adjustable Cam Gears

[sdaddy]

My head has had 0.040" taken off. In timing the cams today, it looks like there is about 5 degrees difference at the cam (about the delta between high and low point in the sprocket) due to the lower height.

Does this sound about right to you?

[Magus2727]

Not sure I am understanding your post. 0.040" off the head is almost indistinguishable when installed. Your tension / idle pulley will make up for the fact that your cams are now 0.040" closer to the crank shaft.

[ZXthrizzle05]

right, that is not a lot at all infact that's a good mill also when cleaning the matte surface

[sdaddy]

Originally Posted by Magus2727

Not sure I am understanding your post. 0.040" off the head is almost indistinguishable when installed. Your tension / idle pulley will make up for the fact that your cams are now 0.040" closer to the crank shaft.

Yes, the tension pulley will take up the "slack" from the left hand side (when looking from the front of the engine) but that in turn throws off the cam timing....

[Magus2727]

Your timing belt will likely have more flex and adjust in length due to tension and thermal expansion. You should be setting you timing TDC so should still not mater...

[sdaddy]

Originally Posted by Magus2727

Your timing belt will likely have more flex and adjust in length due to tension and thermal expansion. You should be setting you timing TDC so should still not mater...

Yes, setting timing TDC with cams held with flat tool at the back end. Comes out at 5 degrees ( at the cams) off. Just wanted confirm.

[ZXthrizzle05]

how did you know you were 5 degrees off?

[amc49]

The discussion is a moot point, he probably read the degrees difference on the sprocket markings, irrelevant since the reason for the adjustable sprockets to begin with. You correct with them back to right, or what you want. There is no way to 'confirm' since every engine will be slightly different. The term '5 degrees' also useless unless knowing retard or advance and which one of two cams.

The TDC mark can be useless too since may not be true TDC which needs to be indicated out with a degree wheel. Simply bumping a stop point pin is close but all engines vary there too.

[1turbofocus]

Correct , the best thing to do is get them close with the tools for TDC then use a compression gauge to dial them in closer till you can get to a dyno

Do a compression test , then move one gear 1 mark , if compression goes up go another mark till compression stops going up by moving the gear , if you go Adv. say and get no gain in compression then go the other way , when done with that gear go to the other and do the same thing , this will get you CLOSE but you need to adjust the gears on a dyno or you may leave some power behind

Tom

[sdaddy]

Originally Posted by amc49

The discussion is a moot point, he probably read the degrees difference on the sprocket markings, irrelevant since the reason for the adjustable sprockets to begin with. You correct with them back to right, or what you want. There is no way to 'confirm' since every engine will be slightly different. The term '5 degrees' also useless unless knowing retard or advance and which one of two cams.

The TDC mark can be useless too since may not be true TDC which needs to be indicated out with a degree wheel. Simply bumping a stop point pin is close but all engines vary there too.

Yes, you're right. I did mean the degree difference on the sprocket markings when the cam's are aligned via the tool. I checked TDC by using a the measuring end of a caliper on #1 piston and it corresponds to hitting the stop point pin. The adjustable sprocket markings are actually both 6 degrees retarded. I'll start with that and follow Tom's compression advice for the initial tuning.