Hi,

What is the range of adjustment for adjusting the intake and exhaust cams using adjustable cam gears on a stock GSR B18c motor with ITR cams.

I've been suggested +3In/+3Ex is quite safe as there is a bit of clearance in the stock GSR motors.

Before anyone flames me - my motor is installed and have been running in my car with no cam gear adjustment for couple of years. I cannot take the motor out just to get it the cams degreed.

Reason I ask is my distributor is almost fully advanced towards the firewall to get to 16deg base timing at idle with the service connector jumped. If i max out distributor adjustment I can get to 18deg. I thought the cam gears were out a tooth but I have checked it and the arrows on the stock gears line up fine.

I've always felt there is some midrange power and smoothness lacking. I've driven other B18c cars and they felt smoother and midrange was heaps more responsive. My top end is fine - I have managed 14.5 second 1/4 mile.

I bought the motor stock but I have a feeling the head may have been milled if the headgasket had been replaced? However, if the head was milled im not sure how much would have been taken off but I'd imagine it would only be a small amount since the donor car was completely stock.

Any input appreciated.

 

Put the car on the dyno to find out for sure where it makes the most power if that's what you're after.

 

Most stock cams will benifit from 1~3 degrees advanced on the intake, far as the exhaust goes i've not had really any power gains..
The rule of thumb is the adjust the exhaust gear first tho.. your butt dyno will only tell so much.

 

should one start by advancing or retarding the exhaust cam?

i would guess, retard.

 

Advancing the exhaust...first.

 

Just move the stuff around. At some point it will run better, at some point it will bend your valves. Hope for the first, expect the second.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DonF &raquo;</TD></TR><TR><TD CLASS="quote">Just move the stuff around. At some point it will run better, at some point it will bend your valves. Hope for the first, expect the second. </TD></TR></TABLE>
Don I totally agree with you.

But in saying that someone must know the margin of safety range for adjustment for a relatively stock motor with stock pistons and mild cams.

 

i have a 97 spec R motor in my civic with the intake advanced 2 degrees and the exhaust retarded 4 degrees, it makes the most top end power like that, but not really that great below 3k rpms..

i tried advancing my exhaust cam and it didnt really make much top end power, but had more low end power

 

Seems like people are safe to adjust to about +4 on the intake side and most dont make that much adjustsment to the exhaust side.

Cheers

 

Pull the plugs, set the valves to 0 lash, lock the head into vtec, adjust the gears for full advance/retard and turn it over slowly by hand. If nothing hits then you have at least 0 clearance at the extremes. Stay short of that as much as you feel comfortable with. Then dyno it to see where the engine wants them.