hehe... retarded exhaust cam

[ryan.hess]

Yeah, that's right... I have retarded exhaust cams 12* to be exact (exactly one tooth on the cog) What kind of performance gain am I looking at? Maybe more specifically, how can I enter that into Desktop Dyno2000? I think it should be good for at least 10hp, if not closer to 20...

[grandprix34]

wat do you mean? You set it to stock timing and went back one tooth?

[ryan.hess]

Exactly what I mean.

[grandprix34]

[Rhedalert]

TIMMY!!!!!!!!!!!!!1

[pocket-rocket]

In DD2k, the numbers in the cam area after EVO and EVC are for the exhaust cams. EVO stands for Exhaust valve Opens, and guess what, EVC stands for Exhaust Valve Closes. So, just subtract 12 from each number. I forgot what they are at in the program, but I know one of them goes to a - (negative) number, so if it was something like 8, it would go to -4. My 91 had hit about 265 hp on DD2k with ported and polished heads and the cam timing, so your estimate is close, I think. Really though, the 91 is probably no where close to 265. Have to factor in the REAL cam specs, 150k+ miles, and living a really hard life from me and previous owners (I put 1 auto in before the 5 speed swap (I blew that one up too), and the auto I pulled out had a "Rebuilt for GM by Hydromatic" sticker on it).

[montessgtp]

Re: hehe... retarded exhaust cam

Yeah, that's right... I have retarded exhaust cams 12* to be exact (exactly one tooth on the cog) ..

Just curious why u did 12 instead of 13...Also u turn the exhaust cams 1 tooth back or foward on the cog pulley? Excuse my ignorance on the questions im not real fimular with timing on these engine yet...

Also how much change in ur idle did u see?!...People ahve claimed lopy ruff idle at around 700?

[ryan.hess]

I forgot what they are at in the program, but I know one of them goes to a - (negative) number, so if it was something like 8, it would go to -4.

See, that's the thing... mine won't let me go negative... it's like, "please choose a number between 0 and 80" or something like that... I don't know what it's deal is. As for why I chose 12*, it's because there are 30 teeth, each tooth is 12* (back 1 tooth=retarded). If it were 15*, I would have chosen 15*. It's still in pieces, so I don't know what the idle's like yet I'm still trying to put together my short runner intake - my last one didn't fit.

[wireman121]

so i pull the belt and turn both exhaust cams back 1 tooth? sounds easier than re-timing the whole motor like in the instructions. thanks!

[SappySE107]

How do you pull the belt and make sure the cam gear is 1 tooth back?

[ryan.hess]

How do you pull the belt and make sure the cam gear is 1 tooth back?

Well, the tensioner makes this a little difficult, because it sometimes moves the rear bank cams without moving the front bank... What I did was make a mark on the belt/all 4 cams with whiteout, and made sure the intakes stayed the same... and moved the exhaust back one tooth. I changed the belt while I did this, so it wasn't quite this simple for me.. but you get the idea. Oh yeah - and it takes some effort to keep the cam where it should be (it likes to jump with no tension )

[wireman121]

The "13 degrees retarded timing" that is on the 60degreev6 website is referring to 13 degrees on the crank pulley, not the individual cam gears. If you read through the instructions, it has you lock the exhaust cam gears first, one at a time, and set the CRANK pulley 13 degrees retarded each time, then lock the intake cam gears in for stock timing. So, wouldnt setting the exhaust cam gears themselves 12 degrees retarded be a completely different calculation?

[pocket-rocket]

It sounds like he didn't want to pull the cam gears off of the cams, thats how he got 12*, and not 13*. Why, he would have one of the 91-93 engines that have the lockrings that you need to remove the cam pulley to get out, vs. just loosening the bolts. I think wireman is right, so therefore you would have 24* retarded cam timing, making one hell of a lope if it would idle at all. The 91 is the car that Ben and I did this too first, and yes it does lope kinda nicely at idle, but with a stock exhaust, sounds like shit at the same time (weird, huh?).

[SappySE107]

It certainly wont have any low end. 17 or whatever I had was so horrible, and the knock retard was crazy. I spent a few days tuning it perfect too and it was still ass. 13 was flawless though for KR...but I gotta tune it still once its back together.

[ryan.hess]

so therefore you would have 24* retarded cam timing, making one hell of a lope if it would idle at all.

Whoopsie... I forgot the cams rotate at 1/2 the rpm of the engine Maybe that's why when I try to start it it's making horrible noises... I think I'd better fix that.