wrd1972

Engine builder just degreed my cam. It is reading 3 degrees above spec for intake @.050" as stated on the card plus this is taking into account he 4 degrees that are built in. It also has 1 degree of advance above spec at center-line.

I'm running the stock crankshaft and the LT4 extreme duty timing set. Based on this the engine builder is a bit nervous since 2 degrees is his personal maximum reccomendation. Thughts?

Thanks all.

96ZCamaro

Should be cool as long as he just goes off of the cam card.

seawolf06

Is everything off by 3 degrees or is it just one spec? If it's everything, then it shouldn't be a big deal because of all the variables like lifters, springs and pushrods, from what I've been told.

SStrokerAce

You can't take into account anything, put a degree wheel on it and it will tell you where it's installed.

If you are running a stock timing chain or a Cloyes (especially the cheap one) it's most likely off because of that not the cam.

Bret

mdacton

If it is off 2-3-4 degrees will it make much of a diff?

SStrokerAce

Depends on the cam. Some are so far off from the design in the first place, who cares. Especially if you have some weak, studs, rockers and pushrods the dam valve will never see the correct timing anyways.

If I'm doing it, it matters to me. I've had a motor run 6° retarded, still made good HP but the TQ was down 40ft lbs!

Bret

rskrause

FWIW, my error of measurement is probably one degree. So, I can't ever say that you should be closer than that. But I wouldn't want to be off more than that. Why? Can't say for sure. I just like things to be "right". Bret: how repeatable are your measurements? Part of my problem is a small diameter degree wheel. Maybe I need to get one of those really big ones? But I find it hard to think a degree either way is significant.

Rich

wrd1972

Engine builder used a large professional degree wheel, quality dial indicator with the lifter bore tool and dead stopped the piston. Everything was checked three times.

I dont think the GM LT4 ED timing set qualifies as a stock timing set.

He checked it two ways:
Checked at .050" it was advanced 3 degree above cam card spec.
Checked at centerline it was advanced 1 degree above cam card spec.

All that being said, It appears that this is a problem?

Javier97Z28

When I checked my setup I was usually within .5* as far as repeat attempts, that was with using a 9" Comp degree wheel. I had the nice comp crank turning nut/lock combo which kept things steady for me, but I also had no heads on the car which probably made it easier to repeat.

Personally my LE3 kept coming in at 2.5-3* advanced when I checked it out. I threw a 2* Mr. Gasket 987G offset crank key in and retarded the cam 2* and it came out just fine for me. After recheck it hit right at .5* advanced, perfect to make up for future chain slack. I had to modify the 987G to work a bit since they're not backcut like stock keys for the hub.

http://web.camaross.com/forums/showp...8&postcount=69

wrd1972

So this offset key might be an option. I dont see how it would mess up the opti timing either.
http://performanceparts.com/part.php?partID=74332

RealQuick

Just get a cloyes timing chain set, it allows you to retard the timing 2 degrees ( options are advance 2, straight up or retard 2).

Javier97Z28

Yes, the 987G is correct. I've had no timing issues and Bryan at PCMforless said this is an acceptable way of adjusting the cam.

The pic in the link you sent isn't a 987G, just a stock picture. The 987G is pictured on the right in the picture I posted. The key on the left is the stocker. I backcut my 987G with a die grinder to make room for the hub.

mdacton

I have a new timing set on the way should be in today, GM stuff was way off

Javier97Z28

The Cloyes 3145 only does 4* increments at the crank.

wrd1972

Do these adjustable Cloyes timing sets let you use the mechanical water pump?

I do NOT want to go electric water pump.