As recommeneded by cam manufacturer,i installed my camshaft -2 degrees.

they recommended this method since it was geting installed in a 302 crossram and it would let the engine rev higher.

result is that car can barelly come off a red light without excessive clutch slipping.

having owned my z for over 20 years i am very experienced with driving a 302 and having to slip the clutch to this extent is ridiculous.

I am looking at re-installing the camshaft at 0 deg, i figure that i will be loosing a few hundred rpms on top, but will regain driveabillity.

my question is: do i need to re-check piston to valve clearance if i re-install the camshaft at 0 degrees, i had more then enough clearance when installed at -2 degrees.

p.s. cam setup was also tried with my 4bbl with same off the line results


thanks

I believe if you set it up at 0, you will have MORE clearance than retarding it. So no you do not have to recheck the clearance.

Actually advancing the camshaft decreases intake valve to piston clearance and increases exhaust valve to piston clearance. If your clearance was tight with the camshaft retarded 2 degrees, you had better recheck it. I recommend to check the clearance with any change. With some checking springs it's easy enough to do, better to check than to grenade the motor!

Eric,
Definitely recheck it but to be honest with you I seriously doubt that you will ever feel any difference in 2 degrees. Sounds like you have the wrong cam for your combination to me.

What gear do you have? and what rpm do you slip the clutch at just from light to light?
A crossram, small cube motor even with a moderate cam and maybe even low gears won't like low rpms.
With a "big" cam, single plane, and 3.08's my 327 had to have rpms and be slipped a lot. By moving to a dual plane the city driving was much better, but it wont ever drive like a new car, some rpm and slipping has to take place. You learn to live with it after awhile, but 2,500rpm+ just to take off isn't my cup of tea for a mostly street cruiser.
What is the duration @.050?

If you retard the camshaft for more low end your going the wrong way. You can get more than 2 degrees with valve adjustment.

2 degrees wont make a differnce in how the car feels.No matter how big or small the cam it,the difference between 2 degrees of cam timing would be about 5 hp and 5 pounds of torque at any point in the rpm range.Most cams are ground 4 advanced,when you hear guys talk about retarding the cam,most are talking about running 6 degees or more retard to extend the power band of small engines on huge doses of nitrous which tends to fill the cyinders with too much pressure in the lower part of the powerband which causes detonation and retsricts how much nitrous they can run at the top of the powerband.I doubt you would be happy with only a 2 degree change and I am not even sure that going 4 advanced would make you totally satisfied.Are you sure the cam grinder meant for you to install he cam 2 retarded?Maybe he was figuring you were going to stab the cam in and line up the dots and if the cam were ground with 4 advance in it and you put it on the 2 back keyway on the timing set it would only be 2 advanced.If you put a degree wheel on it and actually put it in with 2 degrees more intake centerline then lobe seperaion,that thing is WAY late.

If your piston to valve was close with the cam 2 back,then going 2 ahead or eevn 4 ahead will make it closer.Good luck.

What was the clearance before ?

That "should" give an idea of how much you'll have.

I did mine the down and dirty method.
Brought the piston to TDC and with a dial indicator measured clearance at valve stem. (solid cam here) Didn't have to pull head.

2 degrees wont make a differnce in how the car feels.No matter how big or small the cam it,the difference between 2 degrees of cam timing would be about 5 hp and 5 pounds of torque at any point in the rpm range.Most cams are ground 4 advanced,when you hear guys talk about retarding the cam,most are talking about running 6 degees or more retard to extend the power band of small engines on huge doses of nitrous which tends to fill the cyinders with too much pressure in the lower part of the powerband which causes detonation and retsricts how much nitrous they can run at the top of the powerband.I doubt you would be happy with only a 2 degree change and I am not even sure that going 4 advanced would make you totally satisfied.Are you sure the cam grinder meant for you to install he cam 2 retarded?Maybe he was figuring you were going to stab the cam in and line up the dots and if the cam were ground with 4 advance in it and you put it on the 2 back keyway on the timing set it would only be 2 advanced.If you put a degree wheel on it and actually put it in with 2 degrees more intake centerline then lobe seperaion,that thing is WAY late.

If your piston to valve was close with the cam 2 back,then going 2 ahead or eevn 4 ahead will make it closer.Good luck.

Cam grinder suggested me to install the cam @ the -2 deg on the keyway.

I am looking at re-installing it at 0 on the keyway.

From all the replys i am getting, i figure its not worth the trouble to put it back to 0 deg.

I will leave it as is, i am still very satisfied with my setup, just wanting to improve.

I am not worried of braking parts or having to replace my clutch more often that bothers me... its the look from other motorists when i leave off a red light and the noise that little engine creates thru high flowing mufflers... kinda attracts too much attention...

Doug that is dirty! I like it. :thumbsup:

What was the clearance before ?

That "should" give an idea of how much you'll have.

I did mine the down and dirty method.
Brought the piston to TDC and with a dial indicator measured clearance at valve stem. (solid cam here) Didn't have to pull head.

What gear do you have? and what rpm do you slip the clutch at just from light to light?
A crossram, small cube motor even with a moderate cam and maybe even low gears won't like low rpms.
With a "big" cam, single plane, and 3.08's my 327 had to have rpms and be slipped a lot. By moving to a dual plane the city driving was much better, but it wont ever drive like a new car, some rpm and slipping has to take place. You learn to live with it after awhile, but 2,500rpm+ just to take off isn't my cup of tea for a mostly street cruiser.
What is the duration @.050?

car as a 4.10, wish i could tell exactly which rpm, but my OER tach is not precise enough ( i have another thread going for this problem), i figure around 2000 to 2500 would be pretty close.

Trick i have for less off the line clutch slippage; before leaving from a dead stop, wind up the rpms up to 3000 and when the rpms come back down, i slowly let the clutch go and apply slight throttle.

Engines revs much less higher and it doesnt sound like im in a drag race

What was the clearance before ?

That "should" give an idea of how much you'll have.

I did mine the down and dirty method.
Brought the piston to TDC and with a dial indicator measured clearance at valve stem. (solid cam here) Didn't have to pull head.

its not at TDC you need to worry as the valves are closed.



MIne was verified with putty on top of the piston with head temporarilly installed and head gasket ( same thickness as the one i installed). once the engine turned over a couple of times i mesures the thickness of the putty at the thinnest spot and i had more then 0.150,

As pointed out by other members, i wouldnt feel the difference if i re-install at 0 deg, i will use my spare time elsewhere where its more needed.

Many years ago , when my Z was very new, not knowing anything about the crossram, I put one on along with installing the 140 cam, was even looking at the 2nd opional "754" cam. I ran the 140 straight up, being my sole means of transportation, grocery, church, cruise then back to work, I pulled cam and crossram and had the option to put in back in stock (worked behind the Chev parts counter).
Like you , it suffered on the street scene, but once it got moving with 3.73 gear, I found that there was very little road in front of me (we had no walmart side streets back then) , to make is scream.

I never did try to advance this motor until later when I pulled it and installed in my 55 chevy, H/mp car with one carb. I found that sometimes 2 or 4° never really produced anything noticable but 6 & 8° did. Of course, I knew my clearances so I felt safe about doing this.

I did at one time find a motor that was so far off specs, I basically just moved the cam timing gear , one tooth forward.

I waited full full valve lift intake and exhaust then set up the indicator,and used a valve spring tool to check clearance.
I checked at a few points between too...one being with the piston at TDC.

[QUOTE=braz28;1422332]its not at TDC you need to worry as the valves are closed.



Carefull with that thinking.With most performance grinds..the intake and exhaust valves are both off there seats during the overlap period at tdc, after the exhaust stroke.This typically is +- 10* of tdc, where piston to valve clearance will be at its closest point.

All of our talk is about degrees of advance and retard. Doesn't lobe separation have a much larger effect on the power band and torque???

car as a 4.10

Eric,
Just my opinion, but I think something else is wrong. With 4.10 gears you should be able to let the clutch out at idle and drive down the street with no problems.

All of our talk is about degrees of advance and retard. Doesn't lobe separation have a much larger effect on the power band and torque???

Yes..but the lsa is something you can not change once ground into the camshaft..regardless of installed intake center line.The valve timing events and p/v clearance can be altered by wiggling the cam back and forth..but the lsa will always remain constant.
I know where you are coming from..but it does not sound to me that the op is interested in a cam swap...so lsa is, what it is.