Some of you may have been following the fact I was upgrading to new Brodix RR Oval port Heads. While I was in the motor, I decided to change the Timing Chain.

Before changing the timing set, I checked valve clearance and had about .050" max on the intake which was a little tight for me to be comfortable. I knew with the old set, I was 6º advanced (because that's what Harold suggested). I used an offset busing to get there since the CAM has 4º ground in. Anyway, I figured the new timing set would give me more clearance using the standard keyway leaving me 4º advanced.

After replacing the timing set, I checked clearance again and found I now had ~.100" Great but with only 2 deg of change???? I decided to degree the CAM thinking there must be a problem and found now the CAM is now only 2º or 3º advanced. (110LSA - 107 or 108 ICL measured - card calls for 106º). I checked TDC twice and ran my checks 4 times. Always the same answer.

This leads me to believe the new timing set has a built in 1º or 2º error on the retarded side of things. My real question here is this..... (took me long enough right) Should I leave things alone and button it up? (The extra clearance is nice). I will have essentially retarded the CAM 3º or 4º from where is t was. What is it going to do to the way the car runs? Is it going to hurt my 60ft times. What's it do to the torque and power curves? Should I put the bushing in to get me back to 106º ICL?

Help me decide guys...

Troy.

If it was not degreed in originally then you have nothing to base your decision from. Timing sets are all over the place and thats why it's always recommended to degree the cam in.Over advancing the cam will result in opening the ex. valve too earlier in SOME cases. 4 and 6 degrees advance is pretty common on sbc's ground on 106 and 105 lobe seps, but in cases when the lobe sep is wider say in the 112 range then if there is also a good 8 or 10 degrees exhaust duration spread you can get into the scenarios of the ex opening too early and allowing cyl. pressure that should be pushing the piston down to exit out the pipes. Im trying to speak in laymans terms here.A bbc is usually happy with 4 degrees but sometimes there are intake & ex. lobe combinations on a tighter lobe seperationb that will allow 6 degree's. You may have had it over advanced to begin with if it was not degreed in is what I am trying to say.

It was degreed to begin with. It was at 104º. It is now at 107 to 108º. I want to be at 106º ICL but I like the clearance I'm seeing where it is.

I really want to know what to expect from performance. from the 3 to 4 deg change.....

It was degreed to begin with. It was at 104º. It is now at 107 to 108º. I want to be at 106º ICL but I like the clearance I'm seeing where it is.

I really want to know what to expect from performance. from the 3 to 4 deg change.....


Troy,

I could not get any performance change from moving my cam timing from 2* to 5* advanced. I say leave it,

Thanks for the input Tom. Unless I hear compelling evidence to the contrary, that's what I think I'll do. I'm hoping Mike and Harold can find the time to comment.

Troy.

I would leave it alone also. I really don't think you will see anything either way and the clearance is a plus.

One thing that concerns me is if you have .050 more on the intake now you have .050 less on the exhaust now. Did the exhaust have plenty of clearance before you moved the cam? I have found for camshafts with similar specs to yours 1 degree is about .010 in valve/piston clearance with a 1.7 ratio rocker. This is a good ballpark number. Advance the cam 4 degrees and take .040 out of the intake clearance, retard the cam 4 and add .040 to the intake clearance. The exhaust clearance is an inverse relationship to the intake.

There is a very good chance it will run better on 107.

I put clay on one Exhaust Valve around .200 thick and it barely touched the piston so I'm good there. I will double check again before final assembly. Thanks for making me feel a little better guys. I really wanted to leave the clearances wide.

I understand that it will move my peak torque and horsepower up a little in the RPM range. Any guesses how much or will it again be minor?

Verified my Cam position at 107 deg. Intake clearance is .110 and exhaust is a whopping .180. I put one head on and torqued it before calling it a night. I'm starting to get excited. Should be running by the weekend. :D

Can't wait to go see what she'll do at the strip. Too bad it's so damn hot.

Thanks for the input Tom. Unless I hear compelling evidence to the contrary, that's what I think I'll do. I'm hoping Mike and Harold can find the time to comment.

Troy.
=
Hi Troy,
Sorry, been in the shop all day,,
If you have a question I can help with & I don't respond right away you are always welcome to call,, ;)

Glad to hear you have gained clearance but in honesty .050 intake clearance does not concern me at all, I have run less many times.
The exhaust is a different story :D

As was suggested, run it.
Installed position are just a recommended starting point & unless this were a purpose built completely scienced out combo there is in most cases no way a couple of degrees of cam position is going to make any difference in the real world.

Thanks Mike, I was hoping you would say that. I know I can call but I put the post in while I was at work and figured if I didn't get the answers I was comfortable with, I would call you then.

I hate to bother you while you are working when it wasn't an emergency. I feel good about the motor and can't wait to fire her up. These heads are SWEEEEEET!

Won't get to touch it tonight. Will get back at it tomorrow night.

Thanks again for the input,

Troy.