GRINCH
1/2 ton status
Sort of long so you have all the information.
3 questions I need answered. Remember this is a CAD 500 Big Block.
1. Why does my motor like a lot of initial timing over 30?
2. If I have that much initial should I run vacuum advance when timing it?
3. What should the max be with Initial, mechanical and vacuum?
500 Cad 30 Over
MTS Rockers 1.70 ratio
Heads are ported and polished Approx 450 HP and 550 TQ. Peak torque RPM about 2800
cam.315 lobe .535 valve lift 112 LSA Cam is ground 4* advance so intake centerline is 108 and exhaust is 116
Duration @ .050 is 220 in and 226 ex
Running an edelbrock performer manifold
MTS dist with super coil. NO MSD BOX.
I decided to do a whole bunch of reading the last few weeks about timing and vacuum advance and so forth.
First thing I did was take out the fancy piston stop I made and made sure I had a good mark on the balancer for TDC. Made me some tape and marked the balancer.
diameter*3.14/360*2
6.50*3.14=20.41
20.41/360=0.056721
0.056721*2=0.11344
Launched MSWord, opened a doc, table insert, 1 column 45 rows, set row height to exactly .1134, 8 pitch just about fits, first cell type TDC, second gets a 2, 4, 6, etc... to about 88. , clear all but the bottom border, print a couple, measure to make sure your about on (90 degree = 5.105"), put some double sided tape on the back, cut out, clean balancer, install tape, put some scotch tape (maybe some clear lacquer?) over the top and done.
Now I was ready to crank it up.
I decided I was going to try old school and see what the vacuum was like. I hooked a vacuum gauge in the edelbrock manifold in the hole in #7. Once I got it started I let it warm up really good. Vacuum on the gauge showed about 10. I moved the dist until I got max vac around 15. (I'm at about 5500 Ft in Alt) as I moved it closer to 15 the motor didn't sound very good. Pinging maybe? The fuel injection is loud and I run headers an a loud exhaust. The PJIII software also shows vac. It was around 17. and it seemed a lot steadier than the vac gauge plugged into the runner for #7. I was able to peak the vacuum with the dist to about 18 in the PJ software display. RPM's were about 800 and jumping around 20-30 diff.
Motor sounded good and throttle response blipping the throttle was quick and responsive.
Now I was curios to what my timing was at at idle. 34....Yes 34 on the tape I made. I'm using a craftsman timing light with advance dial. I had it set on 0. I thought maybe I might have screwed up my tape when I made it. I used the dial advance on the timing light to verify. Well it showed about 31 on my mark I made using the piston stop.
How can the motor like this much initial advance?
What's going to happen when I hook up the vacuum advance unit.
Could I have other issues like the cam not being degreed right causing this?
I checked it on #4 and saw the same readings.
A few good sites about timing and vac advance. I wanted to run vac advance since I trail ride with this.
http://www.buicks.net/shop/reference/engine_timing.html (A good article on timing)
http://www.gofastforless.com/ignition/advance.htm
http://www.stevesnovasite.com/forums/showthread.php?t=11689 (Really learned a lot from this one had to read it 5-6 times though)
Thanks for your time and I hope you can help me with this.
Dennis
3 questions I need answered. Remember this is a CAD 500 Big Block.
1. Why does my motor like a lot of initial timing over 30?
2. If I have that much initial should I run vacuum advance when timing it?
3. What should the max be with Initial, mechanical and vacuum?
500 Cad 30 Over
MTS Rockers 1.70 ratio
Heads are ported and polished Approx 450 HP and 550 TQ. Peak torque RPM about 2800
cam.315 lobe .535 valve lift 112 LSA Cam is ground 4* advance so intake centerline is 108 and exhaust is 116
Duration @ .050 is 220 in and 226 ex
Running an edelbrock performer manifold
MTS dist with super coil. NO MSD BOX.
I decided to do a whole bunch of reading the last few weeks about timing and vacuum advance and so forth.
First thing I did was take out the fancy piston stop I made and made sure I had a good mark on the balancer for TDC. Made me some tape and marked the balancer.
diameter*3.14/360*2
6.50*3.14=20.41
20.41/360=0.056721
0.056721*2=0.11344
Launched MSWord, opened a doc, table insert, 1 column 45 rows, set row height to exactly .1134, 8 pitch just about fits, first cell type TDC, second gets a 2, 4, 6, etc... to about 88. , clear all but the bottom border, print a couple, measure to make sure your about on (90 degree = 5.105"), put some double sided tape on the back, cut out, clean balancer, install tape, put some scotch tape (maybe some clear lacquer?) over the top and done.
Now I was ready to crank it up.
I decided I was going to try old school and see what the vacuum was like. I hooked a vacuum gauge in the edelbrock manifold in the hole in #7. Once I got it started I let it warm up really good. Vacuum on the gauge showed about 10. I moved the dist until I got max vac around 15. (I'm at about 5500 Ft in Alt) as I moved it closer to 15 the motor didn't sound very good. Pinging maybe? The fuel injection is loud and I run headers an a loud exhaust. The PJIII software also shows vac. It was around 17. and it seemed a lot steadier than the vac gauge plugged into the runner for #7. I was able to peak the vacuum with the dist to about 18 in the PJ software display. RPM's were about 800 and jumping around 20-30 diff.
Motor sounded good and throttle response blipping the throttle was quick and responsive.
Now I was curios to what my timing was at at idle. 34....Yes 34 on the tape I made. I'm using a craftsman timing light with advance dial. I had it set on 0. I thought maybe I might have screwed up my tape when I made it. I used the dial advance on the timing light to verify. Well it showed about 31 on my mark I made using the piston stop.
How can the motor like this much initial advance?
What's going to happen when I hook up the vacuum advance unit.
Could I have other issues like the cam not being degreed right causing this?
I checked it on #4 and saw the same readings.
A few good sites about timing and vac advance. I wanted to run vac advance since I trail ride with this.
http://www.buicks.net/shop/reference/engine_timing.html (A good article on timing)
http://www.gofastforless.com/ignition/advance.htm
http://www.stevesnovasite.com/forums/showthread.php?t=11689 (Really learned a lot from this one had to read it 5-6 times though)
Thanks for your time and I hope you can help me with this.
Dennis
