Timing with .590 Solid..

[Sweet5ltr]

OK,,
Sorry for the late reply,,,, I checked the timing out today on my engine that has the same camshaft (MP .590" lift).
The base timing is around 18deg adv, and the total timing is around 36-38deg adv.
I use a non vac adv unit made by Mallory, so it's pretty easy for me to adjust base and total timing with a few twists of a screw driver and a good timing light...
I also have 1.6:1 ratio rockers too.... giving .630" lift (before lash).

I'm running the Crane Ductile Iron 1.5 Rockers. What did you set your lash at? Car seems to run better with 20+* initial timing. Going to purchase an SFI Damper before we go any further with timing, and go from their. I am using the Mopar electronic distributor with no vac. advance.

 

[67 B-body]

I'm running the Crane Ductile Iron 1.5 Rockers. What did you set your lash at? Car seems to run better with 20+* initial timing. Going to purchase an SFI Damper before we go any further with timing, and go from their. I am using the Mopar electronic distributor with no vac. advance.

Factory Lash setting by the book...... I think it's .028 int and .030 exh?? Could be wrong on the numbers, but it is for sure the factory specs....
If I go any lower in initial timing, the engine will hardly run.. LOL!
It has a lazy rev and will stall when put in gear... Once I hit 18 to 20 degrees initial timing, it Revs up and is very responsive to throttle input. I can then set curb idle and all is good...

 

[Sweet5ltr]

Yeah, anything under 20* initial and the car will perform like a dog and won't idle. Going to lock the distributor once I purchase the SFI damper for accuracy, and going to go with 34* total. Car has a switch panel for the starter/ignition box/electric fan/etc. Can turn the engine over with the starter and fire the ignition if we have any "hard start" problems.

 

[RustyRatRod]

This is why I was trying to convince you to degree the cam. Had you done that, you could have more taylored the camshaft to the engine and it likely could run at 12-14* initial and had zero chance of hot start issues. Also, the cylinder pressure would have been greatly enhanced. That equates to more power. lol

 

[Hemirunner]

I don't understand why you guys WANT lower initial timing? I could see that if you guys were running vacuum advance and a daily driver. I run mine locked out at 34 degrees and use a start retard on the MSD programmable ignition. They run so much better with timing in them and they don't build heat at idle like something with low initial timing. Especially with the low static compression ratios you guys are running. My pump gas hemi runs 12:1 and I haven't built a pump gas wedge below 11:1 in 15 years.

 

[RustyRatRod]

With the camshaft timing more advanced (which it should be in an overcammed situation) the effect on cylinder pressure will be more dramatic than simply advancing the initial timing, that's why. It's not that the engine needs LESS initial timing, it needs MORE camshaft timing. That would allow the engine to have less initial timing, produce more power from the cylinder pressure boost, have less hot start and spark knock problems. Higher compression engines generally require less timing. All he would be doing by advancing his camshaft timing is optimizing what he's using. If all you've ever really run are low compression engines, then sure, you want all the timing you can get and want it in as early as possible.

You really cannot compare the Hemi to a wedge motor in terms of timing. The Hemi's combustion chamber is WAY more efficient than the wedge ever could be. I forget his screen name, but there's a guy over on The Hamb runnin an early Hemi with a blueprinted 13.5:1 on pump gas. You can do a lot with a Hemi.

 

[67 B-body]

For the record, my camshaft is degreed for proper installation. I belive it needed 3 degrees advance. Also for the record, I have 72cc heart shaped combustion chamber heads, .140 domed pistons, file fit rings. I have plenty of compression and it still likes no less than 18deg advance initial timing.

 

[RustyRatRod]

For the record, my camshaft is degreed for proper installation. I belive it needed 3 degrees advance. Also for the record, I have 72cc heart shaped combustion chamber heads, .140 domed pistons, file fit rings. I have plenty of compression and it still likes no less than 18deg advance initial timing.

Yeah, that's cause you gotta pretty rowdy cam probably. They like a lot of initial to idle good, but high compression engines generally do better with less total timing.

 

[67 B-body]

Yeah, that's cause you gotta pretty rowdy cam probably. They like a lot of initial to idle good, but high compression engines generally do better with less total timing.

It's the MP .590.... Using 1.6:1 rockers.

 

[67 B-body]

I don't understand why you guys WANT lower initial timing? I could see that if you guys were running vacuum advance and a daily driver. I run mine locked out at 34 degrees and use a start retard on the MSD programmable ignition. They run so much better with timing in them and they don't build heat at idle like something with low initial timing. Especially with the low static compression ratios you guys are running. My pump gas hemi runs 12:1 and I haven't built a pump gas wedge below 11:1 in 15 years.

Mine jumps up to full advance very quickly....
I may go a bit higher initial in the future (no hard cranking now),,, but I was thinking more timing at idle caused higher temps at idle,,, not the opposite?? However,, I could be wrong on that.

 

[RustyRatRod]

It's the MP .590.... Using 1.6:1 rockers.

Yeah das a bigun. lol

 

[67 B-body]

I was wrong......
I used two other compression calculators today during lunch and found that my compression isn't what I calculated early on in the build... I now see that it should be around 11.6:1 not 13:1!!!! Heck of a difference!!!
I entered all the data into another calculator and came up with similar results....
Not sure what program I used before,,, but it was wrong...
Sorry for the miss-post...

 

[RustyRatRod]

Ha! Many times as I've used them United Engine online calculators, I still booger up and get the deck clearance backwards. That'll really shake your day up. lol

 

[67 B-body]

Ha! Many times as I've used them United Engine online calculators, I still booger up and get the deck clearance backwards. That'll really shake your day up. lol

Shoot!!!! I just realized my mistake was made today,,,,, My original calculations WERE correct!!!
I was entering .140" for dome dimensions where it was asking for CC's!!! Duhh!!
I just entered in the 15cc dome volume and it came out as 13.37:1 with the piston down in the hole .030", .030" larger bore than factory, standard 3.75" stroke, .040" thickness gasket with 4.41" bore, and 72cc chambers...

 

[RustyRatRod]

Yup I got 13.292 on the United Engine calculator. That's a heap.

 

[Stumper]

My RB likes 38 total. I run a 11.3:1 CR on pump gas with a bigger cam .632/.632 (but 1.5 rockers now) and 276/286 duration at 0.5" with a 106 degree LSA. I use an MSD dizzy with the largest bushing (18 degree delta) so my initial is supposed to be 20. I say supposed to be because I can't really measure initial as the readings jump around alot. I am getting some mechanical at my 1300 rpm idle. I've tried stiffer weight springs to settle down the timing readings but the car doesn't like them. My next move might be to take one spring off since it seems like the motor wants more initial at idle.

 

[67 B-body]

Yup I got 13.292 on the United Engine calculator. That's a heap.

Lol

 

[Hemirunner]

With the camshaft timing more advanced (which it should be in an overcammed situation) the effect on cylinder pressure will be more dramatic than simply advancing the initial timing, that's why. It's not that the engine needs LESS initial timing, it needs MORE camshaft timing. That would allow the engine to have less initial timing, produce more power from the cylinder pressure boost, have less hot start and spark knock problems. Higher compression engines generally require less timing. All he would be doing by advancing his camshaft timing is optimizing what he's using. If all you've ever really run are low compression engines, then sure, you want all the timing you can get and want it in as early as possible.

You really cannot compare the Hemi to a wedge motor in terms of timing. The Hemi's combustion chamber is WAY more efficient than the wedge ever could be. I forget his screen name, but there's a guy over on The Hamb runnin an early Hemi with a blueprinted 13.5:1 on pump gas. You can do a lot with a Hemi.

Wow, did we change topics here? j/k lol...

All I'm saying is that since we now have modern electronics and most of these cars are performance based fun toys.... why would you ever try to run 18-20 degrees initial with one of these things? The only reason we need 18-20 degrees timing is for easy starting. Even at an idle that thing is wanting 30-50 degrees of ignition timing. It's going to make peak power at 32-36 degrees with a nice efficient chamber and then approaching 7000rpm it could do with 8 or 10 degrees less depending upon the combo. If you guys want to do some ignition timing fun tests, lock out the dizzy on the MSD and put a programmable digital ignition like the 7531 on it and go to the track for a day. You'll be surprised what the final ignition curve looks like.

 

[Sweet5ltr]

Just purchased a summit SFI Damper and father welded up the distributor for full lockout and installed the damper earlier today. Hasn't started the car yet, but he stated the factory damper was on its last leg.. Car feels like a power house (even down low) with the .590 Solid Camshaft, compared to the hydraulic bumpsticks.. Sounds like a total animal at idle as well, so that is a plus.. Wasn't able to test it in the power department due to the timing being so far off and the factory damper weighing in on my mind.. Going to hopefully be able to give it more than 25% throttle when I get back home in a few weeks and see the difference. Want to take it up to the Dyno as well.

 

[67 B-body]

Just purchased a summit SFI Damper and father welded up the distributor for full lockout and installed the damper earlier today. Hasn't started the car yet, but he stated the factory damper was on its last leg.. Car feels like a power house (even down low) with the .590 Solid Camshaft, compared to the hydraulic bumpsticks.. Sounds like a total animal at idle as well, so that is a plus.. Wasn't able to test it in the power department due to the timing being so far off and the factory damper weighing in on my mind.. Going to hopefully be able to give it more than 25% throttle when I get back home in a few weeks and see the difference. Want to take it up to the Dyno as well.

Awesome!!!!
I can't wait to hear all about it!
I just adjusted my timing a bit more yesterday, and it is now around 25deg adv initial, and 42deg full advance.
It likes the added timing....