What timing degree would you recommend for this setup?-UPDATED...Wrong Cam Info!

[Mfr426]

Hello all, I've noticed a slight hesitation in my car when I step on it in gear and want to get some feedback where my timing should be.

I have a 69 Charger with a 71 383 "G" block installed. I have a MP Purple Shaft "road runner cam" what has the 284 duration and 484/484 lift and a double timing gear set. I have a factory 4bbl intake and a factory Cater 625 w/ stock choke. The carb had a complete rebuild kit to factory.  The motor had excellent compression and burns no oil. The trans is the matching 727 trans and the stock torque converter. I have a factory single point dist as well. Also, factory HP manifolds.

If memory serves I have the timing at 5 degrees now.

Anyone care to suggest where timing should be for this combo. I'm open to any comments (other than saying that I should have never put the RR cam in).

:- )

Thanks all!

Mike R

[deputycrawford]

Firefighter or Chryco would know this better but I would put a vacum gauge on it at idle and set it where the vacum is the greatest. If you don't have a guage then I would set it around 12 degrees and check the maximum mechanical advance at around 38 degrees with that cam. Every engine needs different requirements but I would at least start there. Also I had a problem with my Edelbrock 750 carb (the same style you're using). I had the same hesitation. I changed to a Barry Grant Demon carb and it went away. Im sure you can tune that out of your carb. Someone will know how to fix the hesitation. It mey be a separate issue from the timing though.

[Chryco Psycho]

I would have it in  the 14-18* at idle range & 38 8 totaly at approx 3000 rpm
this should kill the hesitation if not let me know & we will work through it

[Mfr426]

Wow! What am I missing with the timing then? Why would the factory tell you 5 BTDC if that's not the right degree? Is it because I have a G motor w/that cam? Can I screw up the motor by advaning the timing that far?

I appreciate the help guys. I mastered the body work and can do the grunt work on the motor but this timing and final setup is the finese that I dont have (yet).

Thanks!

[Just 6T9 CHGR]

I just had Don @ FBO recurve my dizzy for 18º initial with 34º total at 3200rpm for my 440.  All mechanical advance.  No vacuum advance.
I also picked up his ign set up as well.

I have yet to test it out though.......too damn cold!!    Neil would know about cold though




www.4secondsflat.com

[Mfr426]

Does the curving basicailly make the dist at 18 degrees "out of the box" where it would have been 5 degrees?

[Chryco Psycho]

5* works for emmisions & stock cams , with a lot more duration & especially if the compression is low ti makes a huge difference to have a lot more initial advance + it will run cooler too , yes you need to recurve the dist to limit the high rpm advance so it will not over advance , this can be done 2 ways , either inserting an allen wrench into tthe vacuum advance unit & turning the screw inside counterclockwise 10 -14 turns or just diconnect the vacuum advance totally ,or by welding the slots in the mechanical advance plate to shorten the advance curve 

[Mfr426]

OK, stupid question but if you disable the advance mechanism how does the motor compensate for higher RPM's (with advancing the timing)??

[is_it_EVER_done?]

If I may put my 2 cents in. I would suggest you use a vacuum gage to set your initial timing. Connect the vacuum gauge to manifold vacuum, and adjust (turn) the distributor to reach maximum vacuum. After you reach max vacuum, you will need to adjust the idle screw to drop the idle down to roughly what it was before you started adjusting, then do it all again.

Once you find "highest & best" vacuum, back the timing down till the gage drops by a couple of inches of vacuum. Drive the car around and see/feel if it pings under varying conditions. if it does, back it down a bit at a time (or increase it till it does start to ping, then back it off from that.

Max advance without pinging will give you the best performance/milage regardless of what any specs say. From there you can determine if you want it to advance quicker/slower.

This way is much better than a timing light (in my opinion), since it gives the engine what it want's and need, instead of some generlized spec., and will give you the best results possible without going to a customized advance curve. Just make sure you don't leave it at a level where it pings (even a little) as that will cause damage. Make sure it's backed off to "no ping" and you will probably be quite happy. Should you want to maximize everything, you will need to send out your distributor for a customized advance curve, but even with a pro setup curve, You should "dial it in" as I described above.

P.S. I have GOOD "dial back to zero" timing light that has not been used in YEARS! The best vacuum to slight ping, then back off timing method, is the best way I know.

[Mfr426]

Hey is it ever done, thanks for taking the time to post this detailed answer. I'm eager to hit the garage and attempt to set it up.

I'll post my progress and results.

Thanks again!

Mike R in Reading PA

[firefighter3931]

Mike, the factory roadrunner cam is different from the 284/484 purple shaft. The roadrunner cam is fairly mellow while the 284/484 is rather lopey. Base timing and the advance curve will be different for these two cams. Tuning by vacuum often works well but i still like to get a timing light on it to see where things are.

Ron

[Mfr426]

Thanks Firefighter! When I got that cam package (years ago) I was under the impression that it was the same thing as the RR cam. So, I figured it would be a safe replacement for the stock 2v cam. If I could do it over again it would be something other the this cam. It's seems tempermental.

How does one time a motor at 18 degrees if you dont have the timing marks past the stock numbers?

[y3chargerrt]

Mike you need a timing light with a advance dial in it. This way you can set it to 18 degrees and then set the timing. With the timing light set at 18 degrees all you have to do is set the timing mark to tdc.Then you can set to max advance(34-38) and rev the motor to like 3000 rpms and put the timing mark at tdc.I got one at Carlisle a few years back for maybe 25 bucks.

[Mfr426]

Yep, I do have that. I had NO idea what the hell that knob was for!!! LOL



Thank YOU !!!

Mike R