805moparkid
Slant and AFX Guy
if you get your timing correct you would probably be fine where you are
Tuning with jets, Power valves and an O2 guage
- Thread starter Kern Dog
- Start date
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if you get your timing correct you would probably be fine where you are
I did some work today.
The distributor in the car was pulled. The Mallory instructions show that the stock arrangement is one purple spring and one brown spring. This is supposed to give a 2 step advance curve. The 2 step curve is a result of one light spring that gives a fast initial curve followed by a stiffer spring that delays the curve rate, hence the TWO stage curve.
My 14 degrees of advance is too short to have a 2 stage. The distributor had 2 pink springs and bent tabs to stretch the spring tension. It obviously wasn't a proper curve though. It was modified in 2005 when I had the car tuned at a shop with a dyno.
I mapped the curve today with the #1 distributor in place. From a 1000 idle, it advances right off idle, gaining about 4 degrees every 250 rpms and fully advanced at just under 2000 rpms. Yeah...FULL advance before 2000 rpms!
I took my spare distributor, the one I'll call #2 and changed the springs. It also had 2 pink springs in it. I changed them to to 2 orange springs. I put #2 in the car and found that it starts advancing later. I didn't get to drive the car because I still have some 110 Sunoco in the tank to use up. I need to run 91 octane to test these changes so I know if they are effective.
Distributor #1 now has 2 brown springs in it. I figure to test both in the car to see if I notice any difference.
Sorry to sound pessimistic, but I am still doubtful that I'll see any improvement. Here is why:
With the advance set to STOP at 31 degrees, I can run it up to 3000, floor it and get pinging. To me, this means that since the spark is done advancing, there is NO MORE CURVE to be an issue. If my thinking is wrong, I would surely appreciate a better understanding of it.
It seems to me that moving the curve later would help. The brown and orange springs are heavier than the light ones the #1 distributor had, so maybe it might help a little.
The distributor in the car was pulled. The Mallory instructions show that the stock arrangement is one purple spring and one brown spring. This is supposed to give a 2 step advance curve. The 2 step curve is a result of one light spring that gives a fast initial curve followed by a stiffer spring that delays the curve rate, hence the TWO stage curve.
My 14 degrees of advance is too short to have a 2 stage. The distributor had 2 pink springs and bent tabs to stretch the spring tension. It obviously wasn't a proper curve though. It was modified in 2005 when I had the car tuned at a shop with a dyno.
I mapped the curve today with the #1 distributor in place. From a 1000 idle, it advances right off idle, gaining about 4 degrees every 250 rpms and fully advanced at just under 2000 rpms. Yeah...FULL advance before 2000 rpms!
I took my spare distributor, the one I'll call #2 and changed the springs. It also had 2 pink springs in it. I changed them to to 2 orange springs. I put #2 in the car and found that it starts advancing later. I didn't get to drive the car because I still have some 110 Sunoco in the tank to use up. I need to run 91 octane to test these changes so I know if they are effective.
Distributor #1 now has 2 brown springs in it. I figure to test both in the car to see if I notice any difference.
Sorry to sound pessimistic, but I am still doubtful that I'll see any improvement. Here is why:
With the advance set to STOP at 31 degrees, I can run it up to 3000, floor it and get pinging. To me, this means that since the spark is done advancing, there is NO MORE CURVE to be an issue. If my thinking is wrong, I would surely appreciate a better understanding of it.
It seems to me that moving the curve later would help. The brown and orange springs are heavier than the light ones the #1 distributor had, so maybe it might help a little.
Where did you adjust the mechanical advance?
I reset the intial at 17. The advance stops at 31 degrees which occurs just shy of 2000 rpms. This was with the Distributor #1 in the form it has been since 2005. With the orange springs I put in distributor #2, the curve begins about 400 rpms off of idle and ends about 2400 rpms.
Just a question because I really do not know: Besides stiffer springs, is there any way to get this curve a little flatter? I mean even with 2 orange springs it just ramps up so dang steep.
Just a question because I really do not know: Besides stiffer springs, is there any way to get this curve a little flatter? I mean even with 2 orange springs it just ramps up so dang steep.
So it's all in by 2400? I think that's still too early. But try it.
Are you saying you loosened the two allen head screws under the breaker plate and adjusted the mechanical advance with the little red key spacers?
Yes. the red guages help to set the total amount of advance that the distributor will give. This kit has them in even number of degrees from 14 to 28.
I used the stiffest springs in the kit on one distributor and the 2nd stiffest on the other.
I used the stiffest springs in the kit on one distributor and the 2nd stiffest on the other.
Well, keep messin with it. Cause if you don't think the red keys and spring will make a difference, you need to load the car up and send it to me.
Cute.....
txstang84
Well-Known Member
I think he was sorta serious ;)
Rob, haven't you set up other folks dizzys for them?
Rob, haven't you set up other folks dizzys for them?
A good bit, but I have to have the whole car.
txstang84
Well-Known Member
I dig it
I am in a bit of a holding pattern at the moment. I am strongly leaning toward using the .075 Cometics to drop the CR down to 9.89 to 1. This will give me a great amount of wiggle room for almost any condition. While the heads are off, I want to get them ported and resurfaced. I'm sure this will reduce the CCs of the chambers a slight amount, but the MLS gaskets need a smooth finish to seal right.
Over the last few days I've been playing detective. I looked around for information on the actual specs for the MP 509 cam to compare it to the Lunati I have in there now. It turns out that the 509 actually had a LATER intake closing than this Lunati. The 509 was actually degreed to be 1.5 degrees retarded from the straight up position. THIS explains why the cranking compression actually went UP with the new Lunati and it also explains why the car detonates more now than it ever has.
The dynamic compression calculators ask for an intake closing PLUS 15 degrees. MP seems to refuse to join the industry by publishing specs only THEY use, but The 509 had a intake closing at 74 degrees ATDC. The Lunati is at 56.5. Adding the 15 degrees for computing purposes, the Lunati is at 71.5. If my 509 was retarded 1.5 degrees, would that mean that .75 degrees of that would then be added to the 74? If so, the 509 had a 74.75 degree closing point. The Lunati has 71.5.
Please feel free to set me straight if I have this wrong.
I like the performance of this cam. Driving it with the 110 gas was a blast. It idles a bit better and feels stronger than the 509 and even the 509 with the 1.6 rocker arms.
Months ago I was tempted to go with the Comp XE 294 hydraulic. It has a 73 degree intake closing. If I had better luck digging around for the specs on the 509 I might have had picked a different cam. For now, I'll stick with this Lunati. The EDM lifters give me more confidence in cam life. The performance is great. Once the compression ratio is dropped down and the spark curve is set up, it should run strong and not detonate.
Over the last few days I've been playing detective. I looked around for information on the actual specs for the MP 509 cam to compare it to the Lunati I have in there now. It turns out that the 509 actually had a LATER intake closing than this Lunati. The 509 was actually degreed to be 1.5 degrees retarded from the straight up position. THIS explains why the cranking compression actually went UP with the new Lunati and it also explains why the car detonates more now than it ever has.
The dynamic compression calculators ask for an intake closing PLUS 15 degrees. MP seems to refuse to join the industry by publishing specs only THEY use, but The 509 had a intake closing at 74 degrees ATDC. The Lunati is at 56.5. Adding the 15 degrees for computing purposes, the Lunati is at 71.5. If my 509 was retarded 1.5 degrees, would that mean that .75 degrees of that would then be added to the 74? If so, the 509 had a 74.75 degree closing point. The Lunati has 71.5.
Please feel free to set me straight if I have this wrong.
I like the performance of this cam. Driving it with the 110 gas was a blast. It idles a bit better and feels stronger than the 509 and even the 509 with the 1.6 rocker arms.
Months ago I was tempted to go with the Comp XE 294 hydraulic. It has a 73 degree intake closing. If I had better luck digging around for the specs on the 509 I might have had picked a different cam. For now, I'll stick with this Lunati. The EDM lifters give me more confidence in cam life. The performance is great. Once the compression ratio is dropped down and the spark curve is set up, it should run strong and not detonate.
The 509 valve closing is advertised. The Lunati is @ .050".
The distributor curve will fix your problem. I cannot understand why you don't want to pursue it further.
:banghead:
The distributor curve will fix your problem. I cannot understand why you don't want to pursue it further.
:banghead:
This was my point. The MP numbers are the "advertised" numbers. I thought that the .050 number PLUS 15 degrees gets you back to the advertised numbers.
Is this not a direct comparison?
Yes...I have taken the distributor as far as it can go with the Mallory springs. To slow the advance any more, I'll need some bigger springs.
805moparkid
Slant and AFX Guy
so get some bigger springs or make the weights lighter.
Voeltagear
Well-Known Member
Experience I have with compression over 11.0 is that you can run pump gas BUT, your timing will need to come on late. Data logging OBDII- it will not be in until over 4K! sensor feed back and computer controls are wonderful for pulling out all the performance of your setup "AS IS". best thing to do is build something streetable for your "application". IE pump gas, carb, head, cam selection, etc... Other wise you NEED to spend the time/money to Fine tune fuel AND timing curves. OR just pull out some timing, add some fuel, lose what ever power you were trying to build, and call it a day.
RustyRatRod is not wrong to say fine tune the timing. You will need a lot of patients and a vacuum gauge and knock sensor light (along with your A/F guage) in the car at all times. then you can adjust cruise and power mode A/F's and timing till knock is not noticeable. You will never fully realize the engines potential on pump gas but you will eventually find the bitter edge, then you can pull back a couple degrees and add a little fuel for extreme temps and rest easy. Until then have fun dancing on eggshells every time you hit the loud pedal.
My $.02
RustyRatRod is not wrong to say fine tune the timing. You will need a lot of patients and a vacuum gauge and knock sensor light (along with your A/F guage) in the car at all times. then you can adjust cruise and power mode A/F's and timing till knock is not noticeable. You will never fully realize the engines potential on pump gas but you will eventually find the bitter edge, then you can pull back a couple degrees and add a little fuel for extreme temps and rest easy. Until then have fun dancing on eggshells every time you hit the loud pedal.
My $.02
His compression is "only" 10.7 with Eddy heads and Lunati's stout 261 271 @ .050 108 LSA solid cam. He should run on pump gas fairly easily. I firmly believe his timing curve is the answer now. I have given up getting him to believe it.
Oh my god,too much data overload. No wonder.
txstang84
Well-Known Member
The slowest curve it can make is still all in before 3k? The MSD I used to run could be curved from 1800-4500 all in, are you sure that's as slow as it can go with the parts?
If you can't make it slower than 3k, then this is likely your best option for a slowed curve...
But since you've already decided to open up the chambers by putting in 0.075" gaskets, maybe it'll help...good luck.
805moparkid
Slant and AFX Guy
right... I mean my slant is dead on 10:1 with 246 @ .050 almost 20* less, that thing should be pump easy...
The car may have been streetable with more work with the timing, but screw it....I am tired of being so close to the edge all the time. Driving a car that requires so much attention isn't any fun to me. In a way, it was like having a slutty supermodel for a girlfriend. I was always having to be on the alert.
This car is supposed to be a fun driver, not a JOB. I dont like manual transmissions or manual steering. I want to stab and steer. I want a fast car that doesn't require me to be hyper-vigilant like a marine on military patrol.
I pulled the heads. I am going to have them ported and the thicker gaskets are going on. The miniscule loss of power from lower compression will be nothing. The gains from porting the heads and running a traditional spark curve will be noticeable. I figure 30-40 HP for the porting, 20-25 HP for the timing and maybe a 15 HP loss from the compression. That is a 40+ HP gain with the freedom to run pump gas in any condition. I might even be able to run vacuum advance again to gain a bit better mileage on trips. I gained 1.8 mpg the last road trip by using vacuum advance. In 1000 miles, that makes a difference.
From Don at FBO ignition:
************************************************************************
While you have the race gas in it, crank the timing to the proper 34* and give a drive, you’ll pick up another at least 30-50 HP
*********************************************************************************************
I interpret this to mean that with NO detonation present, the greater amount of timing will result in a big increase in power.
CPMotorworks
Well-Known Member
Did I read you have a GV OD unit on this setup?
Yeah, but I have considered removing it. If the engine performs as I expect it to after the I get it back together, I may switch from the 3.91s to 3.23s or 3.55s and direct drive again. I got almost 11 mpg with 3.23s at freeway speeds in 2011. I do most of the driving locally anyway.
There has been a slight vibration since the install. It is probably because I didn't cram it up in the tunnel high enough and the driveline and U-joints aren't aligned properly. I'm sure that there is some parasitic loss associated with it too. I kept my stock tailshaft and drive shaft in case I didn't want to keep it.
There has been a slight vibration since the install. It is probably because I didn't cram it up in the tunnel high enough and the driveline and U-joints aren't aligned properly. I'm sure that there is some parasitic loss associated with it too. I kept my stock tailshaft and drive shaft in case I didn't want to keep it.
CPMotorworks
Well-Known Member
Well, not to sound harsh but your combo is in left field.
Sounds to me like you wanted a driver that was fairly quick and cruised nice, but have a semi-race cam in an engine that your trying to make run at low rpm cleanly and get decent gas mileage.
I don't think it will do either one very well the way its setup now, no matter the amount of tuning you do.
Sounds to me like you wanted a driver that was fairly quick and cruised nice, but have a semi-race cam in an engine that your trying to make run at low rpm cleanly and get decent gas mileage.
I don't think it will do either one very well the way its setup now, no matter the amount of tuning you do.
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