Mopar Guys....need some help - idle problem

[R.Olds]

The stock intake is J-U-N-K.

The 509 cam is prolly the best street cam they had. That 528 was on 122 LSA IIRC. I would skip that thing.

At 383 inches it will need to idle at about 12-1300 MINIMUM...1500 will prolly be better.

If you can deal with the idle set there, disconnect the tach.

So, IMHO, ditch the intake and carb. A 750 DP and a single plane intake would be better. A 3.90 gear is about as tall as I would go. With a 2.66 1st gear you may get away with 3.73's. 4.10 would be bitchin'.

Tune from there.

Thanks for the info, the intake will have to stay, for hood clearance.
Im not sure what you mean by "that 528" ?
Since I made the tweaks that I did, it does idle great @ 850, I just dont think it should need 32* advance to do it and still only pull 5" vacuum....something is fubar, I will spend sometime next week checking things out more thorough.
I would like to see a DP with 4 corner idle as well, it may get that before this is over.
As far as gearing.....it is what is is at this point.

[raceczar]

The stock intake is J-U-N-K.

The 509 cam is prolly the best street cam they had. That 528 was on 122 LSA IIRC. I would skip that thing.

At 383 inches it will need to idle at about 12-1300 MINIMUM...1500 will prolly be better.

If you can deal with the idle set there, disconnect the tach.

So, IMHO, ditch the intake and carb. A 750 DP and a single plane intake would be better. A 3.90 gear is about as tall as I would go. With a 2.66 1st gear you may get away with 3.73's. 4.10 would be bitchin'.

Tune from there.

Thanks for the info, the intake will have to stay, for hood clearance.
Im not sure what you mean by "that 528" ?
Since I made the tweaks that I did, it does idle great @ 850, I just dont think it should need 32* advance to do it and still only pull 5" vacuum....something is fubar, I will spend sometime next week checking things out more thorough.
I would like to see a DP with 4 corner idle as well, it may get that before this is over.
As far as gearing.....it is what is is at this point.

The .528 lift purple solid cam. I typed 122 LSA but meant 112.

I would look for a Torker or Torker II or better yet a street dominator if hood clearance is a problem. For most OEM headed MoPar stuff a 112 LSA is a killer.

Trying to get my head around the 850 RPM idle. I have a customer car here (for a cam change) that has the little .480 hydro in it and it likes to idle at 1000. Any less than that and it's not happy.

I will look up the LSA on your cam tomorrow. That .528 solid may be on 100 LSA. I'm sure that .509 hydro is on 108.


FWIW...there is no way that a 383 should run on 32* total if that is what I understand you to say. If it's correct it will be between 38-40 total. Should be all in by 2500 or so. That would be 24 on the crank and 14-16 initial.

[R.Olds]

The stock intake is J-U-N-K.

The 509 cam is prolly the best street cam they had. That 528 was on 122 LSA IIRC. I would skip that thing.

At 383 inches it will need to idle at about 12-1300 MINIMUM...1500 will prolly be better.

If you can deal with the idle set there, disconnect the tach.

So, IMHO, ditch the intake and carb. A 750 DP and a single plane intake would be better. A 3.90 gear is about as tall as I would go. With a 2.66 1st gear you may get away with 3.73's. 4.10 would be bitchin'.

Tune from there.

Thanks for the info, the intake will have to stay, for hood clearance.
Im not sure what you mean by "that 528" ?
Since I made the tweaks that I did, it does idle great @ 850, I just dont think it should need 32* advance to do it and still only pull 5" vacuum....something is fubar, I will spend sometime next week checking things out more thorough.
I would like to see a DP with 4 corner idle as well, it may get that before this is over.
As far as gearing.....it is what is is at this point.

The .528 lift purple solid cam. I typed 122 LSA but meant 112.

I would look for a Torker or Torker II or better yet a street dominator if hood clearance is a problem. For most OEM headed MoPar stuff a 112 LSA is a killer.

Trying to get my head around the 850 RPM idle. I have a customer car here (for a cam change) that has the little .480 hydro in it and it likes to idle at 1000. Any less than that and it's not happy.

I will look up the LSA on your cam tomorrow. That .528 solid may be on 100 LSA. I'm sure that .509 hydro is on 108.


FWIW...there is no way that a 383 should run on 32* total if that is what I understand you to say. If it's correct it will be between 38-40 total. Should be all in by 2500 or so. That would be 24 on the crank and 14-16 initial.

The 509 cam is a 108 LSA.
The 32* is at idle only....so far. Im sure once we find out why the vacuum is so low, I can get the initial timing back down in the 20 range.
I quit messing with things at that point because the 5 " of vacuum just didnt seem right to me. I have zero Mopar experience, and wanted to bounce it off of some guys with hands on experience.

[quickd100]

I'd double check the compression ratio, 383 aftermarket piston selection is limited and in most cases decking the block and milling the heads is required to achieve the desired spec. The .528 MP solid cam is a great cam and can make much better bottom end torque properly set up. X2 on the Street Dominator intake, the stock intake isn't much to write home about.Dave

[andyf]

The Mopar .528 solid cam is a much better street cam than the .509 hyd. The 509 cam has a bunch of overlap which is the root of the poor idle quality. Lots of people have had problems with Mopar engines after using the 509 hyd. It is probably the most complained about cam for Mopar street guys. Low vacuum and a high idle speed really kills off the fun for guys who just want too cruise over to the burger joint.

In your situation you might have other problems than just a bad cam choice. Either low compression or the cam is installed wrong or both. A compression check is the obvious thing to do and then work from there.

[Strange Magic]

Check the cranking compression
check the cranking compression
check the cranking compression
check the cranking compression

You want to be at around 170 to 180, anything under 160 is junk! For this application.

[raceczar]

The Mopar .528 solid cam is a much better street cam than the .509 hyd. The 509 cam has a bunch of overlap which is the root of the poor idle quality. Lots of people have had problems with Mopar engines after using the 509 hyd. It is probably the most complained about cam for Mopar street guys. Low vacuum and a high idle speed really kills off the fun for guys who just want too cruise over to the burger joint.

In your situation you might have other problems than just a bad cam choice. Either low compression or the cam is installed wrong or both. A compression check is the obvious thing to do and then work from there.

'

This is essentially what I said. 850 idle RPM isn't right. Obviously the Vaccuum is low.


That .528 is my most hated cam. 112 LSA is just silly for most stuff.


Why would ANYONE spec the .509 cam for a drive in queen? It needs a single plane intake, decent headers and a 1400 rpm idle. Then it's happy. BTW that .528 still wants a 1200 rpm idle.

The OP just has a bad combo.

[mag2555]

The last time I used the 509 cam as I recall now was in a 440 at some 9.2 comp, and I put Rhodes lifters in it from the start!

[wyrmrider]

X2 on the Rhodes lifters on the 509- I have a new set if anyone needs them
X2 on 108 LCA and overlap on 509 being way too much- but he should be able to get this combo to work
X2 on 112 being just fine on a stock head mopar- they do not like overlap
get this combo to work
going to a single plane will just make it worse till whatever the problem is is sorted out
note aftermarket distributor- why?
and do reseal and double check the intake manifold seal
did compression get posted?
for the next build
FOR the record- do not build mopars with open chamber heads- unless it's a resto deal or Stock
and since piston choices are limited (please correct me- please) might as well build with a 440 crank (AND A 400 or 440 BLOCK)

[R.Olds]

Guys, thanks for the replies.....I have been out of town.
As soon as I can get some time to give this guy a hand, I will check the compression and post the results.
I have no idea who suggested this combo of parts. I was asked to take a look at it is all.

I will hopefully have some time this week to get a little deeper into it.

Rick

[R.Olds]

What did I get myself into....LOL
Think we found the issue.
First I checked cranking compression = 100 to 105 on 2 different cylinders…..YIKES!!
I verified TDC with a piston stop and installed a MSD timing tape to the balancer (no room at this point for a degree wheel) After removing the rocker shafts, I got my dial indicator situated the best I could. The intake starts to open 62* BTDC
According to the specs I have it should be 38*……again…..YIKES!!
I even double checked the lift to make sure we had the cam we thought we had, I measured .340 lobe lift x 1.5 = .510. So I am pretty certain it is the .509 cam.

Does anyone have .020 or .050 open and close numbers for this cam?

TIA,

Rick

[wyrmrider]

Does anyone have .020 or .050 open and close numbers for this cam?
509hyd purple shaft- I have a cam dr run somewhere
however you have a compression (or no compression) problem
the advertised duration is useful ONLY for comparison with other MOPAR and factory cams
and is based on the duration (and timing) at an arbitrary lift supposed to be where the clearance ramp meets the acceleration ramp then they add 4 degrees to both the opening and closing duration (timing point)
quite useless

MOPAR is therefore very anti .050 timings
I do not know of anyone knocking off that cam, unlike the factory HP cam
you could check the comp "Purple shaft" series for one with similar lift
check the rest of the compression
but stock 73 and later MOPAR compression and big cams do NOT go together except on the racetrack with good gas

[R.Olds]

One more thing I forgot to bring up....with the cam advanced 24*, how has this thing not made PTV contact (at least it appears they have not)

And with the cam being advanced that much, wouldnt the cranking comp. be through the roof.

This whole thing is bizzar...

[wyrmrider]

you can't tell if the cam is advanced or not checking from the flank
find the ICL and ExCL by measuring down from each side of the nose
(only turn the cam one way)
also
valves cannot hit pistons if the pistons are 200 down the hole

[R.Olds]

you can't tell if the cam is advanced or not checking from the flank
find the ICL and ExCL by measuring down from each side of the nose
(only turn the cam one way)
also
valves cannot hit pistons if the pistons are 200 down the hole

I know the flank is not going to be the most accurate way, but 24*? I will check the centerline for confirmation though.