Need advice - potential new cam and manifold

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Tjhoward84

Tjhoward84

1969 Barracuda Convertible
Joined
Mar 19, 2014
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A few of my buddies and I recently completed the build of a 1969 Barracuda convertible for my buddies wife after my buddies untimely death. My buddy bought a Magnum crate 360 engine for the car. After installing it and getting it started we noticed very little braking. Further investigation turned up the fact the engine created very little vacuum at low rpm. After installing a power break booster pump with little changes to the braking, we are now thinking about changing the cam. The current cam in the crate engine has the follow characteristics:

Intake valve diameter: 1.925
Exhaust valve diameter: 1.625
Intake lift: .501
Exhaust lift: .513
Intake duration: 288 deg
Exhaust duration: 292 deg

Also the current cam had a 108 center line bore.

Lastly, the crate engine came with a M-1 Single Plane manifold. After talking to the tech people at Magnum Performance, they told me that us set up to be run on a track and not on the street. They told me to change out the manifold to something like an Edelbrock dual plane RPM manifold and to a more mild cam like the Magnum Performance P5155563 cam.

My buddies wife who owns the car will only drive the car on nice spring/summer days around town. It will very rarely get on the freeway.

What are people's thoughts? Keep the existing cam & manifold or tone things down with a more mild cam and better performing manifold combo.

The carb us a Holley 750.
 
Yeah that ain't a power brake friendly cam.
 
Throw in a set of Rhoades lifters part # 2018

They will bleed down at low RPM and take some of the harshness out of the cam, and increase intake vacuum.

A smaller cam will help that also, but still consider Rhoades lifters...


Read the second article to learn how they work...

http://www.rhoadslifters.com/Pages/Articles.html
 
I would try a vacuum canister first. That might be enough to do it.
 
krazykuda said:
Throw in a set of Rhoades lifters part # 2018

They will bleed down at low RPM and take some of the harshness out of the cam, and increase intake vacuum.

A smaller cam will help that also, but still consider Rhoades lifters...


Read the second article to learn how they work...

http://www.rhoadslifters.com/Pages/Articles.html
Click to expand...

I think the cam is a roller. Those 2018's will kill it. Rhoades Rollers are close to $300, Will she be good with the noise?

What's the tune up on the engine? Adequate initial timing is key with a hot camshaft. If it doesn't have at least 18*, it's not likely enough.

A smaller cam like you posted would help a lot. You could also get a core hyd roller cam and have one cut to your spec by oregon cams, bullet, comp or any number of cam shops.

Putting an rpm or air gap dual plane intake on it will help as well.
 
The current cam that came with the crate engine is a hydraulic roller cam.

We are trying to keep the noise to a minimum.

Need to make this car a great a weekend driver for a 50 year old woman with a 9 year old little girl.
 
Find out where the initial timing is and let us know.
 
The RPM manifold is a great manifold hands down. It will help with low end power & still breath on the top end great choice.
 
If it were I doing a street driver, it would be;

Edelbrock's RPM
650 Thunder
Milder cam

Resell the single plane M-1, carb and cam.
 
crackedback said:
I think the cam is a roller. Those 2018's will kill it. Rhoades Rollers are close to $300, Will she be good with the noise?

What's the tune up on the engine? Adequate initial timing is key with a hot camshaft. If it doesn't have at least 18*, it's not likely enough.

A smaller cam like you posted would help a lot. You could also get a core hyd roller cam and have one cut to your spec by oregon cams, bullet, comp or any number of cam shops.

Putting an rpm or air gap dual plane intake on it will help as well.
Click to expand...



They also make Rhoades lifters in roller part number 1068

We have them in my son's 91 360 for his 71 Valiant 4 door. We went with a Edelbrock LD340, Hughes 1928 hydraulic roller cam, Rhoades lifters, and early 340 exhaust manifolds, and Holley 80457 600 vac secondaries.


This is our first hydraulic roller motor, and we haven't installed it in the car yet (getting there slowly...). I've Rhoades lifters for years with flat tappet cams and love them. I haven't noticed the extra noise, or it doesn't bother me... The guy who turned me onto the Rhoades lifters told me that if I don't like the noise, to just double up on the hood pad/insulation to help dampen the "tick".... If anyone asks, it's a solid tappet 273.... (Brand X guys are gullable enough to believe it....).


You can still run a good spark curve with the Rhoades. I have them in my 340-S Barracuda with the MP .484/284 cam and they worked great. With stock lifters, it idled very choppy at 1100 RPM and 10-10.5" Hg. With Rhoades lifters I have it at 17° initial spark and 36° total and it runs like a raped ape. Much smoother with 13" Hg and more consistent idle vacuum.


I've also used them in a 318 with stock 340 cam and idled at 22.5" Hg and got 17.75 MPG.
 
Tjhoward84 said:
A few of my buddies and I recently completed the build of a 1969 Barracuda convertible for my buddies wife after my buddies untimely death. My buddy bought a Magnum crate 360 engine for the car. After installing it and getting it started we noticed very little braking. Further investigation turned up the fact the engine created very little vacuum at low rpm. After installing a power break booster pump with little changes to the braking, we are now thinking about changing the cam. The current cam in the crate engine has the follow characteristics:

Intake valve diameter: 1.925
Exhaust valve diameter: 1.625
Intake lift: .501
Exhaust lift: .513
Intake duration: 288 deg
Exhaust duration: 292 deg

Also the current cam had a 108 center line bore.

Lastly, the crate engine came with a M-1 Single Plane manifold. After talking to the tech people at Magnum Performance, they told me that us set up to be run on a track and not on the street. They told me to change out the manifold to something like an Edelbrock dual plane RPM manifold and to a more mild cam like the Magnum Performance P5155563 cam.

My buddies wife who owns the car will only drive the car on nice spring/summer days around town. It will very rarely get on the freeway.

What are people's thoughts? Keep the existing cam & manifold or tone things down with a more mild cam and better performing manifold combo.

The carb us a Holley 750.
Click to expand...

Sounds like you have a 360 'Magnum' 380 HP crate engine.
* 380 HP @ 5300 RPM's
* 410 Ft/Lbs. of Torque @ 4400 RPM's

We just put that Engine Package in for one of our customer's.

We had to pull off the M1 Single-Plane Intake, and popped on an Edelbrock RPM {#7176} Dual-Plane Intake.

It made a World-of-Difference for Street drive-ability.

The Hydraulic Roller Camshaft
Lift ..................... .501"/.513"
Duration ............... 288*/292"
Duration @ .050" ... 230*/234*

Reacted much better to the Dual-Plane Intake, especially at low RPM's.
 
69 Cuda 440 said:
Sounds like you have a 360 'Magnum' 380 HP crate engine.
* 380 HP @ 5300 RPM's
* 410 Ft/Lbs. of Torque @ 4400 RPM's

We just put that Engine Package in for one of our customer's.

We had to pull off the M1 Single-Plane Intake, and popped on an Edelbrock RPM {#7176} Dual-Plane Intake.

It made a World-of-Difference for Street drive-ability.

The Hydraulic Roller Camshaft
Lift ..................... .501"/.513"
Duration ............... 288*/292"
Duration @ .050" ... 230*/234*

Reacted much better to the Dual-Plane Intake, especially at low RPM's.
Click to expand...

You are 100% correct - we have a 1998 Magnum Crate 360 with the exact cam and M1 Single-Plane manifold you mention. Are you saying that with just a manifold change (Edelbrock RPM PN7176) that it solves the low vacuum issue for power brakes and makes the car more "streetable" around town? The manifold is easy to switch out compared to switching out the cam. Right now I am looking at replacing both the cam and manifold and while the shop has the motor out of the car, to also install a set of TTI ceramic coated polished headers.

Thoughts would be apprecaited on low idle vacuum with just the manifold change.
 
You've been asked where the initial timing is. You might be able to fix your problem with NO money spent at all if initial timing is low. Tell us where initial timing is and we can go from there.
 
The JEGS website says the Edelbrock RPM 7176 will not fit '92 later Magnum engines. I have a '98 Magnum engine. Does someone have the Edelbrock RPM manifold number that will fit my engine?
 
RustyRatRod said:
You've been asked where the initial timing is. You might be able to fix your problem with NO money spent at all if initial timing is low. Tell us where initial timing is and we can go from there.
Click to expand...

If I remember correctly, I think the timing is set at 10 deg BTDC. The speed shop that tuned the car did all the timing.
 
Tjhoward84 said:
If I remember correctly, I think the timing is set at 10 deg BTDC. The speed shop that tuned the car did all the timing.
Click to expand...

If that's true, there's your problem. Get you a timing light and look at it yourself. This is easy stuff. It can probably stand close to twice that which will raise the manifold vacuum tremendously and then you will have power brakes. I would bump it to 16 and see if you get spark knock. See if the brakes work better. I am sure they will. You will probably need to readjust the idle.
 
Tjhoward84 said:
The JEGS website says the Edelbrock RPM 7176 will not fit '92 later Magnum engines. I have a '98 Magnum engine. Does someone have the Edelbrock RPM manifold number that will fit my engine?
Click to expand...

I apologize, my error.

It is Edelbrock Part #7577 for the later Magnum engines.
 
I have a Hughes 232* flat tappet in my 360.Even at 14* initial it makes enough vacuum to work the brakes just fine. Jus saying. Even my previous cam the 292/509 @ 18*initial made enough.I just dont understand all the trouble so many guys have. :(
Crank in some timing, for petes sake. Crank it in!
 
RustyRatRod said:
If that's true, there's your problem. Get you a timing light and look at it yourself. This is easy stuff. It can probably stand close to twice that which will raise the manifold vacuum tremendously and then you will have power brakes. I would bump it to 16 and see if you get spark knock. See if the brakes work better. I am sure they will. You will probably need to readjust the idle.
Click to expand...

If it's 9.5-10:1 it will likely take in the 20* range. The distributor will need adjusting to hit a safe total number.

No chance that thing runs clean at idle with only 10*, that's stock cammed 318 territory.
 
Talked to Mopar Performance again today.

At idle, no vacuum, this engine needs 10 -14 degrees of timing.

Total timing at 2,500 RPM and no vacuum is supposed to be 34-38 degrees.
 
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