Chrysler short ram cam choice

General engine tech -- Drag Racing to Circle Track

Moderator: Team

Post Reply
quickd100
Pro
Pro
Posts: 334
Joined: Sun Jul 18, 2004 7:34 am
Location: Nielsville, Mn.

Chrysler short ram cam choice

Post by quickd100 » Sat Feb 09, 2019 9:12 am

I've got an off the wall question for you guys. I picked up a set of original Chrysler short ram manifolds. I've got a 440 Dyno mule to test them on. Also a set of 1-3/4" headers. Heads are cast iron production with standard 2.08/1.74 pocket ported, port matched, nothing earthshaking. Compression will start at 9-1, I can change pistons to get it to 11.2-1 if I'm not satisfied with the output. Carb sizes, I will be starting with a set of 500 cfm Carter's, also have a set of 750 CS Carter's, 800, 850, and 1000 cfm thermoquad.
The monkey wrench in the mix are the short ram manifolds, I need suggestions for cam specs to get the most out of these manifolds. I m not worried about low-end torque or drivability so you can take that off the table. Suggestions????
[img]http://img.photobucket.com/albums/v514/quickd100/9ff3c690.jpg[/img]

Dan Timberlake
Guru
Guru
Posts: 1396
Joined: Tue Jan 15, 2013 8:10 pm

Re: Chrysler short ram cam choice

Post by Dan Timberlake » Sat Feb 09, 2019 11:46 am

As a starting point, the original Chrysler manifold math //may// be contained in the old Hot Rod Magazine article here -

http://wildaboutcarsonline.com/members/ ... ds_1-6.pdf

On line there are some claims the long rams were 30" and the short rams were half that, but I'm thinking the length of the head port, necessary for the simplified Mopar math, may not be included in those lengths.
I sure wish I was in your situation, being able to measure for real.

quickd100
Pro
Pro
Posts: 334
Joined: Sun Jul 18, 2004 7:34 am
Location: Nielsville, Mn.

Re: Chrysler short ram cam choice

Post by quickd100 » Sat Feb 09, 2019 11:52 am

The long rams and short rams look identical except the dividers between the runners are shorter on the short rams. The long rams have dividers walls from the head port to the plenum under the carb.
[img]http://img.photobucket.com/albums/v514/quickd100/9ff3c690.jpg[/img]

PackardV8
Guru
Guru
Posts: 5575
Joined: Sun Jul 30, 2006 2:03 pm

Re: Chrysler short ram cam choice

Post by PackardV8 » Sat Feb 09, 2019 12:02 pm

IIRC, the short ram intakes just moved the torque peak higher, from 2800 to 4400.

One quote in there I'd forgotten is the claim the short ram intake outpulled the conventional dual quad above 4400.

Maybe that's true in the street RPM range with the very low rise iron dual quad Mopar was using at the time. Not so much against today's tunnel ram.

jack vines
Last edited by PackardV8 on Sat Feb 09, 2019 12:13 pm, edited 1 time in total.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering

quickd100
Pro
Pro
Posts: 334
Joined: Sun Jul 18, 2004 7:34 am
Location: Nielsville, Mn.

Re: Chrysler short ram cam choice

Post by quickd100 » Sat Feb 09, 2019 12:12 pm

Correct, the old figures for a 413 were 400hp@5200&465ftlbs@3600 while the long rams were rated at 375hp&495ftlbs@2800. You also have to realise that these motors were installed in 4000+lb street cars with low stall convertors and low numerical gears. When and if I put this motor in anything it will have a convertor matched to the torque peak and also deeper gears.
[img]http://img.photobucket.com/albums/v514/quickd100/9ff3c690.jpg[/img]

Dan Timberlake
Guru
Guru
Posts: 1396
Joined: Tue Jan 15, 2013 8:10 pm

Re: Chrysler short ram cam choice

Post by Dan Timberlake » Sat Feb 09, 2019 12:36 pm

"the short ram intakes just moved the torque peak higher, from 2800 to 4400."

The short rams were also part of the factor skunk works type assault package on the 1959 or 1960 Daytona flying mile competition.
https://www.conceptcarz.com/profile/173 ... -300f.aspx

http://300f.com/media/ama_specs.pdf

First cut at the rpms to go 144 mph with 2.93 rear gear and 26.8" tall tires but neglecting tire slip on the Daytona sand results in GOOD power to at least ~5300 rpm.

https://www.blocklayer.com/rpm-geareng.aspx

quickd100
Pro
Pro
Posts: 334
Joined: Sun Jul 18, 2004 7:34 am
Location: Nielsville, Mn.

Re: Chrysler short ram cam choice

Post by quickd100 » Sat Feb 09, 2019 2:25 pm

So anyway, back to my original question. I'd like a solid flat tappet cam for it. As it's got these unique induction manifolds I'd like to find something that will work well with them.
[img]http://img.photobucket.com/albums/v514/quickd100/9ff3c690.jpg[/img]

Powertrip
Pro
Pro
Posts: 257
Joined: Sat Feb 10, 2007 11:09 am
Location: North West Indiana

Re: Chrysler short ram cam choice

Post by Powertrip » Sat Feb 09, 2019 2:58 pm

I'd be interested in what Mike Jones would spec for it. I do know that when they were playing around with "inertia tuning" back in the day the claim was you had to delay the IVC to see a benefit. Chrysler seems to agree- the cam specs for the 300F are 117 ICL and 112 ECL, 2.5 degrees retarded.
The price of progress is trouble.

Powertrip
Pro
Pro
Posts: 257
Joined: Sat Feb 10, 2007 11:09 am
Location: North West Indiana

Re: Chrysler short ram cam choice

Post by Powertrip » Sat Feb 09, 2019 3:27 pm

The cork in your system will be your cylinder heads, those manifolds flow better than those mild heads.

I had a set of the "long" rams on the flowbench once, they flowed as well as a good aftermarket 4 barrel, iirc.
The price of progress is trouble.

quickd100
Pro
Pro
Posts: 334
Joined: Sun Jul 18, 2004 7:34 am
Location: Nielsville, Mn.

Re: Chrysler short ram cam choice

Post by quickd100 » Sat Feb 09, 2019 4:03 pm

I agree about the cylinder heads being a cork. I'm wedge head poor right now. I've got 2 sets of Indy aluminum Hemi heads and 1 factory cast iron set ready to roll. I just haven't felt the need for any good wedge heads.
[img]http://img.photobucket.com/albums/v514/quickd100/9ff3c690.jpg[/img]

Geoff2
Guru
Guru
Posts: 1006
Joined: Mon Nov 09, 2015 4:36 pm
Location: Australia

Re: Chrysler short ram cam choice

Post by Geoff2 » Sun Feb 10, 2019 4:25 am

Mopar Performance made a series of SFT cams, The smallest & probably best for your mild heads is the P4120659. 284/284* adv. 112LSA. 0.528" lift. May still be available.

quickd100
Pro
Pro
Posts: 334
Joined: Sun Jul 18, 2004 7:34 am
Location: Nielsville, Mn.

Re: Chrysler short ram cam choice

Post by quickd100 » Sun Feb 10, 2019 7:58 am

Geoff I've used that cam before and it was a little torque monster. Unfortunately I don't have it anymore. I was thinking about using one if nothing else pans out.
[img]http://img.photobucket.com/albums/v514/quickd100/9ff3c690.jpg[/img]

Powertrip
Pro
Pro
Posts: 257
Joined: Sat Feb 10, 2007 11:09 am
Location: North West Indiana

Re: Chrysler short ram cam choice

Post by Powertrip » Sun Feb 10, 2019 12:53 pm

Using an off the shelf cam isn't going to tell you much about the potential of those manifolds, you need a unique cam to match the unique characteristics of ram manifolds. Even those short rams are longer than the longest tunnel ram.

Calling Mike Jones...Calling Mike Jones... :D
The price of progress is trouble.

Post Reply