John,
Cam Selection should be based on what you are trying to do and the components that you are going to replace. On the Magnum engines, there are a couple of things that we need to work within. The heads (both stock and ported), tend to like a little more duration on the exhaust. Because of this, split duration cams seem to make more power. The computers can be modified to work with duration figures up to approx. 225 degrees duration. The key is to have idle vacuum of 10 inches or more and the lobe separation angle should ideally be 114 degrees but you can get by with 112 degrees. The heads (with stock valves) tend to flow all the way up to .600 lift so the more lift the better. With 1.7/1 rockers, you can build the lift faster and add additional lift if needed so the 1.7's are a good bet. If larger intake valves are installed and the intake ports modified correctly, then you will see a reversion in flow at about .550 lift but don't worry about this because of flow figures while y!
!
ou are opening the valve. In regards to emissions, duration figures above 220 degrees @ .050, the engines tend to get dirty and will not pass emissions tests (keep this in mind). With high lift cams, make sure you upgrade the valve train components to match the cam (stiffer springs, better rockers and especially the rocker hold-down bolts). Match the cam to the intake manifold you are going to run. It doesn't make sense to select a cam that has a powerband of say 2,500 - 6,000 RPM if you are using the stock intake. The stock intake flows best from 1,500 - 4,000. Match the powerband of the cam to the weight of the truck, the gearing and the torque converter. Sort of a long way around answering your question. If you want my opinion on a cam for your truck, take a look at this custom grind out of Crane (P/N 70HR00003). Give Crane a call and they will fax you the Cam Spec. Card. The figures are 208, 214 degrees duration at .050, lift figures int. .467, exh. .520 inch. Lobe Separa!
!
tion Angle is 114 degrees and the powerband of this cam is 2,000 - 5,500 RPM. This cam is one step above the "RT" cam and will work fine with just about anything you want to do. All of Crane's cams are based on new cam cores (not re-grinds) and can be ordered through places like Summet and Jegs for around $220.00. If you can tolerate slightly more duration and lift, switch to the 1.7/1 rockers and you will have lift figures of .496 - int., .552 - exh., with a couple of degrees more duration at .050 inch. If you really want to get crazy, check out Crane P/N 70HR00004.
Frank
---------------------- Forwarded by Frank T Holloway/CA/KAIPERM on 11/26/99 07:57 AM ---------------------------
jmautz@home.com on 11/25/99 09:34:00 PM
To: dakota-truck@buffnet.net@Internet
cc: (bcc: Frank T Holloway/CA/KAIPERM)
Subject: DML: RE: Re: Hughes Engines Cam selection - Frank
Frank,
Thanks for the suggestion.
The next step in the Hughes line would be the HER1218AL. The main difference
is the exhaust lift is .527 and the duration is longer (in/out = 215/220 @
.050 tap. lift). The rest is about the same. Does this sound like a better
cam for my situation?? I know that loss of low end torque will really kill
me because of the weight of my 4x4 Durango.
They say that they'll do custom grinds, so would the best of both cams be to
use the HER0612AL as the base (duration) then add the .527 on the exhaust
and the 114 LSA?
Thanks for you help!
John
P.S. I will be adding a set of ported heads when I do the cam install.
>----- Original Message -----
>From: John Mautz <jmautz@home.com>
>To: <dakota-truck@buffnet.net>
>Sent: Tuesday, November 23, 1999 9:25 PM
>Subject: DML: Hughes Engines Cam selection
>
>
>> Hi all in DML land!
>>
>> I know at least one of you has installed a Hughes Cam but I don't
remember
>> which one and I would like to know how which one you went with and how
the
>> install went.
>>
>> I'm thinking of their HER0612AL Magnum Roller Cam for my '99 5.9L
Durango.
>>
>> Here are the cam specs:
>>
>> Lift @ 1.6 ratio: in/ex .512"/.512"
>> Dur @ .2": in/ex = 126/131
>> Dur @ .05": in/ex = 208/214
>> Ad Dur @ .02": in/ex = 258/260
>> LSA: 112
>> Open @ .05" tappet lift: in/ex = 12 ATC/36 BBC
>> Close @ .05" tappet lift: in/ex = 40 ABC/2 BTC
>>
>> They make hotter cams but if the magnum roller cam fits their other
>> descriptions this would most likely be my best choice, but if
>you picked a
>> different one I would like to what your reasons were (I could be wrong in
>my
>> thinking).
>>
>> Hughes Engines web site is http://hughesengines.com.
>>
>> Thanks,
>> John.
>>
>
>
>
>
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