| [GMCnet] (no subject) [message #100030] |
Thu, 16 September 2010 13:04  |
larry erd
Messages: 132
Registered: August 2010
Karma: 0
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I'm about to order a new Comp Cam for my 403 rebuild and I see 2 cams
listed.The 260H that was recommened
and the 252H that is listed for RV's and towing and also for better
mileage. Which one is the better choice???
A Newbe
larry erd
'77 kingsley
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| Re: [GMCnet] (no subject) [message #100031 is a reply to message #100030] |
Thu, 16 September 2010 13:36  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Larry, what final drive gearing are you using and do you tow, what intake
manifold will you wind up using, and what kind of exhaust system will you be
using? Do you have carb or fuel injection, is it throttle body or
multipoint? Are your heads ported or stock? How fast do you intend to drive?
All these considerations need to be figured into cam choice. Also, are those
roller cam profiles or flat tappet. Do you have needle bearing rocker arms?
I would be glad to help with the cam selection, but I don't have enough info
from you yet. In all likelyhood, the tech guys at Comp will ask you all the
above questions and more, so be prepared with answers when you call to order
the cam. Feel free to contact me off net at jamesh1296@gmail.com
Jim Hupy
Salem, Or
78 Royale 403
On Thu, Sep 16, 2010 at 11:04 AM, larry erd <1ljerd@gmail.com> wrote:
> I'm about to order a new Comp Cam for my 403 rebuild and I see 2 cams
> listed.The 260H that was recommened
> and the 252H that is listed for RV's and towing and also for better
> mileage. Which one is the better choice???
> A Newbe
> larry erd
> '77 kingsley
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] (no subject) [message #100105 is a reply to message #100043] |
Fri, 17 September 2010 09:51 |
Jim Bounds
Messages: 842
Registered: January 2004
Karma: 0
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Senior Member |
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While it is true there are many variables that must be answered to actually pick
a proper cam spec, when building a motor specifically for a GMC, many of the
perameters are fixed as for the specific application. You do not need to cast
such a wide net-- I mean you know you want the motor to have better low RPM
content, you know you do not want a rough idle, you want good vacuum at idle,
you want to run low compression with regular gas with no funky tuning
procedures.
We took those along with the spec of our motor program and came up with a cam
spec that seems to work in our build. What it will do in your, like Uphy said
may be different. The builder should be the one to spec out the cam if he is
the one making the component, machining and spec. selection. There is always a
"balance" on how specific do you wanna be or can aford to be! That last 10%
will cost you much more that the %. Anyone can build a motor to run, thats easy
and cheap-- building one that will stay together pullinf 12,000 pounds is a bit
of a trick!
We no longer offer a "flat tappet motor", just too much risk involved in that.
a roller cam set up can run as much as $1000 for all the mess that goes with
it. A custom grind flat tappet cam will usually run @ $185 with an off shelf
cam if you can find something you would like @ $100. We used to use a Melling
MT-01 cam-- was a descent overal grind. If you want to use my cam, give me a
call and we can talk about that 321-299-5707.
Hope this helps,
Jim Bounds
-----------------------
----- Original Message ----
From: Howard and Sue <hnielsen2@cox.net>
To: gmclist@temp.gmcnet.org
Sent: Thu, September 16, 2010 5:50:18 PM
Subject: Re: [GMCnet] (no subject)
I have one and love it.
Yes call Jim B.
Howard
----- Original Message -----
From: "Hal Kading" <halkading@fastwave.biz>
To: <gmclist@temp.gmcnet.org>
Sent: Thursday, September 16, 2010 1:50 PM
Subject: Re: [GMCnet] (no subject)
>
>
> Larry,
>
> Arch, who we have been talking about lately, (one of the pioneers of this
> list) along with Jim Bounds and a very experienced Olds engine builder
> developed a low RPM, high torque cam for the GMC motor home. Contact Jim
> Bounds to buy one. I haven't heard any negative comments on the cam.
>
> Hal Kading 77 Kingsley 455 Las Cruces NM
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> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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