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Randy
Dodge Dakota
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11/11/2003
09:24:32
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 Subject: Cam v. 1.7's- if only one...?
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I kinda believe that simply installing a higher ratio rocker arm (1.7) is a "lazy man's cam". Yet I've done it many times. I am thinking of getting the comp cam 3310/3311 HR112. It's got .504/.512 lift with the stock 1.6 rocker arms. Naturally I will be installing new springs if I do this cam. I've calculated the lift of the stock cam with 1.7's to be .459/.459, but my duration won't change as if I did the cam. I do, however, like the benefit of the aluminum roller rocker compared to the mushy stamped ones. My question is- what would the power increase difference be between A.Stock cam with 1.7 roller rockers OR B. The cam I mentioned using the stock non roller 1.6's ?? Aside from the ratio, what would my potential gain be by simply going to roller (not changing ratio) ? Thanks in advance
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Randy
Dodge Dakota
JOIN HERE
11/11/2003
12:02:23
| RE: Cam v. 1.7's- if only one...?
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Nevermind the question about using roller 1.6's with the stock cam, KRC claims 6 hp. They claim 1.7 rollers alone will yeild up to 15 hp. What do you think that comp cam I mentioned will give me if I re-use the stock 1.6 non-roller rockers?
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J and J Auto
GenII
11/11/2003
12:27:06
| RE: Cam v. 1.7's- if only one...?
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The 1.7's also give you around 4 more degrees duration
The 1.7's add anywhere from 15 to 18 hp starting
at 1800 rpm
the 1.6 rollers about 5 hp just by reducing
friction and heat
What is the duratoin of the cam you mention the
stock cam with 1.7's will give you around 254/268
duration and more like a .480 lift 112 centerline
and an overlap of about 36
Stock springs can handle upto a .500 lift without
binding
Larry
J&J Auto
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Randy
Dodge Dakota
JOIN HERE
11/11/2003
15:38:36
| RE: Cam v. 1.7's- if only one...?
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Comp Cam- 200/206 duration @.50, .504/.512 lift using 1.6 ratio rockers, 112 LSA
Stock magnum cam- 250/264 total advertised duration, .432/.432 lift using 1.6 ratio rockers.
those are all the specs I can find on the cams
according to my math- (.432 / 1.6) x 1.7 = .459 is the total lift using the 1.7 rockers
I have seen advertisements saying that increasing rocker ratio will increase advertised duration so I won't argue with that.
I would really like to do a cam AND 1.6 rollers but I just can't afford both. The truck's got a manual trans and 3.55 gears so I don't know if I'd really feel the 1.7's with the stock cam.
-How much gain would you say the Comp cam alone would give me? Would it be significantly more than the 15-18hp you said I'd get by simply doing the 1.7 upgrade?
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Randy
Dodge Dakota
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11/11/2003
15:51:44
| RE: Cam v. 1.7's- if only one...?
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it's a '01 3.9 2wd, club, manual trans, 3.55 lim.slip, should have stated that earlier
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Randy
Dodge Dakota
JOIN HERE
11/11/2003
19:34:41
| RE: Cam v. 1.7's- if only one...?
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Larry........anybody....?
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J and J Auto
GenII
11/12/2003
03:19:27
| RE: Cam v. 1.7's- if only one...?
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The comp cam you are looking at will add around
20 25 hp just a little more than the 1.7's and
you can run the stock springs with 1.6
The 1.7's is just a lot easier to do than a cam
change
I am running a custom crower 268 272 with an
effective lift of .480 with the 1.7's $350 to
have the cam ground to run with the rockers
114 centerline with a 44 degree overlap but I also
run a 1600 rpm stall converter from B&M as soon
as I am rolling I am at 2000 rpm a multiplication
of torque and HP at the rear wheels of about 1.5
and my power still drops off at 4800 rpm
Larry
J&J Auto
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Randy
Dodge Dakota
JOIN HERE
11/12/2003
11:09:12
| RE: Cam v. 1.7's- if only one...?
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Did you say I would be able to use the stock springs with the comp cam using 1.6 rockers?
That would save me ALOT of time and quite a bit of money. Mopar gets like $12 a piece for the upgraded springs.
So the hot setup using the stock springs might be the comp cam AND 1.6 roller rockers.
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J and J Auto
GenII
11/12/2003
11:32:04
| RE: Cam v. 1.7's- if only one...?
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Yes you can run the cam with the stock springs
and it will work just fine.
I would consider the 1.6 crower roller rockers
they would net you another 5 hp by reducing
friction and heat build up but not nessasary
you can use the stock ones Stock ratio is 1.6
but they are not rollers but will run fine
Just be sure you adjust the rockers correctly
either the stock or 1,6 rollers
The roller lifters used in these motors need a
.050 .060 preload
I have actualy installed the same cam in a few
V6's Comp Cam- 200/206 .504/.512 they have nice
power starting right around 2000 rpm and at 2500
really come to life because of the higher lift
Larry
J&J Auto
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Randy
Dodge Dakota
JOIN HERE
11/12/2003
17:07:09
| RE: Cam v. 1.7's- if only one...?
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that sounds like the plan then. I'd get the service manual for it before I open it up, plus I'm sure comp will send their own Destructions. I've always achieved zero lash on the appropriate valve and then give it another half turn. Only 12 of them this time, so it should be 25% easier than what I'm used to.
I read something about the later daks, like mine, that says there will be a factory installed timing chain tensioner when I remove the front cover? I def. want to replace the chainset when it's opened up, but I guess I'll be limited to just getting a stock replacement chainset due to the tensioner. I doubt an aftermarket double roller chain will work with it. Whats your experience with this? Thanks for all the help with this, hope I'm not becoming too much of a pain in the ass.
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