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Crower 15965 beast Camshaft
#1
So I was reading one of you guys' discussions about intake valves sucking in exhaust from adjacent cylinders and it mentioned that having a good understanding of your camshaft would make the mathematics easier on each individual engine. I was thinking to myself that i know next to nothing about the aftermarket parts on mine. At least the ones that I can't see. So I went back through the receipts the previous owner gave me and found the one listing the cam.

   

Not a great pic, but I did post one. Big Grin Either way, I looked up a bit about the cam and it created more questions. This is where you guys come in. The previous owner, and the machine shop that did the build told me it was a 'radical' cam and would cause issues with fuel mileage and vacuum. He also said it was designed for drag. From the little I have read so far it seems it is, " Designed for lightly modified street engines." That seems to fit my car very well. I don't intend to change the cam, just wondering if there are any considerations I should make or modifications I should consider to compliment this part of my engine's anatomy. One site mentioned using a 750cfm or larger carb. I currently have an Edelbrock 650. Thanks for the knowledge guys.
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#2
You are correct that it's really not the drag monster they told you it was. Respectable street cam. However, the 650 is too small if your runninga 4V engine. With that cam 750 with proper jets will put you in the sweet spot. Just get a jet kit (they're really cheap) so you can tune it in along with your timing advance and vacuum.

[Image: 2rr7aiv.png]

Just cruising along minding our own business when BAM!!! The LAWS show up.
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#3
As Mark said, it is NOT a radical cam. It is just a slight bit milder than the CJ factory cam. Chuck
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#4
Thanks guys. Can't remember which site now, but one of them said to use this cam to put it back to "near-stock."

Another question came up though. Flat tappet vs roller lifter. Has anyone made the change to roller lifters and does everyone think that flat tappets are as terrible as I am reading about? What I mean by that is I am reading a blog (and trying to take it with a grain of salt like was suggested to me before) and they are comparing the two lifter types. From what they are talking about my flat tappet shouldn't even make it past the break-in stage. I find this hard to believe but wanted to hear what you all had to say about this. It seems to me if flat tappet cams and lifters were used during the muscle car era there must be some merit to their use.


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#5
Is the engine already built? do you think you need to verify your valve train geometry?
That cam is not radical at all....
http://www.crower.com/catalogsearch/resu...65&x=0&y=0

Flat tappet cams have worked well since the beginning of engines. Roller cams are more efficient, and also made of a different steel than a flat tappet. You can't mix and match your pieces. Flat tappet cams need flat tappet lifters, and the same for roller cams.
Flat tappet performance cams are failing more and more these days, mostly due to modern engine oil. There are a lot of reasons why cams fail during or shortly after break in. Wrong springs, incorrect push rod length are also common culprits. I'm on my 3rd Edelbrock in my 289, and if I wasn't so financially committed, I would pull it for a retro roller Comp Cam, similar to the one I put in my 69/ 351W.
Not to tell on myself, but...
My first cam in my 289 was the Edelbrock performer RPM .496/.520 for a 289. I used the wrong springs, (Summit sent me the chevy springs. I asked the summit help line, and they said they would be fine. WRONG). I didn't measure for "custom" push rods. I had no knowledge of this at the time.
So, between too long of a push rod, and the wrong springs, I got coil bind. Broke a roller rocker almost completely in half! Changed springs, got new push rods, problem solved. (you are getting the readers digest here, I assure you.)
Upgraded to aluminum heads, new machine shop said the 'correct' springs I had on the iron heads were wrong. In order to maintain correct geometry and spring pressure, new springs installed on new/used aluminum heads. Put engine together, and wiped another lobe on camshaft.
replaced with 3rd cam, and now am suffering low oil pressure when engine warms up. I think I have gunk in my bearings. I don't know if I will pull it apart, or just wait until it shits itself. It run great and makes plenty of power, just low oil pressure when it warms up. This while it has Joe Gibbs break in oil in it.
Does that help at all?
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#6
Woodsnake-
It does help, thank you. I think based on what i have been able to find from that build sheet for the motor it was all put together properly. I think I am going to continue to put the zddp additive in my engine at each oil change and run the car like the champ it is. I think that if and when my cam takes a turn for the worst like yours did I will be settled in at my new place and have the knowledge and financials to maybe look at a roller cam. until then I am not going to 'worry' about it and just take care of the car the best way I know how, and with a little help from all of you guys that will be just fine.

Is there a way to verify geometry without taking the whole thing apart?
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#7
Well, it's not easy to do after the fact.
Read this, and a lot should be easier to understand. I had to learn all this the hard way, via my check book.

http://sbftech.com/index.php/topic,317.0.html
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