cam timing and duration
Thread Starter
Racer
Joined: Nov 2007
Posts: 279
Likes: 0
From: Forrest City Ar
cam timing and duration
My engine builders are finished. I remembered to ask about the cam and they said it's timing was .50 with a duration of 244\244. I am not a mechanic so can someone tell me what this really means. I think that makes for quick opening and closing on the values? Also after reading the post on the Holly 4160 I am glad I upgraded my carb from the edelbrock to the holly 4150. So what does those cam spec mean on a 350ci
Melting Slicks
Joined: Apr 2000
Posts: 2,145
Likes: 1
From: Ft. Walton Beach, Fl USA
That is an awfully BIG cam for a street car with a 350. Translated that means you are going to need other components to match such as torque converter, rear gears, correct carb, compression ration, etc. And also alot of patience tuning it to run right. I have a 244@.050 hyd roller in a 396 small block and its rowdy but streetable.
Racer
Joined: Aug 2005
Posts: 347
Likes: 0
From: Pace FL
That is an awfully BIG cam for a street car with a 350. Translated that means you are going to need other components to match such as torque converter, rear gears, correct carb, compression ration, etc. And also alot of patience tuning it to run right. I have a 244@.050 hyd roller in a 396 small block and its rowdy but streetable.
Thread Starter
Racer
Joined: Nov 2007
Posts: 279
Likes: 0
From: Forrest City Ar
It a professional turn key build. Scat crank, speed pro pistons, Dart pro one heads, MSD ect. tuned and hot run on video included with photos of build. They advertise it at 420Hp & 415Tq but the last one they dynoed made 435 so by upgradeing from the edlebrock to the holly I may get as much as 450 at the flywheel. I am hooking it up to a BTO 2004r L2 with a 3000 stall. So what do you think am I going to notice a big improvement over the L48 in my 78? 
Thread Starter
Racer
Joined: Nov 2007
Posts: 279
Likes: 0
From: Forrest City Ar
Thanks:-)) although I don't know alot about the finer detail of engine building I was kidding there at the end. For what I am putting into this Baby I hope she'll burn the tires off! By the way I am going to do the install myself
I have learned a lot from reading this forum Thanks to everone for your controbutions. Tom
I have learned a lot from reading this forum Thanks to everone for your controbutions. Tom
Race Director
Joined: Jun 2000
Posts: 10,049
Likes: 675
From: FL
With a 244 @.050 cam, you are probably looking at a HP peak right about 6000 rpm and a torque peak close to 5000 rpm. You definitely need a loose stall and steep gears. Also, expect no vacuum at idle which will interfere with your power brakes. Also, don't expect to pick up 15 HP just by switching to a Holley unless that Edelbrock was badly tuned. 3-5 HP is more likely.
Drifting
Joined: Aug 2007
Posts: 1,838
Likes: 13
From: Kingman AZ
Thanks:-)) although I don't know alot about the finer detail of engine building I was kidding there at the end. For what I am putting into this Baby I hope she'll burn the tires off! By the way I am going to do the install myself I have learned a lot from reading this forum Thanks to everone for your controbutions. Tom
I have learned a lot from reading this forum Thanks to everone for your controbutions. TomGuess I forgot this
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Racer
Joined: Jul 2001
Posts: 361
Likes: 9
From: Dresser WI
Put that cam in my 355 and have very low vaccum and dialing it in has been a battle. The car feels good at higher rpms but about shakes you out the window at idle. I have a 3000 stall converter and no brakes after one push on them, and looking for something else.
Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
I'm a bit more conservative in my answer.
First : if you have 10.5/1 CR this should be doable. The main thing to consider is the point where the intake valve complete closes. You will be losing compression untill the valve is completly shut. This is what will reduce your bottom end and vacuum because of intake blow back. Not all cams are the same in this respect. Look at the cams mayor intensity for this.
The good new is you can counter this, but you will need to go to a roller cam. Only these types of cams allow for a very short mayor intensity (difference in timing between the .05 and seat timing) in the order of 30°. You will also need to make sure your valve train is up to the work. And since the cam is allowing for a higher rpm, the bottom end needs to be up to it also.
First : if you have 10.5/1 CR this should be doable. The main thing to consider is the point where the intake valve complete closes. You will be losing compression untill the valve is completly shut. This is what will reduce your bottom end and vacuum because of intake blow back. Not all cams are the same in this respect. Look at the cams mayor intensity for this.
The good new is you can counter this, but you will need to go to a roller cam. Only these types of cams allow for a very short mayor intensity (difference in timing between the .05 and seat timing) in the order of 30°. You will also need to make sure your valve train is up to the work. And since the cam is allowing for a higher rpm, the bottom end needs to be up to it also.
Thread Starter
Racer
Joined: Nov 2007
Posts: 279
Likes: 0
From: Forrest City Ar
It's a solid cam. They (Proformance Unlimited) recomend this engine for corvettes. you could also choose from three different cam options 1. daily driver, 2 week warrior, 3 war machine. For the same money I wanted all I could get. We'll see how it acts when I get it in the car. They show a live run of the engine on their web site and the guy keeps saying I want all of the vette guy to call so they will get either good or bad press from this build. Satisifed people tell 2 dissatsified tell 10!!!
Le Mans Master
Joined: Apr 2005
Posts: 6,360
Likes: 429
From: Seattle Area WA
Since it is a solid cam, the advertised duration of 244 isn’t that bad. Without doing all the math, that is "pretty close" to a hydraulic 232 duration number.
The LT1 cam advertised durations are 242/254 which "roughly" equate to 231/239 similar hydraulic.
The LT1 cam advertised durations are 242/254 which "roughly" equate to 231/239 similar hydraulic.
Intermediate
Joined: Jan 2007
Posts: 34
Likes: 0
From: Colorado Springs CO
I do not want to hijack the topic but I have a related question. Can somebody explain the difference a regular duration one at .05. Looking at say a Comp Cam spec it shows advertised duration at 240/248 but with .05 it has 192/200 and I do not know why that difference is important.
Let me know if I strayed off topic too far and I'll just post a new one.
Thanks
Let me know if I strayed off topic too far and I'll just post a new one.
Thanks
Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
The .05" is the duration of the cam where the valve is lifted .05" off the seat. It is a basis to compare cams, since the point where the advertised duration is taken differs from one manufacturer to the other. Also with different cams (hydr, solid, roller) you could have a difference associated with taking up valve lash etc.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
It's a solid cam. They (Proformance Unlimited) recomend this engine for corvettes. you could also choose from three different cam options 1. daily driver, 2 week warrior, 3 war machine. For the same money I wanted all I could get. We'll see how it acts when I get it in the car. They show a live run of the engine on their web site and the guy keeps saying I want all of the vette guy to call so they will get either good or bad press from this build. Satisifed people tell 2 dissatsified tell 10!!!
all thats left is a 4.11 or 4.56.....
Drifting
Joined: Aug 2005
Posts: 1,682
Likes: 3
From: League City TX
The .05" is the duration of the cam where the valve is lifted .05" off the seat. It is a basis to compare cams, since the point where the advertised duration is taken differs from one manufacturer to the other. Also with different cams (hydr, solid, roller) you could have a difference associated with taking up valve lash etc.
