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Cam Suggestions:

 
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jeep_406
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Joined: 12 Sep 2002
Posts: 1661
Location: Tewksbury, Mass 01876
53123.48 points


1972 Chevrolet Nova

PostPosted: Fri Jul 01, 2011 3:19 pm    Post subject: Cam Suggestions: Reply with quote

I'm throwing together a 355 SBC that we're putting in a Nostalgia Dragster. The engine will be used to straighten out the car as it's being put together from scratch.
The engine has flat top cast pistons and stock 1.94/1.50 old cylinder heads. I'll do a multi face valve job and mildly port them, nothing serious. I'll probably pin the screw in studs. Talk about old school!
We were going to use a 350/350 hydraulic cam in it but when I degreed the cam it's much less than that. Thought I'd stay with a hydraulic flat tappet cam with no more than .500 lift. The thought being that when we get the car squared away the owner could sell it as a street engine.

The owner is planning on running dual quads on a tunnel ram. I'm thinking we should just run a single 4 barrel til we build a more serious engine. Any thoughts?

The dragster will weigh around 1600 pounds.
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Paul P
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Joined: 15 Aug 2002
Posts: 2404
Location: Townsend, Mass.
81616.60 points


1971 Chevrolet Chevelle

PostPosted: Fri Jul 01, 2011 3:30 pm    Post subject: Reply with quote

I would go solid cam maybe a Comp 284S maybe.

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=220&sb=2

_________________
2001 Focus 2.0 Zetec
stock cams, bolt-ons and tune
15.63@87 MPH 1/4mi

1971 - Chevelle 408 SBC N/A
6.86@102.5 MPH 1/8mi
10.78@122 MPH 1/4mi
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jeep_406
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Joined: 12 Sep 2002
Posts: 1661
Location: Tewksbury, Mass 01876
53123.48 points


1972 Chevrolet Nova

PostPosted: Sat Jul 02, 2011 2:25 am    Post subject: Reply with quote

Thanks Paul, I was thinking of the XE284H. Hydraulic flat tappet might be easier to sell. I'll check out the solid.
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Paul P
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Joined: 15 Aug 2002
Posts: 2404
Location: Townsend, Mass.
81616.60 points


1971 Chevrolet Chevelle

PostPosted: Sat Jul 02, 2011 10:46 am    Post subject: Reply with quote

Sure thing Jeep. He is putting dual quads on this thing? I would say there is not enough motor to use them. Oh well if he is going that route I would think more cam and compression the better to use them.
_________________
2001 Focus 2.0 Zetec
stock cams, bolt-ons and tune
15.63@87 MPH 1/4mi

1971 - Chevelle 408 SBC N/A
6.86@102.5 MPH 1/8mi
10.78@122 MPH 1/4mi
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Big Dave
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Joined: 04 Dec 2005
Posts: 2646
Location: Tampa Florida
119973.02 points



PostPosted: Sat Jul 02, 2011 11:37 am    Post subject: Reply with quote

I am running off memory here but in my opinion, two fours on a tunnel ram is more streetable than most people think. It acts more like a self priming mechanical individual runner fuel injection induction system than two fours on top of an old school low rise dual quad manifold does (Like I used to have on my 409).

On the street if he is going to continue to run the two fours you will have to pay close attention to the accelerator pump circuit (pump, cams and squirters). On the track getting the power valve the right size is more important. If it weren't for the hole in the hood, it is what I would run on the street again.

If you don't want the hole in the hood there is always the option of a cross ram if you can find the manifold on e-Bay. If you go the cross ram route you are going to get the best performance if you fabricate up a balance tube connecting the two plenums made out of one and a half inch copper pipe silver soldered together.

I would use a solid roller over a solid flat tappet as I run both cars on the street with a solid roller without issue (but I do live way out in the country with next to no stop and go driving). With a solid roller oiling is an issue so if you are anticipating city driving I recommend self oiling tappets like Isky's Red Zone (they do run $650 a set which is probably more than you have in the motor, but you can reuse them for the rest of your life as they are rebuildable and seem to last forever as is).

I choose a cam based upon the head on the motor (I can change the compression to match the cam's requirements before it goes together), the car's weight and it's gearing to optimize my torque curve. In your case I suspect the noise it makes is of higher priority as it will spend it's life at cackle fests just idling; and at most, having to do a burn out to please the crowd. For your application a longer duration shorter LISA is the "best" cam.

On your nostalgia digger what kind of tranny are you going to be using?
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af2
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Joined: 01 Sep 2003
Posts: 5558
Location: grassvalley, ca
71227.76 points


1933 Willys Coupe

PostPosted: Sat Jul 02, 2011 6:57 pm    Post subject: Re: Cam Suggestions: Reply with quote

jeep_406 wrote:

We were going to use a 350/350 hydraulic cam in it but when I degreed the cam it's much less than that.


You degreed it with the Hydro lifter.
Degree it with a solid lifter and you will see a real #

Good luck with it Gene.
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jeep_406
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Joined: 12 Sep 2002
Posts: 1661
Location: Tewksbury, Mass 01876
53123.48 points


1972 Chevrolet Nova

PostPosted: Mon Jul 04, 2011 1:55 am    Post subject: Reply with quote

Thanks for the responses. With the Holiday weekend I haven't had time to do anything. I'll get back to it on Tuesday or Wednesday. One of the problems I'm running into is that the owner had a real hard on for the dual quad set-up even if it slows the car down. He loves the look. I haven't done any work on the heads yet. They're stock 1.94/1.50 open chamber heads. Don't think they flow much at all. I suppose I should flow them before I start. He doesn't want to put any money in this engine.
This engine may end up in an S-10 pick-up I've worked on with him. The S-10 would end up being a street/strip toy that would most likely be a high 12 second piece. There's a 418 SBC in it now that puts out an estimated 625-650 HP. I'm figuring that will end up in the Nostalgia dragster eventually.

Don't know if anyone read about this 418. It had 2 heads with different cc's had to cut a bunch off one to get them even. There were other issues but that was the biggest thing. Who puts an engine together like that!!

Adam, I checked out the cam with a solid flat tappet.
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af2
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Joined: 01 Sep 2003
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Location: grassvalley, ca
71227.76 points


1933 Willys Coupe

PostPosted: Mon Jul 04, 2011 4:19 pm    Post subject: Reply with quote

How far off was the cam?
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Knarley Darley
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Joined: 22 Apr 2004
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PostPosted: Mon Jul 04, 2011 9:26 pm    Post subject: Reply with quote

I am running a 230/230 @ .050 on a 108 with .500 lift in a 383, and that is a great running small block. It is a hydraulic flat tappet, and it has a nice thumpy idle, pulls good to about 6000. Has great street manners with the converter 400 rpm looser than stock. The car even has working air cond.
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Skunkworkx
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Joined: 02 Sep 2007
Posts: 352
Location: Harford Co. Maryland
10318.16 points


1968 Chevrolet Camaro

PostPosted: Mon Jul 04, 2011 9:38 pm    Post subject: Reply with quote

280H in my 406 was great with stock heads and gears all the way to aftermarket 200cc heads, 4.10's, and 4500 stall Smile

230@.050 I/E 110 LSA

Nice choppy note too.

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SMOKEmUP
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Joined: 30 May 2002
Posts: 3169

65097.54 points


1979 Chevrolet Camaro

PostPosted: Thu Jul 07, 2011 12:25 am    Post subject: Reply with quote

I'd pick a cam based on the DCR.
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Knarley Darley
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Joined: 22 Apr 2004
Posts: 1247

540238.26 points



PostPosted: Fri Jul 08, 2011 4:13 am    Post subject: Reply with quote

Smoke please elaborate.
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SMOKEmUP
PostMaster


Joined: 30 May 2002
Posts: 3169

65097.54 points


1979 Chevrolet Camaro

PostPosted: Fri Jul 08, 2011 1:33 pm    Post subject: Reply with quote

I just put some random numbers in the DCR calculator for a SBC (see below). For iron heads like on this one I'd target a DCR of 8:1, assuming a tight quench and decent chamber design. Based on the output below I'd pick a cam with an IVC closing point of around 60 degrees.

For this type head I'd go with a split design with more exhaust, at least 6 degrees more than the intake.

Lift wise, ideally you have flow numbers and match the cam lift to at or near cylinder head flow peak.

Lobe separation:
* 104 - 106 for carbureted non street car.
* 108 - 110 for carbureted street car.
* 112 - 114 for fuel injection.

Based on the above and doing a quick search on the cams DB here. I found a comp cams CS XE268H-10 with 224/230 duration @ 0.05.

Code:

You Entered:
Bore 4.03 (inches)
Stroke 3.48 (inches)
Rod Length 5.7 (inches)
Cyl. Head Vol. 68 (cc)
Deck Height 0.005 (inches)
Head Gasket Bore 4.166 (inches)
Head Gasket Thickness 0.039 (inches)
Piston to Cyl. Wall Clearance 0.003 (inches)
Top Ring Land Height 0.25 (inches)
Piston Dome Vol. -6.2 (cc)

Compression Ratio:
9.659 : 1

Displacement:
355.1(ci), 5.8 (liters)

Bore / Stroke Ratio:
1.158 : 1

Rod / Stroke Ratio:
1.638 : 1

IVC ( ABDC)   Dynamic Stroke (inches)    DCR
40   3.184   8.922 : 1
41   3.169   8.884 : 1
42   3.153   8.846 : 1
43   3.137   8.807 : 1
44   3.121   8.767 : 1
45   3.105   8.725 : 1
46   3.088   8.683 : 1
47   3.071   8.64 : 1
48   3.053   8.596 : 1
49   3.035   8.552 : 1
50   3.016   8.506 : 1
51   2.998   8.459 : 1
52   2.979   8.412 : 1
53   2.959   8.363 : 1
54   2.939   8.314 : 1
55   2.919   8.263 : 1
56   2.899   8.212 : 1
57   2.878   8.16 : 1
58   2.856   8.107 : 1
59   2.835   8.054 : 1
60   2.813   7.999 : 1
61   2.79   7.943 : 1
62   2.768   7.887 : 1
63   2.745   7.83 : 1
64   2.722   7.772 : 1
65   2.698   7.713 : 1
66   2.674   7.653 : 1
67   2.65   7.593 : 1
68   2.625   7.531 : 1
69   2.6   7.469 : 1
70   2.575   7.406 : 1
71   2.549   7.343 : 1
72   2.523   7.278 : 1
73   2.497   7.213 : 1
74   2.471   7.147 : 1
75   2.444   7.081 : 1




My 2 cents.

_________________
Stop running from your pain and embrace your pain. Your pain is going to be a part of your prize.

I challenge you to push yourself.
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