440 Cam Timing Question
#1167446
01/28/12 09:16 PM
01/28/12 09:16 PM
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Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
bobs66440
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OP
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Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
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As some of you know I'm building this 440 with Stealth heads and a Summit 6401 cam. We degreed the cam today and here's what we got. Exh open 2 deg retarded Exh close. 4 deg advanced Int open 2 deg retarded Int close 1 deg retarded These are departures from spec. The crank sprocket has keyway options for 4 degree advance or retard. Are these differences worth worrying about for street car that will likely never see more than 4500 rpm? I entered the differences into my desktop dyne and there was no more than a 5hp difference either way. Thanks! 
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Re: 440 Cam Timing Question
[Re: 383man]
#1167449
01/29/12 11:43 AM
01/29/12 11:43 AM
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Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
bobs66440
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Joined: Mar 2010
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Out in Left Field, NY
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Quote:
Where did the intake centerline come out. Was it advanced or retarded or on spec ? Ron
Here is the cam card, what it's supposed to be...
I went out and double checked everything. This is what I got...
Int open - 1* BTDC = 2* retarded
Int close - 41* ABDC = ON SPEC
Exh open - 54* BBDC = 2* retarded
Exh close - 2* BTDC = 4* advanced
Lobe centerline - Int 109* ATDC = ON SPEC
Lobe centerline - Exh 120* BTDC = 1* advanced
Thanks!
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Re: 440 Cam Timing Question
[Re: bobs66440]
#1167451
01/29/12 02:10 PM
01/29/12 02:10 PM
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Joined: Mar 2008
Posts: 5,746
Ontario, Canada
Dodgem
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master
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
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How is your dial indicator set up off the lifter? variations in angle and such can affect @ .050. I like to do .050 and .100 before and after max lift /2 to get a good read on Intake max lift (intake centerline)
You are using a solid lifter I take it??
You indicating right off the lifter? indicator in pushrod in lifter (I have a short push rod made up for this! Or off the valve retainer?
Last edited by Dodgem; 01/29/12 02:11 PM.
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Re: 440 Cam Timing Question
[Re: bobs66440]
#1167452
01/29/12 02:49 PM
01/29/12 02:49 PM
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Joined: Feb 2005
Posts: 4,313
Prospect, PA
BSB67
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master
Joined: Feb 2005
Posts: 4,313
Prospect, PA
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First, you've measured the intake at 222 degrees duration and the exhaust at 232 verses Summit having them at 224 and 234. Could be your measurements, or it could be the cam. I would not get too worked up about it.
Second, their "-2 BTDC" on the card is not 2 ATDC, it is simply 2 BTDC. I don't know why they would write it this way.
Therefore, both openings are a couple degrees retarded, and the closings are per the timing card.
The cam is ground with a 114 degree LSA, with a recommended 109 installed intake centerline (ICL) As you have it, it's installed at 110 degrees. You can leave as is.
Last edited by BSB67; 01/29/12 02:51 PM.
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Re: 440 Cam Timing Question
[Re: BSB67]
#1167453
01/29/12 04:37 PM
01/29/12 04:37 PM
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Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
bobs66440
OP
top fuel
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OP
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Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
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Quote:
Second, their "-2 BTDC" on the card is not 2 ATDC, it is simply 2 BTDC. I don't know why they would write it this way
Do you think that applies to the difference in the 3 degree/-3 degree discrepancy in the two cards also?
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What is the duration (at .050 lift), lift and lobe seperation on that camshaft?
