Cam difference?
#310096
05/06/09 03:28 PM
05/06/09 03:28 PM
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Joined: Nov 2005
Posts: 1,943
San Angelo, Texas, U.S.A.
1968RR
OP
top fuel
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OP
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Joined: Nov 2005
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San Angelo, Texas, U.S.A.
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So I've got my new engine in, and it doesn't seem to have as much power as my old one. I haven't yet tuned the carb, I think the 727 linkage needs adjustment, and the timing is still kind of rough, but I can't help but think that the cam might be the difference. What differences would you guys predict for these cams? #1 .545”/.545” lift, 241/247 (.050”) and 285/297 duration hydraulic flat-tappet cam This one went in my old motor: stock 440 block (.020” over) , stock forged crank, LY rods, KB hypereutectic pistons, 11:1, Indy SR OOTB (gasket port), Indy 2D intake, 850 cfm Holley DP, 440 Source roller rockers (I’m thinking my next upgrade is going to be Comp steel roller rockers), stock HP exhaust manifolds (someone on the board once said that this was like forcing a racehorse to breathe through a straw) & 2.5" exhaust, Pro Comp dist., 7 qt. pan #2 .520”/.550” lift, 242/252 (.050”) and 310/320 duration hydraulic flat-tappet cam This is the one that's in my new engine: stock 440 block (.055” over), stock forged crank, no-name aftermarket H-beam rods (w/ 7/16” bolts), KB forged pistons, Indy SR OOTB (gasket port), Indy 2D Intake, 850 cfm Holley DP, 440 Source roller rockers, TTI 2 1/8” headers & 3" exhaust, Pro Comp dist., 7 qt. pan So could the cam be the difference, or do I just need to make some adjustments? Thanks for any input. 
"When I'm in a slump, I comfort myself by saying if I believe in dinosaurs, then somewhere, they must be believing in me. And if they believe in me, then I can believe in me." - Mookie Wilson
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Re: Cam difference?
[Re: 1968RR]
#310097
05/06/09 04:38 PM
05/06/09 04:38 PM
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Joined: Jan 2003
Posts: 5,486
SoCal
Brian Hafliger
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master
Joined: Jan 2003
Posts: 5,486
SoCal
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Quote:
So I've got my new engine in, and it doesn't seem to have as much power as my old one. I haven't yet tuned the carb, I think the 727 linkage needs adjustment, and the timing is still kind of rough, but I can't help but think that the cam might be the difference.
What differences would you guys predict for these cams?
#1 .545”/.545” lift, 241/247 (.050”) and 285/297 duration hydraulic flat-tappet cam
This one went in my old motor: stock 440 block (.020” over) , stock forged crank, LY rods, KB hypereutectic pistons, 11:1, Indy SR OOTB (gasket port), Indy 2D intake, 850 cfm Holley DP, 440 Source roller rockers (I’m thinking my next upgrade is going to be Comp steel roller rockers), stock HP exhaust manifolds (someone on the board once said that this was like forcing a racehorse to breathe through a straw) & 2.5" exhaust, Pro Comp dist., 7 qt. pan
#2 .520”/.550” lift, 242/252 (.050”) and 310/320 duration hydraulic flat-tappet cam
This is the one that's in my new engine: stock 440 block (.055” over), stock forged crank, no-name aftermarket H-beam rods (w/ 7/16” bolts), KB forged pistons, Indy SR OOTB (gasket port), Indy 2D Intake, 850 cfm Holley DP, 440 Source roller rockers, TTI 2 1/8” headers & 3" exhaust, Pro Comp dist., 7 qt. pan
So could the cam be the difference, or do I just need to make some adjustments?
Thanks for any input.
2nd cam is laaaazy by those specs. Headers are too big as well.
I say both the cam and headers are the killers here. 
Brian
Brian Hafliger
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Re: Cam difference?
[Re: Old School]
#310100
05/07/09 09:14 AM
05/07/09 09:14 AM
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Joined: Nov 2005
Posts: 1,943
San Angelo, Texas, U.S.A.
1968RR
OP
top fuel
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OP
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Joined: Nov 2005
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San Angelo, Texas, U.S.A.
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I didn't have much of a choice on the headers (the only choices that I know of for Indy SRs are the TTIs that I have or custom).
I figured the cam was going to basically be dead below 3000, but I expected it too really wake up after that. Maybe it's just the tune...
Anyway, what rpm/power band differences should I expect between the old cam and the new?
"When I'm in a slump, I comfort myself by saying if I believe in dinosaurs, then somewhere, they must be believing in me. And if they believe in me, then I can believe in me." - Mookie Wilson
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Re: Cam difference?
[Re: 1968RR]
#310101
05/07/09 12:57 PM
05/07/09 12:57 PM
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Joined: Feb 2006
Posts: 351
michigan
64ssmax
enthusiast
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enthusiast
Joined: Feb 2006
Posts: 351
michigan
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Cam and headers. that cam seems like it would be done at 5250-5500 rpm maybe peak out torque at 3750-4000 rpm. headers too big. I am running a comp hydraulic 295/307 .564/.564 lift and I peak out on torque at 4200 rpm and 5500 rpm for hp. 
"Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end"
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Re: Cam difference?
[Re: 64ssmax]
#310102
05/07/09 01:52 PM
05/07/09 01:52 PM
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Joined: Nov 2005
Posts: 1,943
San Angelo, Texas, U.S.A.
1968RR
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OP
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Joined: Nov 2005
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San Angelo, Texas, U.S.A.
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So would a switch to 2.5" exhaust help any? As I've mentioned, the only option for the SR heads seem to be the TTI step headers.
Obviously switching cams is an option, but as I'm sure most of you know, swapping cams on an Indy-headed motor (w/o the trick valley plate) isn't fun...
"When I'm in a slump, I comfort myself by saying if I believe in dinosaurs, then somewhere, they must be believing in me. And if they believe in me, then I can believe in me." - Mookie Wilson
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Re: Cam difference?
[Re: 1968RR]
#310103
05/07/09 11:26 PM
05/07/09 11:26 PM
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Joined: Mar 2008
Posts: 5,746
Ontario, Canada
Dodgem
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Joined: Mar 2008
Posts: 5,746
Ontario, Canada
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Quote:
So would a switch to 2.5" exhaust help any? As I've mentioned, the only option for the SR heads seem to be the TTI step headers.
Obviously switching cams is an option, but as I'm sure most of you know, swapping cams on an Indy-headed motor (w/o the trick valley plate) isn't fun...
Smaller exhaust will never help. The TTI s2" to 2 1/8" step headers are great!! you likely need more timing as stated above. the timing characteristic of a flat top to a quench step is big. you will need at least 38 total to make her pop!
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Re: Cam difference?
[Re: Brian Hafliger]
#310104
05/09/09 02:09 PM
05/09/09 02:09 PM
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Joined: Nov 2005
Posts: 1,943
San Angelo, Texas, U.S.A.
1968RR
OP
top fuel
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OP
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Joined: Nov 2005
Posts: 1,943
San Angelo, Texas, U.S.A.
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Quote:
2nd cam is laaaazy by those specs. Headers are too big as well.
I say both the cam and headers are the killers here.
Brian
So I've messed with the timing some (it's at 18 degrees initial right now) at that's helped some. But the motor seems dead (and I mean DEAD) at low rpms, and doesn't have the jerk-your-head acceleration that the old motor had at higher rpms (I haven't taken it over 4500 rpm yet, though).
Why would this cam be a bad choice for the engine combo?
"When I'm in a slump, I comfort myself by saying if I believe in dinosaurs, then somewhere, they must be believing in me. And if they believe in me, then I can believe in me." - Mookie Wilson
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Re: Cam difference?
[Re: forphorty]
#310107
05/09/09 02:56 PM
05/09/09 02:56 PM
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Joined: Nov 2005
Posts: 1,943
San Angelo, Texas, U.S.A.
1968RR
OP
top fuel
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OP
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Joined: Nov 2005
Posts: 1,943
San Angelo, Texas, U.S.A.
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The cam is a Howard's. The car is an automatic. I obviously plan to tinker with the timing and carb a little more, but it doesn't seem like the motor is missing a little power, it seems like it's missing a LOT. It's always disappointing when your new engine is slower than the old one... 
"When I'm in a slump, I comfort myself by saying if I believe in dinosaurs, then somewhere, they must be believing in me. And if they believe in me, then I can believe in me." - Mookie Wilson
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Re: Cam difference?
[Re: 1968RR]
#310110
05/09/09 03:32 PM
05/09/09 03:32 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Quote:
2nd cam is laaaazy by those specs. Headers are too big as well.
I say both the cam and headers are the killers here.
Brian
So I've messed with the timing some (it's at 18 degrees initial right now) at that's helped some. But the motor seems dead (and I mean DEAD) at low rpms, and doesn't have the jerk-your-head acceleration that the old motor had at higher rpms (I haven't taken it over 4500 rpm yet, though).
Why would this cam be a bad choice for the engine combo?
18*.... I sure hope that isnt the total... that would
make any engine lazy
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