Down to the wire on cam selection
Thread Starter
Melting Slicks
Joined: Feb 2003
Posts: 2,529
Likes: 27
From: Auburndale Florida
2025 C2 of the Year ('64-'66) Finalist - Unmodified
St. Jude Donor '03-'05-'06-'07-'09
Down to the wire on cam selection
OK..Its crunch time, short block is at the shop, be done in a week or two, tranny is due back from being freshened up...and I am still wrestling on a cam selection. I talked to the tech guys at Comp, Crane and Lunati. In general they picked a cam one step stronger in their line. I error to the mild side. Considering it's an auto, concern about dynamic CR. and idle VACUUM.
My set up: Eagle 383, 9.5 SCR, alum heads with 190cc runners and 64 cc fast burn chambers, performer intake, quadrajet, ram horns, with 2.5inch pipes exiting through a pair of Magnaflows, TH400, Hughes 2500 stall convertor, and a 3:08 rear.
Objective: good all around cruiser, more performance, run on 87 or 89 octane and have a little thump to it. This car was a pig when I got it. wouldn't even spin the tires....
My Cam Choices:
1) Comp Retro Roller XR-270 with 218/224 duration @ .050, 495/503 lift, 110 LSA
2) Comp Retro Roller XR-276 with 224/230 duration @ .050, 503/510 lift, 110 LSA.
As always... different points of view are appreciated. Mark
My set up: Eagle 383, 9.5 SCR, alum heads with 190cc runners and 64 cc fast burn chambers, performer intake, quadrajet, ram horns, with 2.5inch pipes exiting through a pair of Magnaflows, TH400, Hughes 2500 stall convertor, and a 3:08 rear.
Objective: good all around cruiser, more performance, run on 87 or 89 octane and have a little thump to it. This car was a pig when I got it. wouldn't even spin the tires....
My Cam Choices:
1) Comp Retro Roller XR-270 with 218/224 duration @ .050, 495/503 lift, 110 LSA
2) Comp Retro Roller XR-276 with 224/230 duration @ .050, 503/510 lift, 110 LSA.
As always... different points of view are appreciated. Mark
Last edited by mbeeman350; Dec 19, 2006 at 09:02 PM.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
OK..Its crunch time, short block is at the shop, be done in a week or two, tranny is due back from being freshened up...and I am still wrestling on a cam selection. I talked to the tech guys at Comp, Crane and Lunati. In general they picked a cam one step stronger in their line. I error to the mild side. Considering it's an auto, concern about dynamic CR. and idle VACUUM.
My set up: Eagle 383, 9.5 SCR, alum heads with 190cc runners and 64 cc fast burn chambers, performer intake, quadrajet, ram horns, with 2.5inch pipes exiting through a pair of Magnaflows, TH400, Hughes 2500 stall convertor, and a 3:08 rear.
Objective: good all around cruiser, more performance, run on 87 or 89 octane and have a little thump to it. This car was a pig when I got it. wouldn't even spin the tires....
My Cam Choices:
1) Comp Retro Roller XR-270 with 218/224 duration @ .050, 495/503 lift, 110 LCA
2) Comp Retro Roller XR-276 with 224/230 duration @ .050, 503/510 lift, 110 LCA.
As always... different points of view are appreciated. Mark
My set up: Eagle 383, 9.5 SCR, alum heads with 190cc runners and 64 cc fast burn chambers, performer intake, quadrajet, ram horns, with 2.5inch pipes exiting through a pair of Magnaflows, TH400, Hughes 2500 stall convertor, and a 3:08 rear.
Objective: good all around cruiser, more performance, run on 87 or 89 octane and have a little thump to it. This car was a pig when I got it. wouldn't even spin the tires....
My Cam Choices:
1) Comp Retro Roller XR-270 with 218/224 duration @ .050, 495/503 lift, 110 LCA
2) Comp Retro Roller XR-276 with 224/230 duration @ .050, 503/510 lift, 110 LCA.
As always... different points of view are appreciated. Mark
Thread Starter
Melting Slicks
Joined: Feb 2003
Posts: 2,529
Likes: 27
From: Auburndale Florida
2025 C2 of the Year ('64-'66) Finalist - Unmodified
St. Jude Donor '03-'05-'06-'07-'09
A big concern is vacuum to run the lights, brakes etc
Last edited by mbeeman350; Dec 19, 2006 at 09:02 PM.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
The bigger duration will give you the thump your looking for and the 112 LSA will help it pull at a lower RPM. Will work great with the 3.55 too. Upgrading the rear gear to 3.55 will make a very noticable difference in your acceleration and enhance all the other upgrades.
Last edited by 63mako; Dec 19, 2006 at 11:41 PM.
Drifting
Joined: Oct 2004
Posts: 1,496
Likes: 1
From: Lafayette Louisiana
I don't know if it compares to the roller cams but my xe268 with 1.6 rocker arms gives me almost 15" of vacuum. The headlights aren't going to catapult anything when opening but they do work ok for me.
Pro
Joined: Jan 2005
Posts: 535
Likes: 0
From: Southaven MS
OK..Its crunch time, short block is at the shop, be done in a week or two, tranny is due back from being freshened up...and I am still wrestling on a cam selection. I talked to the tech guys at Comp, Crane and Lunati. In general they picked a cam one step stronger in their line. I error to the mild side. Considering it's an auto, concern about dynamic CR. and idle VACUUM.
My set up: Eagle 383, 9.5 SCR, alum heads with 190cc runners and 64 cc fast burn chambers, performer intake, quadrajet, ram horns, with 2.5inch pipes exiting through a pair of Magnaflows, TH400, Hughes 2500 stall convertor, and a 3:08 rear.
Objective: good all around cruiser, more performance, run on 87 or 89 octane and have a little thump to it. This car was a pig when I got it. wouldn't even spin the tires....
My Cam Choices:
1) Comp Retro Roller XR-270 with 218/224 duration @ .050, 495/503 lift, 110 LSA
2) Comp Retro Roller XR-276 with 224/230 duration @ .050, 503/510 lift, 110 LSA.
As always... different points of view are appreciated. Mark
My set up: Eagle 383, 9.5 SCR, alum heads with 190cc runners and 64 cc fast burn chambers, performer intake, quadrajet, ram horns, with 2.5inch pipes exiting through a pair of Magnaflows, TH400, Hughes 2500 stall convertor, and a 3:08 rear.
Objective: good all around cruiser, more performance, run on 87 or 89 octane and have a little thump to it. This car was a pig when I got it. wouldn't even spin the tires....
My Cam Choices:
1) Comp Retro Roller XR-270 with 218/224 duration @ .050, 495/503 lift, 110 LSA
2) Comp Retro Roller XR-276 with 224/230 duration @ .050, 503/510 lift, 110 LSA.
As always... different points of view are appreciated. Mark
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Thread Starter
Melting Slicks
Joined: Feb 2003
Posts: 2,529
Likes: 27
From: Auburndale Florida
2025 C2 of the Year ('64-'66) Finalist - Unmodified
St. Jude Donor '03-'05-'06-'07-'09
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
I know mine is not a roller but I run a lot of duration and I get about 9 inches of vacuum. No power brakes but it runs the headlights no problem. No problem at low speeds either. Little soggy at 2000 rpm but geared like I am it does not spend much time there. It blows the tires away anytime I stand on it. I like the bigger cams. If and when I go solid roller I'll be in the high 230s or low 240s @ .050 with a lift of 550+ with my 383. Yours will have plenty of torque with either cam.
Thread Starter
Melting Slicks
Joined: Feb 2003
Posts: 2,529
Likes: 27
From: Auburndale Florida
2025 C2 of the Year ('64-'66) Finalist - Unmodified
St. Jude Donor '03-'05-'06-'07-'09
The XR 276 (224/230 on a 110 LSA) is 8.76:1 DCR
I had to call Comp to get the intake valve closingtiming numbers ABDC @.50
So it looks like both cams are above the 8.5 DCR threshold
thanks to everyone for their help, Mark
Melting Slicks
Joined: Feb 2006
Posts: 2,209
Likes: 0
From: Mo
The XR 270 (218/224 on a 110 LSA) calculates to 8.85:1 dynamic compression ratio
The XR 276 (224/230 on a 110 LSA) is 8.76:1 DCR
I had to call Comp to get the intake valve closingtiming numbers ABDC @.50
So it looks like both cams are above the 8.5 DCR threshold
thanks to everyone for their help, Mark
The XR 276 (224/230 on a 110 LSA) is 8.76:1 DCR
I had to call Comp to get the intake valve closingtiming numbers ABDC @.50
So it looks like both cams are above the 8.5 DCR threshold
thanks to everyone for their help, Mark
I would go the 2nd cam listed,might think about the XR 280,230/236 on a 110,you have to rememeber this a 383 and a XR 276 in 383 will seems small because of your cubic inches.A XR 280 Is really the smallest I would use.
Pro
Joined: Jan 2005
Posts: 535
Likes: 0
From: Southaven MS
The XR 270 (218/224 on a 110 LSA) calculates to 8.85:1 dynamic compression ratio
The XR 276 (224/230 on a 110 LSA) is 8.76:1 DCR
I had to call Comp to get the intake valve closingtiming numbers ABDC @.50
So it looks like both cams are above the 8.5 DCR threshold
thanks to everyone for their help, Mark
The XR 276 (224/230 on a 110 LSA) is 8.76:1 DCR
I had to call Comp to get the intake valve closingtiming numbers ABDC @.50
So it looks like both cams are above the 8.5 DCR threshold
thanks to everyone for their help, Mark
270HR = 7.85:1
276HR = 7.70:1
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
DCR calculation number seems too high for your setup. Recheck and remember the roller cam open and close ramp rates are quicker than a non roller. Most of the calculators don't take this into account to be on the safe side. Cam # 2 with 9.5 comp, zero deck and .040 quench should be well below 8.5 DCR. Around 8 or less sounds more like it off the top of my head. Lot's of guys on here running more compression with less duration. Your combination should run on 91 octane. Gasket bore needs to be figured also. Got to be missing something???
Last edited by 63mako; Dec 20, 2006 at 08:59 PM.
Drifting
Joined: Apr 2002
Posts: 1,743
Likes: 37
From: Stockton Ca
Don't do it!
I have the 270 w/1.6 rrs 360 ci. TFS heads, AG and Demon 650vs. All forged, 6" rods, no ping, peak @ 32*10.3 SCR 8.4 DCR
Dynoed 280 rwhp @ 5200 315 rwtq @ 4100
The rams horns will not allow those larger cams to breath. Mine clogs up @ 5100. Headers would give 40+ hp/tq over beat up duals.
W/stk converter and 3:08 IT WOULD BE A DOG
the 1.6 RRs will run cooler, add lift, add very little duration.
Add comp to get 10.25, get smaller cam or 3:55 gears
This engine pulls like BB after 3K
JMHO
Ricisan
Dynoed 280 rwhp @ 5200 315 rwtq @ 4100
The rams horns will not allow those larger cams to breath. Mine clogs up @ 5100. Headers would give 40+ hp/tq over beat up duals.
W/stk converter and 3:08 IT WOULD BE A DOG
the 1.6 RRs will run cooler, add lift, add very little duration.
Add comp to get 10.25, get smaller cam or 3:55 gears
This engine pulls like BB after 3K
JMHO
Ricisan
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
I have the 270 w/1.6 rrs 360 ci. TFS heads, AG and Demon 650vs. All forged, 6" rods, no ping, peak @ 32*10.3 SCR 8.4 DCR
Dynoed 280 rwhp @ 5200 315 rwtq @ 4100
The rams horns will not allow those larger cams to breath. Mine clogs up @ 5100. Headers would give 40+ hp/tq over beat up duals.
W/stk converter and 3:08 IT WOULD BE A DOG
the 1.6 RRs will run cooler, add lift, add very little duration.
Add comp to get 10.25, get smaller cam or 3:55 gears
This engine pulls like BB after 3K
JMHO
Ricisan
Dynoed 280 rwhp @ 5200 315 rwtq @ 4100
The rams horns will not allow those larger cams to breath. Mine clogs up @ 5100. Headers would give 40+ hp/tq over beat up duals.
W/stk converter and 3:08 IT WOULD BE A DOG
the 1.6 RRs will run cooler, add lift, add very little duration.
Add comp to get 10.25, get smaller cam or 3:55 gears
This engine pulls like BB after 3K
JMHO
Ricisan
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
thanks Mako, Lunati has a 219/227 duration 500/520 lift on a 112 LSA. The tech guy picked this one. I was leaning toward the 110 LSA to get a little more cam sound and ve a little snappy. I may go to an overdrive tranny and a 355 rear gear later on.
A big concern is vacuum to run the lights, brakes etc
A big concern is vacuum to run the lights, brakes etc
Thread Starter
Melting Slicks
Joined: Feb 2003
Posts: 2,529
Likes: 27
From: Auburndale Florida
2025 C2 of the Year ('64-'66) Finalist - Unmodified
St. Jude Donor '03-'05-'06-'07-'09