Between 2 cams
Thread Starter
Burning Brakes
Joined: Jan 2012
Posts: 943
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Between 2 cams
Unless I get some bad news about the Gen I, 4 bolt main block I dropped off at the machine shop, it should be getting prepped for a 383 crank. This engine is going back into a 1980 with an original 4 speed, 3.08 gears.
Heads are Brodix IK 180, Performer RPM intake, headers. It's going retro-roller cam and the first selection is the XR264HR -
http://www.compcams.com/Company/CC/c...?csid=157&sb=2
The second choice XR270HR -
http://www.compcams.com/Company/CC/c...?csid=158&sb=2
Both these cams have basically the same lift, LS-112 but the 270 has the noticeable idle. How noticeable is noticeable? This is just a street driver with a target HP of about 400.
Heads are Brodix IK 180, Performer RPM intake, headers. It's going retro-roller cam and the first selection is the XR264HR -
http://www.compcams.com/Company/CC/c...?csid=157&sb=2
The second choice XR270HR -
http://www.compcams.com/Company/CC/c...?csid=158&sb=2
Both these cams have basically the same lift, LS-112 but the 270 has the noticeable idle. How noticeable is noticeable? This is just a street driver with a target HP of about 400.
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
Noticeable meaning youll know it has a cam in it but wont be thumping hard or rattling your teeth out. Think the 218 with the 383 will be plenty driveable and get you closer to your goal. Should make gobs of torque!
Thread Starter
Burning Brakes
Joined: Jan 2012
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I am thinking you mean 218 on the intake duration?
Race Director
Joined: May 2005
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From: Millington Illinois
St. Jude Donor '08-'09
Noticable difference between those 2 cams. Cam selection needs to match compression, gearing and intended rpm range and use. A 383 will drop the operating range of the cam you choose about 500 RPM. What is your real calculated compression ratio? You need gasket thickness, Head chamber CC, gasket bore, piston dish CC and Piston to deck height, Bore is 4.030 and stroke is 3.75. Post all these numbers for an accurate calculation and can recommend from there.
Thread Starter
Burning Brakes
Joined: Jan 2012
Posts: 943
Likes: 73
Noticable difference between those 2 cams. Cam selection needs to match compression, gearing and intended rpm range and use. A 383 will drop the operating range of the cam you choose about 500 RPM. What is your real calculated compression ratio? You need gasket thickness, Head chamber CC, gasket bore, piston dish CC and Piston to deck height, Bore is 4.030 and stroke is 3.75. Post all these numbers for an accurate calculation and can recommend from there.
Target CR is 10:1
Original wide ratio 4 speed/ 3.08 rear
Estimated cylinder head cc is 70. Brodix IK 180
Piston dish - good question, the machinist wants to keep the rotating mass as light as possible.
He didn't mention what head gasket he had in mind, I am thinking stock Felpro.
Thread Starter
Burning Brakes
Joined: Jan 2012
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63mako
That much difference (500 rpm) with the 383 gives me the impression that the 264 is out, with the 270 a maybe. Looking at the duration for the 276, it's starting to look like a better fit. Thanks for the information, not having 383 experience is a real anchor.
That much difference (500 rpm) with the 383 gives me the impression that the 264 is out, with the 270 a maybe. Looking at the duration for the 276, it's starting to look like a better fit. Thanks for the information, not having 383 experience is a real anchor.
Team Owner
Joined: Feb 2003
Posts: 30,183
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From: Lake Norman NC
I'd go with that XR270.
I have a XR288 on a 112lsa and it is very streetable, noticeable idle, but very tame at 900rpms (it doesn't shake the fenders), so a step down might be perfect for you. Unless you want to get better flowing heads and go a step up.
I have a XR288 on a 112lsa and it is very streetable, noticeable idle, but very tame at 900rpms (it doesn't shake the fenders), so a step down might be perfect for you. Unless you want to get better flowing heads and go a step up.
Drifting
Joined: Apr 2002
Posts: 1,736
Likes: 37
From: Stockton Ca
Best Advice?
To quote a big time engine builder:
Do your homework and sort throught all the details to find what you think is the best cam possible.
Then go one size smaller! LOL
My CC 270 HR is a little soft off idle in my 355 w/TFS heads and pulls like a big block in the midrange.
The M21 w/3:55 gears does not help to get off the line.
Otherwise I am very happy.
R
Do your homework and sort throught all the details to find what you think is the best cam possible.
Then go one size smaller! LOL
My CC 270 HR is a little soft off idle in my 355 w/TFS heads and pulls like a big block in the midrange.
The M21 w/3:55 gears does not help to get off the line.
Otherwise I am very happy.
R
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Team Owner
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Compression will be the deciding factor. My 383 has 64 cc heads and flattop forged pistons. which ends up being high 10:1 C/R. I had detonation with a Solid roller similar to the cc 282 I then moved up to something like the 288 and it runs fine. If you are actually at 10:1 C/R the 282 would be the smallest I would use. Maybe even ask them to grind either one of those on 112 center line to broaden the power curve
Your draw back is wimpy heads. So you can even go with more cam compared to high flowing heads
Your draw back is wimpy heads. So you can even go with more cam compared to high flowing heads
Le Mans Master
Joined: Sep 2004
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From: Livonia MI
Most major cam manufacturers, have pretty good tech lines, so maybe give then a call, and tell them your engine/gearing set up. Keep in mind, they can vary the cam grind a bit from the catalog listing, such as a little wider LSA. You can also use Crane Hi Intensity lifters that bleed down a bit at low rpms, for better idle/vacuum. Also, an MSD multi spark ignition, helps idle quality too.
Thread Starter
Burning Brakes
Joined: Jan 2012
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Compression will be the deciding factor. My 383 has 64 cc heads and flattop forged pistons. which ends up being high 10:1 C/R. I had detonation with a Solid roller similar to the cc 282 I then moved up to something like the 288 and it runs fine. If you are actually at 10:1 C/R the 282 would be the smallest I would use. Maybe even ask them to grind either one of those on 112 center line to broaden the power curve
Your draw back is wimpy heads. So you can even go with more cam compared to high flowing heads
Your draw back is wimpy heads. So you can even go with more cam compared to high flowing heads
The tech at CompCams did mention the 282, 288 and all things considered he said the 276 would be a better fit.
Thread Starter
Burning Brakes
Joined: Jan 2012
Posts: 943
Likes: 73
Most major cam manufacturers, have pretty good tech lines, so maybe give then a call, and tell them your engine/gearing set up. Keep in mind, they can vary the cam grind a bit from the catalog listing, such as a little wider LSA. You can also use Crane Hi Intensity lifters that bleed down a bit at low rpms, for better idle/vacuum. Also, an MSD multi spark ignition, helps idle quality too.
Drifting
Joined: Mar 2001
Posts: 1,395
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From: Indiana
Here's my chassis dyno with a 355, 195cc heads, and a comp 282s with a single plane. Tourque curves don't get much flatter than this.
Thread Starter
Burning Brakes
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Don't be so quick to dismiss the single plane. The old argument that single planes are no good for low end torque is just bad information that wont seem to go away. I just hate to see someone go with smaller heads/cam and sacrifice power based on old info.
Here's my chassis dyno with a 355, 195cc heads, and a comp 282s with a single plane. Tourque curves don't get much flatter than this.
Here's my chassis dyno with a 355, 195cc heads, and a comp 282s with a single plane. Tourque curves don't get much flatter than this.
Team Owner
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2024 C3 of the Year Finalist- Modified
The wimpy heads haven't been ordered yet. The IK180 heads go with the Edelbrock RPM intake. The builder said with the 200 heads, I needed to go single plane manifold, for the street, the dual plane sounds like the better intake.
The tech at CompCams did mention the 282, 288 and all things considered he said the 276 would be a better fit.
The tech at CompCams did mention the 282, 288 and all things considered he said the 276 would be a better fit.
Part Number: FEL-1204
Which is a match for the 180 head. My 383 intake is the lowest rpm small single plane Weiand Team-G 7531 to port match my Dart 227 cc heads or my AFR 210's that I had on for a year or two
Last edited by gkull; Aug 29, 2012 at 02:12 PM.
Drifting
Joined: Mar 2001
Posts: 1,395
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From: Indiana
Understood. However, my point was that if I can do that with a 355, the additoinal torque from the 383 will be even better and benefit more from the single plane. I understand why you would want to stick with the intake that you already have. It's just a shame to see you limited to smaller heads due to the intake. With all of the money spent on the stroker motor and aftermarket heads, I would not want a releltively low cost intake manifold to dictate what can be done with the rest of a build.
Thread Starter
Burning Brakes
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Understood. However, my point was that if I can do that with a 355, the additoinal torque from the 383 will be even better and benefit more from the single plane. I understand why you would want to stick with the intake that you already have. It's just a shame to see you limited to smaller heads due to the intake. With all of the money spent on the stroker motor and aftermarket heads, I would not want a releltively low cost intake manifold to dictate what can be done with the rest of a build.
Race Director
Joined: May 2005
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From: Millington Illinois
St. Jude Donor '08-'09
RPM intake is a great dual plane.
http://www.lunatipower.com/Product.aspx?id=1988&gid=289
This has 6 degrees advance ground in, 112 LSA and better lift than the Comp. 270 intake duration is smallest with your compression but biggest with your 3.08 gears. DCR will be right for premium fuel. The 264 is out of the picture period. For a 383 with 3.08 gears, 4 speed, 400 HP target, RPM dual plane, 10 to 1 compression and 180 heads this is the exact cam I would put in it. I like a bigger cam but your gearing will make it soft on the bottom end if you decide to go that way. (see post #8) If your open to upgrading your gearing go the next size bigger on the cam and bump compression a little but your heads will restrict high rpm cylinder filling. JMHO.
Edit: Every build is based on a series of compromises. Matching everything in the build as good as you can within certain parameters nets the best end result.
http://www.lunatipower.com/Product.aspx?id=1988&gid=289
This has 6 degrees advance ground in, 112 LSA and better lift than the Comp. 270 intake duration is smallest with your compression but biggest with your 3.08 gears. DCR will be right for premium fuel. The 264 is out of the picture period. For a 383 with 3.08 gears, 4 speed, 400 HP target, RPM dual plane, 10 to 1 compression and 180 heads this is the exact cam I would put in it. I like a bigger cam but your gearing will make it soft on the bottom end if you decide to go that way. (see post #8) If your open to upgrading your gearing go the next size bigger on the cam and bump compression a little but your heads will restrict high rpm cylinder filling. JMHO.
Edit: Every build is based on a series of compromises. Matching everything in the build as good as you can within certain parameters nets the best end result.
Last edited by 63mako; Aug 29, 2012 at 09:46 PM.
Pro
Joined: Oct 2009
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From: Marysville Ohio
I've got a 383 with the XR270HR cam - using AFR 195 heads and the Edelbrock RPM Performer Air Gap intake. Estimate it to be at or just over 10:1 compression, but not exactly sure where it is.
I think you asked about the sound at idle - with the 383, it's not that lopey, but has a nice rumble.
Never had it dynoed - I'm sure I'm leaving some power on the table with that cam, but it suits my driving style. I go up and down 71 between Wilmington and Columbus OH regularly, and it gets plenty of exercise - SO for what it's worth, I'm currently happy with that choice. It has plenty of torque - it goes zoom when I want it to. I would not go any shorter duration.
I think you asked about the sound at idle - with the 383, it's not that lopey, but has a nice rumble.
Never had it dynoed - I'm sure I'm leaving some power on the table with that cam, but it suits my driving style. I go up and down 71 between Wilmington and Columbus OH regularly, and it gets plenty of exercise - SO for what it's worth, I'm currently happy with that choice. It has plenty of torque - it goes zoom when I want it to. I would not go any shorter duration.