383 Cam need 2nd opinion

[turbo36]

Need a second opinion on the cam for my 65' Plymouth Belvedere II

Have two cam recommendations from Comp Cam:
XR274HR-10 //Duration: intake .274 - exhaust .282 // lift: intake .538 - exhaust .534 // lobe sep 110

XR280HR-10 //Duration: intake .280 - exhaust .288 // lift: intake .541 - exhaust .537 // lobe sep 110

Here is the build:
65' 383 Block, bored .060 over - deck cut .030
315 Heads - cut to 71.25cc
flat top pistons
comp ratio 9.5 to 1
1 3/4" headers
Eddy Performer intake
Eddy Performer 600 CFM Carb
Comp Hyd roller lifters
Comp Roller rockers
4 speed tranny
4.10 posi rear
MSD Ignition
tire diameter 26.2"
weight with driver 3,400 lbs

I want a quick/fun cruiser not a strip car.

 

[67 B-body]

WOW,,, are you sure it's 9.5 to 1 comp? .030" shaved deck, 71.25cc heads, and flat tops in my mind would yield a higher ratio than that. I'm guessing the .030" would give you a zero deck piston height or close to it. Do you have a strange pin height on the pistons to drop them back down in the hole a bit to lower that compression to the stated 9.5 to 1?

 

[67 B-body]

Well anyhow, going on something more like 10.5 :1 ratio and pluggin in your specs, The software says the 21-227-4 XE275HL camshaft would give that combo the highest HP and keep things down to the 5000rpm spot. Torque cam in peaking at 2500rpm... Good for stop light to stop light wins..... Should spin the skins pretty easy too with suggested torque at 468.8 ftlb. This is all with the concept of you wanting to keep it a standard hyd camshaft....

 

[turbo36]

WOW,,, are you sure it's 9.5 to 1 comp? .030" shaved deck, 71.25cc heads, and flat tops in my mind would yield a higher ratio than that. I'm guessing the .030" would give you a zero deck piston height or close to it. Do you have a strange pin height on the pistons to drop them back down in the hole a bit to lower that compression to the stated 9.5 to 1?

I should add that I got the engine in "rebuilt short block" condition, the previous engine builder put in the low compression pistons. The rebuild job was a cluster! We had to start over and deck the block to correct a very bad previous maching job.
I looked into stock height pistons (forged Speed pro or Diamond) but that would have resulted in a positive piston height and a comp ratio around 11 to 1.

 

[robinsonwr]

Need a second opinion on the cam for my 65' Plymouth Belvedere II

Have two cam recommendations from Comp Cam:
XR274HR-10 //Duration: intake .274 - exhaust .282 // lift: intake .538 - exhaust .534 // lobe sep 110

XR280HR-10 //Duration: intake .280 - exhaust .288 // lift: intake .541 - exhaust .537 // lobe sep 110

Here is the build:
65' 383 Block, bored .060 over - deck cut .030
315 Heads - cut to 71.25cc
flat top pistons
comp ratio 9.5 to 1
1 3/4" headers
Eddy Performer intake
Eddy Performer 600 CFM Carb
Comp Hyd roller lifters
Comp Roller rockers
4 speed tranny
4.10 posi rear
MSD Ignition
tire diameter 26.2"
weight with driver 3,400 lbs

I want a quick/fun cruiser not a strip car.

Personally I would use the XR280HR because of the 4-speed and 4:10 gear ratio. I would think about an Eddy RPM and a 750 cfm carb though. Those additions will help power and upper power band. What size valves are in the heads? I like the idea of the hydraulic roller actually using one in my 440/512 build.

 

[ga66mopar]

It's easier to live with a cam that's too small then one that's too large. What's the duration at 050?

 

[robinsonwr]

It's easier to live with a cam that's too small then one that's too large. What's the duration at 050?

At .050 that cam is 230/236 if memory serves me right. the cam right above it XR286HR is 236/242 at .050. With the gear ratio and 4-speed with a 26' tire the XR280HR would be the best for the other components he has. I would change to an Eddy RPM manifold and at least a 750 carb.

 

[ga66mopar]

i used the comp cam xe274 in my 440 which has the same duration at 050 230/236 and it's a great street cam.

At .050 that cam is 230/236 if memory serves me right. the cam right above it XR286HR is 236/242 at .050. With the gear ratio and 4-speed with a 26' tire the XR280HR would be the best for the other components he has. I would change to an Eddy RPM manifold and at least a 750 carb.