CSB 331 output?

[Merc Man]

So, I have a newly built .030" over bored 327 that I would like some qualified thoughts about.
We've used flat top pistons, 5.7" rods, 'anonymized' Brodix IK180 heads w/ 2.02/1.60 valves, 1.6 roller tip rockers, Edelbrock Performer EPS intake, Edelbrock 650 carb, mid length 1-5/8" headers - primary lengths all over the place from 12" to 22".
Out of curiousity I installed a Comp XM262H cam that was available, it is adviertised as 262*/268* @ .006", 218*/224* @ .050", LSA 112*. Lobe lift is .308"/.318", Even though this is a marine cam with an advertised 1300-5500 rpm range (for a 350?) I thought it would work fairly well but with a slightly wider rpm range due to the smaller displacement.

Upon installation of the cam I measured the intake lobe to have not 262* but 266* duration @ .006" and exactly the advertised .308" lift. (Also still 218.5* @ .050"). To make me even more confused Comp advertised ivo at 19* btdc and ivc at 62* abdc, which wouldn't even add upp to 262* total duration. Well, to spread the measured duration somewhat evenly the cam ended up at ivo @ 22* btdc and ivc @ 64* abdc. According to my calculations this results in a dcr of 7.89:1 from a scr of 9.86:1 which I guess is not too bad.

With the above setup the engine peaks 347 lbft @ 4200 rpm, this calculates to 278 hp at the very same rpm. With a measured intake air flow of 415 cfm @4200 rpm I feel the torque falls a little short. Also, this air flow compared to a theoretical air flow of 402 cfm @ 100% VE gives an actual VE of 103% which simply looks too high for the torque measured. Could this be from the current dcr or from over scavenging causing a loss of charge?
If I advance the cam to say ivc @ 60* abdc this would result in dcr of 8.12:1 thus increasing torque, correct? Also this could reduce scavenging due to earlier evc, right? Will this in turn move peak torque down in rpm making me loose top end hp? Does the overall performance make sense? I think it is a little on the low side, should I investigate for possible dyno correction errors?

Thanks in advance for any input!

[BrazilianZ28Camaro]

Something is wrong, definitelly it's down on power.

What total timing this engine is set at? What about AFRs? Cam ICL?

The last comp cam I installed on a 406" SBC I built had the IVO number wrong on the cam card.

The cam card had the IVO # at .020" but that value should be at .050" to be correct.

I confirmed that on the Comp's cam simulator (Camquest).

Advancing the cam will shift the torque curve down on the RPM range. Might make less tq/hp if too far from the ideal ICL.

[Merc Man]

Assuming the intake lobe is symmetric the above intake valve events sets the ICL at 111* (card says 110*)
AFR's are very consistent around 12.7. Total timing has been tested up to 36*. I also swapped the carb for a Eddy 750 giving very low pressure drop over the carb and a few more cfm and lbft but still hesitating to rev as I'd like it to do.
Also the Mallory Unilite distributor became a suspect so it was replaced by a MSD unit but still no gains.

I'm going back to the dyno guy early this week to go over all settings again, starting with verifying the damper and timing marks, then do the cam timing again, checking compression pressure.
I do have a Comp XE268H-10 available but I think the long exhaust duration of 280 will hurt more than it helps ...

[Newold1]

You are underestimating the breathing needs of your engine.

Two suggestions:
1. Use a XR276HR Comp Cams shaft and install straight up at 0 224@.050" Intake , 230@.050" exhaust, .510 lift with 1.6 rockers both I & E
2. Would perform much better with a set of 1-3/4" with 28" 4 tube primaries header with a 3-1/2" collector

With your combination should get you to 390HP @ 5900rpm and 370lb/ft. of torque at 4300rpms with 105% VE
Carb needs to be a minimum of 600cfm. This is my calc based on Pipe Max.

[bigjoe1]

Your dreaming !



JOE SHERMAN RACING

[Merc Man]

Joe,

Do you mean me or Newold1's post?

[bigjoe1]

NOT YOU-- THE OTHER GUY



JOE SHERMAN RACING

[Newold1]

Hey Joe
I try to stay wide awake when I work, think and post.
Could you please tell me what's in this "dream" I supposedly had?
Your opinion and experience is greatly appreciated.
Thank You

[user-612937456]

The mid length headers are hurting you, 1 5/8's is probably ok unless you want the engine to turn past 7000 and I don't like the comp cams 262/112 lsa grind, there can be a much better cam grind to optimize your config.

What is the application for the power-plant? What RPM range are you looking for?

[Merc Man]

gvx,

My intention was to keep it under 6k, hoping to see at least 350 hp.
I get the feeling the exhaust is robbing the cylinder, where else does the intake flow go?

[F-BIRD'88]

The lobes on these series of cam are not symmetrical. The opening side is different than the
closing side. Phase the cam by the .050" open close event points no the .006" events.
And adjust it from that if you want.
Advancing the cam will not shift the torque curve down in rpm but will rock the torque curve
at the peak rpm point adding a bit of lower end power and trading of a bit of the top end.
(this is the typical trend effect of advancing-retarding the cam)

If you want to change the torque peak rpm point to any real effect you have to change the duration.
If you want torque use long tube 1-5/8" headers. They make more torque than shorty headers do.

Sometimes on shorty headers you get more torque by running the headers together into a 2 into 1 Merge pipe like 2.5" into a single 3" pipe. EG: flowmaster merge Y250300.
If you want more power and more torque try a single pattern cam with 221@.050" on 108 LSA (104 ish in C/L
EG: isky 201271 ( comp has a similar cam #12-316-4 CS268H-8

Comp "Dual Energy" CS 265DEH-10 is another good one Comp #12-208-2 good torque and power
A 1.6 in 1.5 ex split rocker set will probably be best on all these including the cam you got.

Could use a higher compression ratio shave the 64cc heads to 58-60cc for 10:1cr
Often the "64cc heads" are actually bigger than real 64cc. Compression is your friend, for torque and power,... so....

The performer EPS intake make respond to a carb spacer.
Open for more peak HP....or.split style to keep the fully divided 180deg plenum for torque.
You have to try see what works.
Should have used chevy 062 or 906 vortec heads on this lil motor.

[Stan Weiss]

So, I have a newly built .030" over bored 327 that I would like some qualified thoughts about.
We've used flat top pistons, 5.7" rods, 'anonymized' Brodix IK180 heads w/ 2.02/1.60 valves, 1.6 roller tip rockers, Edelbrock Performer EPS intake, Edelbrock 650 carb, mid length 1-5/8" headers - primary lengths all over the place from 12" to 22".
Out of curiousity I installed a Comp XM262H cam that was available, it is adviertised as 262*/268* @ .006", 218*/224* @ .050", LSA 112*. Lobe lift is .308"/.318", Even though this is a marine cam with an advertised 1300-5500 rpm range (for a 350?) I thought it would work fairly well but with a slightly wider rpm range due to the smaller displacement.

Upon installation of the cam I measured the intake lobe to have not 262* but 266* duration @ .006" and exactly the advertised .308" lift. (Also still 218.5* @ .050"). To make me even more confused Comp advertised ivo at 19* btdc and ivc at 62* abdc, which wouldn't even add upp to 262* total duration. Well, to spread the measured duration somewhat evenly the cam ended up at ivo @ 22* btdc and ivc @ 64* abdc. According to my calculations this results in a dcr of 7.89:1 from a scr of 9.86:1 which I guess is not too bad.

With the above setup the engine peaks 347 lbft @ 4200 rpm, this calculates to 278 hp at the very same rpm. With a measured intake air flow of 415 cfm @4200 rpm I feel the torque falls a little short. Also, this air flow compared to a theoretical air flow of 402 cfm @ 100% VE gives an actual VE of 103% which simply looks too high for the torque measured. Could this be from the current dcr or from over scavenging causing a loss of charge?
If I advance the cam to say ivc @ 60* abdc this would result in dcr of 8.12:1 thus increasing torque, correct? Also this could reduce scavenging due to earlier evc, right? Will this in turn move peak torque down in rpm making me loose top end hp? Does the overall performance make sense? I think it is a little on the low side, should I investigate for possible dyno correction errors?

Thanks in advance for any input!

What was your measured fuel flow @ 4200 RPM (lbs/hr)?

Stan

[pdq67]

Imho, the 1-5/8" dia., 4-tube, long tube headers along with an old isky 270 Mega hy-cam at 9.8+ CR should really wake it up.

Personally I like solid flat-tappet lifter cams because they will produce a skosh more power everywhere vs their hy-cam counter parts.

If you want to go solid, then please consider isky's Z-25 cam. Or at the least their Z-20...

I guess I don't understand why you are using such a small cam when your little engine will just love to rpm if you set it up right. Again, imho the 327 engine was made to rpm.

What are you going to install it in and how are you going to drive it?

pdq67

PS., and don't overlook a Q-Jet that is sized for your engine, it will run great and still to get decent gas mileage.

[Merc Man]

The lobes on these series of cam are not symmetrical. The opening side is different than the
closing side. Phase the cam by the .050" open close event points no the .006" events.
And adjust it from that if you want.

That was my conclusion. Comp seem to have added a softer valve landing by 'stretching' the ramp slightly at the end.

Advancing the cam will not shift the torque curve down in rpm but will rock the torque curve
at the peak rpm point adding a bit of lower end power and trading of a bit of the top end.
(this is the typical trend effect of advancing-retarding the cam)

The torque curve right now is almost as flat as the horizont and within 19 lbft from 3300 to 4800, I would like to see a slightly more aggressive curve peaking a little later.

If you want to change the torque peak rpm point to any real effect you have to change the duration.
If you want torque use long tube 1-5/8" headers. They make more torque than shorty headers do.

Sometimes on shorty headers you get more torque by running the headers together into a 2 into 1 Merge pipe like 2.5" into a single 3" pipe. EG: flowmaster merge Y250300.
If you want more power and more torque try a single pattern cam with 221@.050" on 108 LSA (104 ish in C/L
EG: isky 201271 ( comp has a similar cam #12-316-4 CS268H-8

Comp "Dual Energy" CS 265DEH-10 is another good one Comp #12-208-2 good torque and power
A 1.6 in 1.5 ex split rocker set will probably be best on all these including the cam you got.

I didn't think the Comp 12-208-2 would differ that much from the current cam. Of course the 2* wider LSA would calm the idle down a bit ...

Could use a higher compression ratio shave the 64cc heads to 58-60cc for 10:1cr
Often the "64cc heads" are actually bigger than real 64cc. Compression is your friend, for torque and power,... so....

Chamber has been checked at 64 cc, current comp ratio is 9.86:1 with zero deck height, flat top pistons, .039" gasket. If heads have to come off it must be for a reason greater than increasing comp ratio by .14

The performer EPS intake make respond to a carb spacer.
Open for more peak HP....or.split style to keep the fully divided 180deg plenum for torque.
You have to try see what works.

It has been tested with 0.5" and 1.0" spacer. 0.5" smothed out both torque and afr a bit, 1.0" was a loss in all areas.

Should have used chevy 062 or 906 vortec heads on this lil motor.

I was curious to test those alu heads since the buzz out there has been positive about them and in this case they ended up on this 327 (I have another pair out on a 350 but haven't received any numbers on that one yet). With the flow they claim to have the would be between 5 and 10% better than the GM 062/906 heads so it didn't feel completely wrong and at least shouldn't hurt performance.

Please note that I'm not neglecting any of your thoughts and comments, just adding info as it comes and questioning my own ideas equally

[Merc Man]

Stan,

Unfortunately the dyno is currently missing a fuel turbine so fuel consumption is unknown thus bsfc calculated from there.
What still makes me question the efficiency is the intake air flow vs output in torque. Using air flow and afr numbers gives a bsfc of 0,56 which must be too high ...