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Old 11-08-2009, 04:17 PM
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Why doesn't this combo make more power?

I have a 350 Chevy bored 030 over.
TRW forged flat tops 5.7 rods
Approximately 9.7 compression ratio
Sportsman II cylinder heads
Weiand Action Plus Intake
650 Mighty Demon Carb
Comp Cams Solid flat tappet cam
246@.050 .489 lift 110 lobe seperation
1.6 ratio roller rockers
Mallory unilite Dist.
MSD 6AL ingnition box
The car this engine is in has a B/W Super T10 4-Speed & a 4.56 gear.
On the Chasis Dyno this engine made 266HP & 295lb of torque.
Is this what can be expected with this combo & what improvements would you suggest.

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Last edited by hvy barrel; 11-12-2009 at 09:28 AM.
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Old 11-08-2009, 04:27 PM
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Quote:
Originally Posted by hvy barrel
I have a 350 Chevy bored 030 over.
TRW forged flat tops 5.7 rods
Approximately 9.7 compression ratio
Sportsman II cylinder heads
Weiand Action Plus Intake
650 Mighty Demon Carb
Comp Cams Solid flat tappet cam
246@.050 .489 lift 110 lobe seperation
1.6 ratio roller rockers
Mallory unilite Dist.
MSD 6AL ingnition box
The car this engine is in has a B/W Super T10 4-Speed & a 4.56 gear.
On the Chasis Dyno this engine made 266HP & 295lb of torque.
Is this what can be expecting with this combo & what improvements would you suggest.

Have you had it tuned? spark curve, fuel/air ratio, etc?
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Old 11-08-2009, 04:42 PM
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Yes, I spent alot of time elinimating vacuum leaks, tuning the carb & setting up the distributor.
The A/f ratio was a just a little on the lean side, not too much. about 15:1.
The ignition curve is set to 34 degrees total all in by 3000.
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Old 11-08-2009, 06:05 PM
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What F-Bird describes is the same basic combination I run. I don't run the
sportsman heads, like he said they will work if ported. Will run high tens
@ 3200# with good chassis preparation.
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Old 11-08-2009, 06:07 PM
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thank F-bird, I have felt that the compression was too low.
How much can you advance a cam over the manufacturer's recommended installation?
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Old 11-08-2009, 06:45 PM
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Thanks Guys
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Old 11-08-2009, 07:14 PM
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Toss the Weiand, low rise, stock replacement, 180* intake. It's hurting your mid to top end.
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Old 11-08-2009, 08:08 PM
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Quote:
Originally Posted by hvy barrel
Yes, I spent alot of time elinimating vacuum leaks, tuning the carb & setting up the distributor.
The A/f ratio was a just a little on the lean side, not too much. about 15:1.
The ignition curve is set to 34 degrees total all in by 3000.
15:1 AFR .. lol.... lucky you didn't hurt it IMO...
shoot for 12.5:1

and try a little more timing AFTER you fix the A/F ratio
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Old 11-08-2009, 09:21 PM
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Quote:
Originally Posted by NXS
15:1 AFR .. lol.... lucky you didn't hurt it IMO...
shoot for 12.5:1

and try a little more timing AFTER you fix the A/F ratio
That was according to the dyno. The plugs look good & I don't hear any pinging while the engine is running or under a load. I do plan on changing the jets though. Funny thing is that is any of my buddies are driving behind me they tell me the that it smells very rich.
How much timing are you talking about?
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Old 11-08-2009, 09:25 PM
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Quote:
Originally Posted by sqzbox
Toss the Weiand, low rise, stock replacement, 180* intake. It's hurting your mid to top end.
I already have an Edelbrock Performer RPM that I was running & plan to reinstall. I changed it to eliminate it as an oil comsumption problem I was having.
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Old 11-08-2009, 11:04 PM
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As stated 15 to 1 is far to lean.
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Old 11-09-2009, 07:27 AM
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Funny as it sounds a lean mixture can smell rich due to lean miss fire not rich enough to burn properly and the unburnt fuel goes out the exhaust.
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Old 11-09-2009, 08:20 AM
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Performer RPM is a good choice over the weiand. I was going to suggest the
Edelbrock RPM air gap. Put a 4 hole 1" spacer under the performer and gain a little velocity if you have room under the hood. That should raise those dyno number's to over 300 on the torque and closer to 300 on the HP.
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Old 11-09-2009, 09:38 AM
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Heads

As a few of the guys above said work with the heads. I'm newer to the build sbc but i am always surprised how much of a difference can be made with the way your heads are set up and the combo of heads and cam. Listen to f-bird he really seems to know his stuff as he has helped me out on a few questions.
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Old 11-09-2009, 12:42 PM
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As stated by others the A/F ratio is too lean. It should make best power around 12.5-13:1. Is your carb a vaccum secondary ? Maybe it is not opening all the way. The RPM intake should also pick up power over what you have.
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