Is this a good combo? Intake?
Thread Starter
Pro
Joined: Sep 2004
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From: Madison WI
Is this a good combo? Intake?
Okay, so after making a couple calls (to AFR and Comp Cams) and receiving a lot of advice around here, this is my new idea for the H/C/I combo for my 72 L-48. Stock bottom-end, M-20, 3.43s or maybe 3.55s in the rear...already have LTs and true duals. The car is my daily driver so it needs to be street-friendly, and I'm looking to get 300RWHP or more out of it. Here goes:
Holley 670 Street Avenger
AFR 180s
Comp Cams 270H (224/224 @ .050, .470/.470, 110 LSA)
Edelbrock Perfomer RPM Air-Gap OR just Performer Air-Gap(??)
How well will this combo work for my application? Also, AFR recommended going with just the regular Performer manifold to give me a broader torque curve. Should I do this or would I be better off going with the Performer RPM? Maybe the regular Performer is the better choice, as spinning the stock (rebuilt) bottom end much past 6,000 may not be that wise...In any case, why is it that the Performer intakes only come in a "square/spread bore" config, and not just normal square bore like the RPMs??
Holley 670 Street Avenger
AFR 180s
Comp Cams 270H (224/224 @ .050, .470/.470, 110 LSA)
Edelbrock Perfomer RPM Air-Gap OR just Performer Air-Gap(??)
How well will this combo work for my application? Also, AFR recommended going with just the regular Performer manifold to give me a broader torque curve. Should I do this or would I be better off going with the Performer RPM? Maybe the regular Performer is the better choice, as spinning the stock (rebuilt) bottom end much past 6,000 may not be that wise...In any case, why is it that the Performer intakes only come in a "square/spread bore" config, and not just normal square bore like the RPMs??
Last edited by 72Tornado; Mar 7, 2006 at 03:08 PM.
Instructor
Joined: Feb 2006
Posts: 119
Likes: 0
From: Atlanta GA
I asked a similar question a week ago re: carb/intake options and got a ton of good feedback.
You can actually get away with a Holley 650cfm carb but will be resticted to a Edelbrock Performer Intake. The Performer RPM and Air-Gap intakes will not fit under the stock 72 hood.
At least the lift and lob sep on the Comp Cam are a good choice. Other specs depend on what you want out of the car.
You can actually get away with a Holley 650cfm carb but will be resticted to a Edelbrock Performer Intake. The Performer RPM and Air-Gap intakes will not fit under the stock 72 hood.
At least the lift and lob sep on the Comp Cam are a good choice. Other specs depend on what you want out of the car.
Instructor
Joined: Mar 2002
Posts: 140
Likes: 1
From: east hampton ct
I am running a very similar setup on a 75 350. 270H cam, 180 AFR heads, 9.7 compression, edelbrock performer and a 4165 - 650 Holley. The bottom end was redone but your combo is very friendly for the street. Plenty of vacum at an idle and it will idle at about 800 rpm. It lacks lots of power below 1500 rpm but pulls very strong to about 5000. Above that mine seems to drop off. While its nice to have a 6500 rpm screamer your stock bottom end will like this combo much better. You don't say what your compression ratio is but if you go with much more of a cam be sure to check your dynamic compression ratio. Also check with AFR as to what modificatioons you need to make to their heads so you get proper oil drainback. I didn't and regret it every time I look under the valve cover.
Race Director
Joined: Apr 1999
Posts: 11,520
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From: CORVETTE 77 385 C.I. TEXAS
68-72 standard hoods have limited clearance. One should consider the entire flow path.
You need at least about 3/4" clearance over the vent tubes. So there is not enough room for the RPM intakes under 68-72 standard SB hoods properly set up.
You need at least about 3/4" clearance over the vent tubes. So there is not enough room for the RPM intakes under 68-72 standard SB hoods properly set up.
Thread Starter
Pro
Joined: Sep 2004
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From: Madison WI
Crap, I knew I shoulda mentioned this before 
Firstly, I'm ordering an L-88 hood this Friday, so clearance definitely won't be an issue. From the sounds of it, the Performer fits okay under the stock hood, but right now with just an Edelbrock Torker my air cleaner actually touches the underside of the hood, and I don't want to have to get a drop-base air cleaner (plus, the L-88 hood looks cool) Secondly, I already have the Holley and put quite a bit of money/time/effort into getting it plumbed (no one made the one fitting I needed to convert the fuel pump to the right size AN, so I have four adapters coming off the pump now 
), so there's no point in going back to the old Q-jet.
So what are your guys thoughts in terms of Performer vs. Performer RPM? Thinking about it, I'm really not going to spend much time above 5k, and low-end torque is what makes the car fun...so maybe I would be better off going with the Performer. Will it still give me the numbers I want? Like I said, I'm ultimately aiming for 300RWHP+ and low 13's in a street-friendly car
Oh, and I'm assuming the rebuild was done to stock specs, so it should still be at the 8.5:1 CR...
Firstly, I'm ordering an L-88 hood this Friday, so clearance definitely won't be an issue. From the sounds of it, the Performer fits okay under the stock hood, but right now with just an Edelbrock Torker my air cleaner actually touches the underside of the hood, and I don't want to have to get a drop-base air cleaner (plus, the L-88 hood looks cool
) Secondly, I already have the Holley and put quite a bit of money/time/effort into getting it plumbed (no one made the one fitting I needed to convert the fuel pump to the right size AN, so I have four adapters coming off the pump now ), so there's no point in going back to the old Q-jet.So what are your guys thoughts in terms of Performer vs. Performer RPM? Thinking about it, I'm really not going to spend much time above 5k, and low-end torque is what makes the car fun...so maybe I would be better off going with the Performer. Will it still give me the numbers I want? Like I said, I'm ultimately aiming for 300RWHP+ and low 13's in a street-friendly car
Oh, and I'm assuming the rebuild was done to stock specs, so it should still be at the 8.5:1 CR...
Last edited by 72Tornado; Mar 8, 2006 at 09:39 AM.
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Le Mans Master
Joined: Sep 2001
Posts: 7,739
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From: Unreconstructed, South Carolina
Originally Posted by 72Tornado
Oh, and I'm assuming the rebuild was done to stock specs, so it should still be at the 8.5:1 CR...
When planning a motor, suggest use a CR calculator; this one's handy:
http://www.campbellenterprises.com/R...o%20calculator
Thread Starter
Pro
Joined: Sep 2004
Posts: 690
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From: Madison WI
Originally Posted by jackson
ASSUMING stock type dished 4vr pistons and about 8.5:1 now with 76cc heads ... the smallest chambers offered for off the shelf afr 180 are 68cc ... would raise CR no more than about 0.6 over 76cc heads ... that ain't much. Maybe a better & cheaper choice for YOU would be iron GM vortecs (64cc) and an edelbrock vortec intake? ... those would push the CR up about 1.0 over 76cc heads ... one whole number ... and it'd still be pump gas friendly for iron heads ... & should behave well with the planned cam & carb. I'd definately wait to choose heads/chamber size until after I'd verified whether dished or flat pistons ... I would not order heads based on a broad assumption about pistons/CR.
When planning a motor, suggest use a CR calculator; this one's handy:
http://www.campbellenterprises.com/R...o%20calculator
When planning a motor, suggest use a CR calculator; this one's handy:
http://www.campbellenterprises.com/R...o%20calculator
Any approximation as to what going down to 64cc would do to my compression?
Le Mans Master
Joined: Dec 2003
Posts: 5,727
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From: Fremont CA
Brodix 1016 intake with Holley 4777 carb (650 Double Pumper) works well in manual trans Vettes with SB hoods and gives plenty of hood clearance. I don't think AFR would tell you about a competitors product. I have a very nice one for $120 (they are around $200 new.)
Melting Slicks
Joined: Sep 2004
Posts: 2,412
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Yes, the RPM is a better manifold. It outflows the Performer in most places, even if you're not going to spin past 6K. I'll send you a good article comparing the two when I get home. Those AFR 180s are good heads I'd want to take advantage of them, I'm running the AFR195s and I'm going up to a Victor Jr from the RPM.
Did you get my PM? Not interested? Either way, I'm casting my vote for the RPM version. Also, I would up that compression ratio. Those heads come in a 68cc version I'm pretty sure. I don't see 13s in your future with an 8.5 compression ratio.
Did you get my PM? Not interested? Either way, I'm casting my vote for the RPM version. Also, I would up that compression ratio. Those heads come in a 68cc version I'm pretty sure. I don't see 13s in your future with an 8.5 compression ratio.
Last edited by enkeivette; Mar 8, 2006 at 05:17 PM.
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From: Madison WI
Originally Posted by torqvette
Yes, the RPM is a better manifold. It outflows the Performer in most places, even if you're not going to spin past 6K. I'll send you a good article comparing the two when I get home. Those AFR 180s are good heads I'd want to take advantage of them, I'm running the AFR195s and I'm going up to a Victor Jr from the RPM.
Did you get my PM? Not interested? Either way, I'm casting my vote for the RPM version. Also, I would up that compression ratio. Those heads come in a 68cc version I'm pretty sure. I don't see 13s in your future with an 8.5 compression ratio.
Did you get my PM? Not interested? Either way, I'm casting my vote for the RPM version. Also, I would up that compression ratio. Those heads come in a 68cc version I'm pretty sure. I don't see 13s in your future with an 8.5 compression ratio.
Please send me that article though, I'd be very interested to compare numbers. Matching up the intake to the cam is a bit tricky though, it seems like the RPM matches the cam better (1500-6500 vs. 1800-5800, respectively), whereas the regular Performer's only rate idle-5500...ack, I need some more opinions on this
Last edited by 72Tornado; Mar 8, 2006 at 07:20 PM.
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
"Our first tests here were done on a regular Performer which has a carb pad near stock height. The Performer RPM and RPM Air Gap are about one inch taller and do flow better."
http://www.superchevy-web.com/techni...0406sc_airgap/
http://www.superchevy-web.com/techni...0406sc_airgap/