Author Topic: Carb/intake recommendation  (Read 6569 times)

Offline claude

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Carb/intake recommendation
« on: March 07, 2017, 11:03:59 AM »
Shortly I will be getting my 350 SBC back from machine shop. I will build it myself which will be my first for a complete rebuild. Engine build is in signature. Have done heads and cams multiple times over last 50 years. I am looking for recommendations on a carb and intake manifold to go with my engine.  I am decent at tuning Holley carbs but willing to put best combo on engine. My 85 PU is used daily on 30 mi. round trip and on weekends towing 27ft RV to Forest Service mountains which is a 4100 ft. 40 MPH curvy climb. Any help appreciated.
1985 K20, manual T, 373 gears, 208 transfer case
Rebuilt roller 355 engine, Comp XE264XR cam 212/218 @ .050, .487/.495 lift w/1.5 RR, LSA 110, Dart Iron Eagle Heads with 2.02/1.6 SS valves. 325 HP at 4000 RPM. 335 HP @ 4900.
421 ft*lbs torque at 4000RPM

Offline claude

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Re: Carb/intake recommendation
« Reply #1 on: March 07, 2017, 04:26:42 PM »
The rear gears are 3.73. Just caught the mistake
1985 K20, manual T, 373 gears, 208 transfer case
Rebuilt roller 355 engine, Comp XE264XR cam 212/218 @ .050, .487/.495 lift w/1.5 RR, LSA 110, Dart Iron Eagle Heads with 2.02/1.6 SS valves. 325 HP at 4000 RPM. 335 HP @ 4900.
421 ft*lbs torque at 4000RPM

Offline rich weyand

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Re: Carb/intake recommendation
« Reply #2 on: March 07, 2017, 11:18:14 PM »
Get a Qjet built to your setup by Sean Murphy at SMI Carburetors.
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline Stewart G Griffin

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Re: Carb/intake recommendation
« Reply #3 on: March 12, 2017, 07:44:45 AM »
Since there is plenty of space under the hood of trucks, is there any disadvantage to going with an edelbrock performer RPM vs. the regular performer intake manifold in general?

Offline claude

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Re: Carb/intake recommendation
« Reply #4 on: March 12, 2017, 05:38:18 PM »
Thanks Stewart for reply. I was also leaning towards the RPM but a few days ago I ran across an article online from Car Craft Magazine titled "Dual Plane Intake Manifold Comparison."  They compared 23 SBC intakes On a 406 SBC that produced a minimum of 450 HP and 460+ torque. Manifolds fit in 3 categories based on height: 1. Short, 2. Medium, and 3. Tall. Data listed was for peak HP & Torque ( That was not useful for my lower RPM cam), average HP & Average torque, and finally HP and Torque at 3,000 RPM. The Edelbrock EPS 2701 produced an average torque of 466# and 476# at 3,000 RPM. The RPM 7101 produced 468 average # of torque and 474# at 3,000 RPM. The regular performer was at the bottom of the list in all categories. The "short" Edelbrock EPS performed extremely well even compared to "middle" intakes as the RPM. Both intakes were at the top  for performance with the RPM doing better at 6000+ RPM. Both are square bore setup. RPM is more money but not a deciding factor for me. So, if you or other fellow members have working experience on intakes and or carb, I am interested.
1985 K20, manual T, 373 gears, 208 transfer case
Rebuilt roller 355 engine, Comp XE264XR cam 212/218 @ .050, .487/.495 lift w/1.5 RR, LSA 110, Dart Iron Eagle Heads with 2.02/1.6 SS valves. 325 HP at 4000 RPM. 335 HP @ 4900.
421 ft*lbs torque at 4000RPM

Offline rich weyand

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Re: Carb/intake recommendation
« Reply #5 on: March 12, 2017, 11:36:47 PM »
I looked at the article.  Those are really small differences, under lab conditions. 

I'll tell you what will make a big difference, under street conditions.  Keeping the charge cold so you get a denser charge.  On hot days, sucking air from under the hood, most of these will suffer a lot, because the underhood air is hot, and the manifold and carb are being heated from underneath by oil splash on the lifterbox cover.  For those conditions, what you want is to get outside air, not underhood air, and run it through an air-gap manifold.  That setup will positively crush the rest of these manifolds, and not by a little.

The problem with an air-gap manifold is that performance will suck in the winter unless you use heated air.  This is because the carb is not being heated by the oil splash.  It needs heated air to come up to temp to be able to carburate properly.

Here's the write-up of what, why, how.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=27239.0

Here's a recent picture of the setup, with chrome beanie on the air cleaner and aftermarket cold-air inlet, and after I replaced the mechanical fan/shroud with an electric pusher fan.


« Last Edit: March 12, 2017, 11:45:15 PM by rich weyand »
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline claude

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Re: Carb/intake recommendation
« Reply #6 on: March 13, 2017, 07:32:56 PM »
Rich, I have been following your suggestions for cold air intake and plan on implementing them immediately after installing engine. Like a fool I removed all the factory stuff and tossed when I bought the bone stock K20 years ago.
1985 K20, manual T, 373 gears, 208 transfer case
Rebuilt roller 355 engine, Comp XE264XR cam 212/218 @ .050, .487/.495 lift w/1.5 RR, LSA 110, Dart Iron Eagle Heads with 2.02/1.6 SS valves. 325 HP at 4000 RPM. 335 HP @ 4900.
421 ft*lbs torque at 4000RPM

Offline rich weyand

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Re: Carb/intake recommendation
« Reply #7 on: March 13, 2017, 10:54:02 PM »
Mine came with the stupid chrome pie plate setup, but I found the stock thermac at the salvage yard.

There's a million of them on car-part.com.
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline VileZambonie

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Re: Carb/intake recommendation
« Reply #8 on: March 14, 2017, 08:34:19 AM »
I would say with your cam that the high rise would be the preferable intake. I prefer the air gap manifold as well. The two most common carburetors people are running are the Edlebrock and the Holley for street use. I find that I am always tinkering with the Holley and got sick of spilling fuel onto the intake so I've boxed them all up and use the Edelbrock's now. They're super easy to tune and maintain.

I think everyone is guilty of throwing away things they wish they hadn't.
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline philo_beddoe

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Carb/intake recommendation
« Reply #9 on: March 14, 2017, 01:08:52 PM »
I would say with your cam that the high rise would be the preferable intake. I prefer the air gap manifold as well. The two most common carburetors people are running are the Edlebrock and the Holley for street use. I find that I am always tinkering with the Holley and got sick of spilling fuel onto the intake so I've boxed them all up and use the Edelbrock's now. They're super easy to tune and maintain.

I think everyone is guilty of throwing away things they wish they hadn't.

Easier than a qjet? More reliable?
Behold, the day of the LORD cometh, and thy spoil shall be divided in the midst of thee.  Zechariah 14:1

Offline Stewart G Griffin

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Re: Carb/intake recommendation
« Reply #10 on: March 14, 2017, 02:41:04 PM »
It's good that you found a manifold that might be right for you.  i didn't know such a manifold as the eps existed---it appears to be a special version of the regular performer intake?

Anyways, what i was trying to get at was more of a general question directed towards everyone;  Considering the vertical space underhood for a truck, are there ever any disadvantages to going with a dual plane hi-rise vs. dual plane regular manifold?


As far as my experience with different carbs and intakes, no i really only have experience with stock q-jet or 2bbl manifolds and with carbs, mostly q-jets and 2G's.  So i prefer rochester.   i had a 4160 holley briefly on one car, but didn't work with it for too long so my experience with holleys is limited.   i also did briefly try the holley 300-36 intake on that same car, but didn't have it long enough to really get into it tuning wise.  However, reading up on it, you may also want to consider that manifold as well (speaking of  tall intakes.....).

i presently run a q-jet and the stock factory "hi-rise" iron manifold on the 4.3, and that has turned me on to hi-rise intakes.

« Last Edit: March 14, 2017, 02:48:31 PM by Stewart G Griffin »

Offline rich weyand

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Re: Carb/intake recommendation
« Reply #11 on: March 14, 2017, 04:37:36 PM »
I would say with your cam that the high rise would be the preferable intake. I prefer the air gap manifold as well. The two most common carburetors people are running are the Edlebrock and the Holley for street use. I find that I am always tinkering with the Holley and got sick of spilling fuel onto the intake so I've boxed them all up and use the Edelbrock's now. They're super easy to tune and maintain.

I think everyone is guilty of throwing away things they wish they hadn't.

Easier than a qjet? More reliable?

I haven't touched the Edelbrock on the truck in years, other than to oil the choke plate.
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline VileZambonie

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Re: Carb/intake recommendation
« Reply #12 on: March 14, 2017, 05:02:39 PM »
I would say with your cam that the high rise would be the preferable intake. I prefer the air gap manifold as well. The two most common carburetors people are running are the Edlebrock and the Holley for street use. I find that I am always tinkering with the Holley and got sick of spilling fuel onto the intake so I've boxed them all up and use the Edelbrock's now. They're super easy to tune and maintain.

I think everyone is guilty of throwing away things they wish they hadn't.

Easier than a qjet? More reliable?

Q-Jets have their quirks and have very common negative characteristics that can make them finicky as well. Internal leaks , throttle shaft bushings, choke issues. etc I have one on my K20, I love it but I also know how to work on them. The easiest ones to work on and maintain are the AFB design IMO. I prefer fuel injection over all.
,                           ___ 
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              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline philo_beddoe

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Carb/intake recommendation
« Reply #13 on: March 14, 2017, 10:12:10 PM »
I know, modern vehicles start exactly the same whether its 110 out or -50. Start right up, 15 or 20 seconds later, come down to a perfect idle the whole life of the vehicle.

Anyway, yeah when my qjet craps out, i'll get a edelbrock 14063 and a 27013 intake. They're basic, but i like the powder coated black option. Even i could install..

Oh, and i know this goes against my entire philosophy on being a stickler about factory stock and all, but i can bend a little for reliability and quality.
« Last Edit: March 14, 2017, 10:15:00 PM by philo_beddoe »
Behold, the day of the LORD cometh, and thy spoil shall be divided in the midst of thee.  Zechariah 14:1

Offline VileZambonie

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Re: Carb/intake recommendation
« Reply #14 on: March 15, 2017, 12:30:57 PM »
The factory didn't build what's best for you then let alone what's best in 2017.  It's all about what you want because it's your truck and that's the beauty of it all.
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10