377 SBC build

[Martin161]

Looking for some advice. I know a 406 would be a better build but it’s a car that I inherited. Trying to keep it as my dad had it. Just looking to get the most out of the motor.

400 small block 40 over (4.165 Bore)
3.48 stroke
Flat top pistons with valve relief
Comp cam hydraulic 12-470-8 (.600 lift 314 intake duration 314 exhaust duration 252 on both at 050)
1.5 roller rockers
.039 head gaskets
Flow Tec 200cc heads
Holly strip dominator intake with 2” riser
Holly HP750cfm double pumper carb
Headmen headers with 2-1/2” flow master exhaust.
10-1 ish compression
3200 rpm torq converter
TH 400 tranny

Any opinions on a better intake for this set up? Looking for around 500 HP.
Also is the 750 a big enough carb?
Thanks

[F-BIRD'88]

Get a real deal 8" 9" racing torque converter 4500-5000 stall.
Fully hand port the Flotek heads
The holley 750 DP carb can be nicely upgraded with a holley/proform HP750 carb body kit.

[HQM383]

I think the best advice comes when it is clearly defined what constitutes “Just looking to get the most out of this motor” as that is quite subjective. Five hundred hp has been mentioned but is this predominantly street driven or looking to attain an et time or a bit of both?

[Martin161]

I think the best advice comes when it is clearly defined what constitutes “Just looking to get the most out of this motor” as that is quite subjective. Five hundred hp has been mentioned but is this predominantly street driven or looking to attain an et time or a bit of both?

Sorry yes it is mostly street driven. And I’m really looking for it to be a relatively reliable fun car. And for the combo to be matched best as possible.

[cgarb]

That camshaft seems excessive for what you have to me. People tend to think of a destroked 400 as no torque high winding motors. They can be if you put too much camshaft in them. Think of your 377 as a .125 over 350. Nobody hardly claims 350's are monster RPM engines. If you pick a camshaft appropriate for how you are driving the car, it will perform much better. Might not be 500hp, but more of the power will be where you are using it. I would be going to a good beehive spring set up with your hydraulic cam and find a more modern profile hydraulic cam, maybe one of the Lunati Voodoo cams or a Comp Extreme energy grind. Or call Mike Jones and do what he tells you. He grinds excellent camshafts, every one of his I have been around pick up power over what they replaced.

[ChopperScott]

If you're not looking to make major changes, this is a good read if you're interested in a dual plane intake for street driving. Keep in mind the current AFR Eliminator 4812 is the cast version of the discontinued composite Titon 4804, and costs a lot less...


Dual Plane Intake Test Engine

As we did with our single plane intake comparison, we are using the 406ci small block Chevy first introduced in the May '11 issue ("Build a 400ci Torque Monster For $2,500") and later rebuilt as "Build Big-Hammer Power" in the Dec. '11 issue. We've decided to call this engine Rodney Dangerfield because it gets no respect— only abuse. By the time we were done with this test, the 406 had slogged through more than 150 dyno runs with nary a whimper. The engine is basically the same as the one used in the June '13 single plane intake test, with a change to a milder Crane camshaft that is more in line with what would be used in a dual plane intake application. We've retained the same Crane Gold 1.6:1 roller rockers and 0.080-inch-wall pushrods. We also retained the TFS 215cc heads used in the previous test to ensure we could flow enough air to evaluate the intake manifolds and not the cylinder heads. Because we didn't expect to exceed 500 hp, we chose a more compatible 750-cfm Holley HP mechanical-secondary carburetor that worked well out of the box, needing only minor jet and air-bleed changes from time to time to ensure the air/fuel (A/F) ratio curve remained between 12.5 and 13.1:1. Finally, Westech's 13⁄4-inch dyno headers and 3-inch Flowmaster mufflers directed the exhaust.

Dual Plane Intake Test Procedure

With this many intake manifolds, we expected the competition would be very close. This demanded a very accurate test procedure to achieve best results. This meant that Westech dyno guru Steve Brulé had to control several variables, the most important of which was A/F ratio. Because we were using a carburetor, the A/F ratio is subject to significant swings based on manifold design. Carburetors also don't produce the same A/F ratio throughout the entire power curve. We made sure each test maintained an A/F ratio range within 12.5:1 and 13.1:1. That was the best we could do without custom-tuning the carburetor for each manifold. We also made sure the oil temperature was consistent for each test because cold oil can cost upwards of 5–10-lb-ft of torque and similar horsepower numbers. These requirements eventually dictated a test procedure in which we would subject each manifold to anywhere from three to five test runs until we had two curves within 0.5 percent. Then we averaged those two runs into a single curve. This eliminates an individual "hero" run from tweaking our results. In order to maintain timing accuracy, we used an MSD crank trigger with total timing set to 34 degrees, removing the variable of resetting the timing each time we changed manifolds. We also re-ran the first intake manifold tested at the end of the test to ensure that our 406 was still producing the same power. When the re-test gave us nearly identical results from the first run three days earlier, we knew our tests were as accurate as we could produce.

Overall, the dual plane intake test required the better part of three days, but we think accurate results were well worth the effort. Also, the TFS aluminum 215cc heads now have had nearly 50 intakes bolted to them, and those intake threads in the heads have held up just fine. Hero status is awarded to whomever does the heat-treating on those TFS heads! A big thank you to Fel-Pro for all the intake gaskets we blew through in this test and to Permatex for the big tubes of The Right Stuff RTV we used to keep the oil inside the engine. We've also used the Ultra Grey and Ultra Black with great results. Finally, thanks to Summit Racing for supplying a large pile of 3⁄8- and 1⁄2-inch Allen pipe plugs to seal up many of these manifolds. The Holley intakes came with plugs, though most of the other intakes do not.


Short Manifolds (Less Than 5.00 Inch Carb Pad Height)

Manifold PN Price Peak TQ Peak HP Avg. TQ Carb Ht. TQ at 3,000
Edelbrock EPS 2701 $139.95 506 461 466.2 4.80 476
Edelbrock Air Gap 2601 $225.95 504 458 464.7 4.92 478
Chevrolet ZZ4 10185063 $239.95 500 471 464.5 4.95 467
Weiand Street Warrior 8125 $151.95 501 463 463.5 3.65 470
Weiand Street Warrior 8120 $134.95 502 459 462.8 4.62 471
Summit Stage 1 226012 $131.95 498 459 461.0 4.65 468
Edelbrock Performer 2101 $157.95 494 456 459.1 4.60 470
Prof. Prod. Cyclone 52001 $143.95 487 436 449.3 4.72 471

Our test engine is the same 406ci small-block we used for the single-plane intake manifold test, with a change to more conservative cam timing that is closer to what would be typical for a dual-plane intake manifold–equipped engine. We also used a smaller 750hp Holley carburetor instead of the 850 Ultra HP employed in the single-plane test.

Edelbrock says the EPS is worth 9 lb-ft over the 2101 on a 350ci engine. We saw 12 lb-ft with our 406 over the 2101, and the EPS bettered the 2601 Performer Air Gap in average torque. Even better, the EPS saves $20 over the 2101. Within the short manifolds, the EPS is an excellent choice.

Medium Manifolds (5.00 to 5.30 Inches Carb Pad Height)

Manifold PN Price Peak TQ Peak HP Avg. TQ Carb Ht. TQ at 3,000
AFR Titon 4804 $579.00 510 484 473.6 5.29 467
Edelbrock Air Gap 7501 $234.95 508 474 471.2 5.26 473
Edelbrock RPM 7101 $174.95 504 470 468.3 5.25 474
Weiand Warrior 8501 $217.95 504 466 466.3 5.24 471
Summit Stage 3 226010 $182.95 503 464 465.6 5.25 471
Edelbrock RPM Q-Jet 7104 $199.95 501 465 465.3 5.25 471
Summit Stage 2 226014 $132.95 502 469 464.9 5.18 466
Weiand Speed War 8150 $145.95 502 467 464.9 5.18 467
Jegs 513000 $ 99.99 500 471 464.5 5.29 462
Professional Products Crosswind 52026 $199.95 496 457 459.5 5.24 469

Tall Manifolds (5.30 Inches and Taller)

Manifold PN Price Peak TQ Peak HP Avg. TQ Carb Ht. TQ at 3,000
Professional Products Typhoon 52021 $162.95 499 469 465.3 5.33 471
TFS StreetBurner 30400222 $224.95 501 465 465.2 5.39 473
Dart SHP 42811000 $231.70 501 464 463.7 5.52 470
Professional Products Cyclone-Plus 52013 $177.95 497 458 461.0 5.37 471
Chevy Iron 14096011 $261.06 494 457 459.0 5.45 468
Peak Torque and Horsepower

We have to acknowledge how amazingly tight this field is in terms of peak torque. How close? It is fair to say that it would be difficult to feel the difference of 2 percent of power. That's 10 lb-ft of torque, the difference between the Third Place Edelbrock EPS manifold at 506 lb-ft and the Professional Products Crosswind (52026), which placed 20th. Also note that in the peak-torque category, three of the top five manifolds are Edelbrock castings. When it comes to dual-plane intakes, torque is king, and it appears the Edelbrock has this part of the power curve dialed in.

Torque at 3,000 rpm is another important category that we listed in the initial description chart for each manifold. We opted to include this bit of data because it relates to low-speed power. With a performance torque converter, this would be just after the converter hits. Note that the relatively short Edelbrock 2601 Performer Air Gap manifold makes more torque at 3,000 than any other manifold. Compare its 478 lb-ft to the Jegs manifold's 462 lb-ft, to see that the Air Gap makes 16 lb-ft more torque. We guarantee you will feel 16 lb-ft in the seat of your pants. We think this can be partially attributed to the plenum-wall cutout on the Jegs manifold, but the TFS and Dart manifolds also have this feature, and those manifolds are only down by a single-digit compared with the Edelbrock. For a mild street engine (especially with stock or near-stock heads), this low-speed torque value should be given greater consideration.

Now let's talk peak horsepower. While the field gets a little more spread out in this category, the difference between the Third-Place Jegs Champion and the 21st place Edelbrock Performer is only 15 hp—barely a 3 percent increase. By now, it should be obvious that any manifold you choose within the top 20 will work just fine for a street small-block. Keep in mind that this test used really good heads on a large engine. With a mild 350 with near-stock heads, the differences in these manifolds would be much narrower. And we haven't even mentioned price yet.

If peak torque and peak horsepower are your only goals, then look no further than the AFR composite manifold. Yes, it’s expensive, but it simply bested every other manifold.

Peak Torque and Horsepower

Ranking Peak TQ Ranking Peak HP
1st AFR Titon 510 1st AFR Titon 484
2nd Edelbrock 7501 508 2nd Edelbrock 7501 474
3rd Edelbrock EPS 2701 506 3rd Jegs Champion 471
4th Edelbrock RPM 7101 504 4th Edelbrock RPM 7101 470
4th Weiand Warrior 8501 504 5th Pro. Prod 52021 469
4th Edelbrock 2601 504 5th Summit 226014 469
7th Summit 226010 503 7th Weiand 8150 467
8th Summit 226014 502 8th Weiand 8501 466
8th Weiand Warrior 8150 502 9th Edelbrock 7104 465
8th Weiand 8120 502 9th TFS Street Burner 465
11th TFS StreetBurner 501 11th Summit 226010 464
11th Edelbrock 7104 501 11th Dart SHP 464
11th Dart SHP 501 13th Weiand 8125 463
11th Weiand 8125 501 14th Edelbrock 2701 461
15th Chevy ZZ4 500 15th Weiand 8120 459
15th Jegs Champion 500 15th Summit 226012 459
17th Pro. Prod. Typhoon 499 17th Edelbrock 2601 458
18th Summit 226012 498 17th Pro. Prod. 52013 458
19th Prof. Prod. 52013 497 19th Pro. Prod. 52026 457
20th Prof. Prod. 52026 496 19th Chevy Iron 457
21st Edelbrock 2101 494 21st Edelbrock 2101 456
21st Chevy Iron 494 22nd Chevy ZZ4 451
23rd Pro. Prod. Cyclone 487 23rd Pro. Prod. 52001 436

Average Torque and Average Torque per Dollar

Here's where we lay it on the line. For street engines, it's not peak horsepower that makes your engine feel powerful. Street-smart engine builders emphasize torque, and while peak torque is a good indicator, we think the best judge of a dual-plane intake is average torque. This generates a single number created by averaging all the torque numbers within the test range of 2,500 and 6,200 rpm. We weren't surprised when the AFR Titon composite manifold handily won this contest. What was surprising was the tried-and-true Edelbrock Performer RPM Air Gap was within 2.4 lb-ft of the AFR at less than half the cost. It's also important to note that this evaluation really splits hairs because nearly all these manifolds produce excellent power. Let's take the Weiand 8125 Street Warrior. It made 500 lb-ft of peak torque yet is listed 15th in average torque. But when we plugged its torque curve into our Quarter, Pro dragstrip simulation, this intake is only off 0.15-second and 1 mph compared with the fourth-rated Edelbrock 7101. So you can see that most of these manifolds really do a decent job. Drop out the top and bottom two manifolds, and the total spread between 3rd and 20th is 2 percent—or 9.2 lb-ft of average torque.

For the typical car crafter, average torque per dollar is probably most important of all the ratings in this shootout. Unless your name is Bill Gates, cost and power are equally important. To come up with this evaluation, we divided the manifold's average torque by its price; the larger the number, the more power it delivers for each dollar spent. From the moment we began pricing manifolds, the Jegs Champion appeared to be a front-runner. At $99.99, all this intake had to do was make decent torque and horsepower to win this category. But, as you've seen, this intake ranked Third in peak horsepower and was capable of 500 lb-ft of torque. Trim $30 off its next closest price rivals, and the conclusion is simple: If we were to mash up all the evaluations into one overall winner, you could make a great case for the Jegs Champion intake. Note that the AFR number is a fraction, which means its price was a larger number than its average torque.

The Weiand Speed Warrior 8501 also separates the runners from the manifold floor. It placed a respectable Fourth in average torque and sixth in average torque per dollar, making it an excellent choice.

Average Torque and Average Torque per Dollar

Ranking Avg. TQ Ranking Avg. TQ/$
1st AFR Titon 473.6 1st Jegs Champion 4.64
2nd Edelbrock 7501 471.2 2nd Summit 226014 3.49
3rd Edelbrock 7101 468.3 3rd Summit 226012 3.49
4th Weiand 8501 466.3 4th Weiand 8120 3.43
5th Edelbrock 2701 466.2 5th Edelbrock 2701 3.31
6th Summit 226010 465.6 6th Weiand 8150 3.18
7th Edelbrock 7104 465.3 7th Pro. Prod. 52001 3.12
7th Pro. Prod. 52021 465.3 8th Weiand 8125 3.05
9th TFS StreetBurner 465.2 9th Edelbrock 2101 2.90
10th Summit 226014 464.9 10th Pro. Prod. 52021 2.85
10th Weiand 8150 464.9 11th Edelbrock 7101 2.67
12th Edelbrock 2601 464.7 12th Pro Prod. 52013 2.59
13th Jegs Champion 464.5 13th Summit 226010 2.54
14th Dart SHP 463.7 14th Edelbrock 7104 2.32
15th Weiand 8125 463.5 15th Pro. Prod. 52026 2.29
16th Weiand 8120 462.8 16th Weiand 8501 2.14
17th Summit 226012 461.0 17th TFS StreetBurner 2.06
17th Pro. Prod. 52013 461.0 18th Edelbrock 2601 2.05
19th Pro. Prod. 52026 459.5 19th Edelbrock 7501 2.00
20th Edelbrock 2101 459.1 20th Dart SHP 2.00
21st Chevy Iron 459.0 21st Chevy ZZ4 1.89
22nd Chevy ZZ4 454.4 22nd Chevy Iron 1.76
23rd Pro. Prod. 52001 449.3 23rd AFR Titon 0.82

In-Car Power

What will all this power do in a car? We simulated the 7101 Edelbrock Performer RPM's power curve in a 3,450-pound Chevelle with 3.55:1 gears, a 2004R automatic, 3,000-rpm stall-speed converter, 26-inch-tall Mickey Thompson ET Street tires, and shifting at 6,400 rpm. The Quarter, Pro simulation reported that the Chevelle could run 11.50s at 117 mph with a 1.55-second 60-foot time. That's impressive for a 470hp dual-plane–equipped small-block. Keep in mind that strong average torque is what makes this combination so quick. If you recall, our single-plane intake test—with the same 406ci engine with a bigger cam—the motor made as much as 559 hp, but in the same simulated car with the same equipment, the greater horsepower only pushed the Chevelle to 11.30s at 120 mph. With more gear (like a 4.10:1, for example), the car would probably run 11-teens in the higher-horsepower configuration.

Through it all, our Rodney 406 braved more than 150 dyno pulls, and we’re not finished yet. It might just find its way into our Orange Peel Chevelle.

Cam Specs

Crane Roller: PN 118571 Duration at 0.050 (Degrees) Valve Lift W/ 1.5:1 (w/ 1.6:1 rockers) Lobe-Separation Angle (degrees)
Intake 232 0.525 (0.560)* 112
Exhaust 240 0.543 (0.579)*
*This is gross lift. We set the lash at 0.020 inch, which must be subtracted from the gross-lift number to produce a net lift equaling 0.540/0.559.

As with our single-plane test, taller manifolds generally make more power—although not always, as the results will show. The Performer RPM Air Gap separates the intake runners from the hot oil bouncing off the bottom of the manifold to reduce inlet-air temperatures. When choosing a manifold, keep in mind that it has to fit under the hood.

[steve cowan]

Looking for some advice. I know a 406 would be a better build but it’s a car that I inherited. Trying to keep it as my dad had it. Just looking to get the most out of the motor.

400 small block 40 over (4.165 Bore)
3.48 stroke
Flat top pistons with valve relief
Comp cam hydraulic 12-470-8 (.600 lift 314 intake duration 314 exhaust duration 252 on both at 050)
1.5 roller rockers
.039 head gaskets
Flow Tec 200cc heads
Holly strip dominator intake with 2” riser
Holly HP750cfm double pumper carb
Headmen headers with 2-1/2” flow master exhaust.
10-1 ish compression
3200 rpm torq converter
TH 400 tranny

Any opinions on a better intake for this set up? Looking for around 500 HP.
Also is the 750 a big enough carb?
Thanks

I like the 377 cubes.
My opinion, bump up compression to 11.1.
Ported heads and intake it will make 500 easy.
There is nothing wrong with a 750 carb either.
I like to run a 8" converter with say 4.11s and 27" tyre it is still ok on freeway - 60mph at 3100 - 3200 rpm.
As far as the 300-25 intake manifold, I believe they are excellent especially once ported.
They will handle 600hp engine.

[lefty o]

Looking for some advice. I know a 406 would be a better build but it’s a car that I inherited. Trying to keep it as my dad had it. Just looking to get the most out of the motor.

400 small block 40 over (4.165 Bore)
3.48 stroke
Flat top pistons with valve relief
Comp cam hydraulic 12-470-8 (.600 lift 314 intake duration 314 exhaust duration 252 on both at 050)
1.5 roller rockers
.039 head gaskets
Flow Tec 200cc heads
Holly strip dominator intake with 2” riser
Holly HP750cfm double pumper carb
Headmen headers with 2-1/2” flow master exhaust.
10-1 ish compression
3200 rpm torq converter
TH 400 tranny

Any opinions on a better intake for this set up? Looking for around 500 HP.
Also is the 750 a big enough carb?
Thanks

should make 500 as is, but id probably change up the cam a bit.

[bigcam406]

Most off the shelf flat top pistons i have seen for your 377 end up being around 10.5-10.7 to 1 compression. That cam is an old Comp Magnum grind, pretty rowdy hydraulic roller back in the day. Intake and carb will suffice for your combination. Sounds like a fun street engine, go out and enjoy it for a bit to see if you like what it gives you. 500 hp should be no problem on pump gas.

[GARY C]

I think the best advice comes when it is clearly defined what constitutes “Just looking to get the most out of this motor” as that is quite subjective. Five hundred hp has been mentioned but is this predominantly street driven or looking to attain an et time or a bit of both?

Sorry yes it is mostly street driven. And I’m really looking for it to be a relatively reliable fun car. And for the combo to be matched best as possible.

What street? The Boulevard at 45 MPH and 3000 RPM or the Hyway at 70 MPH and 2800 rpm?

This will play a big part on cam converter and gear, the rest of the combo should be ok.

[F-BIRD'88]

It will not get anywhere even close to 500 bhp until the heads are ported generously.

[lefty o]

It will not get anywhere even close to 500 bhp until the heads are ported generously.

[prairiehotrodder]

I agree with F-bird on the 500 hp goal. I built a 377 many years ago and I know 500 hp requires good heads and bit more serious of parts than what most people think. Mine used AFR 210 heads and a solid roller with 11-1 CR. I've learned from hearing of other people's mistakes that the chinese heads usually don't deliver the power, even if they bolt on and work just fine. I'm not saying your combo is wrong, it looks alright to me and i like the holley intake and i think a 750 carb is just fine. I tried an 850 demon on my 377 and it gained nothing over a holley 750 vacuum carb. I do prefer the carbs that have the milled off choke though.
Brian

[mag2555]

With that cam and it’s .600” lift and those out of the box 200 Cc heads I can’t for the life of me see why you can’t make 500 Hp.

3 months ago I did a old set of Trick flows getting them to 260@ .500” for use on a 364 purly street SBC going in a fully loaded 65 B body.

With 10.25 comp and a cam of 218/226 , 462”/ .470 on a 112 the motor made these numbers well below 6000 rpm.

The intake was a Victor jr 2 bbl that I modded to take a 4 bbl.

[Martin161]

Thanks everyone, I’m going to try this set up as is and see what get for numbers. I really appreciate all you guys taking the time to give me the info. I’ll keep you posted on this thread with numbers!