400hp Pump Gas Roller 340 Strip/Street Build

[ethan santin]

Hey there FABO,

I have had a 60 over 71 340 block sitting around and have become motivated to start building it. I sent out a cam recommendation post a little while ago but I wanted to get more opinions about the overall build. I want the build to shoot out around 400hp. Its going into my duster and I'm putting my 904 as well as my 3:91's behind it. I want to prioritize performance over steerability, but not to the extent to where it is almost unstreetable, I do plan to drive it. Curious as to how any of you would go about building a roller 340 like this. What head and cam combo would you choose and why? Any recommendations, or links to builds in magazines would be awesome, feel free to share any other small block Mopar builds that meet this criteria that aren't 340's.
Thanks for reading.
Ethan

 

[273]

Hey there FABO,

I have had a 60 over 71 340 block sitting around and have become motivated to start building it. I sent out a cam recommendation post a little while ago but I wanted to get more opinions about the overall build. I want the build to shoot out around 400hp. Its going into my duster and I'm putting my 904 as well as my 3:91's behind it. I want to prioritize performance over steerability, but not to the extent to where it is almost unstreetable, I do plan to drive it. Curious as to how any of you would go about building a roller 340 like this. What head and cam combo would you choose and why? Any recommendations, or links to builds in magazines would be awesome, feel free to share any other small block Mopar builds that meet this criteria that aren't 340's.
Thanks for reading.
Ethan

Solid roller ?

You willing to run whatever stall that's needed.

400 hp ain't a crazy amount for a 340 especially where driveability ain't much of a concern.

425-450 hp probably a good goal especially with aftermarket heads.

I'll post some magazine builds.

 

[Bodyperson]

Ya, big intake valve good with that bore.

 

[273]

340 X Head Buildup - Return Of The Mad Scientist 340
Bold Numbers Are PeakBase 1:340 as originally tested; stock build, stock 340 "X" heads, Comp XE268H cam, Air-Gap intake, 800 Edelbrock carb, 151/48-inch Hooker headers, stock valvetrain, stock electronic ignition

Base 2:Reconfigured 340; as above with street-ported #051 heads, Comp custom MM-series solid (lobes 6581/6582 110 LSA), Comp 7692 Magnum pushrods, Probe 1.6:1 Roller Rockers, 750 Speed Demon carb, MSD distributor

Plugs:Swap Autolite #63 for Denso Iridium #IQ24

Space:Add 1-inch open carb spacer

HDR:Replace Hooker 1 5/8-inch primary tube headers with 1 7/8-inch primary Hooker Super Competition headers

#051 Head Flow Tested At 28-Inches Of Water.Superflow 600 BenchPorted By Steve DulcichTested By Steve Dulcich

	Intake	Exhaust
Lift	Stock	Ported	Stock	Ported
. 100	53	63	46	57
. 200	106	126	87	95
. 300	162	181	113	132
.400	194	230	120	160
.500	191	253	126	179
.600	192	241	127	183

Corrected Brake TorqueSuperflow 901 DynoTested At Westech

RPM	BASE 1	BASE 2	PLUGS	SPACE	HDR
3500	396.1		425.3	410.0	413.8
3800	412.0		433.5	420.2	411.2
4000	409.3		434.4	426.8	413.9
4500	409.4	425.8	429.8	433.8	417.9
4600	406.3	427.0	428.3	431.1	425.8
5000	396.0	417.9	417.4	433.8	431.0
5500	369.9	410.3	410.9	420.3	422.9
6000	335.8	394.0	394.8	399.5	407.1
6500		363.8	362.9	374.4	385.4

Corrected HPSuperflow 901 DynoTested At Westech

RPM	BASE 1	BASE 2	PLUGS	SPACE	HDR
3500	263.9		283.4	273.3	275.7
4000	311.7	330.8	325.0	315.2
4500	350.8	364.8	368.2	366.8	358.0
5000	377.0	397.8	397.3	413.0	410.3
5500	387.4	429.7	430.3	440.2	442.9
5700	391.6	435.5	436.9	446.9	452.1
6000	383.7	450.1	451.0	456.3	465.1
6300		458.9	459.7	464.6	472.4
6400		455.8	455.3	464.9	474.8
6500		450.3	449.1	463.4	477.0

 

[gzig5]

I just did a 340 with mildly ported ProMaxx aluminum heads, 10.8:1 compression, and a 242/247 Solid flat tappet cam. With no tuning and the wrong rockers we got 460hp on the dyno. You don't need a roller cam to get 400hp. If you already have it, fine. But you can get into 500hp with a less expensive SFT cam.

 

[Bodyperson]

I just did a 340 with mildly ported ProMaxx aluminum heads, 10.8:1 compression, and a 242/247 Solid flat tappet cam. With no tuning and the wrong rockers we got 460hp on the dyno. You don't need a roller to get 400hp.

That's pretty good. You ported them beyond what promaxx does to the head?

 

[273]

This definitely more than you want, still a good read, it's hard to find a 400 hp 340 build.

340 Big-Block Engine Buildup - Giant Slayer
340 Big-Block Engine Buildup - Giant Slayer

RPM	Ft/Lb	HP	BSFC LBS/HR
4000	400.3	300.9	.392
4500	421.6	361.2	.385
5000	459.0	437.0	.373
5200	459.3	454.7	.381
5400	458.0	470.9	.379
5600	454.9	485.0	.392
5800	449.9	496.8	.396
6000	460.1	525.7	.415
6200	454.0	535.9	.435
6400	452.0	550.9	.438
6600	457.7	575.2	.436
6800	446.8	578.5	.442
7000	439.2	585.4	.457
7100	437.7	591.7	.550
7200	431.6	591.6	.586
7400	414.4	583.9	.552
7500	407.1	581.4	.536

 

[gzig5]

That's pretty good. You ported them beyond what promaxx does to the head?

Member NC Engine Builder did the work. I did a long thread on the build a couple months ago but don't have it handy. He didn't spend very much time on them but got them close to 280cfm. These are the standard 171cc port version, similar to Edelbrock and SM. With the 1.6 rockers I planned on and some tuning it should be goof for a solid 480+ IMO.

 

[273]

Here's an good 400 hp/425 hp 318 similar build on a 340 gonna be similar but at a little less rpm.

Chrysler 318 Engine - A Powerplant To Brag About

On The Dyno318 Mopar Street EngineSuperflow 901 Engine Dyno Stp Correction Factor Tested At Westech Performance Group

RPM	TQ	TQ	HP	HP
	BASE	PORTED	BASE	PORTED
3,000	335	335	192	192
3,200	342	340	208	207
3,400	351	356	228	231
3,600	365	369	250	253
3,800	374	379	271	274
4,000	379	384	289	293
4,200	378	383	302	306
4,400	375	383	314	321
4,600	376	382	329	335
4,800	375	386	343	353
5,000	372	384	354	366
5,200	367	383	363	378
5,400	361	379	371	390
5,600	355	374	379	399
5,800	350	371	386	409
6,000	345	365	395	418
6,200	341	360	402	425
6,400	329	345	401	421

 

[Bodyperson]

Member NC Engine Builder did the work. I did a long thread on the build a couple months ago but don't have it handy. He didn't spend very much time on them but got them close to 280cfm. These are the standard 171cc port version, similar to Edelbrock and SM.

Thanks. Promaxx advertises 250 at .5 lift or so. I have a set. Nice looking head.

 

[gzig5]

Thanks. Promaxx advertises 250 at .5 lift or so. I have a set. Nice looking head.

If you find my thread, he got close to that before he started on them. And really didn't take much time to get another 20-25cfm. They are nice.

 

[273]

10 to 11:1, airgap or single plane, headers, Edelbrock heads or clones, Trick Flow or ported Edelbrock heads or clones if you want to step it up, 235-245 cam etc... kind of the ballpark.

 

[crackedback]

You could probably hit 400 with a 220@.050 roller cam with 520ish lift with much problem. Likely a bunch more than 400 with a cam that small.

 

[Bodyperson]

Stock Stroke 340 Build with NC Engine Builder

 

[PROSTOCKTOM]

Stay with a roller cam. Way to many benefits for not that much more money in the grand scheme of things.

Tom

 

[RustyRatRod]

A stock stroke 340 will make 400HP fallin outta bed with the right cam and head work.

 

[autoxcuda]

Stay with a roller cam. Way to many benefits for not that much more money in the grand scheme of things.

Tom

A solid roller? I hear good Johnson hydraulic rollers were $1k a set.

 

[Oldmanmopar]

JOHNSON ? Everytime I hear that name my blood pressure goes up.

 

[ethan santin]

Thank you for all the feed back everyone. Sorry i forgot to include that yes it will be a solid roller not a hydronic. I am also aware that 400 ponies is not very difficult for a stock stroke 340 to spit out. I wanted to stick to that number (or range) in order to keep the engine more street able.

 

[ethan santin]

I just did a 340 with mildly ported ProMaxx aluminum heads, 10.8:1 compression, and a 242/247 Solid flat tappet cam. With no tuning and the wrong rockers we got 460hp on the dyno. You don't need a roller cam to get 400hp. If you already have it, fine. But you can get into 500hp with a less expensive SFT cam.

Very neat thanks for sharing. What where the rest of the specs for your camshaft? where you running a stock bottom end and what intake manifold are you running?

 

[273]

Oh I see you narrowed it down lol

 

[crackedback]

Most shelf rollers are going to be in the 240+ @.050. You don't need that to hit 400

Might have to have someone cut you a cam. Brian at IMM, NC engine builder, PRH could help getting you there.

400hp with ported alum heads (ported iron too), small roller, headers, air gap and 750 holley will get you there easily. The smallest shelf roller will push 450+

 

[273]

Most shelf rollers are going to be in the 240+ @.050. You don't need that to hit 400

Might have to have someone cut you a cam. Brian at IMM, NC engine builder, PRH could help getting you there.

400hp with ported alum heads (ported iron too), small roller, headers, air gap and 750 holley will get you there easily. The smallest shelf roller will push 450+

The smallest I've seen when I wanted to build a kick *** 273 was comp had (don't know if they still do) 229 solid roller, on the dyno program the 273 really liked it, don't about in reality

 

[273]

Just checked they don't but do have like a half dozen in the 230 to 243 range

 

[gzig5]

Very neat thanks for sharing. What were the rest of the specs for your camshaft? where you running a stock bottom end and what intake manifold are you running?

See the link in post 14 for my build thread. Cam info in post 12 i think. Edelbrock Air Gap intake