Streetable high power 340?

[blueduster340]

Is it possible to make a 350-400 hp 340 and still be able to drive in on the street? What would you need to make this kind of power?

[ohioDemon]

a 340 with 9.5 cr. a good set of headers, an edelbrock air-gap intake/ 750 holley and a stock 340 hyd cam should put you right in the ballpark on hp.

[Plymouth10]

Sure it can be done,ohiodemon's suggestions & perhaps a good port job, tti headers,or cppa, maybe rasie cpr a tad if desired. I like the race d.u.i. hei style distrib's, can bring 15-20 hp alone {race version}

[blueduster340]

any other opinions? The 340 is a later low compression engine. Should I look into raising the compression? And I was looking at putting some headers, an rpm air gap, maybe a hotter cam, x heads on it. Anything else I should look at? It will have a 727 behind it. What kind of torque converter should I look at? And the car will be street driven and maybe taken to the track a few times a year.
Thanks.

[72Challenger]

I happen to be right in the middle of just such a build right now myself. I'm modeling mine after the buildup done by Mopar Muscle in the December 2000 through February 2001 issues. When they were done they got 391 HP in a pump-gas friendly package that was very streetable. Then a little later they went nuts and bumped it up to 477!

They started with a .040 overbore, stock crank, and TRW forged pistons with 1.840 compression height ('68 - '71 spec.) They actually just bought a rebuild kit from P.A.W. and added a few upgrades like moly rings and the forged pistons. Stock X heads with new valves, other than that a pure, bone-stock resto. Made 281 HP, a little more than the stock advertised 275.

Then they bolted on an Edlebrock 800 CFM carb on an Air Gap manifold, Hooker Competition 1 5/8" headers, and a Comp Cams Extreme Energy 268 cam with new valve springs. Bingo! 391 HP with bolt-ons. Not bad at all.

For the next stage they replaced the hydraulic cam with a solid, the Eddy carb with a Demon, the stock heads with ported ones, and the small tube headers with some bigger ones, and got 477 HP.

How far do you want to go? As you can see, it's pretty easy.

[blueduster340]

Thats exactly what I was looking for. I was looking at getting that exact cam, intake manifold, and those headers. What kind of Demon carb did they use? I was looking at maybe getting one of them also.

[72Challenger]

750 Speed Demon double pumper. Not necessarily the best choice for a street machine with an automatic, but good for making numbers on the dyno.

[1980cobra]

can i reply p10??

[Plymouth10]

doba1980 NO...... lol, i dont care man...

[blueduster340]

Would a 625 or 725 Road Demon be a good choice for a carb or is there something better to get?

[rumblefish360]

1980cobra I say reply constuctively without throwing "FORD" in our face.

blueduster340; An example cam would be a MoPar purple 280 duration, and you would need more comp. Reduce chamber volme about 10cc's. The X heads are fine except there large chambered heads. (72cc's) This is to much on a low comp. engine. Mill them if you want to. I myself, would resell them and pick up a small chambered head.
A 280* cam and 9.5-1 (iron headed or 1 pt. more comp. with alum. heads, edels.) with RPM intake and 750 cfm & headers will create 400 HP.

[1980cobra]

my last few posts i havent said one word about a ford . only about 318's.just want to see some fast 318's

[blueduster340]

If i threw in some pistons to raise the compression would the x heads be fine to use? What compression should I shoot for?

[Plymouth10]

I would go at least 10.1 cpr myself.

[rumblefish360]

Yes. More comp. is needed.
I disagree with 10-1 on a iron headed engine. Detonation would be a problem with a small cam and todays octanes at the pump. 10 -1 is pushing it.
9.5-1 max, 10.5-1 max with aluminum heads.
Remember head gasket thickness has a play in the comp. ratio, so don't for get to factor that in. Grab a set of cometic gasket from the link below.

[Plymouth10]

oh is this an 89 oct engine?

[blueduster340]

yeah the highest octane we have around here is 89 i think. I want to be able to drive the car on the street but I want to have power. It will see the strip a few times a year at the most.

[Plymouth10]

I agree with RumbleFish ,sorry i missed that part, 10.1 is a strech with that..{89}

[72Challenger]

The Mopar Muscle article I refered to earlier didn't mention final compression ratio, but the Speed-Pro pistons I'm using have 7.5cc valve reliefs and stick above the deck by .018. With a FelPro gasket and NHRA-spec 68cc heads, that works out to 9.8:1 compression. A little high, yes, but my heads seemingly had been cut by a previous owner. That's the only way I know of they could have cc'd out to exactly 68. Stock they do seem to be about 72, which means if you follow the magazine build up exactly, and have uncut heads, you should have 9.4:1 compression. This would be fine with 91 octane, you may need to back off the timing a little to run with 89. Then mix a little good stuff at the track for the racing fun.

[blueduster340]

Would the Comp Cams Extreme Energy 268 work well with 9.4 compression? And does anyone have a link to the arcticle or know where I can find it?

Thanks for all the help.

[rumblefish360]

Yes it would as well as the next 2 down from it. (274 or 284 xe cams. The 284 could use more comp. but would do OK.)
try this;
http://www.moparmusclemagazine.com

[riverside]

Blue Duster 340, Be careful with airgap manifold I tried to install on my duster and couldn't close my hood. Not enough clearance for my stock hood to clear. I tried low profile air cleaners, still no go. Good luck with your engine build up.

[72Challenger]

Oh yeah, forgot to mention that part. I measured clearance to my stock flat hood, no go. I will need to either buy a bulge hood or cut a hole and mount a scoop. My engine isn't quite done yet, so I have a little time to prepare for this.

[blueduster340]

I'll be using my stock hood with the dual hood scoops so I'll have to substitute the air gap for the performer rpm then.

[rumblefish360]

Aren't they the same height. Basicly the same intake manifold with a slight difference.....

[sbfinne]

If it is going to be a daily driver go no more than 10-1.
I only drive mine on select times,so I recommend as much squeeze as you can live with.If you want to slay the BB giants you need the higher cyl.pressures.I use TK-7scf or racing fuel mixed with BP prem.This setup makes awesome power and a roller cam upgrade is in the works.

340-.10 over
Air-Gap Man.
Harland Sharp 1.6
Thunder Edel.750cfm
484 Purple Cam
Stage 1 J-heads.They flow nice
11-1 Forged pistons
Cope 904 Auto
489 3.55-Moser axles-
TTI headers into x-pipe 2.5
10in 3400 stall conv.

[72Challenger]

Sorry blueduster, that won't work. The Air Gap and the Performer RPM have exactly the same installed height. There is a new Performer Air Gap, but not for Chryslers. As usual we are last in line for the new stuff.

[bbeckwith]

That's weird, the RPM Airgap fits under my stock hood just fine. What motor mounts are you guys using? I have the sandwich(biscuit) type. Maybe with the spools the motor is setting up higher?

[72Challenger]

All I did was measure the clearance with my existing setup. The Air Gap is over 2" taller than my stocker, and I have about 3/4" clearance with my drop-base air cleaner. My mounts are stock '74 small block.

[blueduster340]

I guess I'll have to wait and measure when I get the motor put in if it will fit or not. If it won't fit I'll look at a different intake manifold. How tall is the air gap?