11 second A-body small block build?

In the infancy stages of planning a small block build for my newly acquired 68 Barracuda and looking for opinions. Currently a mild 318 w/ 727 automatic, but I have a stock 360 short block with Keith Black HE pistons and iron J heads already machined and ready to go as the basis of the new build. Not looking to stroke it since the block & stock rotating assembly are already done. 3.55 gears already in the 8-3/4" rear end so hoping to keep those too. 1-5/8" headers already on the car, but planning a new exhaust system as the existing is horribly bent 2.5" pipes.

Looking for input on cam, convertor, intake, carb, etc. Ultimate goal is mid-to-high 11's thru the mufflers at about 3550 lbs including driver.

Thanks

I ran consistent 11.40-11.44 with the following, in a '70 Duster @ about 3200 lbs with me and 10 gals gas in it:
358" 340, ported X heads, 750DP Holley, single-plane intake, MSD, Crane MFT .580/.600 lift, 12.5:1 CR, Stahl 1 7/8 headers.
Holley blue, Moroso electric water pump, pan evac, 8-point cage. 7.10s on 15x4s in front.
Jack Arnew's modified upper control arms (car always went dead straight & carry ft wheels at launch).
4400-stall TA converter, RMVB mostly stock 904, Dana 60 5.38, 13x31s on 15x12 wheels (mini-tubs, springs moved to rails).
The fewer pounds you have to move, the better for literally everything. That said, it always liked more ballast in the trunk.
It was never a street car, so everything that wasn't needed was gone except 1 seat and a finished interior.

Gonna need better or ported heads and/or, like topside said, lighter weight.

It’s gonna take those heads being pretty good to do what you want at that weight. Just went through several motors/ upgrades on my 3300 pound Dart. Bone stock 360 shortblock.
It started with stock Eddie heads, 4500 8 inch vert, 750 Holley, 1 5/8 headers, 4.10 gear, and a 727. Cam was a comp solid flat tappet. If I remember right it was like 244@50, had a missmatched( for the combo) Mopar M1 single plane on it. Ran 12.23 at 109 and change

I had the heads mildly ported( not a full tilt job by any means) and milled about 30 to help compression a bit, also ran 028 mr Gasket head gaskets. , heads went in range of 260 ish at 550 lift”
Ditched the M1 for an airgap, installed a 950 Holley I had that was known to be very good, Howard’s solid cam 260/264 565/565 lift,
After those changes, car went best of 11.26@ almost 119. Most of the time though 11.40’s in the summer.
Cam really woke it up. 8 inch convertor is a requirement, and just cutting the heads a bit and minor porting helped take advantage of the upgrades.
Strongly recommend the airgap, works nice
I think your going to find that with your weight and 3.55 gears it tough to get where you want.

You might be able to dip into the 11's if your combo is 100% working on a great weather day other wise I think your going have to change something. We have raced a Duster 3200ish lbs, dedicated race car, but not all chopped up for 15 years now with a 360. Dana 60, 4.56 gears, 30" tire, 727. The compression has always been 10-10.5:1. We've ran .a 533/.533, .519/.524 hydraulic cams, .528/.528 solid cam. We picked up a good bit when we went to a 8" 5000 stall convertor. All engines were shifted at 6,000, used a Victor 340 intake with a 750 Holley. We've ran steel X (I think X and not J but could have that backwards), Edlebrock and Trick Flow heads. We ran the Edelbrocks the most and that combo was typically a 11.60-11.80s combo, best it ever went was a 11.51. Trick Flows we only have a few runs on but ran about a tenth quicker than the Edelbrocks. The steel heads ran 12.00-12.20s. We used to have cheap hedman headers on the car, but have since put Dougs 1 5/8 headers and with a 12" glasspak muffler.

Lots of good advice here... IMO more gear ( 4.10, 4.30 or 4.56 ) less converter ( 8 inch ) just a quick note : years ago my good 340 was broken and I had a basically stock 318 ( 340 cam, LD4B intake, 750 carb, and stock 360 heads ) with a 904 , 10 inch converter and 3.91 gears it went 13.20s in my 3200 lb Dart I put in an 8 inch Turbo- Action converter and it went 12.60s with no other changes. I went 11.30s with a 340 at 9 1/2 to 1 compression , ported " J" heads and a 557 lift Mopar Purple shaft cam . I went 10.50s ( 10.40 best ) with a 360 Magnum short block, 11.5 to 1 compression , W2 heads , 590 lift cam, made 549 hp ... currently set up has gone a best of 11.07 at 119 with the same 360 Magnum short block ,40 over to 367 c.i. , W2 heads , 585/595 lift cam, 10 to 1 compression on pump gas made 527 hp and 467 tq on the dyno. All my combos are ran thru the mufflers ( 3 inch Flowmasters ) with either 1 7/8 TTI headers or my previous Tubular Automotive 1 7/8 headers , Victor intakes and an AED prepped 750 hp carb. I wont even get into my R3 block/ Indy 360-1 head 408 thats a whole story in itself... these are just a few of the small block combos I have ran over the years.. your results may vary

Thanks for the info guys. I had 3.91 gears and an 8” ATI converter in my last A-body and could end up there again, but was hoping to keep the 3.55’s but time will tell. Gears are an easy change after the fact, engine not so much.

The basic logic is that the engine's a pump, and the drivetrain is a lever.
So, more you can pump (airflow and RPM), and the better your leverage (converter stall and gearing), the harder the car will run.
Obviously traction and weight are big factors, but you still have to create power and apply it efficiently.
W2s were worth a lot for me, and ported Batten (aluminum) W2s, an 850, a .630 roller, and 6,000 RPM stall were worth .80.
By then it was 368", and mid/low 10s.
Shifted it usually at 7500, occasionally 8000.

Man !!! .. my old 627 lift roller cam 340 /W2 head 12.5 to 1 compression I shifted at 7,200 ran 10.70s... now I am only shifting at 6,000 / 6500 leaving at 2,000 .. I guess I should mention that my car is slowed down via throttle stop to run 11.50s at 114 with 1.49-1.51 60 ft... I really like the W2 heads I wish I had them on my 408 instead of the Indy 360-1s

Interesting comment. The Indy heads are pretty much aluminum W2 heads.
Would rather run them any day of the week than W2’s. Depending on which flavor, they have a good bit more potential than W2’s as well.
And, aluminum you can fix.

We had a problem with them when they arrived from Indy that my engine builder had to fix before they were able to be used and I have had a problem with breaking their rockers on three different occasions , I only shift at 6,500 and we aren't running a lot of spring pressure . I understand that was an on going problem with their rockers. Indy no longer makes or offers them anymore they sent me what they had left in stock but they weren't the ones I needed. I ended up driving three hours one way to buy a used set because I couldn't find them anywhere. A friend had one that I was able to get the second time I broke one. I have to go to Harland Sharp, T&D or Hughes to get a complete new rocker system and they aren't cheap. That motor is out now due to a cracked stroker crank and my W2 / 367 back up motor is in now. My ancient W2 ductile iron non-roller rockers have been fine for over 25 years with out any breakage

Those Indy rockers have been known to be junk forever. Yes, a good rocker system isn’t cheap.

If you’re not running in the 11s it’s mostly the car setup. Use the Wallace calculator, weight to mph. 3.55s won’t get you where you want to be, neither will 6000 rpm. You ain’t got a 572 big block torque monster to move that car with those gears.

Two things I would change is the rear gear (4.56 to 5.13 ratio for 1/4-mile racing) and switch to a decent 904 tranny and good 8 ich converter with a low gear set in the 904
I've seen NHRA stock class racers (SB Mopar) gain from .12 to .18 ET in the 1/4 mile with that switch to a good race 904 tranny by freeing up the drive train and losing the internal weight in the 727 compared to the 904

Thanks for the input. We’ll see what the budget allows when the building process starts this fall.

Nitrous or a turbo will get you there with those gears at that weight.

Ha, so would a 440.

It will cost more, but in the long run, these would be much better options:

360 Magnum with stock Eddy heads, small .520 cam, inexpensive 76 mm turbo, 3:55 gear, 2,500 stall, aftermarket fuel injection. You will have to purposely try not to run 10's.

OR

6.2 Hemi w/8 speed conversion, 3:55 gears

Ya for sure you could use a power adder but for the ET you are looking for it’s absolutely not needed.

Not needed, but would make it very streetable, easier on parts, better fuel mileage, etc. It's a no brainer really.

10:1 comp, with Eddy heads, a .580" hyd. roller cam, SFT preferred by me, an air gap or similar intake =430>440hp and thats whats needed to go 11.6>7's@3550lbs, Min 3500 stall, 4200TA even better. Eddy heads only flow around 250cfm@.600 lift so you need that bigger cam to get the flow.

Porting your J's is expensive and not worth it in my opinion with big chamber cc. Best if money allowed would be TF190 heads that flow 280@just .500" so you can use a low street lift cam, something like a comp XE275HL and have more power.

Its all doable with 3.55's however your trap rpm will be in the 5500 range with 26" slicks which is ok for a mild cam. A 4.10 gear and 28" slicks would get you trapping around 6000 rpm with slip and pick up your 60 and ET and would be a better way forward and use a big enough carb, the standard 750DP may run good but a 950 should make more hp especially with TF heads.

You will need about 450HP to run high 11's...maybe even 475HP. And lower gears with no stroker, or leave the gears and put a 4" crank in it.

I'm having a hard time thinking why a 408 with 240-250 cfm j heads can't get this done.

Years ago I knew a guy that had a dart sport with a 408 and edelbrocks with a .557 solid purple shaft ...It went high 10's.

Yep, I just went 10.77 with Eddie’s and a 565 gross lift flat tappet cam, 1 5/8 street headers, and the car is 3300 +
Big issue is gear, 3.55 will make it a good bit more difficult.

as gears have been mentioned, how would a 10.80 combo using 4:30 gears be affected using 3:91's or 3:55's ?
using the lower [numerically] gears would affect the converter stall, correct ? if so, by how much ?
i will be guessing the gears mentioned will possibly raise the stall speed a small amount [of course depending upon weight] ?

Got a guy here running a street/strip 340/416 Demon in our NSS class, TR with 2 x 650's, mild hyd.cam .463/.494", around 10:1, stock J heads weighs around 3250@the line with just a 3500stall, 3.91/28" tyre and has been a best of 11.23@118, SS springs, around 445 fwhp. shifts@5500, traps@5800.

Probably not as much as we think, mopars like to grunt. If you can hook it.

You don't need a stroker, my Duster ran 10.60s with a 360 J heads and .510 lift cam, get your car set up good and should be able to run 11s, but you will need more gear and convertor.

My dakota isn't that fast but it's got a build the op might be interested in. I a 2000 360 magnum engine in my 91/96 dakota race truck. I call it my projunk yard dakota.lol any way the magnum block is stock bore and stroke. Has stock rods and stock crank. Has
KB107 pistions
Comp cams 550 soild lift cam
PRW 1.6 Roller Rockers.
Mike at B3 racing rocker arm ration correction kit.
Smith Brothers 3/8 push rods
Out of the box Trickflow 190 cc
Ported indy single plane intake
Holley 650DP ported to flow around 800cfm
2 inch super sucker carb spacer
Hooker 1-5/8 headers. 18 inch header exstions
Turbo action built 904 transmission
8 inch 5500 stall coan converter
Ford 8.8 with full spool and 4.30 gears
Hozers 28x9x15 slicks.
With a sliping converter, which wasn't built for my build. Came with the transmission. Best pas has been 11.24 at 116.8 in the 1/4 and 7.15 at 96.7 in the 1/8. , i guessing the dakota with me in it weighes around 3300/3400 pounds. All passes are made on 93 pump gas. Forgot to add that the compression is right around 11.1. I think with the converter built to my engine specks thst the truck has a low 11 hi 10 second pass in it. At least I hope it does.lol

Looks like a good setup mopar65! The Magnum 360s make a good base for a small block build, I ran my present 360 Magnum short block as fast as 10.70s before having to upgrade the crank and rods from stock to aftermarket after doing that I went as fast as 10.40 , now running 11.00s with lower compression with a little tuning it would run 10.80s as a matter of fact it just went 11.12 at 119 ( deep staging so minus a tenth for that would make it 11.02 ) yesterday at partial throttle stop only shifting at 6,000 , the air was really good with a tail wind.

Wow sounds like you have a great running engine. I was going to build a 13.1 compression 360 stroked to 426 cubic inches. But huges engines said they didn't know when they were going to get more cranks in. So I ended up buying a 397 stroker gen3 hemi engine kit. Now just need about $3000 to get it built.lol i think I picked the wrong time to build a engine. Lol I need to get the torque converter pulled out and sent off to get redone.

The most compression I was at was 11.5 to 1 when I ran the 10.40s same motor is at 10 to 1 now for pump gas using W2 heads . I also have a 408 inch stroker 9.8 compression , R3 block , Indy heads but the crank cracked

Wow very nice. Wish my dakota was that fast

It’s been a 40 year thrash 318s ,340s , a 360 and a 408… I’ve always liked the Dakotas ! If I haven’t had my 92 D150 since new I would build one

The dakota is my first if you woukd call it race small block. My 65 plymouth B body and my 73 dart swinger were big block 440. My 65 ran 10.50 in the 1/4 and my 73 dart ran 10.40 in the 1/4. But because of health issues I havent got to race my dakota in over 2 years now . I have a 692 lift solid roller I bought for the 425 I was going to build. I thought about putting it in my 360. But not sure if it woukd be to big for it.