Build me a 9.80 512 low deck

I'm considering building a 512 low deck, I have a 230 71 date 400 block.
It will be for a 71 valiant, the car currently has a 383 that runs 11.70's and it weighs 3050 with out me in it.

I'd like opinions on heads, cam and rotating assembly.
Thanks

What kind of shape is the 383 in? If the rotating assembly is in good shape on that engine then you might just try adding some Trick Flow heads and a roller cam and see where you end up. Then if you want to go faster build the 400 block and move the good parts over to the new shortblock. That way you can work your way there without having to spend all the money at one time.

If the 383 is shot then obviously that plan won't work but if the 383 shortblock has decent compression then you can probably drop into the 10's with just good heads and a big cam.

First thing to do is sonic that block and find out if you have a good block to build on the early 400 block are prone to core shift and may not be suitable for what you want to do,
here is my lo deck 512 build
molnar 4.250 crank
molnar H beam rods
Icon pistons
.690 bullit solid cam
crower solid roller lifters
manton pushrods
BCR girdle and aluminum main caps
Trick Flow power port 240 heads
Trick flow open plenum intake
12.3 compression
should run 9.80-9.70 in my 3150# dart
there is more to this but this is the basic list.

Thanks Andy
The 383 is actually in good shape but an old school build, old dome piston setup, 292/509,906 heads, tm6 intake with a 950hp Holley.

Thanks Dartman

Well if the ring seal is good I might just stay with the 383 for one more season. Put some Trick Flow heads on there and swap in a decent roller cam and that engine will wake up a bunch. I'd ditch the TM6 and bolt on a Trick Flow intake. The 950 carb should work fine.

440source. Com

My old 518 C.I . pump gas Duster ran high nines with me (260 lbs) in it at 3450 lbs. through the full three inch exhaust system to the rear bumper hooked up with the air cleaner on using 91 octane OR non ethanol 91 octane cheap pump swill
The motor was a 1976 400 block with four sleeves in it, Mopar brand Ductile iron main caps with ARP main studs. SR M.W. heads, Harland Sharp 1.6 single shaft roller rockers, Manton Series 3 3/8x.120 custom made for the motor pushrods, Indy 400-3 intake, 1.5 inch Wilson reversion spacer and a old Holley 1050 List # 9375 Dominator non HP carb.
It had a Chinese RPM 4.300 stroke crank in it, I bought one of their 4.150 stroke Mopar rod and 440 main size cranks and had it offset ground down to 2.200 rod journal size and had the mains and counterweights cut down to fit the 400 main and clear the block. It had a set of custom Ross 22.0 CC full dish pistons with a set of CAT brand BB Chevy type 6.800 long H beam steel rods, that combination made right at 10.8 to 1 compression.
The cam was a custom ground Comp Cams solid roller lifter grind with 260@ .050 on the intake with .420 lobe lift and 266@ .050 on the exhaust lobes with .409 lobe lift ground on a 108 LSA installed at 107 ATDC on the intake lobe
That combination made 727 HP the last time it was on a DTS engine dyno in Klamath Falls, OR at 4300 ft. elevation
You can get the same results with similar parts
I used that motor as a test mule in the car and I made a bunch of changes to it from day one until I sold it, it was a good one

My first low deck combo was a 499, 440-1 heads, bowl ported only with 2.19 intake valves, 1050 Dominator on an Indy single plane, heads cut to 62 cc with flat top wiesco pistons on aluminum BME rods. About 12.8 compression, 2 18 x 32x4 headers, 282/290/110 rollercam, .717 lift int,.680 ex. It ran 9.58 ,141 mph at 3,000 lbs, the first time out. The 512 built similarly ought to be a touch faster.
If you go SR or EZ-1 heads fully ported, you can make it that way too, and maybe a bit cheaper.

Don't forget to run 9's you'll need a bunch more safety equipment and a license.

8.60's @ 2330#

400-499
Molnar crank and rods. JE pistons roughly 12.5-1 . Indy intake. Indy SR's 295cnc. Comp 630/650 solid. Harland Sharpe 1.5 rockers. AED 1000cfm 4150. UCC 5800 stall 8". 4.56 gear.

There is probably more in this motor with a dominator and a roller cam.

If you want to be half way scientific about it you can go to Wallace and try a few calculations. 9.80 @3300 lbs will require roughly 700 hp. It is fairly easy to make 700 hp on dyno with a 512 engine. A pump gas 512 with a decent EZ head and a 270 duration roller cam will make 750+. You'll lose some power in the car depending on headers, coolant temp and converter but 750 on the dyno should get you down the track at 9.80 if you can hook it up the whole way.

So basically what you are asking for is as easy as ordering some parts and bolting them together. I'd still use the 383 and increment my way to 9.80 rather than building a new engine and starting over but either way works.

Thanks for the replies

Building one right now for Car Craft....will make around 700+ using a hyd. roller cam, 11.5:1 (mixing pump gas and race gas), TF heads and TTI headers. Really easy build, very low maintenance....power to 6500rpm.
Brian

Hey Brian, how is that TF build coming along? Post some pictures if you have them, I'd love to see what it looks like.

So how much horse power is gained using Trick Flow heads over the old stand by Edelbrock RPM's. Haven't heard much about them. Anything extra needed like B-1's ?

I can't give any advice on the stroker but like others said, if the 383 is good, use it. Especially if it has decent cr. Friends of mine ran 10.20-10.40s with their 383 in a '63 Fury back in the late 70s and early 80s. They used steel max wedge heads with a welded up Edelbrock and later on Zeeker heads. There were things done but no reason to get into that.

The CNC port program that Modern Cylinder Head has for the Edelbrock/Stealth head produces numbers very similar in flow to the already CNC ported Trickflow Powerport 240.

Build a good combo with **matching** pieces and its not difficult at all.

I run a 500 stroker in a 440 block.
Its been 9.91 @137 footbraking in a 3600lb car. ( probably had better in it but we run a 10.50 index so I never pushed for more)

Indy 500 rotating assembly in mine.
Eagle 4.15 stroke crank
Eagle rods
wiseco flat top pistons at zero deck
Indy SR heads opened up to max wedge ports
Indy modman intake with 2 edelbrock 600 carbs
Comp solid lifter cam 608/615 lift (i think)280s duration
a 727 with all good parts, 8 inch PTC converter
4.56 gear with a 29.5 10.5 W

subtract the weight difference and or go with more cam and you are there. We went with a mild cam for the sole purpose of not turning a bunch of rpm and keeping the motor alive. I'll go to a better block and turn up the wick eventually.

How I'd do it....

-Indy SR CNC 295's, PRH prep(355cfm)
-Indy 400-3 intake
-4500/1050 carb
-2" headers
-.650-.700 lift easy on parts roller cam
-1.5 HS rockers
-flat top pistons(12:1 with 78cc heads)
-import crank and 6.535 rods of your choice

Should be an easy 750hp depending on exactly what you did with the cam.

You could use 440-1 CNC 325's for about $700 more, most of which is the added cost of the offset rockers(which is the main reason I suggested the SR's in the first place).

Dwayne won't the EZ work for your suggested build also

That's my basic combo currently in an RB block on pump gas.....Switching over to the same combo in a 400 low deck this year....

The EZ head probably gives up some power to the SR due to the exhaust port design. Not sure how much, Dwayne and I have talked about this a few times over the years since I'm making more than 900 hp with my EZ heads. We've thought about prepping a set of SR heads and doing the test on my 514 but I don't really want to give Indy $2K of my money just to figure out if the SR port makes more power or not.

Thanks Andy I didn't know how much better the SR was compared to the EZ's

The SR 295 ex port is 35-40cfm better than the EZ 295 ex port, plus on a low deck the SR ex port is at the "normal" RB block height, which allows for a few more header options.
For the little difference in cost between the two heads, I'll take the extra ex flow.

No brainer for me, SR all the way. I have always liked the SR heads.

.


Other than the cam....pretty much my motor 👍

Are B1 heads in your budget?