Chevy406

iTrader: (12)

This winter I am re-working my '69 Nova that I have been beating on for the past 10 years. The body got a fresh coat of viper yellow paint, and is now back in my basement slowly getting put back together.

The interior will be pretty much untouched, with it's '89 Grand Prix bucket seats, rear bench, and 6-point rollbars. The drivetrain starts with my "seasoned" 406, a TH-400 with manual reverse valve body & 10" 3,500 stall, and a 10" 8.5 rear with 3.73's. This combination has dyno'd 660 rwhp on 200hp nitrous jetting, and runs 6.5s in the 1/8th. As part of the winter project, I disassembled the engine to replace rings and bearings after 4 years of use. At this point I have the short block back together with the following parts:

• 4340 Eagle crankshaft for 400 SBC with 6" rods
• Eagle rods - forged 6" h-beam with ARP bolts
• 4-bolt splayed main caps
• Weisco Pro-Tru forged pistons
• Total Seal rings (gapless top), hellfire equivalent
• Clevite racing main. rod. and cam bearings
• Isky solid roller 260° @ .050"; .602" lift

For the past 8 or 9 years, I have been running a pair of Brodix -8 heads. They have 2.05"/1.60" valves, 1.550" springs, 7/16" studs, 198cc intake runners, 58cc chambers, and are stamped "Slover Porting". They are decent heads, but a compromise of smaller intake runners for my street driving. This is all topped off with a Victor Jr. and 830HP Holley.

All that background was given to help with recommendations for finishing off the engine. I would like to bump up the power (like who here wouldn't). I have been at the same performance level for a few years, so it is time to step it up some more. My first criteria is to keep it streetable, so compression stays ≤ 11:1 and intake runners can't get too big. So the question is, should I look at different heads, adding a second stage of nitrous to my Cheater kit, different stall converter, keep existing setup and save up for boost, or other ideas? Sounds like I need to turn this into a poll.

One more thing - right now I have about $1,500 in my car fund, and yes, money is always an issue...

JPH

iTrader: (2)

2 things I would suggest, port the heads more, and 4000+stall. what rear gear you running?

Chevy406

iTrader: (12)

I don't know - the head porting is pretty complete. It's tough to get a good picture of the runners, but there isn't much restriction in them.


I agree that I could use more stall. An 8" converter would probably pick up the 60' nicely. It currently runs 1.6 sixty foot on motor and 1.4s on nitrous. The rear gear is 3.73. I'll probably not change that since I street drive it quite a bit.

Interesting results on the poll. 4 responses and they are all different. I chose more nitrous... But I kind of suspect it will just go back together as-is, and I will patiently work on either a supercharger or turbo.

sick240

i don't mean to hi-jack your post but i'm looking at building a 406 myself. whats the up's and down if any? you can pm me to keep this off your post. thanks for your input, chad

Shawn @ VA Speed

iTrader: (3)

I think you could optimize the cam and pick up some great hp,cam technology has come a long way in the past couple of years-then spray it harder

Chevy406

iTrader: (12)

There are a few items to consider with a 400 SBC. With the larger main journals, they seem to want more oil volume. I had oiling problems with my first build, but once I went to a 7-quart oil pan and high volume pump that fixed the lubrication problems. The next item is stock 400 rods are quite short at 5.565". You should plan to upgrade to a longer rod with good rod bolts. Also 400 engines are externally balanced, so make sure you have the correct balancer and ring gear. My Eagle crank is internally balanced, so I am OK with standard SBC balancer. I haven't pushed a stock block past .030" overbore. I think .040" would be OK, but that would be the limit. I was very interested in stroking it to a 420" or 434, but that would have required quite a bit of clearancing on the stock block. I even had to clearance the block for the stock 3.75" stroke and aftermarket rods.


I like the 400 setup, but it isn't much (if any) advantage over a similarly built 383. Spend as much money on heads as you can afford. If you are starting from scratch, look into a set of 18° heads. You need matching pistons, headers, and intake, plus shaft rockers. That's a little too steep for me since I already have a complete engine... I am actually starting to consider a big cube LS2 build with L92 heads for my next Nova's power. I have seen that combination put down 523 whp with a pretty mild cam.

Chevy406

iTrader: (12)

Sounds like a good idea. I hadn't even considered looking for a better profile cam. With my 2-piece timing cover, plus the engine still on a stand it would a breeze to go ahead and change it now. I always thought there was some room for improvement with it. I'll have to study up on the best profile now...

ZONES89RS

iTrader: (25)

Just give the damn thing to me and ill handle it

Chevy406

iTrader: (12)

^^ Zones89RS your idea was on my list.... just waaay down on the list. If you could line up a sponsor to finance us, I would be glad to act as car owner and let you "handle it".

Shawn @ VA Speed

iTrader: (3)

hey man if you send me all your engine specs i'll give you a good cam recommendation

Chevy406

iTrader: (12)

I appreciate it Shawn. I'll work you up a PM with all the specifics.

edit - I just wrote a short novel. Hope it doesn't put you to sleep. Catch you later...

1997bird

iTrader: (2)

How about a 288*/296*, 259*/267*,.640"/.640" (gross lift w/1.6 rockers),111*+3*, I would also have the cam ground with the LS1 firing order (1-8-7-2-6-5-4-3)for better harmonics control. Your HP should peak should be @ 6400-6500 rpm & your TQ should be @ 4600-4700 rpm. You didn't say as to how much rpm you wanted to turn so I figured for the street you would want your peak at 6500 rpm, but be able to carry it nicely to 7600. The cam has lobes designed for your lower lift street grinds, so you shouldn't be killing you valve springs. This cam should also provide a decent amount of manifold vaccum and you will probably not need to run a vaccum canister for the brakes.

Here is a link to a LS2 403 build that I helped with. https://ls1tech.com/forums/dynamometer-results-comparisons/869674-our-latest-403-532-rwhp-491-tq.html

P.S. You can get these cam lobes from the supplied link in my sig, and Ed is a sponsor here too.

RAGENZ28

iTrader: (5)

We shift our 406 at 8,400 Since you're into nitrous and drive it a lot on the street I would run your cam on a 114 lobe.

I voted other, I would get a better rear end and upgrade the chassis, with the right cam and some nitrous that things going to haul *** and it'll need to be setup right.

Pick of one I work on. This one just ran 9.60 on motor, we're still tuning the motor and chassis.

RAGENZ28

iTrader: (5)

I did mine .020 over, 6" rod, 4340 everything, they are some what known for running on the hot side, but mine never got over 180* I had a nice 1 1/4 core griffen radiator and a street electric water pump and a black magic fan.

Blocks are not the greatest and have those steam holes.

82 camaro

I say cam change it looks as if you have decnt heads and valve train. spend the money for a cam and new converter but remember you will need to decide do you want to run all out on the gas or NA. and pick your parts for that set up.

chevyguy7802

iTrader: (3)

Nice build! Ive always been a fan of the sb 400's!

MrOverkill

iTrader: (1)

Heads AND camshaft are going to pay the biggest dividends for you IMO.

I have a killer set of Self Racing Motowns w/ 2.10/1.625 Titanium valves, Jesel rockers and a custom Isky nitrous stick thats .714"/278*@.050" on a 114* for my little 406 and it makes over 800whp on the unit but its a dedicated nitrous mill. It will rev well over 8000 but it likes to be shifted around 7600-7800rpm. 800whp with 23* IRON junk is pretty impressive, and I'm pretty sure you can pick up some nice power with a proper cam even with the heads you have now.

Your block would be my only concern if your considering a bigger hit from the unit, I've split more than one production 400 block in my day. Usally in the deck surface and around the steam holes, I'd pin the steam holes if you can......

AutoRoc

Beautiful yellow Nova!

Toss the plate and do a custom built Induction Solutions Fogger.

A custom cam to accent the nitrous would be cool.

The converter might be fine as is...ya never know.

Top Secret

I would say boost, but you would need to change the pistons, and maybe the heads. 200cc intake seems very small for a 11:1 400..

capn smokey

iTrader: (1)

Sell it all and go LSX