Flareside

I'm new to the small block world, so I could use some of that vast "forum knowledge":) The heads I have on my new 406 are Dart II iron heads, which are supposed to be the same as the current World Products Sportsman II heads. Are they any good? They have supposedly been professionally hand ported, but I haven't removed the intake to confirm that yet. No flow numbers available :( What would be a ballpark HP figure for an engine like this:

406 cubic inches, 400 block .030 over.
4-bolt mains with splayed caps (original 2-bolt block.)
GM 3.75" stroke 4340 steel crank (bought as a raw forging, part number 24502460.)
5.7" GM forged rods with ARP bolts.
Crower solid roller cam and lifters. Intake duration 244 @ .050", lift .564". Exhaust 253 @ .050", lift .582" 277/285 seat to seat duration. 110 LSA
Speed-Pro flat top forged pistons. Claimed 11:1 compression ratio.
Sportsman II 200cc angle plug heads, professionally hand ported and matched to intake.
750CFM Holley mechanical-secondary double-pumper carb.
Edelbrock Victor Jr. single plane intake manifold.
Hays steel 40 pound flywheel.
2.02 + 1.60 Manley Severe Duty valves.
Crane Gold 1.5 full roller rockers.
Moroso stud girdles.
MSD HEI distributor with the vacuum disconnected, MSD 6AL box set at 6000 rpms.
Cloyes double roller timing chain.
Hooker SuperComp 1.75" into 3" ceramic coated headers.

The engine is currently tied to a Richmond 6-speed and a 4.11 rear. Throttle response in first gear is fine because of the crazy low ratio (over 12.5:1 with the 4.11 and 3.01 first gear), but second on up are lacking torque at low rpms. The jump from first to second is HUGE! My other C3 is a mild big block, so I'm used to an engine that will pull cleanly up a hill from 1000 rpms. I know the 406 will never be as smooth as that, but I think it can be better than it is.

One other tidbit: I have a bunch of timeslips for the car, and it seems to average around 112 in the 1/4, with a best of 114. High 12s.

What would you change if it were your engine?

Thanks!

-Joe


[Modified by Flareside, 6:21 PM 11/4/2002]

gkull

If you can believe the listing on DD2000 head flow downloads. the stock flow was 243/162 cfm at .600. I imagine that with some work the 200cc intakes and exhaust would come up quite a bit. I have only ran them on a 355 ci race motor that was in a class required to have iron heads and less than 360 ci. In their day they were the top iron head 14 or so years ago. The area right under the valve is so huge that they really require 2.05 - 2.055 intake valves.

I'd say if they were done right they might flow as much as the more modern 190 -195 cc AFR So I ran a dd2000 simulation with AFR190 port flow and your stated equipment and I guessed on the actual cam specs valve events at

in. 14 50
exhaust 58.5 14.5 which gives a 110 lc

You would have max of 539 hp @6000 and 540 tq at 4500

It should be a runner! :D

Flareside

Thanks gkull! These heads don't sound as bad as I had feared. 14 years is a long time.

The cam is a 110 LSA grind. Good guess.


[Modified by Flareside, 8:24 AM 11/5/2002]

sinistervette

If that holley is still only flowing 750cfm, have it worked on. Add an 850 base plate, blend and radius venturis and airhorn and you will probably find that missing low end, mid range, and you will find more top end also! I'd also ditch the vic jr, and go to a brodix hv1000 intake, it is superior to the vic jr.I've built many 400/406 small blocks, and none of them were lazy on the bottom. I built a similar to your 406 earlier this year, 11.8-1 comp., 5.7" rods, all pro 200cc iron heads, these outflow the dart/wp heads but only a little, 2.08I/1.60E valves, brodix hv1000 intake(out of the box!), isky solid flat tappet cam .570I/.585E lift, 264*I/274*E dur@.050 108*lobe centers, hooker super comp 1.34" full length headers. Dyno'd with and 850cfm dp holley that I modded(flowed 930cfm) 608.4@7200rpm/539.5tq@5900rpm. Changed to a 750dp modified(flowing 815cfm) dyno'd 546.3hp@6600/528.0tq@5900rpm. As you can see, you loose a lot of upper rpm hp with the smaller carb, although you do not loose much torque. This thing had 500+hp/500+tq from 3000rpm up! Anyhow, you get that carb tuned right, and you will be supprised how well a sb 400 can run! :cheers:

Flareside

sinistervette, the carb is a box stock Holley 4150. List #9379 http://www.holley.com/HiOctn/ProdLin...SC/0-9379.html

Are their any out-of-the-box carbs that will work well with my combo?

Are you running GM rods over 7000 rpms? Currently, my MSD is set at 6000, and I suspect that it could go higher. My rods are supposed to be GM "pink" rods with ARP bolts. The crank is 4340 forged, and the block has splayed caps. Seems like they should have used an aftermarket rod. :confused: Is this a mismatch?

I would be very happy if I got this thing to 600 hp!


[Modified by Flareside, 8:40 AM 11/5/2002]

gkull

Do you have the cam card or CC part number? You might have some miss matched parts. But a hand blended VJ is an up to 8000 or so rpm intake. I will not argue power numbers with different big single planes. I would imagine that they all run within a few hp. I prefer the smaller lower rpm singles. Like the Weiand 7530 or 7531. the plenum is much smaller. That's whay they have 7200 & 7800 rpm ratings as max. Much more street friendly. With that big plenum and hot cam jetting can be tricky. What is your intake manifold vacuum at idle?

I would think that a 406 with 11:1 compression would be a torque monster.

Flareside

Sure, here are the specs (Crower part#00423, grind#277R): http://www.crower.com/misc/cam_spec/...part_num=00423

The lift also seems a little low for a solid roller. Maybe I'll check piston to valve clearance to see if 1.6 rockers are in order.

My impression of these 406s, from what I read here on the forum, was that a solid 406 will have a ton of power and that traction would be an issue. Beyond a standing start, traction is not an issue with this car...

gkull

IMO that cam falls under the "sounds bad azz, but isn't" catagory. When I plugged in those Crower cam event numbers the DD2000 figures just fell on it's face. You have 30 degrees of valve overlap. Which means that you don't have any dynamic compression or vacuum at lower rpms. That setup doesn't come alive till 3500 rpm. The cam card has it setup for 106 lobe centers. That's a all show and no go:( I also noticed that it was refered to on page 39 of their online cat. as the power beast roller level #4 2750-6750 rpm designed for strong midrange and high end hp 7000+ rpm.

sinistervette

Flareside, I do all my own carb work, so I'd have to do some looking for what is available out of the box. I'm sure there are some out there. You should check around your area for a carb builder, normally guys running stock cars/drag cars know of one! As for con rads, Yes they are stock gm rods, not even pink units! They have 180,000psi ARP bolts in them, and I weigh each rod and piston(sepreately) myself keeping them within 1/2 gram from low to high weight. I also shot peen and deburr the beams. I've used some pink rods in the past as well as Aluminum, forged, billet, but for my own use(low budget) I stick with gm stuff. The only rod that has ever broken on one of my engines was an aluminum crower unit, after 650-700 laps in a stock car! I was told that I was between 350-400 laps too many on those rods! :eek: So much for "if it ain't broke don't fix it"! I'd say your camshaft is killing your output as well as carb. The vic jr if portmatched to your heads, and maybe even a spacer will put you in the ballpark of the hv1000 out of the box. I've dyno'd both units, was running vic jr before the hv1000, and on my set up I put a 1"open spacer on, then a 1" 4hole spacer and was actually better from 4000-6800 rpm, but was down 11+hp above 7000 rpm. If you want to keep the vic jr, and do get a better carb you might want to try and experiment with the open and 4 hole spacers. They are cheap, and very usefull in higher rpm/hp tuning. I just got a call from a friend, he said if your carb is box stock, it will have #68 primary jets, #81 secondary jets, and a 6.5 power valve. Do you know what kind of vacuum you car is pulling? I personally would go up on the front jets to #74-#76 and raise the secondary jets also to #84-#86. Keep the secondary jet # an even "10" bigger than the primarys. If you check you vacuum, and lets say you have 10" at and idle, try a 8.5 power valve, if you have 6" at an idle go to a 4.5 power valve. Keep the power valve 1.5 lower than your idle vacuum. This should help some, and if I locate a part # for an out of the box carb, I will IM you. :cheers:

DeenHylton

There is something definetly wrong with your combination. If your time slips are in the "high 12's " your not making much more than 400 HP. My original 350 was built to the Holley specs (similar to Edelbrock specs) of their 420 HP engine combinations. I turned 12.80's at that point. My blower motor only makes 485 HP and turns 11.50'-11.70's depending on blower ratio. Using both DD2000 and Quarter Junior software both show I'm producing right around the 485 HP figure. There is an older gentleman that runs at Woodburn with a built mild manner 400 (daily steet driven C3) running a stock converter...he runs 12.50's
I'd sell the Dart/Sportsman II's and get a set of 195 AFR's or larger. Get a set of quality H-beam rods (will need to rebalance engine). Change your roller cam for one with more lift ( around .650") and get a larger carb. You should be shifting around 6800-7000 RPM depending on cam profile. I figure that would get you into the low 11's at least...IF you can put all the power to the ground. Deen

Flareside

Great info, thanks! The motor currently pulls 11" of vacuum at 1100 rpms. The motor will go lower, but I like it there. It pulls around 9" at 900. It also has a vacuum can for the brakes. I'm not sure about the jets, and it's already running a 1" spacer. I'll have to check on the jets and whether it's a 4 hole spacer or not when I get home tonight.




[Modified by Flareside, 7:58 AM 11/6/2002]

Flareside

Thanks Deen. What trap speed did you run in those 12.8 runs? Auto or manual? I think my ETs are in part because of the car's gearing.

I've thought about replacing parts, but I'd like to optomize this combo before I go there. I really think this thing should be a little faster than it is right now.


[Modified by Flareside, 8:08 AM 11/6/2002]

gtsyellow

600hp is REALLY pushing a pink rod, 450 was the accepted use of that rod. if you only drag race it in 11 second bursts they should live but again your pushing it. the $300-$400 scat 4340 I-beam oliver copies are a much stronger rod and extremely cheap for how damn good they are. the big end of the rod is reinforced & the quality is 1st class.

DeenHylton

Flareside: My MPH were low...around 106...I attribute that to having my 10" converter setup loose(by my request). I was running 3.90 gearing with a 4000 stall converter and 26" tall slicks. I estimate I had over 600 RPM of slip in high gear.
When I installed the blower (only 5 lbs. boost) I went back to a 3.55 gear and a taller slick (28" tall). My ET's dropped to a best of 11.55's at 116 MPH, still with the 4000 stall converter.
Next I tried a 150 shot of nitrous, my ET's have only dropped to 11.30's but I've picked up 9 MPH to 124MPH. I haven't fully sorted out the NOS. I'm having traction problems even in 2nd gear (automatic) depending on track conditions and the tires are hunting for traction even at 80-90 MPH. According to DD2000 and Quarter Junior the car is now capable of running 10.60's IF I can get the power to the pavement. Deen



[Modified by DeenHylton, 4:57 AM 11/7/2002]

Flareside

Thanks Deen. The type of results you're seeing are the reason why I think my car should ET better than high 12s. You ran a 12.8 at 106, my car is running the same 12.8, but at over 112. Most of the guys on the forum running high 12s are not over 110. I'm going to take it to the strip this weekend for some testing.