Help With 406 Engine Build
I'm in the process of buying parts for a 406 engine build, Flat top pistons, 5.7 rods,air-gap intake, the trans will be 700r4, 3.73 gear. This will not be a daily driven vehicle, however I want to be able to enjoy this car on the street and take it to the track on occasion and be proud of the results. What I'm needing help w/ is the cam and head selection. I do want a cam with a nice lopey idle. However performance more important then lope. All input will be greatly appreciated.
Then i`m the guy you need to see, I just happen to have a set of vortec heads for sale, and I reside in Alabama one in the same. On the flip side there are alot of heads out there, and there`s a lot of cams, If you plan to run pump gas the flat top pistons are out or you`ll have to get bigger chamber heads. A 400 can take alot more cam than a 350 will, the 50 extra cubes swallows cams, a lopey idle cam in a 350 will idle smooth in a 400 so you can get pretty large before a 400 starts to lope. I would use this as the advantage, you could run a sizeable cam that still idled smooth and use it as the sleeper approach. a bigger cam will require a high stall converter, and the 700 trans will have to be beefed otherwise it`ll gut it rather quickly. Depending on what rear is in the car, it may have to be changed also, if it`s a typical 7.5 inch 10 bolt a 400 will gut it too, with C clip axles, they just aren`t safe. It also comes down to how much do you have to spend, and how fast do you wanna go?
Well actually I have a set of vortecs myself, trying to possibly upgrade saw 406 engine build-up in Super Chevy using votec heads liked it alot, possibly will model my build up after that. Now I do want to run pump gas, yeah I know the 700 will have to be upgraded and the rear end too. Currently looking for rear-end now....Looking at spending around $1,700 for the top end, I know that ain't that much, but I figure if I can't get what I want spending that then I don't need it.
If you want to use 64cc chambered heads on a 406, use a dished piston.
Here is a recipe that works pretty good.
5.7" GM rods cam clearanced rod bolts
Stock GM 400 cast crank. (rebalanced)
GM L-31 vortec heads (062). upgraded machining for high valve lift.
KB 168+30 22cc D dished pistons. or KB147 18cc D dished pistons.
O decked block.
Comp Cams XE284H-10 cam 1.5 rockers
Edelbrock Performer RPM Air gap
750 Holley 4779
3000 Stall 11" th-350/400 converter.
I suggest trading/selling off the th700r4 for a TH-350
If you want an aluminum head try the Summit racing Street and Strip
200cc aluminum heads PN# SUM-162111
Either way will get you a rockin trouble free street/strip 406.
Pump gas ready and 460+HP 500 Ft/lbs torque.
I like that combo looks pretty good, now the problem would be the fact that the short block is already together, so there is no changing the pistons I was looking at those aluminum summit heads but I didn't know if they were worth anything, I haven't heard anything good or bad about them have you had any experience with them or know anyone who has, if so what do you/they think of them.
With a flat top piston and a64cc head your cr is going to be pretty high.
Your cr with flat tops and 64cc heads on a .030"+ 400 will range from 10.73 on a stock non decked block to 11.40 if the block is "0 Decked" That's a little high for everyday trouble free use with full timing on pump gas. You really need about 98/100 octane for 11:1 compression.
Do you really want to have to mix fuel all the time?
So, if you're stuck with the flat tops and 92 octane gas I would suggest using a 70+cc cylinder head.
I recomend The Dart Iron Eagle 215 (72ccchamber) look here
Or if you want aluminum Dart Pro 1 215 (72cc) Not a bad price
Your cr with a flat top piston on a .030+ 400 with 72cc heads will range from 9.90 on a non decked block, to 10.46:1 on a "0 decked block" using a felpro gasket. This is as high as I would build for every day real world street use.
re: drilling steam coolant holes in cylinder heads for 400ci SBC's
In my opinion and experience if you use the RPM Air gap manifold with the extra water port at the rear of the manifold, steam holes in the heads are not nessessary.
Hook up the drivers side left/rear water port at the back of the manifold to the water bypass port on the top of the water pump with heater hose. If you're using the OEM heater thats where the hoses should be connected to.
Much improved cooling on any SBC especialy while the thermostat is closed or cycling during intial warm up.
The Professional Products Crosswind manifolds have these extra rear water posts as well.
Use the same Comp XE284H-10 cam and Edelbrock RPM Air gap manifold.
Build the motor along these lines and you'll have a real nice street/strip performer. You can be proud of that. :thumbup:
I really appreciate all the info you've offered me on this build. Now I did forget to mention that the block is "0" decked so I guess that would knock the Summit brand heads out the equation w/their 64cc, (or would the aluminum be forgiving enough on the cr that I could get away with it?) So more then likely it would be one of the dart heads, you gave the link to. (looking at Summit website now and their saying the aluminum head has been discontinued, and they only have one for sale)I'm looking for a head with the 72 cc and 215 intake runners you've recommended. Now I do have 2 questions, 1st, do all non after market vortec heads have 64 cc? 2nd, the size of the combustion chamber, I know can be decreased but can it be increased?
You can open up a combustion chamber by around 5cc's on a SBC head with some creative chamber deshrouding etc. If you do it right you can actually pick up some flow and enhance swirl. Even if you were to invest the time and effort take 5cc out of a 64cc chamber x 8 chambers you would still be right on the edge as far as compression goes.
Wouldn't it be a lot simpler, cheaper and better to just swap the pistons out for the right ones for a 64cc head (KB hyper pistons are under $300) or pay the extra few dollars to get the next available Dart Pro1 72cc head package or some other comparable head like a Edelbrock Victor Jr with 70 cc chambers.
Another workable option would be the Brodix IK180 with the larger 70cc chamber.
Not a bad price and wouldn't take much to tune up the out of the box airflow with some general port cleanup and contouring. Say dissassemble them check em over and spend around 2 to 3 hours on each head. You could come up with a pretty good package. A lot simpler than trying to open up combustion chambers to lower the cr. These heads also have a lot lot of potential beyond the out of the box flow. The out of the box flow numbers are good for a 180cc port head. These heads have good low/mid lift numbers would be tempted to bolt them on and try them as is, first.
Make sure you get the rotating assembly balanced, a good friend of mine just built a 406 with 5.7rods and didn't-his engine has some bad vibrations and I'm surprised he hasn't lost the bearings in it already.
I also heard the Summit heads were made by Brodix.
I actually wish I woudl have put those in my motor. If you used a hydraulic roller or solid roller with duration in the 250 or so range I think you might get away with pump gas, 91/93 octane though. That should lower the DCR enough to make it work, but I could run some calcs if you are interested at all. I've heard of it being done. With 0 deck, and a .035 or .040 head gasket, your quench will be right in the perfect area to fight detonation.
BUt with that kind of cam you will have a fire breather! I would think it "could" be streetable, but might be tough to live with over time. Big stall to make it work, 4000 or so maybe. It depends if you want something like that. WOudl have to be tuned very carefully.
All in all, sell the vortecs and get some Iron Eagles or something like F-BIRD said in the 72 or 76 cc range and they will produce more HP and TQ and get the comp ratio right without swapping pistons (which I would think woudl cost more money). You will be happy with the Eagles, I have a set on a 355 and they work very well.
Now I was actually thinking about going w/the 294 extreme energy comp cam which has a duration 250/256 @.050, until F-Bird gave me the specs on a nice 406 engine build using a 284 extreme energy cam. Giving just what I would be looking for as far as power is concerned. Now as I've said before the car will probably only be driven on the weekends and maybe once during the week, so its not going to be a daily driven vehicle so thats why I was hoping I could get a bit more extreme w/my components, but also like F-Bird said I'm not trying to be mixing gas everytime I get in the car either. So yea if you could do the calculations it would be greatly appreciated.
Over camming the motor will not adjust the real dynamic cylinder pressure
(the cylinder pressure and temp that the engine actually sees when actually running at rpm) enough to allow running a 11.5:1 compression ratio on pump gas without detonation in a actual car on a actual typical day.
You'll be moving the valve timing away from the sweet zone that the Rpm manifold makes best power at and make the motor peaky at best.
Many people advocate the DCR theory based on intake valve closing point as a cure all for running high compression on pump gas siting this and that mag article or the famous "I heard that...." In the real world in the on the street its just not that simple.
Running a motor on a dyno for 6 seconds with 60Deg F water and air temps is a lot lot different than in car actual conditions. Give that same motor a good dose of typical 110-140F under hood air temp and see how it does in the real world on a summer day.
A motor that knocks even a little makes less power and will loose its edge ( ring seal) very quickly. Is it worth it 5000 miles down the road when the motor starts to huff out the breathers and gets lazy cause the rings are beat to death.
You might be able to get away with say a 1/4 or so more cr with a cam thats too big but 11.5:1 is not going to happen without retarded timing and or over rich jetting to keep it from knocking.
If you want to build a combination around the XE294 cam I would keep the compression ratio under 10.30:1 (aluminum heads) and go with a ViC JR manifold and bigger port heads for more rpm.
This combination using the XE284 makes a very nice street/strip motor overall using vortec heads and a RPM manifold. Makes a lot lot of torque. The actual running cylinder pressure is high. Don't need a ton of cr.
So do you think that was the "0" decked block and aluminum heads the "Summit Brand" my CR would be in that 10.3 range, please say yes because the more I look at those heads the more I want them, and I've spoken the machine shop in my area and I'll have to pay around $450 to change to screw in studs, bigger springs and a good reworking. Not to mention the specific intake and roller rocker arms I'll have to be that could only be used w/Vortec heads.
There is a good article in the latest Engine Builder magazine that has some good info on heads and breathing.
The guys interviewed in the article are tops in the field. It's well worth reading.
Thanx! For the link Tom I will definitely read through not only that one article, but all info on that website!
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