406 build - Cam?
 

Well I finally have all my parts ready for my 406 rebuild, but have concerns as to my choice of cam. I know this is an older grind and have read lots of posts as to not using it, thus my concern.

Here are my build specs, if you see any issues, I would appreciate knowing before I assemble...cam or otherwise.

- 400 SBC, casting #330817
- Stock GM22N crank, -010, with 2 bolt mains, I was going to go with studs and a Milodon Diamond Scraper windage tray, but seems like way to many hassles with reusing the stock oil pan. New plan here, ARP bolt upgrade only. (4 bolt stud kit for sale...)
- Stock 5.565” rods with ARP rod bolts
- TRW Hypereutectic H601P, +030, 12.5 cc dished pistons
- bottom end was previously built, blueprinted and balanced, (very low miles since complete build as 406) so I will be reusing these parts with new rings and bearings throughout
- 10.263 calculated static compression ratio
- Speed Pro Chrome Moly Rings
- Crane cam 1064-k, 488 / 510 lift, 234 / 244 duration, 109 / 119 lobe sep. (with 1.6 ratio roller rockers 520 / 544 lift)
- 1.6 ratio roller rockers
- Patriot Performance 195cc (White Perf.) ported heads, 65cc chamber
- 1.46 oversize springs, 7/16" studs
- heads setup for hydraulic lifters with 550 max lift
- Flow numbers for the heads are:
- Intake - 400L = 223, 500L = 252, 600L = 263
- Exhaust - 400L = 170, 500L = 183, 600L = 184
- Edelbrock Performer RPM intake
- Quick Fuel Q Series 750 carb
- Hooker 2210 long tube headers, with dual 2 1/2" exhaust
- MSD Digital 6 / HEI ignition, with MSD Blaster HVC Coil
- Transmission is the stock WC T5, with future TKO 600 upgrade in the plans
- Rear end is the stock 10 bolt with 3.42 gears, axle tubes will be welded and braced with aluminum support cover

Intended use will mainly be a Sunday driver until the complete driveline has been upgraded, than likely see more strip use with some occasional autocross.

I am expecting the power output to be +400 HP/tq, but if anyone can give some more definite numbers it would be appreciated.

Thanks for reviewing...

Re: 406 build - Cam?
 

It's not to bad of a cam for the street. Should be somewhere around 410-420 hp and about 450 lbs of torque I'm guessing. More then enough for the street. It may not be so good for autocross though, a wider powerband really helps there. If you want to make a lot of power, and not worried about mileage or price, then afr 210's or motown 220's, along with a stiffer cam...... something like http://store.summitracing.com/partde...4&autoview=sku. It would work with the heads you have now, but you would probably be starving for air on top end.

Re: 406 build - Cam?
 

The heads are brand new so I will not be going another route this go round. From my limited knowledge, I feel anything above 200 is more in line with drag racing and will likely effect streetability due to the higher RPMs needed to see the effect of the larger ports and cam required to match up.

I have continued my search for the perfect cam and based on some findings as well as recommendations from Camquest6, I am thinking of going with a Comp Cams XE274H.

Xtreme Energy XE274H Hydraulic Flat Tappet Camshaft Only
Lift: .487''/.490''
Duration: 274°/286°
RPM Range: 1800-6000

I think this will give me the power and drivability I am looking for.

The engine output based on the CamQuest program comes out as
Peak Horsepower 478.1 hp @ 5500
Peak Torque 510 ft.lbs. @ 4500
These numbers seem high to me, but if they are even 10% high, I am sure I will end up happy. :burnout:


I have been trying to also calculate my dynamic compression ratio with this cam but am confused as to how to determine my "Intake Closing Point (degrees) ABDC @ 0.050 lift plus 15 degrees" for the below calculation.
http://kb-silvolite.com/calc.php?action=comp

Cam specs (As per Comp cam details) are as follows;
Duration - Intake 274, exhaust 286
Duration @ .050 lift - Intake 230, exhaust 236
Valve timing @ .006 - Intake closes @ 64 ABDC

With these specs, how do I get the right Intake Closing Point number for this calculation?

Re: 406 build - Cam?
 

A 406 due to its larger size can tolerate higher cc heads and still make good bottom end.

I like roller cams due to the amount of lift you can shoehorn in - something with close to 0.600" lift and the duration specs would be a street terminator with those heads. Of course you would need new springs and retainers and roller cams are $300, plus lifters; but it is worth it.

In theory with the right parts and tuning, a street 406 can make about 500hp and not have to rev much past 6000 rpm.

Re: 406 build - Cam?
 

I like what you guys are saying, but the bigger heads and roller cam will need to wait until my second re-encarnation of this engines build.

For now, I am trying to keep the costs of the engine down (based on the short block foundation I have) and with the stock rods in there I am concerned about reliability, so am not looking to push it to the max....at this time.

Once I have the rest of the drivetrain completed, (that $700 roller cam setup is going towards buying a TKO trans) then I will return back to the motor with some serious horsepower goals and a power adder in mind :nod:

For now I just want to complete the motor with a hydraulic cam and then move on to the next mods, so any other suggestions or ideas in that realm would be appreciated.

Re: 406 build - Cam?
 

You ask the cam manufacturer. ;)

http://www.compcams.com/Cam_Specs/Ca...x?csid=87&sb=2

The comp XE274 closes 64 ABDC

so you DCR should be around 8.34:1. That's on the high side, becareful.

Given the huge 406 cu in you have, you could probably swing one cam larger.

Re: 406 build - Cam?
 

That is where I got my numbers from too.

The intake closure of 64 ABDC is valve timing @ .006" lift though. The calculation asks for this number at ABDC @ 0.050 lift plus 15 degrees, thus my confusion. How can I find / convert the degrees to this cam timing location?

Re: 406 build - Cam?
 

.050 plus 15 is probably the same as .006.

Hears what I'd do for that cam. Take the .006 duration and subtract the .050 duration.

274 - 230 = 44

Divide that by 2

44 / 2 = 22

This is the amount of cam duration to reach .050 tappet lift. But .050 tappet lift is 0.075 valve lift. Since our .050 valve lift is 2/3 of .075, we'll multiply our 22 by that.

22 * 2 / 3 = 14.66666666666666666666667

So you see, .050 valve lift plus 15 is the same as .006. ;)

Re: 406 build - Cam?
 

Based on my 406 experience, I highly recommend you zero deck the block. This way you can get the ideal .040" quench. This will keep the motor from being knock sensitive. Trust me, this is how I built my 406. I'm running 11.0-1 compression on pump gas with no knock.

Also, I like to look at the cam's advertised duration vs. the @ .050 duration and choose the cam with the tighter figures. As an example, my cam is a solid roller. The advertised duration is 268/276. Sounds small right?

The duration @ .050 is 238/246. The cam has a very aggressive ramp. The performance from this cam is stellar. If you run an agressive ramp with good lift, the cam will not need long duration. This will only move the power band up. Based on your rod length, you will not want to rev the 406 higher than 5800.

Re: 406 build - Cam?
 

Using your calculation with 1.6 rockers;

This is the amount of cam duration to reach .050 tappet lift. But .050 tappet lift is 0.08 valve lift. (with 1.6 rockers) Since our .050 valve lift is .625 of .08, we'll multiply our 22 by that.

22 * .625 = 13.75

How were you totaling the degrees (with 1.5 rockers) to equal 64 ABDC? With the 1.6 rockers would this now be 65.25 degrees? If so, this would provide a slight improvement to 8.23 DCR would it not.

Re: 406 build - Cam?
 

If less DCR is what you want, and your heads can handle the extra lift, then yes, it is a bit of an improvement.

Re: 406 build - Cam?
 

You guys have brought up some good points that I missed / forgot and I am lot more knowledgable for it :thumbsup:

So here is where I am at;
Pistons are 0.020 below deck height. (as measured during disassembly)
I have read that these "rebuilder" type pistons (H601P) are manufactured to be 0.020" below the deck, so if that is the case, my deck height may already be at 9.000. As mentioned this block already had machining when it was built to 406 previously. Seeing that I do not have the paperwork of the blueprinting, I think the only way I can confirm this is at the machine shop?

With the pistons down 0.020 and a .041 gasket, the .061 quench is way outside the .045 maximum it should be. I have searched for thinner head gaskets but came up with .039 as the thinnest without o-ringing the heads.

If I stick with the current quench (.061) I have the following compression ratios:
With XE274H CAM (64 ABDC)
SCR = 10.239
DCR = 8.288
With XE284H CAM (69 ABDC)
DCR = 7.97
I may have to pull out timing to prevent detonation due to the large quench.

If I can cut the deck and reduce the quench to .041 (0 deck with .041 gasket) I have the following compression ratios:
With XE274H CAM (64 ABDC)
SCR = 10.718
DCR = 8.666
With XE284H CAM (69 ABDC)
DCR = 8.33
I may have to pull out timing to prevent detonation due to the high DCR and heat it creates.

With using the 1.6 rocker ratio the DCR numbers improve but ever so slightly...

:crazy:

Which of the two evils is a better way to go?

Re: 406 build - Cam?
 

Hey Brian,
Wow that was a lot to read ....
Saabster is right with the .050"+15* = .006" sorta thing. 8.3:1 is good.

Keep in mind - a heavy car with a lazy stall at sea level will ping a lot easier than a lighter car, with more torque, stick shift, and at 4000' altitude (calgary).

I'd probably look at zero deck, xe284h (what's the duration @.050" on that?) and make sure you have a cold air intake. That should run just fine.


Drop by if you're in Acadia sometime, I just got mine running. 10.3:1 CR, cast iron 305 heads, Isky Z-25 cam, 240/240 @.050" on a 108 LSA. I keep breaking driveline parts, and I need to tweak the carb, but it runs good and strong tho...

Re: 406 build - Cam?
 

The combo sounds good but I would question using a 5.5 rod. It is a relative week rod . A stock 5.7 rod would be a bit stronger. I would hate to see all those good parts be ruined by a rod failure.

Re: 406 build - Cam?
 

I think these 2 cams might be what your looking for. I have had both and was very pleased with them. These are both COMP Cams.

CS 290B-4
Duration- Intake-290 Exhaust- 304
Duration @ 50 lift-intake-255 Exhaust-266
Gross valve lift- Intake-540 Exhaust-534
104 Lobe Separation

CS 280B-6
Duration- Intake-280 Exhaust-285
Duration @ 50 Lift- Intake-242 Exhaust-250
Gross Valve Lift- Intake-507 Exhaust-532
106 Lobe Separation

Re: 406 build - Cam?
 

Yeah that is my biggest concern as well. That is the reason I don't want to push it to the 500 HP mark until I have a suitable rotating assembly. There are a lot of different opinions on the stock component strength, but my preference is to keep it all together so it can be upgraded down the road.

Those are both solid lifter cams...I want to stay hydraulic flat for now.

I checked out your photobucket :thumbsup: :cool: :thumbsup: nice job on your car!!

Re: 406 build - Cam?
 

Thanks .....good luck on your build. By the way have you checked out a 6 inch Rod?

Re: 406 build - Cam?
 

I ran the xe274 with 1.6rr on my 406. About the biggest comp cam you can run in the series before your going to pick up a slight lope.
9.5:1 compression for me and it ran 87 with no problems. So you got room with 93 octane.

selling it all now
https://www.thirdgen.org/forums/engi...tml?highlight=

Re: 406 build - Cam?
 

XE284 it is than. I do want some lope at idle. :nod: