Allright guys help me out here i have been playing with desktop dyno all night and that thing is driving me crazy. Anyway I need some advice on which camshaft i should go with or if i should even change it. Last year i went 13.5 at 102 mph with nearly the same setup except i had stock 350 heads on the motor and this year i stepped up to the vortecs, also had a performer eps intake. Here is my current setup: 406 5.7 eagle rods about 9.1 compression .30cc dish keith black pistons Stock Crank RPM air gap intake (vortec) 750 edelbrock carb Vortec heads (guide plates, screw in studs, high 500 lift springs) current camshaft is a comp XE268 with .477/.480 lift and advertised 268/280 duration Current converter is a 2500 stall but willing to go to 3000 Which cam do you think would give me the extra boost to dip into the 12's or should i just add 1.6 rockers and get 508/512 lift and leave the cam in there? Im hoping the head swap alone will be enough to drop me to a low 13 if not high 12 but i want to change the cam while its apart if i need to

I'd say the XE274 if you wanna keep the motor extremely streetable. You should EASILY run 12.50's or better with that cam, a 3000 stall, and decent gearing. If you don't, something is majorly wrong.

You can't to the rockers based on what you said about your valve springs. You could step up to the XE274 and still use those springs.

I know of a guy who runs LOW 12's with a similar cam and Vortecs (ported on the exhaust side only) on top of a 413 (.060 over) in a HEAVY late 70's Camaro. The only difference is he's running ~10.5:1 compression.

He had his car weighed and it tipped the scales at just over 3700lbs without him in it.

Hope that helps give you an idea

would the jump from the XE268 to the XE274 be a big enough jump to justify getting it? the cam that is in the motor has less than 15,000 on it. I mean i think the cam is only like 150 bucks or something but how much will it gain over the 268?

What are your intentions with this motor? Daily driver kinda car or weekend racer? What gears do you have? The XE268 is pretty mild even for a 350 let alone a 400. I'm asuming your valve spring diameter is 1.25" so that'll limit your choice of cam unless you want to pop the head off and have them cut for larger springs.

The XE274 will work with your springs and will definately give you a huge boost in performance as long as you have like 3.73 gears and a 2800-3300RPM stall. If you can hook up theres no doubt in my mind you'll hit 12's. If not blame it on the Edelcrap carb, throw it against a wall and buy a Holley

Thanks for all the input guys... let me clear some stuff up. The heads have had all the work done to them for higher lift, valve guides cut down etc etc so the springs are not a concern unless the cam has like 580 something lift. As for gears i have a 4th gen posi with 3.73 richmond gears and currently i have a b&m 2500 holeshot converter but may be stepping up to a 3000. As for a daily driver.... last year it was a daily driver and it went 13.5 but this year it will prob be drove 2-3 days a week and on the weekends. Here is a pic of the car by the way

motor: Last years combo same internals but had stock 350 heads with steam holes on the engine, also just had a edelbrock eps intake, short headers and a peg leg 3.23. went 13.5 with 1.8 60fts

Lift isn't the only factor when selecting springs. Cams like the XE274 use small diameter, "drop in" springs. Cams with more duration and really aggresive ramps will require more heavy duty springs or else you'll break the weak springs and/or get valve float problems. So for instance the XE274 requires Comp Cam's 981-16 valve spring which is standard diameter (1.25") and has a inner dampener. Now, the XE284 requires the 986-16 which is a dual spring with a 1.430" outter diameter


Specifications for recommended XE274 springs:
* Outside diameter: 1.254 in.
* Inside diameter: .880 in.
* Seat load: 105 lbs. at 1.700 in.
* Open load: 295 lbs. at 1.250 in.
* Coil bind: 1.150 in.
* Rate: 423 lbs.

Specifications for recommended XE284 springs:
* Outside diameter: 1.430 in.
* Inside diameter: .697 in.
* Seat load: 120 lbs. at 1.750 in.
* Open load: 280 lbs. at 1.250 in.
* Coil bind: 1.150 in.
* Rate: 296 lbs.

Notice the difference in pressures? More aggresive cam needs more aggresive springs regardless of lift. Lots of guys throw in these huge cams with inproper valve springs and they're taking a huge chance. If that spring breaks and the valve drops into the cylinder while your flying down the track at 6000RPM you're in for a world of hurt ...All for a $80 part.

Your 406 is near identical to mine. Except I used the 21cc KB pistons for 9.8:1 cr.
I went with a Comp XE-284H-10. (It was a free-bee) Works well in 383's and 400's. They need a bit more cam.
I have a 3500 stall and 4.10's.

how does that cam idle f-bird i know my xe268 is really smooth im looking for a rough idle this time around. also what do you run with your combo?

This cam definatily has the rough racey idle
Manifold vacuum will be reduced. May want to add a Vacuum resivoir canister to help the power brakes
function better and or a auxillary vacuum pump.
The carbs power valve will need to be selected to compensate for the reduced manifold vacuum too.
Likely a 4.5" power valve. It will want increased initial timing at idle. More the merrier. I run mine locked out at 36 deg at idle.

I have not tested this motor yet. The car is buried under a foot
or so of snow .... expecting low 12's @ 109MPH.

Low 11's, high 10's on the juice....

HAHA sounds like a little too much cam for me.... I dont want to loose power accessories and stuff. Just want people to know i got a nice cam in there. I am thinking about a lunati either the

0010: Adv. Duration: 292°/292°
Gross Lift: .480''/.480''
RPM Range: 2000-6000

or the 0012:Adv. Duration: 300°/300°
Gross Lift: .515''/.515''
RPM Range: 2500-6500

07102
Adv. Duration: 285°/285°
Gross Lift: .507''/.507''
RPM Range: 2200-6200

I was told the vortecs flow best are around .500 lift so i am looking for something right around there. I dont see how the xe274 is going to change anything as much as i would like it to, that is only one step bigger than what i have now {the xe268} and that is pretty much a stock idle sound to me.....



Yeah i didnt totally understand that 88iroc350 thanks for clearing that up. I do have the correct springs for the xe268, i bought the whole kit when i bought that cam... springs, retainers, cam, lifters, timing chain. Would i still be able to use those if i were to use say 1.6 rockers with the 268 cam? Or with the 274(without 1.6's)?

Never too much cam,, just not enough motor....

Don't whoose out on me now.
The power brakes will still work but may get exhausted from time to time. But its not as bad as all that.
part of the joys of a rough idle cam.
A vacuum canister will solve this issue.
I've run much bigger cams without one.



the XE274 will have a choppy idle and marginal brakes too so.....

But the XE284 has the idle sound (and power) you're looking for in a 400.

I elongated the pushrod holes on my heads and have a
half set of 1.6 rockers to try on the intake side.
Testing will tell wether they help or.....

If you had more compression and only cared about speed I'd recommend Crane's smallest "Saturday Night Special" solid cam.

Specifications:
* Advertised duration: 280 intake/288 exhaust
* Duration at .050 in.: 244 intake/252 exhaust
* Gross Valve Lift: .518 in. intake/.536 in. exhaust
* Lobe separation: 106 degrees
* RPM range: 3,200 to 6,800
* Performance usage, good mid-range torque and horsepower.
* 11:1 to 12:1 compression ratio recommended

I know a guy with a 10.5:1 400 with vortec heads running 11.70's on motor with that cam, 4.10 gears and a 3500RPM stall. A few of my friends have used this cam in various other motors with amazing results. All very streetable cars too

haha f-bird yeah im sure if i heard your car idle i would want that cam but i dont know if i like the idea of not having enough vaccum for my brakes. I dont really want to mess with a canister or anything. The springs from my 268 cam wont work with either of the 274 or the 284 will they? You dont happen to have a sound clip do you?


Yeah i really wish i would have gone with the -18cc dish but my dad talked me into the .30 cc ones... said they would be better for the street... wish i wouldnt have listened. Ooo well live and learn. I would replace them but 245 bucks is kinda steep i think. My heads are already 64cc so no more gain there really, im going to run a thinner head gasket this time.

also im kinda scared at putting the stiffer springs back in the engine because the first time around with this engine mated with a t5 i kept on breaking pushrods and screwing up rocker arms. So last winter i took the motor back out and removed the comp cams springs and put in stock springs and new rocker arms along with hardened pushrods and it didnt happen again. This time i plan on getting a good set of roller rockers(not the cheapo proform roller tips that kept breaking).

broken pushrod/rocker arm

Looks like the rocker's push rod seat may not be machined right. I'm not real crazy about Proform valvetrain parts.
I use Crane Stamped steel heat treated rockers with the roller tip. Has been on 3 sets of heads on 2 motors
with big and small cams. No wear or problems.
Ya get what you pay for.

Another problem guys..... the first time i put the engine together with the 268 cam in there i had to grind my connecting rods in spots to clear the camshaft.... would i have to do that all over again if i switched to the 284/296 cam? I cant see it getting much bigger.... not even sure if it is any bigger physically? help please...

Really hard to say for sure. If you just ground the rods
to just clear the XE268 you may be in trouble with a larger cam.
When we did mine we clearanced the rods for the biggest race roller cam we had on hand at the time. That way anything I wanted to try in it, would fit.

You could try the new cam first in an an over advanced position (say 10 extra degrees) and then in an over retarded position (10 degrees) from where it should be installed (cam card) to verify enough clearance. I'd say, if it passes this test without contacting the rod bolt heads, you're good to go.

I REALLY should have read this post a week ago!!!

Just last friday, I went to watch a 406 I just had built at a machine shop on the dyno for a break in and tune!

I'm running a Scat forged crank, SIR rods (internal balance), KB147 pistons, Dart Iron Eagle 70cc chamber heads at 200cc intake cfm's.

Professional Products "Crosswind" intake (cheap RPM air-gap lol), and a Speed Demon 650 DP.....and the XE274H Compcam.

....It didn't go well for me. Wiped a cam lobe.

And it only ran for 5 minutes and started clacking. Happened during initial breakin....

Oh, and we were also trying to run 1.5 RR's on the intake and 1.6's on the exhaust. Doing a search, it almost seems like a common occurance with these cams. P**sed me off. They returned the old one and the new one should be here in a coupla days. I hope they check the lifter bores and geometry one more time.....

EDIT: BTW - I read about a Vortec 400 setup in CHP. I was really considering it. By far cheaper than the route I went!! And it has some gonads!!!

ooo man sorry to hear that about your motor..... Thats exactly what i dont want to happen. I guess i will have to spend some extra time checking all my clearances. Someone told me the differences in the two cams was only about the thickness of a paper clip so i dont think ill have to do to much more grinding if any.

Thanks camarokev400... - I don't think it's a rod clearance issue at all. It managed to wipe one cam lobe.

I've personally never had that happen on any engine I've built myself, but of course the one I paid to have built did. They tell me maybe one out of every 100 they build will wipe a lobe on break-in.

But seriously, I done a search on this board for "wiped cam lobe" since this happened, and it appears that it's not as uncommon as you might think when using a Compcam.....

But I think it almost has to be a lifter not spinning in the bore because it didn't damage all the lobes. Should find out in a few days I guess....

Hmmm that scares me... .im about to be replacing my camshaft LOL i dont want that happening to me, ill be sure to check out my lifter bores.

well i went to summit last weekend and picked up my xe274 camshaft and lifters, harmonic balancer, crankcase evac system, and a few other goodies(cheapest trip there yet only 350 bucks), i also got my eagle crank this week (cncmotorsports.com 180 bucks for a brand new eagle 400 crank). Now i just need to put it all together and check my clearances and get it balanced.

its together and ready to go in

vortec heads

Nice.

May I ask what valve covers those are? Those look great.

Looks awesome!! Did you have any work done on the heads (porting)??

I got the valve covers off ebay from some guy.... not sure what they call them the title was tall vortec style valve covers.... they were 75 bucks to my door. As for the vortec heads, they have had work done to them to accpept the bigger springs, guide plates, and screw in studs. No port work done. I plan on going to the chassis dyno once i get it all broke in and get the bugs worked out of it. Right now though i am in the process of redoing the engine bay, started out as just taking out my clutch pedal turned into this>>>

2

engine again

and the firewall holes covered up with plates until i can get a non ac heater box

Looking at your pics, it seems your swap is going well. I personally wanted to paint the whole engine bay, but there were just too many hard lines and wires in the way for me. (And I'm keeping my AC)

So I just cleaned it up and dropped my engine in.

Hi,

What sort of paint did you use on your engine bay? I think almost everyone here would recommend Por15 rust paint. Will stop those nasty rusties dead in their tracks, permanently

Dyno numbers? Update please? It looks like an awesome build