427TRI

Just wondering if any of you all ever had a chance to dyno a 427 3X2, not neccessarily in stock form? Any comparisons of a single 4 v 3X2? Any experience with various cam configurations with the 3X2?
A very unique manifold btw, 180 on the center and 360 when you crack the outboards open. With big, short runners. Also wondering if a cam config can be optimized for the beast. L88's too big, current Crane too small. But question really is tight LSA or wider lsa???Thnx for your help! :chevy

Ganey

Actual nos. w/ engine on dyno & off road sidepipes are 368 HP @ 5750. TQ 419 @ 3500.

:cool:

Tom454

Which one?

Big port 435HP or small port?

mountainmotor

Those relatively short runners of the manifold would benefit from a LCA of 108 for deeper breathing.
Same with the 2- 4barrel intake that Edelbrock offers for the Small and Big Block block Chevy
Would have to watch the duration @ .050 though or idle would get out of hand for some.The kind of idle I like! :) Terrorize the cats and dogs

427TRI

Gentlemen, thank you for your quick replies. Its a big port motor. Mountainmotor, your reply rifleshots exactly what the real question is. I've read up on cams as much as my novice level allows. Conclusion, pretty tiight lsa. However, I would also, I beleive, have to move up in duration, else I'll lose upper rpm power as the torque curve drops off quicker. Now have 238/248 @.050 on 114, was settling on 110 but with 243/251, and a 108 would require me to run 250+/260+ to set my shift point at 6800. HOWEVER, this is not a stock vacuum outboard setup and it has idle circuits on all three carbs.Believe it will allow a typcial 5" Hg cam run at 8". No power accy's either.

108 seems pretty radical. And to allow an old L88 to operate in its intended 3800-7000 rpm range, where would duration be set? Like to keep lift at .600 for durabilities sake.
THNX again.

Mr. Ganey, thnx you Sir for the benchmark. I was hoping to pull over 500 lbs ft at 4000-4200 rpm. Might be unreasonable then.

mountainmotor

427,
No problem! been off work cruzin the net.I really like a 106-108 LCA.Problem on a street car is depending on duration those things won't "clean up" until 2000 rpm or so.Again it depends on the duration.

Post your trans,rear gear and exhaust and will get you some specs to toss around.

Your stock exhaust port flows .580 so the quest for no more than .600 lift is substanciated

I would be interested in hearing about what year Corvette you have as well :D


[Modified by mountainmotor, 4:08 PM 2/1/2002]

427TRI

Mountainmotor, alas, its a 67 Chevelle. The 427 is a crate L88 I bought used as a kid. And the tripower was a wim, which turned out to be quite a good performer ( 17+ mpg). But so far, quicker ET's with the old Winters/850dp intake. Richmond 5 speed, 3.55's 26" slicks ( tranny is new), which should give plenty of gear for this short stroke big port mill to "spool up". 2"/3.5" Hookers, 3.5"Xpipe, 3" system.

So far, the cam that comes closest to what I think I need is an Ultradyne grind, 243/251@0.050 ( 276/284adv), 585/600 110LSA. Closes intake at 78 vs 86 ABDC now.

fwiw, the L88/Richie combo will find a new home, plans are for a 505 dressed to look like the orignal 396/325 for the Chevelle. L88 needs a lighter ride to approach low 11 ET, IMHO.

But I digress, yeah I was really trying to match cam choice up to the wicked short, direct and large runners of the 3X2 intake. So far, the cam choice would be the same for 1X4 or 3X2, it seems.
ThNX for your help...

Know of any 67's or 69's looking for a drivetrain?!

mountainmotor

Quote"
"
"Mountainmotor, alas, its a 67 Chevelle."
I knew that! :) Welcome.
The Ultradyne 292 255 586 intake
302 264 586 exhaust
ground on a 107 with the intake centerline put in on 105 will be you best bet for the ci and weight of car.You have the exhaust to support this.Check intake valve to piston clearance carefully.
the other is a A impeller Jet Boat cam that will peter out on you at around 5500 -5800 rpm depending on how good the heads are.

I like 67 Chevelles.Especially with the wheels in the air ahead of a Ford!

ML67

I dyno'd a 9.7:1 CR 540 w/ 3 x 2 induction system. The cam was a stout Comp Cams roller w/ 261/ 272 duration @ .050 and .690" lift. It made 655 HP @ 6200 rpm on pump gas.

Not exactly a stock 427 test!

BTW the intake and carbs are for sale:

http://forums.corvetteforum.com/zerothread?id=224940

Take care,

Mark

mountainmotor

Mark,
Curious to know what the total CFM of a Tri Power set up is.

Chuck Harmon

A BB tripower is right about 1000cfm @ 1.5hg pressure drop.

Chuck

427TRI

Mountain, thnx. Boy, the cams you "pros" come up with are much hairier than the grinds I'm accustomed to.

Three Holley 500 2 bbls flow 1125 and the stock setup used a smaller center carb, so 1000 must be correct.

Great MOUNTAIN MOTOR setup, dont ya think!? Often wondered why guys with big inch mills didnt run trips. They're awesome, but a lil 430ci only needs 835 cfm @ 6800 rpm.

Chuck Harmon

Holley rates 2 barrels at 3.0"hg instead of 1.5"hg like they do for the 4 barrel carbs. This gives the 2 barrels a seemingly higher rating because of the greater pressure drop.

Chuck

gdh

Hey 427, that's why we tend to call him "O God Like One" MotorMountain has kept many of us out of more trouble than we would ever admitt too. :cheers:

427TRI

Chuck, yes, the 2300 series 2 bbls I use flow 375 cfm in "4 bbl terms".

Comp tech has me in one of their Drag race magnum series of cams, Crane in their F314 ( run the F304 now), a buddy in a Comp "tight lash" custom with two lobe profiles ( seems like the strongest choice, but the ramp profile are very, very fast for a 5000 mile a year street car - imo). My Ultradyne choice was their "sleeper" cam. Smaller than Mountain's.

So MountainMotor's the man huh? :cool: I always thought the wide 114 lsa I run now was a compliment to the big ports / high r nature of this motor, but I realized that I could get more peak by tightening the centers and lengthening the duration to keep the rpm band up.

Hey, if it was an oval port stroker, I'd be happy to shift at 5700. But this old L88 is a natural 4000-7500 motor, and I'd like to get it back to stock specs ( in output but not compression!) without using the original cam. ( was thinking solid roller to get back the power loss of 1.25pts lower compression, but not durable enough for my street use. )

Mountain, keep in mind my calc'd compression is 10.8:1. I dont know the static number. ALum heads might need more with these MONGo cams? Yes? I mean I'm starting to feel "undergunned" with only a measly 11:1!




[Modified by 427TRI, 8:08 AM 2/3/2002]

mountainmotor

Quote:
"fwiw, the L88/Richie combo will find a new home, plans are for a 505 dressed to look like the orignal 396/325 for the Chevelle. L88 needs a lighter ride to approach low 11 ET, IMHO"

I took the 502 and Tri Power motor into consideration when posting cam specs.
With 502 and 850 with better manifold a 110 LSA would be the choice.For comparison with respect to your compression question the cam will make 565 + Horsepower in a 9:1 454 with 850 carb.11:1 will only help
The 114 would work better with tunnel ram and good gear or big inch motor with dual or single carb a pump gas motor ect ect.

Are you going to run through mufflers?Since the Richmond appears to be going away,what will replace it?If you could tell me exact heads,gas you want to use ect and if the 3.55's will still be used another cam might come to mind.Also is this Chevelle stock weight?

Carefull using cam maufactures advice.Some of the Techs"not all" rely on feedback from the field.Get a guy thats over exuberent or otherwise giving poor feedback and the correctly cammed combination will win. Some techs will put a guy on the conservetive side just to make certain the car will be a sucsess based on the other end of the phones input towards tuning abilities ect.Might even hang the phone up,call right back and get another recommendation!
More information needed.

Greg,Thanks for the kind words!Might come to Canada this summer to see if the sound of tires burning differs any from down here!




[Modified by mountainmotor, 11:47 AM 2/3/2002]

Flareside

This sounds aweful close to the posts by Gene, the moderator at the Chevelles board. Is that you Gene? I hope it is because you've helped me a bunch! This is a GREAT group of guys here. A little less "intense" than TC :lol:

Did you install your Richmond yet? Mine's still on the garage floor...

Here's more recent cam info: http://forums.corvetteforum.com/zerothread?id=226051

-Joe (Tripower over at TC, but I guess that should change since I sold the 3x2 ;))

427TRI

Joe, yeah its me. I figured some folks over here might be more familar with making a small ci 3X2 really sing.

Mountain, I said too much in that last post. Forget about the 496, thats IF I do a final concours style resto on the car. What would you run if you had an M20/3.08 posi as your limiting factors!? Sure, a darn 505 ci., 10.25:1 stump puller, stroked, 225@0.050 on a 108, with a QJ, all in orange!

The 430ci is an old L88 crate I bought when I was 17. Bowl work on the 074 head castings, but not much, they've been shaved a few times though. ( 0.015 total). Pistons replaced with TRw's ( and 0.030 over)to yield 10.8:1, cam replaced with the mild Crane solid. Other than that, its all like the General made it. ( oh the 3X2 is a custom deal I built - all mechanical w/6 corner idle IF I need it ).

Built the exhaust to what I assumed was free flowing specs for an L88 type mill: 2" Hookers 3.5" collectors, 3.5"X3" Dr Gas X, Magnaflow HUGE case 3" muffs and 2.5" tails ( just because 2.5" looks best on a stock muscle ride and I figured after those 55gal drums I use as mufflers, the 3"v 2.5" tail was more asthetics than perf.)

The Richie5 goes in within a month. with 26" slicks, its like 4.56s. OK, should finally have enough gear for this thing.

Best cam choice I have run across, so far, is a custom Comp, TL280/290-1 ( high torque), which sports 250/255 @0.050, .600/.612 gross, 108lsa and recommended to install +2/+4 adv. Seems like a nice replacement for the old L88 grind huh, ( and 1.5pt less compression). But Comp says ramps are pretty stout and might affect durability, but I dont trust the techs, as you mention. this thing seems as quick as some of the roller grinds however. This is a street car. Raced maybe 3X/yr. Driving on "tour" for 8-10 hrs straight some times too.

I really appreciate the guidance here.




[Modified by 427TRI, 1:09 PM 2/4/2002]

Tom454

Gene... maybe you can shed some light on a problem I have...

I also have a modified tripower setup with idle control for all 6 barrels. I have been trying to find the "long" style idle adjustment screws so I can reach those suckers easier. The end carb throttle bodies which I have are missing a few idle adj crews...

I am assuming you have the same outboard throttle bodies that I have... which include the idle adjustment screws, unlike the GM carbs.

Question.. do you know the origin of those non-GM throttle bodies? If I can get a Holley "LIST" number for their original application, maybe I can locate some idle scews. I have a few of the "long" ones, Holley still sells the short ones as are used in the center carb metering body.

Holley claims no knowledge of such things. I guess all the Holley old farts have retired.

Tom

69L71

Hey Gene/Tri.

Good to see you over here with 158+ posts. It wasn't too long ago I was over at Chevelles.com looking for cam advice and now you're over here! Looks like there's a deep well of knowledge in both places. Its good to see that there are plenty of gear heads that like 2-seat cars. We're not all concourse geeks.

I still haven't decided on my cam but I'm following your ordeal closely. My motor will wind up being a tad milder than yours but your conversations help keep me fueled and ready for spring. I'll be pulling the body back off again in a month or so and that's when I'll probably start playing desktop dyno games.

Did I hear you're parting with the Richmond 5? Why is that? I'm actually toying with picking one up.

Good luck in your search.