AFBCamaro

Hey guys I was just wondering. I have an ex tbi car(stock heads), headers no cat, Performer rpm intake and 600cfm Edelbrock carb. 3.42 gear(posi) The engine moves pretty damn good, but my stock cam is hurting me. I decided on Crane 274 H06 cam.
218 dur INT/EXT
.450 lift
and 106 LBE !!!!!
(I know about the roller cam issues and low lift of the crane cam, but im not changing springs etc.I want this very cheap)

I been looking for an average duration for a 305 with a extremely tight Lobe separation(for the choppy idle). Will i give up alot of torque? How chopy do you think it will be? Will my brakes work with it? I know that 218 duration on a 305 is just about right but im concerned about the 106 sep. I love the chopy ride(when the engine sound like its gonna shut down at idle) but i dont want my power brakes to go.

In the crane discription it says, Rough idle, lower vacuum. Good low/mid speed torque with HP. I dont mind losing some at the bottom end but like i said will i see major problems with it?

Thanks in advanced.

FastBroker

That's probably one sep up from what you should use for duration. Too little lobe sep, too. Lower lobe sep actually gives you more overall lowend torque whereas more lobe sep tends to giv more high-end torue, which tranlates into high-end hp.

Blade

I don't know about getting that choppy idle on a TBI car. My cam's supposed to be "choppy" by the idle is smooth as silk. I think the ECM auto adjusts it so it's not choppy...

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92 Z28 L98 350
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Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires...

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)

FastBroker

He has "ex-TBI" car, now. TBI/TPI systems will smooth out the idle of larger cams because of accurate fuel calculations and from correct spark at idle.

AFBCamaro

The "more" torque theory of lower lobe separation is only true to a certain point. After that the exact opposite is true. "given enough duration"

The closer the lobe sep the more overlap the engine has, hence the choppy idle and lower vacuum.

This is what i figured, a 218 duration on a 305 will make power from around 2600-6200 rpms, now if i drop the lbe enough it should peak at a lower speed say 5300rpm. which is just fine for what i want. But my question is will my power brakes be affected a lot. I know it will be choppy, i just dont know how much. I want it very choppy without giving up much. I had this idea of a low lobe higher than what I need duration cam for a while now, and have been trying to find the right camshaft. I think this is it.

If anyone here is using anything close to this please let me know. Or if you have ANY ideas/thoughts. I would appreciate them.

TBI/TPI, thats to much "smoothing" out for me, i like horribly metered fuel. If i could tape a fuel cell on top of the manifold i would.

FastBroker

Of course, my man...

By the way, that cam won't have a power range of 2600-6500, it will be somewhere in between. Also, the peak of the torque isn't usually at the high-end of the powerband range.

Look in the Summit/Jeg's catlogs in the cam sections and you will get some good ideas of where powerbands are and how big they are.

I'd go a little smaller, for your combo. Actually, I'd use the generic Summit cam that has 204/214 deg with about .420"/.442" of lift. This will give you excellent results over stock and should cost you less than $100 for cam/lifer/gaskets and a six ack.... I have used a lot of these cams and lots of the 204/214 in 350's. Great daily driver but not to lopy of an idle. But all you should care about is get up and go and a 305 with your setup will be ok. If you are more venturesome, get the generic 214/224 cam. Nice too, but with your manifold, daily driving and mileage will suffera little and for very little power gains.



[This message has been edited by FastBroker (edited October 07, 2000).]

dsmanimal

I think that cam will be just fine, although I'd rather see you go with a 110 degree LSA cam. If you have a standard transmission, the 106 LSA won't hurt your off idle performance much.

AFBCamaro

Thanks for the replies guys. You guys never let me down. I listen to you probably more than i do to Crane cams.

My car is an auto with 3.42s out back. I really dont mind a drop in low rpm power as long as is not exagerated, besides with ****ty street tires is better not to have to much and floor the gas pedal from a stop. Less guess work. The power will eventually come. HEHE

I know the power band isnt in the 6000 rpm range, i said i probably would be on a 305 without the 106 LCA.

Most importantly i want the damn thing to lope!!! I like that fast idle lope. I dont know if ill get it with some of those other lower duration higher LCA cams you suggested(Summit). If you think they will(lope) then by all means ill use them. I just know that the 106 LCA will give me enough overlap to sound extremely racy without giving up to much. "I hope"

I have a 350 block sitting on my garage floor waiting for me, so this 305 isnt my project perfection. Its my project, "i dont have enough money for the 350 right now make the 305 sound like an animal in the mean time project."

Thanks again guys

AFBCamaro

Hehe Fast! I am a little more adventurous. Do you think ill choke off the heads if i use 214 224 summit cam?

This is an clipping of what crane cams says about the cam.

Rough idle, moderate performance usage, good low and mid-range torque and HP, mild bracket racing, auto trans w/2500+ converter, 2600-3000 cruise RPM, 8.75 to 10.0 compression ratio advised. Basic RPM 2200-5200

I guess my fuel economy will go to hell then.
Im getting confused shouldnt a tighter LCA give you more overlap hence making higher rpm horspower higher in the band.(Increasing high speed breathing because of higher overlap.) If so why do they say good low and mid range torque, maybe the duration is not enough to affect a 350s torque with good set of heads.

Thanks again, guys

ws6transam

Maybe you ought to check out my sound bytes of the Comp Cams XE262H cam as installed in my 305. I just used it to turn a 100.8 MPH quarter mile this weekend, and it has a tough idle.
http://www.isthq.com/~dan/fcar.html



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Daniel Burk
http://www.isthq.com/~dan/fcar.html
'84 Trans Am WS6/L69
KB SFC, Moser axles, Torsen Diff. PST suspension, Braided stainless brake lines, Koni struts, 11-inch rear disks,Spohn Adj. torque arm,
Ported 305 heads w/1.94"intake valves, Comp Cams XE262H, Griffen alum. radiator,
Turbine Technologies 2500 stall converter, underdrive pulleys, Crane Hi-6 & more.
1.05g skidpad verified.
New best E/T! 14.039 at 100.82 MPH in 41 degree air at Stanton, Michigan.

FastBroker

Tighter/lower lobe sep = more overlap = more LOW END power. Higher Lobe-sep = less overlap = more high-end... Generally, of course but good general rule. Have fun

woops

[This message has been edited by FastBroker (edited May 03, 2001).]

AFBCamaro

Tigher lobe separation (numerically lower)=more overlap

Wider lobe sep (numerically higher)= less overlap

Thats why alot of cam manufacturers increase separation when there is more duration to smooth out idle.(less overlap)