Need a camshaft recommendation...

[jonrpick]

I need a new cam for my 350. I have the POS 290hp crate motor. I hate it. I sends half the gas out the tailpipe at idle. No low end torque whatsoever.

Anyway... Since I'm rebuilding everything else it seems I figured I'll use the opportunity to put in a suitable cam.

Here's the specs on the motor:
http://www.sdparts.com/product/12499529/290HP350LongBlockPreEmissionsGMCrateEngine.aspx

And here it is broken down into the individual parts:
http://paceperformance.com/index.asp?PageAction=VIEWPROD&ProdID=84482

Regardless of how it shows on the dyno chart, it doesn't perform as one would expect.

I'm running the stock Q-Jet manifold and exhaust manifolds from my old 305. I'd been running an Edelbrock 1406 (600cfm / electric choke / vac. secondaries) on there with an adapter, but I just bought a nice used Edelbrock Q-Jet to drop on there instead.

Can anyone recommend a cam that'll give me more low end torque, better idle, and better fuel economy?

Tell me about "RV" cams...

 

[Randy92782]

you don't think the fuel problem is in the carb do you??

 

[jonrpick]

you don't think the fuel problem is in the carb do you??

No... the carb was brand new. The old Q-Jet ran fine on the 305 and did the same as the Edelbrock on the new motor.

I think it's just too much overlap in the cam. The symptoms of that are a rougher idle (than stock, it's not a racing cam), less low-end torque, and worse gas mileage, as well as all the extra gas running out the tailpipe at idle...

Oh yeah, low vacuum. It pulls like 15" Hg at idle, where a truly "stock" cam should be like 22" Hg (IIRC).

 

[reddog64]

comp cam 268H

 

[cheyennek20]

On Comps website you can download a free Cam choosing program that lets you plug in all the info from your vehicle. It's very similar to Desktop Dyno in use. I originally ordered my cam from Summit with their tech help and after I got the program, I ran all my info through Comps Program, and it actually chose one bigger than I did. It was pretty close on the dyno numbers:

428 hp @ 4800 rpm

588 lb/ft @ 2850 rpm

That seem pretty good to me, but mine's not a DD.

 

[longbedder]

comp cam 268H

I second that.

Cams labeled as RV cams are great for trucks also.

 

[jonrpick]

What about the 255?

I want the max low-end torque and vacuum at idle...

 

[longbedder]

The 255 would work well also...

What diff ratio do you have? If it's 3.73 or numerically lower, I'd go with the 255. If you've got 4.10's or numerically higher, I'd suggest the 268.

Or, if you're waffling between the two, you could just get the 260H, right in the middle.

 

[jonrpick]

The 255 would work well also...

What diff ratio do you have? If it's 3.73 or numerically lower, I'd go with the 255. If you've got 4.10's or numerically higher, I'd suggest the 268.

Or, if you're waffling between the two, you could just get the 260H, right in the middle.

It's a 3.73 gearset turning 31" tires... I don't want to go back to 3.08's EVER... A 3.42 may work, but it's not a big enough difference for me to invest the time and money.

Everyone will think I'm nuts but I'd like to make close to the same peak torque #'s, but push the peak down to about 2500rpm.

I haven't seen a cam that would do that alone though...it'd require more than just that probably.

 

[BILTIT]

Put a pontiac motor in it. Outpull a chev 350 anyday and can be had for cheap. Thats what i am doing because my 350 sucks too, i am also a pontiac engine fan (pre-80's) so that helps.

 

[jonrpick]

Put a pontiac motor in it. Outpull a chev 350 anyday and can be had for cheap. Thats what i am doing because my 350 sucks too, i am also a pontiac engine fan (pre-80's) so that helps.

Well eventually it'll go to a straight-six, but for now, just getting the Chevy to run good is the main thing...

I also don't want to spend a lot, so I was thinking of just dropping in the basic, 260hp Chevy cam...that seems to be the base cam for their low-end crate engines.