Big cam causing misfires??? 490/490 w/1.6 RA

[96c1500FullRebuild]

It needs to be tuned. With that cam you're running way lean, hence the lean popping. Your timing is probably way off too. If you don't want to wait for the 0411 swap, go to Black Bear Performance, they tune "black boxes" all the time. 10" of vacuum is low, perhaps a vacuum leak???

http://blackbearperformance.com/

I didn't know they tuned these. I contacted them awhile back about the 0411 swap. I will reach out about a possible start tune.

The previous build I had this motor in had the same vacuum so I don't think there is a vacuum leak. I sprayed starter fluid all over all vacuum connections when I first fired it up running like this with the same theory to no idle reaction.

 

[Bloodwater79]

Are your heads ported? the stock flow out of the iron vortec heads peaks around .400 lift. the extra you are adding from the rocker arms is not giving you any gains, and might cause reversion where the head flows back into the intake dropping your vac. just my 2 cents.

 

[96c1500FullRebuild]

Are your heads ported? the stock flow out of the iron vortec heads peaks around .400 lift. the extra you are adding from the rocker arms is not giving you any gains, and might cause reversion where the head flows back into the intake dropping your vac. just my 2 cents.

Im not running stock vortec heads..

 

[96c1500FullRebuild]

Well I reached out to blackbear and as it turns out they do tune the black boxes. Im going to give this a whirl and see how they do. Ive heard mixed things across the board but its a cheap solution for now until I get my own tuner. Thanks guys. Ill update when I get the computer back

 

[arrg]

10" of vacuum is low, perhaps a vacuum leak???

His cam is 230/236 on a 110 LSA.

 

[CrustyJunker]

That's a super popular all-around performance cam in SBC world. I bet it sounds awesome too!

Tune will definitely help the most. It probably needs a couple more degrees of initial timing, and maybe the idle bumped up. Your vacuum should come up a couple more inches with that alone. They should know how to do all that.

Between the low vacuum and maybe a bit lean on the low end, that'll make it stumble and pop. EGR at low speeds with that kind of overlap might cause some misfires too. That duration coupled with a 110° LSA is mighty tight for fuel injection!

I'll be honest, I have no experience with aftermarket Vortec intakes. I have heard the marine intake had some gains, but not sure at what power range. Plus I'm also not sure how easy that stuff is to find anymore...

I'm not sure how much you wanna spend or how creative you want to get. If you're hunting for max power, you might want to look into something like the Holley 300-263 with a throttle body adapter, or an Edelbrock Pro-Flo/Chevy Ram Jet style intake.

 

[Supercharged111]

That's a super popular all-around performance cam in SBC world. I bet it sounds awesome too!

Tune will definitely help the most. It probably needs a couple more degrees of initial timing, and maybe the idle bumped up. Your vacuum should come up a couple more inches with that alone. They should know how to do all that.

Between the low vacuum and maybe a bit lean on the low end, that'll make it stumble and pop. EGR at low speeds with that kind of overlap might cause some misfires too. That duration coupled with a 110° LSA is mighty tight for fuel injection!

I'll be honest, I have no experience with aftermarket Vortec intakes. I have heard the marine intake had some gains, but not sure at what power range. Plus I'm also not sure how easy that stuff is to find anymore...

I'm not sure how much you wanna spend or how creative you want to get. If you're hunting for max power, you might want to look into something like the Holley 300-263 with a throttle body adapter, or an Edelbrock Pro-Flo/Chevy Ram Jet style intake.

Stock cam sits on a 111 LSA, LSA isn't everything with fuel injection. Marine intake gives a boost around 3000+, but with that much cam I might be thinking more along the lines of a ramjet. That's a lot of cam for a truck, I didn't see a mention of gears or converter stall speed? There should be no issues tuning this motor though. The cam and intake are a definite mismatch.

 

[96c1500FullRebuild]

That's a super popular all-around performance cam in SBC world. I bet it sounds awesome too!

Tune will definitely help the most. It probably needs a couple more degrees of initial timing, and maybe the idle bumped up. Your vacuum should come up a couple more inches with that alone. They should know how to do all that.

Between the low vacuum and maybe a bit lean on the low end, that'll make it stumble and pop. EGR at low speeds with that kind of overlap might cause some misfires too. That duration coupled with a 110° LSA is mighty tight for fuel injection!

I'll be honest, I have no experience with aftermarket Vortec intakes. I have heard the marine intake had some gains, but not sure at what power range. Plus I'm also not sure how easy that stuff is to find anymore...

I'm not sure how much you wanna spend or how creative you want to get. If you're hunting for max power, you might want to look into something like the Holley 300-263 with a throttle body adapter, or an Edelbrock Pro-Flo/Chevy Ram Jet style intake.

I plan on spending some money long term but looking for a quick fix right now to have some fun. It was an excellent cam prior to fuel injection so I wanted to see what I could come up with on a tune and actually get some numbers on it.

Stock cam sits on a 111 LSA, LSA isn't everything with fuel injection. Marine intake gives a boost around 3000+, but with that much cam I might be thinking more along the lines of a ramjet. That's a lot of cam for a truck, I didn't see a mention of gears or converter stall speed? There should be no issues tuning this motor though. The cam and intake are a definite mismatch.

Ill do some digging on these options, like I said im new to the fuel injection so I have no idea whats out there..
As for a stall and gears, ill be throwing a 2000 stall in it soon and it has factory 3.73 rear end. I did a quick burnout upon first fire up and discovered someone may have thrown a LSD in it so that should be fun!!




Keep the info coming guys!! I'm learning as I go in this injection world and hoping to learn the tuning soon and appreciate all the advice I can get.

 

[L31MaxExpress]

Pull that cam out and put something more truck and truck intake friendly into it. I have tuned both the Lunati Bare Bones hotcam and the Comp marine 270 roller cam in Vortec trucks with the stock intake and black box.

The cam you have needs around a 3,000 rpm stall and 4.56 gears to run well in a truck.

Could also yank out the lifters and put some Rhoads V-Max lifters in it. Adjust them on the base circle of the cam with a 0.020" feeler gauge between the rocker and valve tip. You bottom them out like a solid lifter to where the feeler gauge just slides with light resistance. Will give you more vacuum, a smoother idle and stronger off the line torque.

 

[Supercharged111]

You know you have too much cam when L31 tells you to yank it.