torque converter issues after a cam install?

[oldred95]

I keep reading threads about guys having problems with their truck wanting to creep forward with their foot on the brake, at stoplights after a cam install. I guess I'm not fallowing on how a cam could affect the torque converter like this. Is the engine producing that much more power even at idle to make the converter stall or whats the deal?

[Summit1]

Maybe having to turn up the idle to compensate for a big cam is causing their roll...

[oldred95]

Could be but it seems like most guys complain about that unless I'm dreaming this up. This is a computer friendly cam so it can't be to wild of a cam.

[airdeano]

on EFI the goal is to promote a high vacuum signal to the MAP sensor. this will
keep the fuel load from getting to high during idle. to most will increase the idle
speed to 700-750 in drive to compensate for the vacuum deficiency. a good chip
tuner can revamp and correct this error. the higher idle speed will tend to pull
against the low stall of the converter. this causes "creep". adding the performance
cam and a converter can usually create double penetration into the power band.
as the converter lets the engine slip into a higher output, the cam is increasing the
power easier without pulling against "loading" trans, gear or tires.
"computer friendly" is a wide term... generally under 218° @ .05 is gentle enough
to use a stock tune or a custom upgrade can always improve output.
airdeano

[oldred95]

on EFI the goal is to promote a high vacuum signal to the MAP sensor. this will
keep the fuel load from getting to high during idle. to most will increase the idle
speed to 700-750 in drive to compensate for the vacuum deficiency. a good chip
tuner can revamp and correct this error. the higher idle speed will tend to pull
against the low stall of the converter. this causes "creep". adding the performance
cam and a converter can usually create double penetration into the power band.
as the converter lets the engine slip into a higher output, the cam is increasing the
power easier without pulling against "loading" trans, gear or tires.
"computer friendly" is a wide term... generally under 218° @ .05 is gentle enough
to use a stock tune or a custom upgrade can always improve output.
airdeano
I would love to put a 2500-2600 stall in there but I don't want to drop that kind of money into it right now.

Here is the cam I'm looking at getting. Both badburban and Brian of TBIchips recommended it and said its a very nice cam and fairly easy to tune.
http://store.summitracing.com/partdetail.asp?Ntt=CL12%2D249%2D4+&N=0&part=CCA%2DCL12%2D249%2D4&autoview=sku&Ntk=KeywordSearch

[Fast305]

That cam is too mild in my opinon to get the gains you are after. I would recomend one of the 256 series cams running around, such as this crane cam Z-256-2. It features 206*/218* @ .050 and a 112* lobe seperation but less duration overall than most. It is NOT a lazy action cam. It flings those valves open and sets them down quick. The lift is real high for the duration which helps wake up these engines. The lift is .432" on the intake and .459" on the exhaust. Think of this cam as a non-roller alternative to the F-body LT1 cam. The RPM band is 1,200 to 5,800 and the cruise range is 2,200 to 2,600.

http://www.cranecams.com/index.php?...501&lvl=2&prt=5

Comp makes one that is almost identical in their Xtreme Energy line. It is the XE-256-H. Here are its specs, 212*/218* @ .050, and .447"/.454" of lift on a 110* lobe center. I have one on my shelf that was in the old 355 before the LT1 cam went in.

In my experience you can expect these cams to run pretty good on a stock chip, or on a mail order chip, but don't expect them to run perfect unless you learn how to prom tune. You can however expect about 230-235 FWHP and 345-350 ft/lbs through cast iorn manifolds, a low restriction exhaust, and the stock TBI/Intake setup. I would recomend atleast a VAFPR to go with these cams as they will tend to run richer than stock at idle and leaner under load. The VAFPR works by lowering the fuel pressure lower than stock at idle but raises it under load up to near 17 psi.

[oldred95]

I think that rpm range is a little too much for a TBI with 164,500 miles on it. I think revving to to 5000 is gonna be plenty high, 5800 is rediculous imo. Two chip tuners have told be that anything tighter then 112 lobe seperation is pretty hard to tune by mail order. I know this cam will be far better then stock and will do what I need it to do. I don't want a wild cam that is a nightmare for daily driving, I just want all around more power and the cam I linked you to should deliver it. Both badburnban and brian of tbichips highly recommend this comp cam. I'm sure your cam would be fine if I had the need for it but I don't, this is not a race engine, its just a daily driven street engine that needs some new power.