maj3stic

Ive been reading a lot between here, pirate4x4 and few other Chevy sites trying to get a correct answer but can't seem to find one, so here is my problem. I have a 350/290 which from what I read is like the worst crate engine there is but I picked it up in a crate for 800, which I could not pass up the deal. Anyways I was orginally planning on going TBI, I have the harness, computer, and trottle body from a 93 suburban. I made an adapter plate for my intake and then started reading more forums and started to get slightly concerned.... I've read in different forums that the cam that came with the 350/290 (0.450" / 0.460") would not work with TBI setup. Yet on other sites I have read that the PCM would have to modified, which is not a problem, because I already knew I was going to have to modify the firmware to disable the transmission controls since I dont have an automatic transmission. So finally will the TBI and PCM work with the stock cam on the 350/290?
Thanks again in advance for any information you guys can provide.

91interceptorZ

iTrader: (3)

yes it should work, you have to be pretty far out of stock size for the computer not to work with cam. There shouldn't be a cam/crank sensor in those, just a basic motor with a throttle body instead of a carb. What you should compare is the lobe seperation, duration, and lift to a stock cam that came in a '93 chevy. I would bet it would work just fine.
Example: Ran my car with everything plus more listed below on stock computer for a short time, didn't run perfect, but not bad. and my cam is pretty large.

RFmaster

https://www.thirdgen.org/forums/engi...te-engine.html

See post #9

Cam change should be considered.

//RF

maj3stic

I read that post prior to posting. My outlook on the post was it was debated back and forth and never a clear answer. I have actually read similar posts on ih8mud and pirate4x4 about the same thing. Seems everyone has an opinion but no one has a clear cut answer.

RFmaster

Yes, everyone has an opinion - that almost certain! FWIW, I would look into getting a slightly smaller cam. That 290 HP engine uses old style large chambers for grand total 8.5:1 compression. According to several online data sheets that engine comes equipped with Cam Part#3896962 Intake Lift-.450" Exhaust Lift-.460"
Intake Duration @ .050"- 222 Exhaust Duration @.050"- 222
LSA -114deg
which results in low idle vacuum. As it was mentioned before TBI is a speed density system that relies on MAP input for fuel and spark (among others). I would look for a shorter duration cam - no more than 210 deg at 0.050 with LSA 112 to 114 deg and similar lift. You'll loose a bit of top end power but torque will move down in RPM range which should be OK for a street driven car or truck. Ideally stock TBI ECM likes to see idle at 16 to 18 in-Hg (30 to 40 KPA) which smaller cam will deliver.
As far as cam selection - the list is long so spend time looking at specs and ask questions before committing. Swapping cam while engine is on the stand is straight forward. With oil pan off double check main and rod bolts torques while making sure that there is no crud there.


//RF