9C1 cam with stock TBI?

[blackdeathmessenger]

Hello all, was hoping to get some input/possible advice on a situation I have found myself in. I'm not looking for the most power, just longevity, and was hoping to keep a roller cam in it for not a ridiculous amount of money. When I had my 355 built, I put in a stock (96-02/03) Vortec roller cam out of a junkyard 98 Tahoe which seemed to be in good shape, which is now a source of the issues I'm having. My truck is an '88 with almost stock everything. That being said, I've searched, and researched everywhere on if the cam swap I have in mind to keep this motor going for the time being will work, or if I have to swap back to the crappy flat tappet cam that was stock in this truck (with basically no results/inconclusive). My buddy gave me the roller cam out of his small block, which turns out to be 90-92 9C1 Caprice cam. Will the cam work with the stock computer, or will it just cause more issues? Thanks.

 

[Supercharged111]

What issues is the current cam causing? We stuck a Vortec truck cam in my friend's TBI truck and it runs fine.

 

[blackdeathmessenger]

One of the biggest issues, is, and has been, the idle. It keeps surging/searching for the idle. I also have less vacuum, which I can definitely feel in my brake pedal, and most recently, I've had issues with extended cranking time before starting and now when it does start, I have to hit the gas and rev the engine to get it up to normal idle. Yes, I have checked all of my sensors/connections, and tested them as well. Timing is at factory setting, and I even tried swapping the computer, just to make sure (it ran the same, if not worse). The only thing that makes sense after all my checking and testing is the camshaft. I wouldn't be surprised if there's just an issue with this one, but if I have to swap it anyways, was hoping the cam I got for free from my buddy would work for the time being

 

[blackdeathmessenger]

I also ran a OBD1 test on it, and it came back with a couple of codes related to spark and lack of vacuum/the map sensor

 

[Supercharged111]

The 9C1 cam is basically a low lift LT1 cam. That one will have longer legs and may not act right at WOT, but I really can't say for sure. What codes did it throw? And how's your fuel pressure?

 

[blackdeathmessenger]

Which is what everyone on every other forum has eluded to, that it's basically a L98 cam, but no mention of if it'll work properly with the stock computer. I never actually go to wot since part throttle acceleration is usually enough, even on the highway. Codes were 25, 34, 41, 42, 43, and 51

 

[L31MaxExpress]

Which is what everyone on every other forum has eluded to, that it's basically a L98 cam, but no mention of if it'll work properly with the stock computer. I never actually go to wot since part throttle acceleration is usually enough, even on the highway. Codes were 25, 34, 41, 42, 43, and 51

You have more of an issue going on than anything the camshaft is causing. Code 51 is a Chip/Memcal malfunction. Code 25 is for a IAT which a truck does not have. Code 41 is for a cam sensor that a TBI also does not have. Code 42 is probably from setting the timing. Code 43 is a knock sensor code.

I had a LT4 cam in a 350 TBI that ran flawlessly.

With the EST connector open, set the timing about 4-6° BTDC and it should make stock like vacuum. Actually if anything the stock L31 cam should be making more vacuum than the TBI cam. I do not even set the timing on a Stock TBI at Zero, they are gas drinking slugs if you do.

 

[BeXtreme]

It sounds like you have a massive vacuum leak from somewhere. It might be combined with fuel delivery issues. If you want to verify you have a vacuum leak, start it up and get it nice and warm. Then turn off and short the A and B pins on the ALDL connector together. Turn key on(not start) and wait 10 seconds. Disconnect the IAC valve and remove the jumper. Start the truck.

If your idle is very high after you do that... you have a big vacuum leak. If it sits down around 650, then you have other issues.

 

[BeXtreme]

You have more of an issue going on than anything the camshaft is causing. Code 51 is a Chip/Memcal malfunction. Code 25 is for a IAT which a truck does not have. Code 41 is for a cam sensor that a TBI also does not have. Code 42 is probably from setting the timing. Code 43 is a knock sensor code.

I had a LT4 cam in a 350 TBI that ran flawlessly.

With the EST connector open, set the timing about 4-6° BTDC and it should make stock like vacuum. Actually if anything the stock L31 cam should be making more vacuum than the TBI cam.

Plus all this as well

 

[blackdeathmessenger]

Well, the scanner I used also mentioned code 25 also being for spark reference signal, 41 also showed 4 different possibilities. 1) Cam sensor failure, 2) cylinder select error, 3) electronic spark timing, 4) ignition system fault. It also said all the codes were current, if that makes a difference. I know obd1 doesn't usually store codes unless there's serious issue(s). I've also seen it eluded to that the L98 cam and LT4 cam were very similar as well, but no one actually said anything involving my specific setup, which is mostly stock, aside from the cam and an Edelbrock tbi intake. Everyone else was doing custom chips. I might need to see if setting 4-6° on the timing fixes anything