I just completed the second attempt at installing the LT4 hot cam into my LB9... Yes, LB9 (Please no bashing). Anyway, the first attempt at installation, everything went smoothly, cranked the car up and it ran really strong. It sounded really loud and had a hefty and rough sound to it at around 1000rpm and the exhaust had a really clean or almost odorless smell to it. I tried to put it in gear and it almost died out. Keep in mind that did no custom tuning to the prom yet. Well my fun was spoiled because I had to remove the intake manifold to have it sent to a machine shop (long story). After I got it back, I slapped everything together, cranked up the car and now it runs totally different. The exhaust tone is a lot "quieter" and the exhaust smells as though the gas is not burning efficiently if you will. I also noticed that there was now condensation or some sort of liquid coming out from the exhaust pipes. When I put the car in gear it idles fine. All in all, the engine is not running NEARLY as strong as it was the first time. Whats wierd is that I can drive my car around with the stock chip without any problems... Any suggestions? Thanks Jeff

Well after what I have been reading . . . everyone tells me that after you do an LT4 Hotcam swap you need to have your computer tuned. So go get it tuned professionally and you will be all set!

Sean

might want to make sure you didnt drop the dist. in a tooth off when you reinstalled it. good luck

If all you changed was the intake, then Im almost 100% positive you didnt put the distributor in correctly. Bring the #1 cyl to TDC, and start over with the distributor.

I agree. Check your timing and ignition system and get a real tune and you should be good to go.

here we go again with this. you CANNOT put a V8 distributor in one tooth off. or ten teeth off.

you bring #1 to TDC. where ever the rotor points is where you put the #1 wire. then out the rest in accordingly. your timing may be off. check with a timing light with the EST unplugged.

Thank you everyone for your responses. I checked my timing by bringing #1 piston to TDC then dropping in the distributor and setting #1 spark plug to where the rotor was. I also checked the timing with the EST unplugged and set to 6* BTDC (manufacture setting).

Lemme throw in another thing I noticed. When the car idles, it doesnt have a really "noticeable" lope at idle, it has more of a continous deep noise almost like a subwoofer would with non-stop bass.

Ill have you all know the stock springs are still in. I have no idea if this could be the cause of it...? But I have new springs waiting to go in as soon as I can tackle the problem.

I just got through with some custom tuning to get the BLM's as close to 128 as I could, the closest I got was BLM 126 and INT 124. The car idled smoothly as if there were the stock cam still in.

I keep bringing up idle quality because I know this is a fairly big cam, let alone for a LB9 and for it to be idling smoothly, just doesnt seem right.

Jeff

Why not?

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It's a 350, but there is a fella at the track I go to that has a LT4 HC in his car. Sounds reasonably stock to me.

I wouldn't drive that car hard without proper valve springs in it.

because its just a bad terminology for not setting up the distrib and checking timing

Well, not trying to argue, or hijack the thread...and maybe I don't know the proper terminology...but my car would run "a tooth off". Just pulled it out, turned it a bit, slid it back in...just right. IIRC "a tooth off" it was 40+ initial timing.

Ummm, am I the only person reading that and thinking holy sh1t? You're in for a world of hurt if you continue to run stock LB9 springs with the HOT cam.

Tim

Wait, your running stock springs on a .525 lift cam?!?! The lift is too high, and the ramp rates too agressive. Theres your problem right there man. CHANGE THOSE SPRINGS! You should consider yourself lucky that one of them hasnt shattered yet. Also, did you check for valve guide clearance? .525 lift is REALLY pushing it on stock un-machined heads. Most say NOT to go over .480, ESPECIALLY with stock pressed in studs.

DO NOT, I REPEAT, DO NOT RUN THAT MOTOR ANY MORE, OR YOU WILL DO SOME SERIOUS DAMAGE.

well all you had to do was turn the distributor until you got the proper initial timing. you didn't have to pull it out and turn the shaft one tooth. but then again you probably couldn't because the wires wouldn't let you turn it that far. amazing how my car can run and get proper initial timing with the rotor pointed at the left tire and not the #1 plug.

I just got through installing the new valve springs. Started up the car and still sounds the same... Here is a sound clip of another 3rd gen but with an LT1 -

http://www.fierolt1.com/mm/hot_hotcam.wav

Thats how my engine sounded and ran before I needed to remove my intake the first time. Like I mentioned earlier, my engine currently runs a lot smoother and has an almost slight lope when in park.

I am double checking and even triple checking timing, seals (vacuum leaks), sensors. Just to let everyone know, the engine hasnt seen above 3,000RPM since the cam swap.

Oh BTW, Im running 1.5 rocker arms so the total valve lift is .492 - .525 is with 1.6

Jeff

That sounds DAMN good

I was under the impression that the higher the LSA is, the better quality idle you will have. Maybe the ton of lope you had at first was from a vacuum leak.

How does the car run?

I did some very minimal prom tuning so far and the car runs good I guess (no stalling, sputtering, hiccups, sneezing...), altough it uses a lot of gas. I did some logging and the BLM's come out to some outragous number, IIRC BLM=146 and INT=131

Maybe your correct OneBinky about all the lope I experienced may have been caused from a vacuum leak, oh well. But Im still stuck with this dilemma of that continuous deep noise when idling in gear.

Maybe Ill take a quick recording of what I am trying to explain tomorrow as soon as I find a microphone.

Jeff

Anytime you change the flow in your car, it changes the needed calibration of the chip. If you had the intake in a machine shop, was it for porting????? When I pocket ported the heads and added larger valves on my heads it changed a lot of things....

With my stock 85 computer and chip I gained a thousand rpm of power on the top end. With my 89 computer and custom chip, I gained 1000 rpm of power on the low end (and some on top as well). So any changes you make will affect things. If the car idles like a stocker, that just means that you did something right. If it is making noise, that just means the exhaust pulses are resonating a little differently with your cam timing.

Another thought. Try kicking your timing up to around 16* initial advance. My ZZ4 really likes 16*. I would hate to try it at 6* timing and you have more cam than I do.... I can surely understand it if you don't have any power.

this cam stock 1.5 rockers and stock springs no big deal,been done many times............now as for the sound,lope etc when i installed this cam on many occasions the motor will lope and sound radical while the ecm tries its best to understand what the hell just happened and will clean up as best as it can that is when you will have to go the step further and program the changes the only model to accept the cam swap is a mass-air car and it will still require prom tuning to get the most of your newly installed cam and mods..............

I am also running the hot cam in my 305. I have the same problem as you. And I've been talking with tpis about the car and explained to me that the hc is too big of a cam for the 305. If you just look at the specs thjey look fine: 218, 228 duration at .050 and .492 lift w 1.5 but if you look at the duration at say .200 lift it is crazy i don't recall off hand what it is but compared to say an lpe 211 or eve a zz9 this cam is a lot more radical. When i get home tonight I will get the specs for the hot cam and post them tomorrow. i will also try to get the specs for one of other cams. The little 305 just can't pull enough air to make this cam work.

Thank you very much everyone for your input. Good news, I got more into depth with custom tuning the prom and the engine is starting to pull together. Theres still some fine tuning that needs to be done, but as of now Im happy with how its running.

I managed to find a microphone, so later on today Ill record how it sounds.

chikn305, your combo is almost exactly the same thing that Im running, minus heads and TC. How much stall are you experiencing with the S10 TC?

Jeff

Did you have the tubes off? Did you mark them and get them back on in the same place?

It is very easy to get the LH and RH intake tubes mixed up, doing plenum service, whatever, they look identical but can be easily replaced backwards, leaving a gaping vacuum leak. This happened a few years ago to someone on the board.

Kind of a PITA to check, but it could explain what happened.

Good luck!

{chikn305, your combo is almost exactly the same thing that Im running, minus heads and TC. How much stall are you experiencing with the S10 TC? }

The tc stalls around 2000 it's not quite enough. I think a 24-2500 would work perfect