TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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i got a 91 z28 305, and i just swapped a cam into it. i cant get the timing right! its f ing frustrating lol. i unplug that plug on the passenger side next to the strut tower then i time it, get it right, turn engine off, unplug battery, plug that plug back in, wait 30 sec, plug battery back up, then check timing and it is bouncing so much and runs like crap. runs crappy with that thing plugged in. i cant figure it out. please help me out.
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yes speed dens, part number is COMP Cams CL12-212-2 . im from camas Washington
From taking a look at the cam, it is .230/.230 duration @.050 and on a 110 LSA. You def need a tune with that much duration because of SD. With MAF it would have been more forgiving. The LSA will cause the idle to be choppy and lope, but the duration takes the cake for your problem. That is a massive cam for a 305, especially with TPI up top. The reason that the timing is going all over the place, is because the ecm is not tuned for the cam and does not know how much air is entering(vaccumm is down). This will cause (if I am not mistaken) it to hunt for an idle and go up and down in rpm, which will throw the timing out accordingly. Not to get your hopes down, but that cam has a very small window to operate and you will not be using it to its fullest. Because the curve starts late and it will end early due to the TPI not letting the motor breathe.
Someone let me know If I am wrong with this assumption, as I am a MAF guy and have not dealt with SD that much.
On the plus side, if you ever want to up the cubes of the motor then that cam will work great (350ci+) with an aftermarket intake.
__________________ '86 Camaro IROC
350 with Comp Cam .480/.495 lift 212/218 duration, Vortec heads, Edelbrock Vortec TPI baseplate and Runners, 700R4 with Shift kit Long Tube's with custom Y-pipe into 3" Flowmaster, and 3.27 Borg Warner gear with Disc. Runs 13.41 @ 102mph with 1.918 60' on a Street Tire.
i called a chip company and they told me that the duration at 050 was to much because of a vacuume issue? i went to tappet because i wanted more power cuz of money restrictions....should i go back to original cam and dont worry about it? or could i get shorter push rods? i have a manual trans.
Shorter push rods won't do anything for you except throw off you valve train geometery. Leave stock length push rods in it.
Didn't know you had a manual trans or I obviously wouldn't have said get a stall.
It's up to you about swapping the cam back. Roller cams generally make more power because of higher ramp rates and such also they are more computer friendly from what I understand. I personally wouldn't go to a flat tappet from a roller setup. Flat tappets are cheaper though.
What company did you call? Arizona TPI did a chip for my bro's wife's GTA it has a healthy cam and AFR heads in it and it runs flawlessly.
Agreed, that's a horrible cam for a near-stock 305 TBI motor. Surprising it runs at all with the stock tune.
If you're out of funds, put the previous cam back in. It's still considerably hotter than stock, but not the lumpy bastard your new one is.
Just to give you an idea how far you're gone from stock, the original LO3 cam is about 179/192 @ .050 (the "peanut" cam as we call it on this board). You added more than 50* OF .050 DURATION OVER STOCK!! That change is beyond big, beyong huge, it's enormous. And it's killing you in this case.
You have two options, use the cam that is in it and get the thing tuned, or put the other cam back in and leave it alone. Either way you are going to spend some time fixing it. Did you call comp cams and ask what they recommended for a cam? I have a cam that I used in my 305 and worked really well. It is a crane cam 114122 .204/.214 @.050 and .423/.446 lift on a 110LSA. If you are interested PM me. Cam has about 10k km on it. You may need to tune still but it will be alot easier than the one you have now, by a long shot.
i was looking at this one. comp 12-262-4. i called hot chips and he said this is the biggest cam he recomends for my car. can anyone confirm? if not then i will swap back
That cam is still pretty big for a fairly stock 305 setup, but it is better and still needs tuning.
Question, why do you want to go so big? Bigger is not always better when dealing with motor components when you drive the car on the street, or it is a daily driver.
it is a daiily driver yes. i was told by a few people on these fourms that that cam that i got first would do great then they said the cam that i just posted, the 12-262-4. so what is a good cam for my car then. i just want a bit more power and a lil more rev for a good price?
If you want a cam with a little more power, I have one and if you are interested PM me.
Stay within the 204-216 range for duration and no more than .470 lift (with stock heads) The LSA you want to stay 112-114, but the 110 will also be good, but may need to tune for idle.
A Good one would be 12-388-4. It is made for TPI motors, so it will work very nicely
If you are going to swap back go back to the roller setup. Get something with a 112-114 duration A split pattern high teens intake mid 20 exhaust something along those lines and you should be fine.
I ran the big Crane Compucam in an 88 I had 350TPI car. I don't remember the specs but I think it was like 218/226 on a 114. It ran great with absolutely no tuning. And I picked up a TON of power up top and didn't feel like I lost a thing on the bottom end.
If you are going to swap back go back to the roller setup. Get something with a 112-114 duration A split pattern high teens intake mid 20 exhaust something along those lines and you should be fine.
I ran the big Crane Compucam in an 88 I had 350TPI car. I don't remember the specs but I think it was like 218/226 on a 114. It ran great with absolutely no tuning. And I picked up a TON of power up top and didn't feel like I lost a thing on the bottom end.
He has a 305 not a 350.
__________________ '86 Camaro IROC
350 with Comp Cam .480/.495 lift 212/218 duration, Vortec heads, Edelbrock Vortec TPI baseplate and Runners, 700R4 with Shift kit Long Tube's with custom Y-pipe into 3" Flowmaster, and 3.27 Borg Warner gear with Disc. Runs 13.41 @ 102mph with 1.918 60' on a Street Tire.
Comp makes a 210/220 cam that is badass in the 305's
The cam would not work to well on the street though. Good for the hwy and the drags, but light to light you want something a little less, especially with a 305. That cam will start turning on to late. But....he does have a stick so it would be better than an auto w/o a stall.
. i cant figure it out. please help me out. 
90 TA pretty much stock 
