CAMARO82

82 Camaro Z28
I have a Z28 Camaro with a 350 engine, I just put in a new comp racing cam with a lift of 470, and a Holley 670 Street Avenger Carb. I ran my car before adding my mods and got a 16.1, but yesterday I ran it with my mods and got a 20.0, not once but twice. Could it be in my carb adjustments or linkage somehow,, It seemed my car bogged down big time at bottem end, and even at top end... My MPH was only 68 Im so Mad right now, I know my car is at least a low 15 now and im slowly gonna bring my times down with money and time. ANY SUGGESTIONS???
Greg

Flash84Z28

What other mods do you have? Those street avengers are supposed to be ready to go out of the box. Is your timing way off? Did you hook up a vacume advance? Did the car stumble and shutter (like it was going to die) or did it just bog? Is your kickdown cable hooked up?

Damn a 20.0!? Somethings messed up...

-Matt

CAMARO82

I have comp lifters, flowtech headers, a holley pollished intake, Im not sure whats all in the car but It should be running better. When we put the cam in we advanced the cam a couple of degree's, but that should improve it. Is the Transimission Kickdown supposed to have a little screw and nut on the rail that it slides on because my old carb did and this new one doesn't.... IM SO SO FRUSTRATED!!

Greg

CAMARO82

ANYONE????? SOMETHING IS WORNG... Any Suggestion is Greatly apreciated

Stroked-Z

Alright Camaro82 obviously something is wrong here.

Make sure all your rockers are adjusted properly. if you have a vacuum guage then i suggest you connect it. It will tell you what type of adjustments you are going to need. The carb should be ready out of the box but most arent although the Street Avengers will perform much better than your standard "out of the box" carb. You timing is also an issue. How many degrees did you advance the timing when you installed the cam.

Also check your initial & total timing as well as the springs/weights in your distributor.

We need more details as in what is going on. Is it pulling of the line hard then slowing down or vice versa. Is it popping through the intake or sputtering out the exhaust ect....

Give us more details on what is different now. Also what RPM are you shifting your car at.

Jester

I am going to move this, simply because I seriously doubt the problem is related to the carb. You'll get more help on the general board.

After so many changes at once, the problem could be alot of things. My first guess would probably be that you screwed up when advancing the cam, and now the cam timing is off. How did you advance it exactly, and how much? Also, check the basic things like the timing curve and that the valves are adjusted right. Make sure there are no vacuum leaks. Basically go back over what you did..and try to find the problem.


would probably also help if you were more specific on exactly how it's running. does it miss? does it bog? does it run fine except being way down on power?

CAMARO82

Well it runs fine but it just doesn't seem to have the power it should on bottem end, It really boggs I guess, I shift at around 4500 RPM (redline) I know I have an exaust leak by my collector but thats not it, It just plain Hops of the line then Bogs down.... IM SO CONFUSED

grumpygreaseape

run a quickie compression check on a couplefew cylinders and post the #'s

zippy

why are you shifting at 4500rpm? what is your timing at all the way through? how much initial and how much total advance?

Mark A Shields

Were 82 Camaros CC. If so, did you go with a vacuum advance distributor?

CAMARO82

I said around 4500, Thats redline on my car

Mark A Shields

4500, sure that's not the yellow line on the tach? Sounds awful low. Course it is your car guess you would know.

zippy

well, an 82 camaro didn't come with a 350 either though so that shouldn't apply to your engine anyway. more or less the point, 4500 rpm, isn't enough with that cam. your going to have to rev it to around 5500 to get enough out of it to make it worth your time.

CAMARO82

And then going down the track I was shifting from second to third and it wouldn't shift I had to let off the gas for it to shift. SO I was pretty much in second cause my it wouldn't shift all the way down the track

Mark A Shields

I would check to make sure your TV cable is adjusted properly and at the correct geometry.

CAMARO82

Yeah I will check that soon, Whats everyone elses redline??

No4NJunk

Camaro82,
You have about the same mods I do (with the exception of a few things) and I am running very low 9s in the 1/8 (low 14s in 1/4). And thats with tire spin. You should also be shifting around 5500rpm not 4500. That cam makes power up to about 5000 (plus or minus a few hundred depending on application) and so you should shift 400 above peak.

CAMARO82

I don't want to blow my engine, so how can I make sure my redline isn't 4500??

grumpygreaseape

yo-if the cam isnt centerlined properly you can rev it to 20,000 and it still wont build cylinder pressure where you use it. ck. compression on a couple

bubafett

We are trying to answer your questions, but you will not answer ours.

Where is the ignition timing set? Initial and total advance.

The car will not be running "fine" if it is running 20s at 68mph.

Did you break the cam in properly or is a lobe wiped?

Why did you advance your cam? These cams dont require any degreeing and recommended installed strait up by comp cams.

It sound to me like you dont have any cylinder pressure.

1. Back off the adjusting nuts on the rocker arms and reset the valves. I dont think they are sealing ie. closing on all cylinders

When the ext starts to open set the inlake to zero lash + 1/2 turn.

When the Intake opens and is almost all the way back down set the exaust the same way.

2.Reset the ignition timing. Try a total advance of 36 for starters.

3.The transmission is not hooked up to the proper vacume port. You may have the spark and port vacume reversed.

4.Your redline is when the engine stops making power. That is when to shift. You wont blow this motor up at 4500. Try 6000.

grumpygreaseape

exactly the direction i was attempting to steer this. get a handle on the most logical thing first. seems that we are trying to fix all parts around the most probable one, the one that started this problem-it begins with cam and ends with shaft. criminy we are even dissecting the driving and shifting habits of the operator. gimme a compression reading off a couple holes so we can take the next step-before you rebuild the trans, hire a driver and double check to see if maybe the clocks have all sped up.

RB83L69

So what cam is it really? What heads do you have on it? What gears? What converter?

A showroom stock motor has a higher "redline" than 4500 RPM. That doesn't mean that you should be spinning it higher, only that the motor should be capable of it. There's no risk of grenading the motor at 5000 or 5500 if it's built right, even if it's with all stock bottom end parts.

Unless you know exactly what you're doing, you should select a cam that's right for the rest of your combo, and install it straight up.

I have to agree with the other post; it sounds like your cam is the root of your problem. Car runs OK, you make a change, it goes slower, = you made the wrong change. I doubt the carb is your problem unless it's totally FUBAR.

CAMARO82

Well I took it to my friend, and he said it could be in the tranny.. Thats all I know now, Im taking it to a tranny place manana

CAMARO82

The cam is the right cam for my engine, The cam was installed correctly, My car was doing great with My Holley 600, But when I installed my 670 it seemed to mess up... Does a 350 tranny have a vacum advance, even if it used to be computer controlled?????

91L98Z28

Dude, not trying to flame you here, but...

these people are trying to help you, and they are asking GOOD questions! they can't help you without the answers to these questions.

First, a lesson in redline. The "redline" painted on your tach is only applicable to the STOCK motor in STOCK configuration. your 82 z28 came with a very anemic, "dark ages of smog" 305. The motor probably had no power at 4500 anyways. Now, let's say you go and buy a GM ZZ4 crate motor and drop it in your car. Is the redline still 4500? NO! If you shifted a ZZ4 at 4500, you'd be throwing away the best 1000rpm it has to offer! Redline on a modified motor is determined by the quality of the motor build, the cam specs, compression, intake/exhaust/head combo, it all matters BIG TIME.

Second, the "right" cam. Sure, there a lot of "right" cams for your engine. A comp 305H series cam is the "right" cam. It will slide into the block, a stock timing gear will bolt to it, and it will fit right in. A comp 240H series cam is also the "right" cam. It too will slide into the block, bolt to your timing gear, and what not. The difference? One cam has so little duration that your motor could idle at 400rpm and run smoother than your great grandma's cadillac, the other has so much duration it will idle at 2000rpm and not even run good below 4000rpm. OH yeah, and they'd both suck for a street driven camaro! You NEED to tell us what cam you have. a MODEL NUMBER.

Third, the cam being installed "correctly". Sure, the timing gears are on there, and so is the chain, by golly! It even spins and runs. But wait, you said you advanced the cam. How much is correct? Did you degree it? Did you just advance it one tooth on the timing gear? what did you do? If you don't know, and you can't tell us, then we don't know, and if nobdy knows what's going on inside your engine, then nobody knows how to fix it.

Fourth, timing. We need to know how much initial timing you have (unplug your distirbutor vacuum advance, hook up a timing light, start the car and let it idle, and read the timing marks on the harmonic balance). We also need to know your total timing (with the vacuum advance still unplugged, rev the motor to 4000rpm and read the timing. You DO have a dial-back timing light, or a timing tape on the balancer, yes?) If your timing is way retarded or you never set it after installing the cam, for all you know you could be 20-30 degrees retarded, in which case your motor will run lame!

Fifth, cam break in. you DID break the cam in, right? The instant you start the car with the new cam, you have to take it to at least 2000rpm, and KEEP it there, for 20 minutes. Why? The cam and lifters need to establish a wear pattern, and this process needs splash oiling from the rest of the reciprocating assembly, hence 2000rpm minimum requirement. If you didn't do this, you might as well just start taking it all back apart and buy yourself a new cam.

If you don't know the answers to the above questions, or don't know how to find those answers, then my suggestion to you is to find someone in your area who has some experience with this stuff, and ask for help. Tell them you are new, you got this stuff and you don't know whats wrong, and you want to know if they will help, and then LISTEN to what they share...and learn! Whether that be a local machine shop/race shop, or racers at the drag strip (find someone who friendly and has a reliable 13 or 14 second car to prove they know what they are doing). You may also want to pick up some books and educate yourself (lingenfelter, smokey yunick, and others all have books on small block chevies that are VERy educational). Bottom line is if you are only doing 20 flat, then something is either very very wrong, or very very mismatched. My 4 cylinder 98hp 2.5 fiero can manage a high 17 at 75mph!!

Good luck dude, let us know if you can answer the questions and we can be of more help!!

firerider76

Well I can say this from experience.If the cam is a good aftermarket cam,don't advance it unless you want to spin the motor up high to make any noticeable power.I was running a 350 bored over .030. A good bottom end,edelbrock performer rpm intake,accel b.p. dist.,crane roller tip rockers,and a comp. cams 270cam(.480 lift on both sides),world products heads with 2.02,1.60 SS valves.And I topped it off with a 750cfm Carter Comp. carb. My downfall was that I advanced the cam 4 deg. on the timing chain during the build( cuz I was told it would make better low end torque).Much to my dismay it wasn't that strong on the bottom end but if I revved it to 6500 rpm it ran like a bat of hell.I believe you need to retard the cam back to straight up and your prob. will be gone.At least thats what I did.

91L98Z28

By the way, according to the online calculators (http://users.erols.com/srweiss/) you are probably only making 90-95HP. If the only thing you had wrong was the cam was a few degrees off in either direction, or the timing was only a few degrees off, or one cylinder was dead, you woudln't be that low on power, thats why we are asking all these questions either there is a ton of little things that are off moderately, or one or two things which are hugely off, like cam timing way off, or ignition timing way off.. you won't find some little fix that solves the problem, well unless the fuel filter is clogged or a metal fuel line is kinked/crushed at the carb or some silly problem like that...

good luck

bubafett

If the car ran fine with the old carb.

THEN PUT IT BACK ON.

But you said, the cam, intake, and carb were changed. Now you have trans "problems".

I have improved my car from a 12.70 to a 11.95, by ignition, valve adjustment, and carb adjustment. No parts changes.

There is room for improvement in everything.

The first thing I did was ask what could be wrong? And then listened to what was said.

Do you want to improve your situation?

I think not.

jdrobley

i still have not seen the reply as to the size of cam it is (duration at .050''. generally the engine will run best if you install the cam straight up. if you can get more power by advancing it, they you bought too small a cam. if you se more power with it retarded, then it is too big. by advancing the cam, you could be running into problems of cylinder blead off in which you are loosing power because the valves are opening too early and either releasing pressure before the end of your power stroke or the intake is opening and exhaust is clowing too early and you are pushing a little exhaust up your intake. you do say that it is a comp cam. these guys make some pretty good cams and you may have picked one that is either too big for your engine or just right as is. i would recomend that you put the cam in straight as it should be or get the correct cam for your car. i think it would run much better.

jess

let us know the cam stats and we can help you better.

BMmonteSS

I know you all are trying to help this kid out but I have a buddy with about the same problem. She (yes a girl gear head) just a built a 350 for her monte. It has
.040 over
domes
76 cc duble hump heads
brings compresion out to 9.5
214 dur .454 lift
stock intake
full length headers
holley 750
new turbo 350 tranny
3.42 gears
the problem is that it is just lame. It ony pumps up to about 130 psi on all cylinders. She got a g-tech recently and has recorded a best of 7.2 0-60.
I have a monte with almost an identical motor it pumps up to 170 psi and runs a traction limited 5.8 0-60. Her BF built the motor so i'm not positive he installed the cam right but it seems to me that its acting like its way advanced. We already checked the valves to make sure they weren't adjusted wrong. Just wanted to see what the resident gear heads have to say, keep up the good work
:rockon:

grumpygreaseape

here, a new taker of our helpful nature, who sent you? some kind of messageboard fairy? was it because you would offer the hope that some of the effort provided by the good people of this board would actually be of use and would make the time spent by all involved not seem so um, like, ummmm, whats the proper vernacular, oh, wasted? and to put this into perspective for our perpetually slow diagnostician- people who are genuinely interested in helping a complete stranger are a rare find these days. methinks anyhow. so now its you up to the plate, ready? 130 across the board? dry i assume? whats the #'s look like with a couple squirts of oil in the hole? these hens teeth double hump heads with 76 cc chambers, must be very rare indeed.what is the casting #? what side is either the alternator or a/c compressor on? nuff for now. take this and run with it my son-do us proud? seeya :hail:

Zepher

iTrader: (1)

Camaro82, you should really listen to the people on this board, the wealth of knowledge here is unprecedented.

I did a carb to TPI swap on my 86 Trans Am recently, actually got it running a month ago. Did a cam swap as well.

I don't think that I could have done this swap without the help of the people on this board.

So try and answer all of thier qestions to the best of your ability and I guarantee that they will solve your problem.

Thanks again guys,

Zepher

BMmonteSS

I'm not sure what the casting numbers are on the head but they are off a vett form the 70's they have 2.02 1.6 valves and were freshly rebuilt. I'm really wounderig how much cam timing effects cylinder pressure.

RB83L69

Cam timing dramatically affects cyl pressure.

That 268 cam should run OK in that 350 combo; that is what that series of cames was originally designed for. In the late 70s and early 80s, everybody and both their brothers was taking those crap smog heads (those are NOT "double-hump" heads) and sticking domed pistons under them to "bump up the compression". Nobody seemed to realize that this impaired flame travel so much that the motors would actualy have run better with flat-tops. The HE cams were set up to make the best use of this strange situation, and worked fairly well. It was a bit much for a stock converter and the 2.43 and 2.73 gears that were tyical in those days, but with a reasonable gear and a stick or a converter, it made a strong runner.

I recall seeing 165 psi readings typically on motors like that when I worked on them; 130 is definitely too low. I doubt it's a ring problem, since in order to bleed off that much compression, there would be so much blowby that the dipstick and PCV valve would constantly be getting blown out of the motor.

Vattes in the 70s mostly had the identical same heads as Impalas or vans or anything else. There's no point in romantically putting the magic "V" word in front of casting descriptions, especially on a Camaro / Firebird BBS; no fairy dust sprinkled itself off the body onto the castings and imbued them with mystical properties. An 882 casting is an 882 casting, no matter what shape of sheet metal (or fiberglass) it came wrapped in from the factory. And of course, anybody can jam large valves into almost any heads, but by itself, it doesn't affect the flow very much unless the ports are opened up - and can actually make the car go slower if it stays pinned into a low RPM range by gears and converter.

Anyway, installing a cam advanced usually improves low-end torque and raises compression test readings; retarding one reduces low-end torque and moves the power band up a few hundred RPM. The earlier comments about this farther up in the post are backwards.

So, I suspect that the BF has the cam retarded one tooth.

The original poster still needs to tell us what his motor is built out of; without those details, it's impossible for any of us to diagnose a motor we've never seen.

jdrobley

thanks for the correction,
jess

BMmonteSS

We knew the domes would mess the flame travel up when we planned out the motor but we did it anyway because those heads are what we had at the time. It sounds like the cam is off a tooth to me too. the specs on the cam are as followed
@.05 lift 214 dur
.450 lift
110 lobe sep
It just a 350 poked .040 over
this thing should run better than it does, is there anything else funky that could effect the cranking compression other than a leak some where