asdfg68plus1

Hey, I just got my firebird, but when I have it on, the engine always wants to cut off and you have to rev it a little. The previous owner said it was because since it has open headers, the back pressure makes the engine want to cut off and that once I put an exhaust on it, that will go away. Was this true?? if not, what is the solution to this??

Thanks,
Peter

Sparkytfl

That's BS. But we need to know a lot more about the engine to know what the problem really is. Year, how much of the engine is stock, what parts have been changed, carb or FI...

asdfg68plus1

The engine is a carbed 350 that was rebuilt about 5 miles ago. The pistons, cams, and heads are from an 88 Corvette, it has hydraulic lifters, and summit headers. The carb is a Rochester off of a late 80s truck. I have no idea the year or model of the engine, but I can check tomorrow when it is light outside. The engine is not the stock engine for the car, as the original v6 was swapped out for the 350.

Sparkytfl

Aluminum 113s? Not bad.

Wouldnt a late 80s quadrajet be the computer controlled kind? If so you'd better have the appropriate computer in there now along with a cc distributor and its sensors. If it's a non-computer quadrajet, well make sure its tuned right and that it's a vac-advance distributor properly set up. And with a carb conversion, make sure the fuel pump was done correctly so you're getting enough fuel and at the proper psi for a carb.

You're probably better off reposting in the carb sub-forum. The chance of this being related to your headers is very low. Some people do say that without a full exhaust, your valves cool too fast when you shut the engine off and can warp ruining your compression, but the backpressure thing is bogus.

regal301

you can't tune the carb with no exhaust sorry

put a freakin exhaust on the car then set the timing and idle,then go from there.

the trucks didnt get the ccc b.s. as early as the cars

regal301

ah....... the "corvette parts" line from the seller,thats normaly how the story of how someone who just got screwed starts.......

88 vette has a roller cam,not hydraulic.
late 80's trucks......carb?.... 87 up were tbi.
you better take some pictures and get some casting numbers to see what you REALLY have.

87350IROC

iTrader: (2)

Actually all '87 up SBC's have hydraulic roller cams.

asdfg68plus1

Thanks guys, I'll have a look tomorrow and see what information I can find for you. Is there any way to tell what the cams and heads are without opening up the engine?

regal301

NO........... 87+ f-body and caprice/roadblaster got roller cams,trucks did NOT get roller cams till 96+ (vortec)

87350IROC

iTrader: (2)

...double post...

87350IROC

iTrader: (2)

Great. You claimed they weren't hydraulic. Which is false. The factory rollers are hydraulic.

regal301

figure out if the heads are cast iron or aluminum,and if they are what the seller claims they should have 4 bolts down the center holding the valve covers on.(centerbolt)

88 vette heads are aluminum and have centerbolt valve covers.

87350IROC

iTrader: (2)

The L98 iron heads along with all '87+ F-body iron heads have centerbolt valve covers. A better test would be to see if the heads are magnetic.

regal301

they are referred to as roller or hydraulic flat tappet...... are you an *** or somthing? like there would be a solid lifter in a 80's or 90's sbc.

regal301

READ WHAT YOU POSTED.............

mmadden55

anyway it sounds like a carb problem probably need to adjust the idle.

87350IROC

iTrader: (2)

No, I just don't want you spreading false information to this poor guy.

All of the following are valid descriptions:
Hydraulic flat tappet
Solid flat tappet
Hydraulic roller
Solid roller

You specifically said "not hydraulic". That is straight false.

regal301

see if the heads are aluminum, look for the centerbolt valve covers,and if you have iron heads you will have to pull one cover and get the casting number.

asdfg68plus1

Well, I went to go try to, unsuccessfully, find the numbers and such, but it's dark, so it'll have to wait as I couldn't see anything, but I did notice that the valve covers were centerbolts, but nothing other than that. I just looked a vin decoder and the original engine turns out to be a 305, not a v6. The car also came with extra 305 heads that need to be rebuilt, and the guy said that when rebuilt, they would raise the compression ratio of the engine and boost the power over the heads currently on it.

mmadden55

If you have a magnet and it sticks to the heads they are iron. Also there are no solid roller or solid lifter cams stock in a third gen. It is either a flat tappet cam Hyd, or a Hyd roller. The injected cars came with the hyd roller cams for the most part.

regal301

you have issues pal........

we are talking about an 87 up motor,there are NO solid lifters relavent to this conversation,the choices are roller(and the hydraulic part goes without saying)and hydraulic flat tappet.

then you blurt out the garbage that all 87+ are hyd. roller cams which is bullshit.

then i told the op to check if the heads are aluminum,and you say lets see if they are magnetic, i think we all learned it 1st grade how to tell iron from aluminum...........

regal301

verify they are 305 heads then throw them out.305 heads some times have smaller chambers and can raise compression but the also have smaller valves,and if they need work........forget it.
go throw them back through the sellers front window of his house.lol

87350IROC

iTrader: (2)

Yet, you suggested the best way to find out is to see if they are centerbolts. The OP never once said the motor was '87 and up. Supposedly the heads, cam, and lifters are '87+, but who knows.

asdfg68plus1,

Put a magnet to them. That is the easiest way to tell if they are AL.

Also, it would be useful to grab the block casting number. I believe it should be behind the drivers side head. You may need a mirror to see it.

89rs454

Better yet go dump the whole engine off on the sellers door step and get a ltx ls1. First rule of thumb is to never trust what a seller has to say if the engine is not stock, there 80% of the time lying if there trying to boost the motors specs! There's that 20% that really have nothing to hide and will be honest. IMO

87350IROC

iTrader: (2)

Agreed. This motor sounds like a real mess.

asdfg68plus1

I'm just glad that the engine runs, and the seller gave me receipts of a lot of parts that have been replaced in the engine recently, which is a little comforting, but tomorrow, I will try to find everything out for you guys so that I can get this running well and some good ol' American muscle!

89rs454

Well that's good, with out being there it's hard to say but i would look at the carb and fuel first, then go from there. good luck man.

asdfg68plus1

Thanks, I'm sure having an exhaust would help the process a bit since I'd actually be able to hear things and go from there. The exhaust pipes are sitting in the back, and I got a v6 y pipe and a v8 y pipe, then the rest of the exhaust. I really hope it isn't really restrictive, but from what I've read, the chances of that are slim...

asdfg68plus1

So I went and looked at the engine, and since it is no longer exhaust related, I'll go start a thread in the Engine forum to see who can help! Thanks for all your guys' help!
Peter

Sparkytfl

It should be obvious just looking at the heads if they're aluminum, most people dont paint aluminum heads. Heres what real 88 vette heads look like, http://s278.photobucket.com/albums/k...8vette-102.jpg If your oil fill hole is on the front of the passenger side or back of the driver side cover you'll be able to see the number without pulling the cover.

88 vette 113 heads have 58cc chambers, so (if you really have 113s) putting 305 heads wouldnt give you more compression, just lower your flow.

asdfg68plus1

The heads were magnetic, so they definitely aren't aluminum, which is a little disappointing... I did find out the engine is actually a 350, though, so that's good at least... I'm just going to assume the pistons aren't Corvette pistons, and I wouldn't be checking anyway because I won't be tearing into the engine quite yet...

Sparkytfl

How did you determine that much is even true? You checked the block number behind the driver side head right?

Now you need to pull a valve cover off. Tell us the casting number of the heads (hope they're not 882s or anything). See if your valve seals were even replaced. Try to look down one of the pushrod holes at the lifters and see if you have a hydraulic roller or hydraulic flat tappet cam (and hope the cam is even of the matching type). http://www.hotrodders.com/forum/atta...chmentid=25111 Look for the "spider" and "dog bones" that a roller would have.

Corvette pistons arent anything special, I dont think they were forged at the time. But either way, if this engine was rebuilt properly, in a way that will last, then the block would have been rebored and used corvette pistons couldnt have been used.

Chances are everything is so mismatched that you're going to have all the power of a modern 4banger with all the poor gas mileage and limited lifespan of a dying carbed 350.

I know lemon laws usually wont save you in a private sale, but a lot of times you do have some legal rights if the seller outright lies to you.

torque_is_good

you are thinking about disclosure however the selelr simply may not have been "aware" thus, not knowingly telling a lie.

Also, there is probably a no-warranty statement in the P+S

UnderCover89TBI

iTrader: (25)

sounds like you got taken around the block there buddy