Engine Problems HELP!

[80vette_ca]

I finally got my 1980 out and it was working good until I stopped at a red light. Well the light turned green and I punched it. All the car did was go a bit and then it lost power and I heard the exhuast go kind of like a poping noise only a deep pop. So I let off and then got on it agan only not as hard and it worked fine. Another problem for you guys, I made a right hand corner and around 45-50km/h and the engine died on me. I have no idea what happened, but I remember it happening to me one other time when I made a sharp U-Turn. I begging you guys for some help on these problems because I just want to enjoy my baby this summer instead of having it in the shop like last year. My engine is nowhere near stock incase you are wondering and I had the carb rebuilt last year. Please help me.

 

[Chick]

I'd look at the float level in the carburetor.

 

[SLICKMAN]

I agree with Chick, it sounds like the float is set to low..

 

[Stallion]

"All the car did was go a bit and then it lost power and I heard the exhuast go kind of like a poping noise only a deep pop."

Maybe it backfired?

 

[vets4-2]

My friend has the same problem. But he's in Iraq right now, But I'm sure when he get's back he'd be GLAD to go up and help you!

 

[80vette_ca]

Hey guys thanks a lot for the advice on the float I will have to check that. As for it backfiring I know it wasn't that because It did that to me earlier in the day. Any ideas on why it backfired, I'm not exactly the pro when it comes to the day to day operations of a car.

 

[AKRAY4PLAY]

carburation is the problem, if the floats are low like Chick has pointed out, when making a corner the fuel sloshes to one side of the float bowl and the main jets don't get any fuel. this creates an instant lean air/fuel mixture that won't sustain combustion, and the engine dies. you may also have poor accelorator pump(s), this will also cause the engine to stumble under quick throttle changes. what kind of carb do you have and what are the mods to your motor?? we can help you farther with the added info. best of luck getting it right, Brian

 

[Stallion]

It might have backfired because your ignition timing might be off? What kind of distributor do you have? Mechanical?

 

[80vette_ca]

Here's the specs on my engine, I think this is everything. To the best of my knowledge the distributor is the original HEI. Would a new MSD ignition make a big difference or should I just stick to what I have?

350 CID BORED AND STROKE INDEXED TO 357 CID
SPEED PRO HYPEREUTECTIC PISTONS
PLASMA MOLY PISTON RINGS
CRANE PERFORMANCE CAMSHAFT
(454 LIFT, 248 DURATION INTAKE, 244 DURATION EXHAUST)
EDELBROCK PERFORMER INTAKE
625 CARTER SUPERSERIES CARBURETOR
ADVANCE CURVE KIT IN DISTRIBUTOR
MELLING HIGH VOLUME OIL PUMP
SEALED POWER 1.5 RATION ROCKER ARMS
1.94 1.88 INTAKE AND EXHAUST STAINLESS STEEL VALVES
PORT MATCHED HEAD TO INTAKE AND EXHAUST
K&N HIGH FLOW AIR FILTER

 

[SLICKMAN]

If your getting a backfire as well, you need to check and make sure the firing order is correct. I have seen some l98's be off were two wires were in the wrong spot and still run like almost normal. The firing order is 1-8-4-3-6-5-7-2

 

[JohnZ]

Sounds carb-related to me; check accelerator pump function and float level.

 

[Stallion]

If your getting a backfire as well, you need to check and make sure the firing order is correct. I have seen some l98's be off were two wires were in the wrong spot and still run like almost normal. The firing order is 1-8-4-3-6-5-7-2

How do you check your ignition firing order? Just curious.

 

[AKRAY4PLAY]

80,
i am 99% sure the carb is the culprit. if you have the original Q-jet, try throwing it on and see what happens. if not, try and get the carb guy to fix it, or better yet get an Edelbrock tuning kit with manual and do it yourself. the good thing about the Carter carbs is they are very easy to tune. you may also want to get a vaccum guage an check that you don't have a vac leak. vac leaks lower the pulse signal to the carb and make the motor run very erratic at lower rpm and on takeoff. if you have a vac problem, the guage will be bouncing all over the place, if not it should be steady around 14-16 inches with your cam. Brian

 

[80vette_ca]

Hey guys thanks a lot for all of the advice. I don't know what I'd do without the knowledgable people on this form, not to mention people that are willing to help out a guy in trouble. I will talk to my mechanic about checking the float level and I'll check the firing order as soon as I can. Quick question. I used my desktop dyno and it said that I was runing around 450hp and about the same in torque. Does this sound about right to you guys?

 

[AKRAY4PLAY]

80,
sorry, but i think the 450 figure is a little generous. cams are measured two ways, total duration and duration at .050" lift. your cam card should list both figures. you may have entered an incorrect cam profile in the program and it threw your numbers off. if the heads you have are iron and the cam is 244* total duration then i would ballpark your motor to be in the 300-350hp and around 330ft/lbs. double checking your build and getting an accurate hp figure will enable you to better dial in the carb. most tuning books will give a close range of jets to use for a certain power figure, helps cut the guess work out. Brian

 

[80vette_ca]

Personally I like the 450hp figure better. Either number is still enough to blow the decals right off an import. Humm, maybe I should get me some of those decals, especially the Type R ones. I hear they add 50hp. Future plans for the car include a higher lift cam, bigger carb (850-950cfm sounds good) change out the heads, bore the sucker out all the way, put some titanium pistons and rods in, and add a little bit of juice and deffinitly a bigger speedo, the 140km/h just isn't cutting it anymore.

 

[AKRAY4PLAY]

you can always get one of those top fuel dragster rear wings and create more down force than a falling M1 tank. those idiots must all have problems with their trunks staying closed. good news is there are at least 10,000 ways to performance build a small block. you might want to think about the amount of power and where you want it in the rpm range. most street cars and especially heavy ones need a lot of torque to turn quick ET's. by boring your existing block and installing light weight rotating assembly parts, you get more into high rpm engines and they perform more like rice burners, just better. bigger displacement, but mainly increasing stroke give you much better torque. you may be better off building a stroker, they are generally be less expensive than rev motors and most of the time out perform them. do some searching in this forum and you will find tons of info on building big power engines. as for your carb, i think you should stay in the 650 to 750max range. over-carbing will give you serious drivability issues. i am making 600hp with my 406 and only running a 750cfm Barry Grant carb. let us know what your dreams are and i think we can give you more options than you know what to do with. now the fun begins!!!! Brian