Performance Issues after complete Engine Rebuild

[Stuart522]

I just finished a 66 (or mechanic did at my expense) new 390 block, CAM, aluminum intake manifold, new 650 Carb, new upgraded ignition, new/rebuilt stock transmission. new headers, dual exhaust.
I drove it a little today, until the fumes from the new leaking gas tank or from engine i couldn't take it anymore? so i'm not sure what that is? i do have a gas tank leak at filler hose, but this seemed more engine exhaust/CO2.

but besides that it is terribly SLOW! I'm kinda sick about it, well all that invested, it should at least be able to outrun a scooter at the line, and it can't.
is it the transmission, 3 speed? rear end? I expected this thing to be responsive and feel the power, right now her nickname is "Molasses" It ran as if it was a beater that i could have bought for 5k and not put any money into it...

Any ideas? I just spent a lOT of money and although it looks good, it drives like my grandma's chrysler...

[redstangbob]

Welcome to the forum, post pics when you can. I moved your post into the modified section as your engine and components are no longer in stock form, and you should get better answers here. good luck, Bob C

[kzguns]

What position is the gear selector in? if you have a cruise-o-matic you should be in the second position then you will start from 1st gear. the 1st position from N will start you in 2nd gear.

[kzguns]

Also there is a doughnut gasket at the filler neck to tank area, also check the filler cap gasket

[Stuart522]

Thanks REdstangBob!

[Stuart522]

What position is the gear selector in? if you have a cruise-o-matic you should be in the second position then you will start from 1st gear. the 1st position from N will start you in 2nd gear.

Hi and thanks for answering.
at first i was in the overdrive, then moved it, it helps a little..but i was still getting beat off the line by old beaters in the ghetto. and scooters.

[Stuart522]

Also there is a doughnut gasket at the filler neck to tank area, also check the filler cap gasket

thanks, i think that's what it is, have mechanic checking it out. again no time and expertise for me to do it.

[Stuart522]

http://s1045.photobucket.com/user/Stuar ... slideshow/

[Stuart522]

Also there is a doughnut gasket at the filler neck to tank area, also check the filler cap gasket

So you think that is causing the fumes? definitely the gasket to trunk is not there and gasket at tank is where its leaking from. just wasn't sure if you were answering for gas leak or fumes or both?
hope its for fumes, cause that would be somewhat easy.
thanks!

[Stuart522]

My guess is the rear end perhaps? can hear it making noise, mechanic noticed as well, i don't know why he won't replace it, i've only asked like 5 times...and i almost think he told me he did at some point. (the problems with not being there to supervise people...that you pay money to do their jobs!)
mechanic thinks car is 'peppy'. i started laughing, then got in my escalade after driving the tbird and felt like i was in a porsche...

maybe i'll stick the 390 in a 66 mustang that needs everything....

[kzguns]

I've had a leak and fumes from the doughnut gasket at the fill tube/tank and fumes from the cap gasket. These cars arent sports cars. You shouls see what diff. ratio you have. I have had 3:70 and it was very spirited off the line but was screaming on the freeway. I now run 3:18 and its a great compromise.

[Stuart522]

Well to update. Have spent another $13,000 on this car.
runs great if i stay on beach road at 35mph. Took it on highway, started overheating.
Put gas in it, the whole inside of car smells like I spilled a 5 gallon gas jug in it. Just bought a CO Monitor, becuase it stills smells horrible in the car, i couldn't drive it with a normal person, with a female, they would be getting sick after 5 minutes, so what good is it,
Still Slow as molasses, New rear end, 3:50. (all i hear is it's a ''heavy car"), well buses are heavy and they're quicker than me?? so how did they manage that?
Runs like crap, misses, sounds like it's running on 5 cylinders.
mechanic tells me he closed up the air vents in the bottom of the car at rear,...well guess what, they aren't air vents, they are trunk drain tubes....

Are there any mechanics in the United States???? it really doesn't matter, bc if i spend another dime on this thing, i'm the idiot. well i'm already the idiot..

I've spent $35,000 on a piece of censored worth about 5k, i just want the CO (Carbon Monoxide) to take me, i can't take it anymore.
I guess i could trailer it around, push it off the trailer and stand next to it and get all the compliments, then when it's 1:00 am at night, i could push it back up on the trailer and drive home....

[Alan H. Tast]

The presence of a gas smell typically means something is leaking or allowing vapors to escape to atmosphere. There's not a whole lot to the fuel system to track down - it's very basic in its makeup.

1. Have you replaced ALL the rubber fuel lines, including the one behind the splash shield on the driver's side behind the front wheel, the rubber line from the sender to the hard line, and from the engine to the frame rail? If any of them are rotted out, you could be sucking air along with allowing fumes to enter the passenger compartment, leading to poor performance.
2. Did you replace the O-ring in the tank for the fuel filer tube?
3. Did you replace/regasket the gas cap? There's several threads in this Forum related to gas caps not sealing correctly and allowing gas/fumes to escape. Search for these discussions.
4. Did you remove the gas tank to check for leaks or clean it out? It may have pinhole leaks up high that is allowing gas fumes to collect in the trunk/passenger compartment and not letting any gas drip out onto the ground. If it's rusty inside, gunk suspended in the fuel could be getting past the filter in the tank on the fuel pickup and working its way up to the fuel pump, fuel filter and carburetor, resulting in poor performance.
5. Have you thoroughly checked the steel fuel line running from the tank to the engine bay? Is it dented, corroded or otherwise compromised? Again, if it has pinholes, it can suck in air and produce some of the issues you describe.

The above are all things you as an owner/novice mechanic can check, but this also means getting your hands dirty, getting under the car and spending time with it. Simply throwing new parts on an engine does not equal "problems solved" if the parts downstream from it are not in good condition.

[sseebart]

Well to update. Have spent another $13,000 on this car.
runs great if i stay on beach road at 35mph. Took it on highway, started overheating.
Put gas in it, the whole inside of car smells like I spilled a 5 gallon gas jug in it. Just bought a CO Monitor, becuase it stills smells horrible in the car, i couldn't drive it with a normal person, with a female, they would be getting sick after 5 minutes, so what good is it,
Still Slow as molasses, New rear end, 3:50. (all i hear is it's a ''heavy car"), well buses are heavy and they're quicker than me?? so how did they manage that?
Runs like crap, misses, sounds like it's running on 5 cylinders.

I'm not sure where you're located, but if there's another mechanic in town familiar with older cars, it's worth a second opinion. The sluggishness and overheating sounds like the timing is set incorrectly and/or other tuning issues.

I haven't built up an engine with speed parts since I was a kid (so, a long time ago . . .) but I remember that my high performance engines were very finicky. With an aftermarket cam, ignition, intake, etc, it's also possible you've got mismatched parts. If you can list the specs, others here may be able to offer advice on making it all work.

~Steve

[jtschug]

Also, a 650 cfm carb is on the smallish side for a modified engine. Most go with a 700 or a 750.

I agree that it sounds like tuning -- ignition timing, cam timing, and carb tuning are needed.

Fire your mechanic, he is charging you way too much money to be screwing around and giving you a car that doesn't run right.