cant go fast for long....help!?, drives around town all day, but not on highway! Options

[rbmorrisiii]

Ok, so i got this car ('73 1.7L) about 2 months ago. single carb - yes i know this isnt the best fuel intake, but i am going to try to make it work. I tried to drive it home - about 90 miles, but it only went about 15 miles before it slowly crapped out. losing speed unitl i had to pull over. it would start again and drive, but couldnt go fast for long.

so, I: changed fuel filter, spark plugs, oil, cleaned oil screen, pulled gas tank and ran all new fuel hoses and clamps (found a kinked line which i thought was the problem - also found the vent in the gas tank to be smashed, so i re-opened that and ran a new hose to underneath the car) the lines looked fine running through the car - and when i blew them out they seemed to be free of any clogs etc.

I reconnected everything, and started her up today. same problem. she ran a little better and could run all day around town, but took her on the highway and she would only stay in 5th gear for like 20 seconds then started tanking in speed - down-shifted to 4th.....3rd...then pulled off the highway...noticed some smoke in the back so i pulled over to let her rest. the smoke was coming from the HE's - both sides on the "opening" closer to the muffler. the PO had screwed in wood screws into the gap i'm assuming to keep them from rattling, and that gap is where the smoke was flying out of. after a 15 minute rest i started up and drove for another 15 minutes with no major problems.

Why wont she go on the highway!

I'm stumped!

I'm new to the mechanical arena so overexplain things if you think you need to.

whats my next step? someone told me the timing may be messed up, 'cause when you switch to carbs you to need to adjust?!?!

help!

Thanks for all the help in advance, so glad to finally join the 914 world!

ill have pics of my bag of bolts soon!

-R.B.