what to fix next?

[tim21391]

problem is.. runs good in town.. bad on interstate wont go over 55.. acts like a mysterious person put a governor on it but theres not one.. so far i installed these parts to fix the problem.. new fuel pump. new coil. new cap. new rotor. rebuilt carb. tested the moduler in the hei distributor.. and still nothing.. kinda getting fed up with it.. spent around $300 on nothing.. its on premium gas. accel hei distributor with msd cap. accel coil. 402 big block. holeley 700 or 750 i dont know.. i dont know whats next.. i thought it was not getting any fuel at highway speeds so thats why i swapped out the old pump with a new one and that wasnt it.. what to fix next basically everything that deals with spark and fuel is new.. the fuel filters are not clogged since i blew threw them all including the two in the carb

[71swb4x4]

Could it be the transmission?

[Rack Man]

How about the accelerator linkage...??


RM

[tim21391]

what do u mean tranny? it shifts into second and third fine but i cant go into forth because i have a shift kit in and it shifts into 4th at 70 mph but the other three gears seemed fine just when it got to 55 it quits.. what am i lookin at on the linkage? like if its hitting something? when it cuts out you know u reached the limit because it slowly lets off.. and then when u back off the gas to about 50mph u punch it.. its got plenty of power then as soon as it hits 55 again it stalls out... i heard to check the pick up in the tank

[mikajo39]

Make sure the mechanical advance on the distributor isn't bound up? Not enough advance at high speed could lower your performance.

[joes50pu]

Sounds like you have a Rev Limiter. I installed a MSD 6AL box on my truck with the replaceable RPM Chips.

Other possible causes could be plugged exhaust, secondaries not opening.......etc.,

[tim21391]

how do you check secondaries

[72 cheyenne pdx]

You may need to replace the throttle cable as that was happening to me. I could floor it and max out at 50 mph. My wife's grandfather said he never replaced it when I got it, so I am unsure if this stretched or he replaced it and forgot that he did. Have some one push the gas pedal all the way down while you see if the linkage is going through its full range.


Good Luck.

[cdowns]

have you removed the fuel sender from the tank to inspect the intank filter and conditions inside the tank? have you checked to make sure the tank is vented properly? a whooshing sound when removing gascap right after using truck is a bad sign and tells you that theres a venting problem

is it a 6cyl originally? they had smaller gaslines

lazyman rubber fuel lines collapse and kink as well as cause vaporlock when lying on a hot manifold, they're great firestarters too

[tim21391]

well my dads friend came over i knew he was an engine expert since hes racing a 64 dodge 330 with no spray running 9.1 at 160 mph so he came over and instantly found the problems.. the floats or whatever you call it were set low.. he took off the two side screws off the carb and shook the truck and no gas came out.. then he had me start it while he reset the thing that you take two screws off top of carb one in back one in front and then took it on interstate and was running 80mph

[71swb4x4]

Glad to hear you got it fixed.

[C20-67_N_MO]

Glad to hear it was a simple fix.

And good to have a friend that knew what to do to lend a hand!

[PanelDeland]

The big question here is
"Did 'you' Learn anything?"

[tim21391]

well that wasnt the case.. it ran for the dude who fixed it then i took it out again and it wouldnt go over 55 for me

[purple'69]

Its your muffler bearings.

[powerbench]

funny you should say muffler bearings.........i had a colapsed muffler once that did all most the same thing.......blocked the flow at higher rpms......what rpm does it stop pulling at?

[trusty72]

sounds like its a timing issue to me, either set wrong or the chain is stretched . will cause exactly what u describe.

[gkesseru]

Sounds like you have a Holley. There is a level screw in the side of the front bowl and one on the back bowl. You remove the screw plug on the side and adjust the float level screw on the top of the bowl until the gas just start spilling out out the side screw hole, then back off a hair.

Once it started having problems again, did you pull the screws to see if there's gas in the bowl? From your friends actions, it looks like you are running out of gas above 55. Could be from bad fuel filter, bad fuel pump, kinked fuel lines, bad fuel pickup in the gas tank, or clogged vent holes in the cap. If you are running out of fuel, try running in 2nd gear and see if you run out of fuel at the same RPM that you ran out of in Drive. That should tell you if it's a fuel flow problem.

[joes50pu]

Count your shifts and make sure your getting high gear and not stuck in second.

[tim21391]

im getting all gears but my 4th gear i had set up when i rebuilt the tranny to shift into 4th at 70 mph.. so i am in third when im having the 55 problem.. ya i have a holley.. fuel filters arnt plugged checked that i installed new pump and still didnt fix it.. and exhaust is new so i cant count that.. and muffler bearings im not that dumb come on now.. and we pulled the screws out and re seated them or whatever its called and it ran fine for the dude but now its not... so im thinking clogged pickup.. cap is new too so that cant be it

[usmcchevy]

Originally Posted by tim21391

im getting all gears but my 4th gear i had set up when i rebuilt the tranny to shift into 4th at 70 mph.. so i am in third when im having the 55 problem.. ya i have a holley.. fuel filters arnt plugged checked that i installed new pump and still didnt fix it.. and exhaust is new so i cant count that.. and muffler bearings im not that dumb come on now.. and we pulled the screws out and re seated them or whatever its called and it ran fine for the dude but now its not... so im thinking clogged pickup.. cap is new too so that cant be it

The TH400 is a 3 speed trans...

[68Stepbed]

Is there a particular rpm it's qutting at? Or is it just at 55mph period? Also, why is your tranny setup to only change into 4th gear at 70mph? That seems odd to me.

[tim21391]

hell i dont know what gear im talkin about but all i remember is that you go on interstate and you punch it.. with our shift kit installed u hit 70 mph and it shifts