low power at high rpm

[palmer6691]

hey i got a strong 350 in my pickup and it seems that when i take it up past 4000 rpm it just doesnt have any power. it doesnt cut out it just seems nutless. ive tried two different hei distributors and the same results.

could it need an advance recurve kit? could carb tuning make that much of a differnece? it has stock metering rods (edelbrock 600)

thanks

[777stickman]

Need more info, such as:

Year of truck & motor? 2W or 4W? Auto or stick? Were any mods done to bring this condition on?

[palmer6691]

o yes sorry,
its actually a 54 international pickup project on 1981 chevy pickup frame 2wd with 373 gears
th350 with kit.
350 with 170cc world products heads and crowler 1800 to 5800 edelbrock intake with 600 edelbrock carb right out of the box at 1400 ft elevatio

i put the motor in only a while ago and its never really ran good in the high rpms and but when it shifts it hits hard and runs good until a bit after 4000 rpm.

[j cAT]

Originally Posted by palmer6691

hey i got a strong 350 in my pickup and it seems that when i take it up past 4000 rpm it just doesnt have any power. it doesnt cut out it just seems nutless. ive tried two different hei distributors and the same results.

could it need an advance recurve kit? could carb tuning make that much of a differnece? it has stock metering rods (edelbrock 600)

thanks

I would simply replace the fuel filter....especially if you have the metal tank....replace this filter every year especially in dusty areas...

cut open the old dried out fuel filter, see how much dirt is in it..

[palmer6691]

fuel filter is only about 3 months old and the motor and tranny only have about 4000 miles on them

[j cAT]

Originally Posted by palmer6691

fuel filter is only about 3 months old and the motor and tranny only have about 4000 miles on them

check fuel pressure

[777stickman]

Make sure you're getting WOT at the carb with someone pushing the pedal in the cab. Look down the throat to see if all 4 butterflys are fully open.

Check timing at 3,000. Should be around 35 degs.

Base timing at idle should be 10-12 degrees.

Last thing is cam timing. A cam that is advanced too much will have great low end and not much top end.

[palmer6691]

yes ive got wot

ignition timing is 9 deg at idle (ive got 9.6 compression so im playing it safe) but ive never checked it at 3000

ive never checked fuel presure what should it be? do i just check it at idle?

the motor was professional built so the cam is probley right but i will check it if everything else fails
thank you for your input

[j cAT]

Originally Posted by palmer6691

yes ive got wot

ignition timing is 9 deg at idle (ive got 9.6 compression so im playing it safe) but ive never checked it at 3000

ive never checked fuel presure what should it be? do i just check it at idle?

the motor was professional built so the cam is probley right but i will check it if everything else fails
thank you for your input

with your symptoms I have experienced low fuel pressure / restrictions causing loss of power at the high rpm's..your vehicle is something I don't know what it would be , but before spending money on it I would check that out..

with a guage hooked up with a longer hose to monitor pressure you could go for a test drive see if the pressure drops off...

[777stickman]

Most stock mechanical fuel pumps will deliver around 5-6 psi. If you want to check it while driving you'll have to incorporate a T fitting in the supply line to the carb.

Another thought that crossed my old muddled mind is the possibility of a restricted exhaust system? Pull the muffler/s and go for a drive. (I recommend doing this at around 4am just so your neighbors know you're serious about getting this project running!!).

Swap carbs with someone for a test. Pull some plugs and check for lean or rich conditions.

The timing check of 34-35 degs at 3,000-3,500 is called total advance. This takes into account your 9 deg initial and the weights in the dist going full extension. Different weights and springs only determine how soon or late total advance is achieved in the rpm range. Many SBC guys time their motors using this procedure.