Jump to content
HybridZ

lack o top end


Silent

Recommended Posts

maybe it's just me, being used to a 300 whp cobalt and zingin it to 8k without any fuss. or the fact it's a bone stock l24 with who knows how many miles on it's anemic nature by todays standards.

 

short story.

 

yesterday i change out the intake/manifold gasket, surface the intake manifolds to get the years of crap off them, clean the carbs. stick it all back together. jump in it. fire it up. take it for a quick spin. it runs just fine at part throttle. go wot in first or second, no balls. it feels like it's done by 4k rpms.

 

the only thing added many moons ago was a header. i have not checked the timing in it, just synced the carbs and set the afr on em. did a quick sea foam to it. nothing major. my thinking is it should at least pull to 5500 without much of a fuss. it doesn't. it feels like im pushing the crap out of it and doesn't want to do anything.

 

is there something im missing here? maye a hidden secret somewhere to help out in the power area? hell im thinking of sticking my modded 3 screw su's off my 3.1 on there to experiement in some way of getting more top end out of it. also thought about sticking the 260 spacers on there to move the curve up a tad.

 

any idea's?

Link to comment
Share on other sites

Do the basics first:

 

1. Valve adjustment.

2. Change the plugs and properly gap them.

3. Change the points and set the dwell.

4. Change the cap and rotor.

5. Set the timing.

6. Sync the carbs.

7. Change the fuel filter(s).

8. Adjust the clutch.

Link to comment
Share on other sites

well. put my modded 3 screws on it last night. did all the crap again. part throttle is freakin amazing. once it goes wot it struggles. bad. im thinking it's lean. whats weird is, this is with sm needles. it pulls it's little buns off at part throttle.

 

fuel filter is new.

checking the timing tonight. re-syncing the carbs. not used to points, so this should be fun. cap and rotor are brand new

Link to comment
Share on other sites

points will be gone this weekend. don't have the desire to mess with it.

 

new plugs goin in tonight. wideband going on it this weekend to get the sucker dialed in right.

 

you get rid of your sig, and i'll get rid of mine!

Link to comment
Share on other sites

I've got a similar problem with my '72 240Z. I put in a Pertronix and it runs light years better than with the points. Ever since I did so however, it struggles around 5000 RPM and up, whereas with points it would rev to the redline. I'm NOT going back to points though so I'd like to figure out what the problem is.

 

All new cap, rotor, coil (Crane PS40), plug wires, plugs (NGK), freshly overhauled 3 screw SU's with SM needles, carbs synced, timing set to 10 degrees BTDC.

 

I think it has something to do with putting the Pertronix in, or with the vacuum advance not working personally as I put in the Pertronix and coil at the same time and didn't have the problem before. I'm going to try another vacuum advance can as soon as I get my hands on one. Any other suggestions?

 

Greg

Link to comment
Share on other sites

the plugs were nuked. bad. changed them out last night. changed the needles out. the sm's were just way to much for the little 2.4 liter. set the fuel mixture. the idles so much smoother now and runs good as well. it seems this car was never in any sort of "to0n", even we a friend and i brought it back from cali 3 years ago.

 

it will half ass get out of it's own way now. on the right track it seems.

 

i think it stems from me working with a laptop of my ss for the past year that threw me way off base of what i remembered from when i had my 280. it's all comming back to me now. slowly. like, short bus slow.

:)

Link to comment
Share on other sites

finally caved in and put a pertronix in there.

 

pulled the choke cable maybe a 1/4 inch. hit the key. fired instantly. reved so much smoother and faster now. looking at the points, they were shot.

 

somehow in this swap i lost my water temp gauge. doh!

 

old brittle wires. ghaaaaaaaa

:)

Link to comment
Share on other sites

it pulls to 4k. then i just shift. i don't have plates on the car right now so im not pushing my luck. once i redo the rear brakes i will be taking it on a spiritied run. so far it revs so much better, a lot cleaner and no struggling. i might set the valves this weekend as well

Link to comment
Share on other sites

You said you set the afr and you're getting a wideband. Is it fair for me to assume you have a narrowband. If so, I need one, care to sell?

 

 

points will be gone this weekend. don't have the desire to mess with it.

 

new plugs goin in tonight. wideband going on it this weekend to get the sucker dialed in right.

 

you get rid of your sig, and i'll get rid of mine!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...