My girlfriends T/a starting popping at the track everytime around the end of 3rd gear, 5,000 rpms, which screwed up the track times. I'm thinking the stock 1985 fuel pump is crapping out, any other ideas?? Its carbed btw.

 

coil. i think stock iginition systems are good up to like 4-4500 rpms if u go with aftermarket products that go up and past 5000rpms it souldnt pop like ur saying.

 

You are correct. Not enough fuel.

It's leaning out.

Don't overlook the fuel filter either, especially if it's a Q-Jet.

 

i thought the stock ignition system wasnt that good up around 5k rpms?

 

It could be detonation. If the iginition timing is too far advanced, you will get spark knock at the higher RPM's. If this is the case, it should be happening in 1st & 2nd gear also, unless you/she shifted before reaching 5K RPM. In any case, it only takes a couple of minutes to check the timing.

 

A properly working HEI will work well untill about 5000-5500 rpm.

She doesn't by any chance have glasspacks on her exhaust system does she? Those things pop like crazy.

 

Myn pops too when the rpms drop from revving, hmm I'll check into timing.

 

This is a great excuse to upgrade your igniton anyways "Just in case"

 

as far as i know most stock GM HEIs are good til 4000-4500rpm after that they loose spark current dramatically. it doesnt mean they wont fire a stock engine at 5500, because they will. but a hopped up engine puts alot more stress on the ingition. the factory programs the control module to have great dwell time at lower RPMs where the factory designed the engine to operate in. in most cases all you need to help the factory HEI out is a HP control module. other pieces can be added to make it better but this is the first thing that shoud be upgraded in the ignition if your motor turns past 5000 RPM.
also definatley check your fuel pressure at the end of the track; mount a gauge where you can read it.

 

That would be an exhaust leak.

 

no glasspacks don't pop like crazy.

cherrybombs pop like crazy.

there is a very big difference

 

No there isn't. Cherry Bombs is a company who sells glasspacks.

Kind of like Kleenex. They've become "the name". Even when all you have in the house are Puffs, everyone asks "Where's the kleenex?"

 

Exhaust leak? Hmm I don't hear a ticking sound, or does that only apply to the exhaust manifolds?

 

Mine usually does that when the timing is off. It randomly started the other day. Discovered the dist cap hold downs came loose. I have a performance Accel HEI distributor which works great to 6500 which is as far as i have wound the engine. Check the cap for wear also. The stock style caps and rotors are easy to burn up. Cheap metal inside. I even burned up the rotor that came with my accel. It's always good to have a fuel pressure gauge to just to make sure you have enough fuel. That can cause it to. I delt with all these problems when I swapped engines last year. Sorry bout the long reply. lol Thats my take.

 

You wound your H.O. to 6500 RPM?? Wow, Most I have seen is 5200.

Oh yea, forgot to add, when you wind a motor real high, will it just blow up or will it give you hints to let off or shift?

 

As the saying goes "... it always runs best right before it blows up..."

5200 is the best your L69 could do? That cant be right... my sickly L69 used to hit 6000 without complaint, untill I replaced it with a 350 temporarily.

 

Thats because my L69 is laying on the floor of my garage. I have a different motor in my car now. Forged bottom end. It's a performance motor. The bearing went out in the stock one a littl over a year ago. Heck no the L69 wouldn't make it, esp if I still had my 700r4.