loss of power after warm

[86reddawg]

so i've been noticing lately that on my way to work, when my engine finally gets really warm, around the 200degrees area, i lose all lower rpm power, and lots of higher power. from a standstill at wot, it doesnt sputter or anything, just feels like it has about 50hp and no torque... once it gets to about 2000rpms, you can notice the hp immediately building up and pulling stronger, but not as hard as it should be. It's almost like the timing has been set way to retarded, but i checked yesterday and it's right at 8degrees advanced.

btw, this is for an 86 lg4 carbed car - i rebuilt the carb about 6 months ago, and left most of the stock calibrations where i thought they originally were. Also, the only thing that has really changed is recently i installed the STB, and it sits right infront of the air filter, turned sideways, so it blocks 85% of the surface area in the front... is it pulling in lots of warm air and not performing well? or is the engine just getting old and losing compression when it gets warm? i have no way to check the compression unless someone in the knoxville, tn area wants to lend a hand...

[WS6 VERT]

Sounds about like my old LG4. It was great stone cold, could spin tires and what not. Once warm, it wasn't so great. I've since moved on to better things graemlins/devil.gif

[86reddawg]

could this be a problem with wrong temp spark plugs? i replaced the cap and rotor at last oil change, 1.5 months and 2000 miles ago... i cant for the life of me figure out why it runs strong when cold and like crap when hot... it takes about 30 minutes of normal driving, or quicker in stop and go traffic... any one have any ideas?

[LL6]

If I had to guess it would be your fuel pump and/or accelerator pump. The pump could be weak. Check it for how much psi it's developing. My old L69 ran like a scalded cat until it would get real hot. Around 4k rpm it would put your face into the steering wheel because it lost power so drastically. Turned out I had 1.5 psi and the o-ring around the plunger was flat missing in my accelerator pump. graemlins/lol.gif Ran a lot better after the fix.

[RobP]

I remember there was a recall on my 85 Z28 LG4 for vapor lock. They put some more vacuum hoses and valves (just what an LG4 needs :rolleyes: )
Anything to do with that guys?

[ June 02, 2002, 19:03: Message edited by: RobP ]

[86reddawg]

Around 4k rpm it would put your face into the steering wheel because it lost power so drastically. well it does the complete opposite... i've got no power at lor rpm then alot more at high - needless, i thought fuelpump was faulty, so replaced with standard autozone replacement about 1.5 months ago as well (was actually doing what you said, ran out of steam getiing on interstate) however the running out of steam problem was not fixed - it eventually stopped when i unhooked the charcoal canister (which was somehow causing my gas tank to keep a vaccuum)

[86reddawg]

well i think i found part of the problem... a while back i bought a one inch spacer for my open air filter... they only thing they had was plastic - i was unwary about it, but i used it - seemed to work ok... now apparently since it's alot warmer out, and the engine gets a bit warmer, there were a few places where it actually started to melt a little, and one of the melted places seemed to grab the secondaries and leave them wide open when it was warm and gooshy enough to stick... so i was just sucking in hordes of air and juct choking out until i could really use it at higer rpms... i tightened the secondaries flap a bit, and that seems to help alot, but not effective all the time. Does anyone know, for starters, where i can get a nonplastic one inch spacer for a quadrajet?

btw, the spacer is needed in my engine, a while back, the throttle lever got caught up against the air filter...at about 5degrees away from WOT...in the middle of the town square - man oh main i thought i was gonna rear end some one - the brakes were *just* strong enough to keep me from moving and i think most people thought i was trying to be an ass and brake stand at each stop light until i could find a parking lot to kill the engine and unwedge the throttle cable...

[Pantera61]

I could see how that would suck. I am not sure where to get a space that big. Smaller maybe. Did you check the usual: Summit and Jegs? If not I would check there first unless somebody else knows of a place.

[Michael]

Yes I have a 86 camaro TPI and I also feel power loss when engine is warmed up. Could swear the car feels 1 sec quicker in the 1/4 when cold then when at 190 deg F.

Have asked a few people about this and they said it is normal. There is power loss when the car is warm. So I have stopped thinking about what it could be.

[WS6 VERT]

Yeah, its a proven fact that the hotter the engine, the less it performs. Thats the whole theory behind carb spacers, "cool cans", ice bags, etc... I always let my car sit for a few hours just before attempting my "best run".

I know when I had the 305 TPI, that car took off like a cheetah with its ass on fire when stone cold, but when fully warmed up, it was mediocre.

[86reddawg]

nonono, we're not talking one or two secs in quarter mile, more like 10-15 secs more... like something somewhere is wrong - it would seem the secondaries was part of the problem, it isn't choking out so much, but it still feels like it's lost about 8 secs when hot...