No power!

[cmpcpro]

Hello all... since I got my car, I've never really beat on it. Never done any burnouts or such. So anyway, tonight my friend talks me into doing a brake stand, out of the blue. So I go to do it, and nothing! I finally got frustrated and put the gas pedal all the way down, and it just bogs! LOL!! The brakes old it still, if I let off the brakes a little bit more, the car will just move forward. I didn't want to try that again, as like I said, I'm not one to thrash, but isn't that really bad? I thought a 302 had a little more go than that. Even though the rear has 3.00's its an open rear end!! What gives?

Thanks

PS: Tranny and rear to be changed soon, motor is now being considered.

[cheezsnake]

Does the car bog down when you hit the gas without the brakes? Sounds like it could be a carburetion or timing problem. Do you have a 4 barrel carb?

[cmpcpro]

Yes! It does bog down without the brakes. And yes, it's a four barrel Holley 600 Vac sec. I've tried jets, and springs. Only thing I haven't tried to backing down the accelerator pump.

[cheezsnake]

The engine bogging down when you first hit the gas can be pretty common in street cars, especially with vacuum secondaries. I had a 351C with an Edelbrock 750 that did the same thing. If I accelerated steadily there was no problem. But, if I hit the pedal all the way to the floor the car would bog down a little before it took off. That short initial bog you get, though, should be followed by a surge in power as the RPMs climb. You can correct some of this by advancing the timing a little. But, there may be some other problem with the carb that's causing it to dump too much fuel. If your engine doesn't recover quickly from that initial bog than something else is wrong, either with the carb or the ignition system.

[cmpcpro]

Thanks!

It is exactly like that. Not too bad, but pretty bad. Could it also be the Accel pump?

The thing about this is, it seems to get better the bigger jet I go! I went up to 70's and it was actually better with the bog part, but when I went back to the 66's I felt more power overall.

What would you think a good size jet would be? And I never hear/feel the secondaries come on anymore, I used to, before I put in the easy spring changer thing. Should I feel those kick in? Or maybe they are kicking in when I feel the bog?

Thanks!!

Chris

[cheezsnake]

That's odd that the bigger jets improved things. I would have guessed that they should have made it worse. Usually, when the engine bogs down intially on hard acceleration, it's because you're getting too much fuel. It takes the engine a little bit until the RPMs pick up before it can use the fuel. If the engine loses power at high RPMs, you might be getting too little fuel. From my experience, that initial stall happens when the secondaries first open. I suppose it could be the accelerator pump shooting too much gas in. I can't give you a recommendation on jet size...it's been too long since I messed with those on that carb, but with a 302 I wouldn't get too radical. A common mistake a lot of guys make is going too big with the CFMs when the engine can't use it anyway. A 600 is probably about right for that engine. I currently have a 289 with a 570CFM Holley.

[68Ragtop]

Hey guys, this may be out of the blue but have you changed your fuel filter lately? My car was losing power to the point where it finally wouldn't move unless I let it gradually built up speed, so before you get too far into messing with the carb, just give the fuel filter a once over. They are cheap as all get out and take next to no time to change out. Just a thought.

68Ragtop

[Rev]

Kinked fuel lines will also cause a power fall off at speed. That's happened to me before. Was an easy fix though and easy to find.

Rev