Need help with old school truck problem.

**Street Fighter** · 11-30-2012, 02:31 AM

i HAVE A 69 CHEVY TRUCK THAT HAS A 350 BORED 30 OVER WITH 10 TO 1 FLATTOP PISTONS. A CRANE CAM WITH 467-490 LIFT A RPM INTAKE AND A 750 HOLLEY VAC.THE PROBLEM i HAVE IS THAT THE TRUCK FALLS ON ITS FACE IF YOU FLOOR IT ALL AT ONCE.BUT OK IF YOU EASE IN TO IT.I HAVE TRIED TO CHANGING JETS AND POWER VALVES BUT THE SAME PROBLEM. i HAVE TAKEN THE CARB OFF MY CAMARO WHICH IS THE SAME SIZE CARB AND TRIED IT ON THE TRUCK AND IT DOES THE SAME. COULD THE CARB BE TO LARGE FOR THE TRUCK. THE ENGINE HAS VORTEC HEADS 194/150. SORRY ABOUT THE LARGE LETTERS BUT i WAS TOO LAZY TO START OVER.

**Too Fast** · 11-30-2012, 02:46 AM

I don't think the carb is too large. Theoritically it should be a 650. Have you tried adjusting/calibrating your accelerator pump? I fought and fought a hesitation problem on my 30 over 400 in my GTO for a year, it had a 750 Edelbrock on it. I tried many different things to that carb, then tried a massive ignition upgrade, but nothing stopped my hesitation until I put on the Holley 750 vacuum secondaries. Problem fixed. And gas mileage went down.

So the carbs work ok on the Camaro? Are your secondaries opening too soon? Ignition timing good? Harmonic balancer showing TDC correctly (no shift on the balancer)? Gas is good in the truck? Truck runs great and has good power/response otherwise? Spark advance normal? Fuel flow/PSI ok?

**pajeff02** · 11-30-2012, 03:32 AM

What is your engine vacuum reading at idle?

**5150** · 11-30-2012, 04:32 AM

The spring on your secondary's might be to soft and opening to soon causing the bog. I would try putting a stiffer spring in. As well as what the others have said.

***SMWS6TA*** · 11-30-2012, 09:07 AM

fuel jets in the carb to big?

what's the fuel pressure?

**Street Fighter** · 11-30-2012, 11:43 AM

I could not ask for many more out of the truck other than the falling on it's face every time I try to floor it at low speed. This have been going on for years and each time I park it I forget about it and until I decide to drive it again.The truck has good power it'll sit you back in the seat once it decide to move out, but I deal with guys that will leave you looking foolish if that happens with one of them.

**Street Fighter** · 11-30-2012, 11:50 AM

About 23 and once you hit the thottle it goes to about 5 or 6

**pajeff02** · 11-30-2012, 06:24 PM

That's good then. As already posted, the accelerator pump and secondary spring tension are your most likely culprits. How's your fuel pressure and float level in the carb?

**Street Fighter** · 12-01-2012, 03:19 AM

Thanks to all that gave me their advise on this problem with my truck, Like I stated in another post ,I found the problem.The timing was way too high.The dist. must have gotten moved at sometime way back,because I have been trying to solve this problem along time.I reset the timing, adjusted the carb,after checking the float level,then went for a test drive,it is doing just what it is surpose to do now when you nail it. THANKS TO ALL FOR YOUR HELP.

**pajeff02** · 12-01-2012, 03:50 AM

Good to hear. Any pics of her?

**Too Fast** · 12-01-2012, 10:58 AM

Glad we could help.

**Street Fighter** · 12-01-2012, 06:25 PM

Originally Posted by pajeff02

Good to hear. Any pics of her?

I am going to get my daughter to show me how to post some pictures. I have the 69 chevy truck, a hot 77 camaro, a 73 Hot Dodge charger, And my 99 trans am that I have big plans for once I retirer.I plan on heads cam stall,headers and tune.It have some upgrades now but they are small. be looking for the pictures soon. the TA was bought new and have 42,000 miles on it.the camaro 35,000 the charger 30,000 and the truck 50,000 all of the old school rides have been upgraded by me years ago.All are alot of fun to drive and always gets me a horn blow or a second look.

**REVNORR82** · 12-02-2012, 01:51 AM

I know this is after the point but i had an issue with timing on a truck the dist always move and it was the stock hold down for the dist i was running a msd pro billet and the stock hold down was a little worn/bent got a billet one dist never moved again just a little food for thought.

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**pajeff02** · 12-02-2012, 06:19 PM

Originally Posted by Street Fighter

I am going to get my daughter to show me how to post some pictures. I have the 69 chevy truck, a hot 77 camaro, a 73 Hot Dodge charger, And my 99 trans am that I have big plans for once I retirer.I plan on heads cam stall,headers and tune.It have some upgrades now but they are small. be looking for the pictures soon. the TA was bought new and have 42,000 miles on it.the camaro 35,000 the charger 30,000 and the truck 50,000 all of the old school rides have been upgraded by me years ago.All are alot of fun to drive and always gets me a horn blow or a second look.

Heck, may as well throw up some pics of the entire stable. Good mix of vehicles you got there.