Need help with my 69 pickup.

**Street Fighter** · 12-31-2007, 04:53 PM

I hope that someone can give me some ideal about my truck.Frist let me tell you what's it's doing.The truck have a 350 bored 30 over,flat top 9to1 pistons.Elebrock rpm intake,Crane 467/494 lift cam,headers, a 750 holley,And a set of vortec 525 max lift heads.The truck have run good about two years now with this setup and I had no problems, run good.Now the truck do not want to let you nail it coming off the line, and if you do it wants to bog down. spit and pop, But if you ease in on it everything is ok no bogging.Now let me tell you what I have done to try and find the problem.I took the 750 off my camaro and tried it, same thing .carb works great on the camaro.Removed the distributor from the camaro and tried it, same thing.changed plugs,changed wires,checked compression,175-180 per cylinder. Could it be the cam that is giving me this problem. I Also changed fuel pump and filter.Need help finding this problem.The cam have been the truck about 5years,Intake and heads put on two years ago.

**Stone** · 12-31-2007, 04:56 PM

Originally Posted by Street Fighter

I hope that someone can give me some ideal about my truck.Frist let me tell you what's it's doing.The truck have a 350 bored 30 over,flat top 9to1 pistons.Elebrock rpm intake,Crane 467/494 lift cam,headers, a 750 holley,And a set of vortec 525 max lift heads.The truck have run good about two years now with this setuup and I had no problems, run good.Now the truck do not want to let you nail it coming off the line, and if you do it wants to bog down.But if you ease in on it everything is ok no bogging.Now let me tell you what I have done to try and find the problem.I took the 750 off my camaro and tried it, same thing carb works great on the camaro.Removed the distributor from the camaro and tried it, same thing.changed plugs,changed wires,checked compression,175-180 per cylinder. Could it be the cam that is giving me this problem. I Also changed fuel pump and filter.Need help finding this problem.The cam have been the truck about 5years,Intake and heads put on two years ago.

Solid or roller lifters? Does it chatter?

**Bobby97SS** · 12-31-2007, 07:43 PM

Vacuum leak?

**Street Fighter** · 01-01-2008, 09:53 AM

Originally Posted by 05 Stone Srt-4

Solid or roller lifters? Does it chatter?

The lifters are Hyd. and there is no chatter.just popping and bogging.

**LS2Tuner** · 01-01-2008, 10:07 AM

Well I would venture towards a lean backfire.......
Many posabilitys. What are you running for timing?
Is the vac advance still hooked up? If so do yourself a favor and disconnect.
When you say 750 Holley are you refering to a 3310 vac secondary?
Yes if you have worn a lobe off or way down it can cause a backfire also.
What kind of TOTAL timing are you running?
Intial I could care less about.
You said you changed the plugs what did they look like? Was there a pair or one that was white as a ghost?
Stock conv.?
Gears?
Let me know I'll try to help as much as I can without being there.

**Street Fighter** · 01-01-2008, 07:06 PM

Originally Posted by LS2Tuner

Well I would venture towards a lean backfire.......
Many posabilitys. What are you running for timing?
Is the vac advance still hooked up? If so do yourself a favor and disconnect.
When you say 750 Holley are you refering to a 3310 vac secondary?
Yes if you have worn a lobe off or way down it can cause a backfire also.
What kind of TOTAL timing are you running?
Intial I could care less about.
You said you changed the plugs what did they look like? Was there a pair or one that was white as a ghost?
Stock conv.?
Gears?
Let me know I'll try to help as much as I can without being there.

The truck has a 3310 vac. secondary carb.373 gears.2500 stall.The plugs looked good to me a little browness in color.I do have the advance connected and it's working .Would the truck run as good as it does,idle good.pick up speed good and still have a bad lobe?Like I said if you don't nail it coming off the line you would never know there was a problem with the truck.Also I don't know the total timing.But the intial is 15degrees.

**LS2Tuner** · 01-01-2008, 07:59 PM

Originally Posted by Street Fighter

The truck has a 3310 vac. secondary carb.373 gears.2500 stall.The plugs looked good to me a little browness in color.I do have the advance connected and it's working .Would the truck run as good as it does,idle good.pick up speed good and still have a bad lobe?Like I said if you don't nail it coming off the line you would never know there was a problem with the truck.Also I don't know the total timing.But the intial is 15degrees.

There is a few quick things you can do to improve what you already have.
Can you borrow a timing light from one of your friends that has the knob on it where you can check total timing? You'll need to rev the motor to probably 25-3000 rpm to get the full mech. adv to come in.
If you do this I would start with it at 36* total and go hammer on it to see if it pings. If it doesn't try 37* and so on once you find where it pings back it off a degree.
I would disconnect the vac adv. first off unless your trying to get gas mileage and not performance. After you do that you can put more initial timing in it which will help that thing rev.
Second take the acc. pump cam on the linkage and change the screw to the #2 place which will advance the cam some= more fuel quicker on the acc. shot. If that helps I would replace that tiny .028 squirter with a .031.
A vacuum leak could be causing this lean pop also.
Set the idle as LOW as you can while keeping it running. Now take some brake clean or carb clean and spray in all down the intake where it seals to the head and around the carb base looking for a idle change.
These are HEI dist that your interchanging?
I would also check the voltage at the power wire going to the dist. to make sure it's seeing batt. voltage.
One other tell tale thing you can do to see if your cam is going away is put a vacuum gauge on it to watch manifold vacuum. If the lobe has went away the the needle will be erratic.