I have recently finished my 355 it has world heads 2.02/1.6, an edelbrock 3702 cam, 3704 intake, shorty headers and 1.5 roller rockers.
The timing is set to 6*advanced it idles fine but at highway speeds it has a stumble and pops through the tb, rpms drop 1-200 it happens 3 or 4 times then comes out of it and runs fine for a minute of two and happens again.
It has a stock tune is that the problem? i dont want to hurt the motor i have a ton of time and money in it so any experienced advice would be great!

 

I pulled the plugs and they were very lean but my afpr is maxed out how do i get more fuel with out getting bigger injectors? Would a chip solve my problems

 

Check fuel pressure! How much fuel pressure are running? Bigger injectors will not help you if you do not have adequate fuel pressure and volume...

//RF

 

What you are experiencing is normal for an untuned modded engine. I experienced exact same day one. Lean backfire. I dont think the timing table(truck) is at issue. I would leave it as is for now. Can always change "idle" timing later as that may need some change.

As was stated your fuel pump may not be up to task. Did you add a FP gauge. I would do that for sure. What size injectors at what FP? You can up FP temporarily and see how engine responds. I would consider getting a datalog ALDL cable ASAP and load winALDL and check the BLMs. you are most likely gonna see very high BLM. Seperately the AE or pumpshot will need to be increased considerably. That is seat of pants unless you invest in WB. It goes without saying no WOT

 

I have 55 pound injectors but i dont have a fp gauge yet it is still on order im guessing that my fp is 15-17 psi with the regulator turned all the way.
ill go borrow a fp gauge from a buddy get to check it for sure.
Im looking for a quick but not long term fix just so it is safe to drive it im going back to work in a few weeks and dont really have time to learn how to data log, though i would like to, ive looked in to it alot but it seems like it takes alot time to get started.

 

I dont think one should max the FP regulator. Maybe 80%. I maxed mine with a TPI pump and blew a new reg gasket. Maybe the stock TBI pump it wont be an issue. There is a nice spring that will give higher FP than stock at topdownsolutions. Issue is whether the stock FP will deliver?

 

what fp would u recommend, also would a chip with better fuel table help, im going with a mail order chip for now does anyone believe that the chip will make a difference, i dont have time to make my own, so any recommendation on a chip?

 

Measure and verify your fuel pressure. Without knowing what your actual FP ordering a chip is meaningless. 55lb injectors can supply adequate amount of fuel to a modified engine at higher pressure - hence you do not need bigger injectors.

//RF

 

so i finally got my fp gauge it says i have 16 psi at idle i also noticed that the headers melted the o2 sensor wire could that be a problem fp seems adequate but it still doesnt run very well in gear but in idle it revs fine no backfire any ideas (map sensor, o2, idle air, tps)

 

replace the 02 sensor and re-exam wire route. Same on starter wires.

After that pull codes.

 

I checked all my wire everything looks good, i fix the o2 sensor, and the computer has no codes. I put in my 255lph fuel pump today and im waiting on a stiffer spring for the afpr what kind of fp can i run before the injectors go static.
After this im out of ideas, it runs like xxxx, could i possibly need bigger injectors it just seems like it is starving for fuel, could the map sensor be bad? just some thoughts but im no expert.

 

So i solved my problem I set up my base timing to 14* and it cleared right up, runs great, i want to thank everyone for the help. i think this is the most knowledgeable car site on the web.