surging (truck) around 4300 UPDATE! MSD Causes problem

[broncoman6524]

ok i drove my truck on the highway yesterday on the way to look at that k20. my dad was driving adn wanted to see how it ran with the new intake and carb. when he stomped it and it wound up to like 4300 in 2nd, the whole truck would like surge back an forth. sort of like a misfire or fuel starvage.

it did this in 1st gear and 2nd gear...

anythoughs on what this might be? the plug wires are kinda cracked from getting toasted on the headers. but not burned through to where they arc on stuff...could there be enough "electical pressure" to at this rpm range they Could "jump" out and cause a misfire?

its a 350 hei, msd, standard fuel pump, edelbrok airgap performer, 1406 carb, and gm performance 290hp motor.

im thinking that the "standard" fuel pump isnt enough for the motor. when i put it in i just bought a stock filter for an 84 blazer.

 

[Hogback Fabrication]

Your fuel pump flows plenty for your motor. The wires may be causing your problem. If they are in bad enough shape to arc they would probably arc all the time.

Do you still have the stock distributor with an MSD box? What brand wires?

It could be either fuel or spark.

 

[4X4HIGH]

It sounds to me like valve float. That usually doesn't happen until around 5500 rpm but if you have weak springs it could definately be what you're experiancing.

It could also be your plug wires arcing at a certain rpm especially if you already know they're cracked and not looking too good. Easy enough to change them out and see if you can duplicate the problem.

 

[broncoman6524]

it sounds to me like valve float. That usually doesn't happen until around 5500 rpm but if you have weak springs it could definately be what you're experiancing.

i thought this too...hmmm maybe i need to take it back to the dealer. (warrany on motor)

yes it is a stock distributor. (4pin) so it has the fancy msd module eliminator thingymabobber. inside it. and theyre accel 8.8 wires. they arent bad enough to where they arc, but where the cracks are you can see the 2nd layer of insulation around the copper cores. if that makes sense

 

[4X4HIGH]

I'm pretty sure i read on MSD's website or in their catalog that you cannot use copper core wires with their products.

 

[broncoman6524]

huh. i did not know that...lemme check my manula for the stuff...

 

[broncoman6524]

hmm you are correct my friend.

"solid core spark plug wires CANNOT be used with an MSD Ignition"
these are my wires. http://store.summitracing.com/partdetail.asp?autofilter=1&part=ACC%2D8033&N=700+400020+4294864973+4294908395+115&autoview=sku
since it says that they are "silver coated copper core"

they cant be used w/the system correct? guess i REALLY need plug wires now huh!?

 

[4X4HIGH]

Well, glad i could help, sorta. The best wire you can buy is the MSD's they aren't cheap but they last a long time. I usually change mine about every 5 years just for GP (General Purpose).

 

[broncoman6524]

im leaning towards those Or the taylor spiro wires. idk im just gonna swap wires for now and see what happens.

 

[4X4HIGH]

I've run both the taylor wires and also the accel wires and had bad luck with both brands. After running the MSD's i'll never run a different wire again. It's your choice though but at least swapping them for anything else to check for your problem sure won't hurt.

 

[jtrux]

i've run the accels, msd's, and taylors. I did not notice a difference in all of them but in the end I stick with taylors for personal preference. For 45 bucks walk into oriely's and pick up the universal accel kit, i've used them on two trucks and they did there job.

 

[broncoman6524]

Ok. found my original thread. so i talked to my neighbor who is a master gm mechanic. he said to pull the msd stuff OFF and run stock. (6a box)

Did that drove PERFECT. Wehn i jumped on it, it kicked down into 2nd and stayed there till 80 then i let off and slowed down

I called msd they said to hook my box's ground directly to my battery instead of a ground straight to my fender.

Ill do that tomorrow and report my findings.

Im so happy that ive gotten this almost figured out. The solutions im seeing are, bad box, bad ground, weak coil, weak power wire going into the box (original coil wire).