to much fuel? new plugs? not enough power

[mhorn0817]

welp ive finally tried getting on the new musatng i picked up...i was taking it a little easy when i got it so i could get use to it, i went out last night and went to have some fun and the power is just not there like it should be...some info on the car is...

new 331 stroker motor all forged internals
edelbrock rpm heads
edelbrock rpm air gap intake
crane 1.6 roller rockers
snyper NOS nitrous kit 50-150 shot (not fully installed)
holley HP seres 750 mechanical secondary carb
lunati cam # 51014 500 510 lift 284 292 duration
lunati billet steel double roller timing chain
bbk equal length headers
flowmaster exhaust
holley external fuel pump
holley fuel pressure regulator
autometer fuel gauge says 7psi
full msd ignition,new

i checked the timing and its dead on, kinda seems like it may be getting to much fuel and boging out but im not exactly sure...i was cruising down the highway at 55 in 5th gear and mashed the gas and it didnt really do anything except backfire....1st gear feels ok then when i shift into 2nd and just doesnt pull it just goes...

what should i do and check?

 

[5.0Droptop]

Do a WOT pull and stop and check the plugs for color. If they are white its lean if they are brown its ok if black its rich.

make sure it has the correct plugs in it.

Check the plug gap as well. The gap maybe differnt than a regular efi 5.0 since its carbed and has a differnt ignition set up most likely.

 

[dcurtis]

Sorry I don't have an answer for you but, I am currently building a 331 stroker with the same cam as you, only I am going with an edelbrock rpmII efi intake and rhs heads, so I was wondering if you could put a soundclip of your car on here, the only soundclip I found was also on another forum but people were saying it wasnt the cam it was said to be.

 

[SMOKEDYA]

I THINK YOUR RUNNING WAY TO RICH WITH THAT BIG OF A CARB. PEACE




JOHN

 

[mhorn0817]

ok, what kind of plugs should i use and what should i gap them at?

i will try to get a soundclip of the car soon for you, just remind me

what kind and size carb do you think i should put on there?

 

[vristang]

Maybe try tuning the carb before replacing it...

What gears do you have?

 

[joel5.0]

A 750 Holley is not too big of a carb for a 331, do need to tune it as mentioned above (specially with a 180° intake View attachment 314032 ), and the process starts like 5.0Droptop recommended.

 

[mhorn0817]

im not the best carb tuner so im assuming i should take it somewhere to be tuned

im unsure of the gears in the car but they are low (numerically) , i have a set of 410's ill be putting in this coming weekend. the guy before said it ran 11.5 on nitrous and with 373 gears. would gears make an impact like that?

what exactly do you mean by a 180 intake? whats wrong with my intake? what would be a better intake?

 

[joel5.0]

180° intake as in double plane....... a small single plane would have been a better choice.......IMO.

 

[mhorn0817]

ah ok,how come? which would you suggest?

 

[joel5.0]

The Weiand Xcelerator would be a good alternative, also keep in mind that even though is "doable"..... a shot of NOx with a dual plane requires additional attention to evenly spread out its hit through the engine. Another item you don't mention, is the total timing setting and the advance curve set in the distributor. LUK

 

[jrichker]

Backfiring out the intake is either a valve stuck open or a lean mixture or spark plug wire(s) connected to the wrong cylinder(s). Check compression on all cylinders and then look for vacuum hoses loose, cracked, or misconnected.

Sticking valves: If a intake valve is bent, has a bad spring or is misadjusted, the engine will sometimes backfire through the intake. Use a vacuum gauge connected to any convenient spot on the intake manifold. Run the engine at 1000 RPM & look for 18-21 inches of vacuum with a steady needle. A problem intake valve will make the vacuum gauge needle sweep 5-10 inches.

Backfiring out the intake has been known to rupture the power valve diaphram in some models of holley carbs. Once the power valve diaphram ruptures, you get an overly rich mixture.
See www.chevyhiperformance.com/techarticles/74058_carburetor_valve_problems/index.html for more information on power vavle problems
or
http://www.automedia.com/Holley_Power-Valve_Blowout_Protection/pht20011001cb/1

 

[mhorn0817]

im not exactly sure about the timing, how could i tell?