i was looking at summit reman q-jets, and i had a couple questions.

1. are they a good deal (750cfm, $280)?
2. what is the best main jet/rod combo for my 355?(motor specs in sig)
3. should i go w/ something else?

as odd as it seems, this motor is getting me back and forth 80mi. a day to tech school so driveability and fuel economy are somewhere in the back of my mind. it seems to want more fuel. i have r42ts equivelant plugs 34° total timing, 15° base/manifold vac timing. the engine runs good up untill 2.5k-3k and then falls away and feels weak. iv'e been playing w/ the timing for a week now. when i thought i had too much timing, (ping @ light throttle when warmed up) it ran a lot stronger up untill it warmed up. now it's driveable, but still pinging if its "lugged" slightly, and hiccups ever so slightly when loaded (taking off up hills, ect.). the engine is'nt nearly as powerfull as it should be. since i am pressed for time every day of the week, a new carb seemed to be a good choice, since i need the car to be available every day. any thoughts/ideas will be greatly appreciated

 

I don't think it is a carb problem but more that you are over cammed for the rest of your combo.

Drop the cam down to around 225/225 @ .050 and you will see the engine wake up.

 

That is a big cam alright.
Not sure if I mentioned this to you before, but i'm interested in your combo, i'd like to see it running "right" and see how it goes.

I think you can kiss fuel mileage goodbye though

Rods/jets depends on so many factors it's not even funny. I asked that question once before (search for my threads on q-jets, I posted a thread with rods/jets as the title actually...).... Mainly, high speed air bleed throws off recommended rod/jet setup.

What's the carb now?
What's static CR?


falls off at 2.5-3k sounds like either fuel delivery, like you're thinking or spark (ok, duh eh?)..... Perhaps get the coil and module tested? Plug wires are known-good?
Any kinks in the fuel line or anything like that? Float level is good?

I'd just do up a junkyard non-cc q-jet, if I were you. Play with that for a bit.
Maybe first borrow a known good carb to let you know if it's a carb problem in the first place.

 

thanks for the replies.

fast355, i was hoping on doing that sometime later on. when i can borrow another car. i learned a lesson though, dont take the guy's word for it who's selling you the enigine when he says, "oh it just a mild cam"its more like a mild NASCAR cam. i will always find out specs on what i get before i put it in the car

sonix, i am curious to see how it runs when/if in tune too, hahaha. the entire igniton system is 4 months old so its a known good system. static C.R. is NOT calculated but its around 10.5-11:1. the fuel mileage, well i meant that its not a racecar and i basically want to run as lean as possible w/o sacrificing too much driveabiliy. (as much to be excpected from the combo obviously) it's funny though, we have very similair combos. i just seemed to have taken too many "shortcuts" to try and get my car up and running asap.

 

you *too* eh? mine isn't running now, can't get it to fire up to break it in, just started puking oil /coolant...
I'm getting to it though.

how much vacuum advance do you have? EGR? Might want to ensure those are there and "correct" to maximize efficiency.

 

EGR? Is an understatement, that cam has PLENTY of built-in EGR.

 

big cam big as far as the carb goes ive used them for daily driving to my hotrod tothe rece car these carbs are extremely easy to set up an the best part is they hold a tune . ive tried alot of other carbs an i like vacume secondary i have tried mechanical seondary and just didnt care for it not that it was nt a good performer just wasnr what i wanted dubble pump good luck an if you have emissions to go through i dont think so and as far as running the same everytime out the box dont think so if i was to rank carbs right now id say edel brock thunder series #1 qaudra-jet #2 holley#3 although the holley performance is unmatched on the quarter untill the thunder series this is vacume secondary and bsed on my experience

 

 

^^ if only the EPA would see it that way."See mr. treehugger, the obnoxious lift and overlap from this aggresive camshaft promotes exhaust gas recirculation."

anyhow, as an update, im going to try and borrow some bigger carb and see if that helps. if it does, i will probably go to the 750DP. i tried a 650 dp, and that helped a lot. it just leaked vac. at the throttle plate shaft, so i couldnt idle.

 

They do now days. Ever take a look at the LT4 and LS6?

 

EPA just sets the standards. How the manufacturer meets them is up to the manufacturer. My '90 Bonneville doesn't have A.I.R. I picked up a '91 L27 that doesn't have EGR. But, my mom's '93 L27 does have EGR.

Now,

 

I have a 750 Speed Demon carb in my sig for sale if anyone is interested.