98 LS1 Surging

**bwcubicle** · 11-24-2013, 04:06 PM

Hi i am new at this site. Just bought a 63 chevy II with 98 LS1 motor, 92mm fast throttlebody, Competition cam 219 227 duration at .50 607/614 lift 112 lobe separation. ET performance CNC heads. This car is idling up and down a little and it is surging or hunting just crusing down the road around 25 to 30 miles per hour. Is this too much cam for the stock computer? Is this computer trying to run the car off vacuum? I am lost. Nice car but i am sick about the way it is running. Guy told me he had it tuned and tuner told him it needed a stall converter. Cant really see how that would help, with it doing it at idle? Help please

**0rion** · 11-24-2013, 08:45 PM

sounds like it needs a better tune AND a stall. I'm assuming it's an automatic. I would put at least a 3500 rpm stall in it. It does sound like your idle airflow tables are off. Do you know who tuned it the first time?

**bwcubicle** · 11-25-2013, 02:58 AM

I was told it was a place called XP Racing in Oklahoma. I bough the car in Oklahoma. I dont really want a stall as i am not using the car for racing. I just want a nice cruiser. Will a cam this size cause problems with the electronic tuning on this type engine? I had rather take the cam out of it than go with a stall. I dont want the high rpm and slippage that a stall gives. Also the person i bought it from said the Tuner said he had to drill a small hole in the throttle body to be able to tune it. I am not sure if he meant for test purposes, or if he was bypassing some functionality. I know i am throwing a lot of information at you that may be confusing. If the car can be tuned with the combination i have i would love that. If not i had rather take cam out instead of installing stall. I live in Mississippi, how would i find someone that could tune this car? I am use to carbureted cars

**0rion** · 11-25-2013, 03:47 AM

first off.....are you familiar with lock up stall converters? Once locked up which is ~40mph they drive exactly like stock so you're not running around at higher rpm's all the time. If you're not familiar with them I would hunt around for someone that has one and take a ride with them before you did all the work of pulling the cam over it.
Secondly....the way these cars work is they have tables in the pcm for air and fueling that control how the car runs/drives. When you go to a bigger cam you have to adjust those tables. When not done correctly you'll get the issues you're having. That cam isn't what I would pick for an automatic car but it should drive pretty decent with a good tune.
Lastly.....the fact they drilled the throttle body tells me you need a better tune. I'm not familiar with that company but we have a bunch of people on here from OK that might know of them. Drilling the throttle body is the old way of tuning. No reason to do that anymore really. I'm not aware of any tuners in MS. Put up a post here and see if you can find any references. I would ask around locally and get plenty of references before paying for a tune. A tune can make or break how a car drives.
The bottom line is without a stall and a good tune you're going to have small issues with how it drives but that car can be made to run pretty decent on the street. My suggestion is to do some research and don't rule the stall out until you can ride in a car that has one. I run a 3500 in mine with a 228 duration and .588 lift on a 114 and it cruises around just fine. My wife takes it for groceries on a regular basis during the summer.

**bwcubicle** · 11-25-2013, 04:03 AM

I am not completely opposed to the stall. Can it not be tuned correctly without a stall?

**bwcubicle** · 11-25-2013, 04:05 AM

Is the throttle body messed up now it is drilled?

**black04gto** · 11-25-2013, 04:33 AM

i wouldnt say that the tb is messed up now from what i gather its just an old out of date way of doing things. the stall would just help the car run smoother with a lumpy cam like that. i have a friend with an 87 IROC-Z that has a 350 TPI with full bolt on and a cam that has a 3200 stall as a DD. Ive driven it myself and honestly its pretty easy to drive around. Your issue with the surging could be fixed with a better tune. Was the car used as a track car by the previous owner? If so the tune has prolly been run wide open throttle and not much during normal driving so the tuner didnt put much time into ironing out the mid range details. Just a possible answer.

**0rion** · 11-25-2013, 04:56 AM

as far as the throttle body.....most tuners would rather have that throttle body stock but depending on how much they drilled it out it could probably be worked around. I've even heard of guys using a pop rivet to fill that hole and then re-drilling a hole back in it the size of the stock hole. I would talk to a tuner before doing anything though. I'm sure there's some reputable tuners somewhere down there but like I say.....get references before having anyone tune it.

**bwcubicle** · 11-25-2013, 05:03 AM

Haven't figured out how to post on here yet, just a thread

**bwcubicle** · 11-25-2013, 03:07 PM

Would u mind recommended a type converter that will work on these type engines, and that will be used on the street 100% of the time?

**black04gto** · 11-25-2013, 03:09 PM

Yank. Hands Down.

**jb3golf** · 12-10-2013, 09:08 PM

Is it just me or is a 92mm fast tb too big for a stock manifold set up? I would look at getting a stock unit and go from there. ...hmmmm

**Firebirdjones** · 12-11-2013, 04:00 AM

On the throttle body hole, if this helps at all, you could silver solder them. I solder drilled holes in carbs quite often when the tuning goes a bit too far, then redrill.