jdk971

i am not a mechanic. my builder and mechanic put a ls3 480, rs500 transmission 3.27 first gear, and 3.36 out the back in my 63 corvette.
no complaints with build or power of engine. in fact jake the builder did
a excellent job.
i have a couple of questions
1. i get a bucking in 1st gear at low rpms, is this normal feels like old timing
advance in old sbc
2. when cruising i feel a slight surge or back off on and off, like a miss, but
it is not a miss. i think.
3. when i back off a slight pedal press, it sounds like it is back firing out back
i have heard this is normal.

thanks jim cols ohio

3pedals

iTrader: (3)

Carb?

redbird555

iTrader: (14)

Im going to take a shot in the dark here and say its fuel injection because the ls3 480 from gm is just an ls3 with a hotcam. With that said who tuned the cars pcm? Was it just a mail tune from gm or was the car strapped to a dyno. Honestly if it is fuel injected then its probably something in the tune that needs to be addressed.

1lejohn

iTrader: (9)

How low of rpms does it buck at. Is the rs 500 a standard trans? Almost sounds like its the torque convertor if it was an auto.

hivoltagedriver

iTrader: (1)

I think your 1. and 2. are related, and might be in the driveline. It's hard to explain, but I got the same kind of thing with my 6-spd GTO a little bit. Your cam isn't huge like mine was, so it shouldn't be too bad. You don't have a stall convertor to soak up some of that like you would with an auto, so you feel every little bit of slack in the driveline during your throttle transisions.
3. is most likely normal pops or burbling on deceleration that you will hear with an LSx motor and a free-flowing exhaust.

jdk971

i believe you are right, talked to jake the builder and paceperformance where
i got the engine and pcm. it seems the gm computer has had some tuner problems. i hate to spend 500 bucks, for a tune, but it seems a lot of the bucking with low rpm first gear and surging can be tuned out. i hope so for
the cash. today i started up in second and had less of a bucking than in first.
i am glad you think the pops and stuff is nothing to worry about. if it was a
standard sbc with a carb, and it back fired like this i would worry about fuel
washing down the cylinder walls.
so far i like the engine and the keisler rs500 tranny. i am going to upgrade
the halfshafts to big block ones along with the joints. only regret is having
these mufflers. i believe they are too free flowing, loud.
thanks again jim