I know that there are several guys on this board with strokers and bigger cams. A few of you have chimed in when I was deciding on my setup a few months ago. I need your input again.

My setup is a TSP built LS2 402 with ported L92 heads, L76 intake assembly, UD pulley, Kook 1 3/4" LTs w/ORP, and a 236/240, .598/.605 114 cam.

I'm very happy with the performance of the car. My specific issue is idle transition. The problem is most pronounced when I run the A/C and am in stop and go traffic. For example, if I'm sitting still idling at 950 rpms and I need to move forward a little, I give a little gas and ease out on the clutch. But then I have to stop again quickly and push the clutch right back to stop. This will cause the idle to "flare" up a little and then drop down to 400 or 500 rpms (instead of 950) and then it bounces back up to 1500 to 1800 rpms. Sometimes it may do this "bounce" once, sometimes, twice.

Can this be fixed with tuning? Does anyone else have this problem? It was especially annoying when I was driving at the Eureka Springs Corvette weekend last month. There was a lot of traffic, so I was constantly have to creep forward in traffic and everytime I pushed in the clutch, the idle "bounced." So it sounded like I was driving along blipping the throttle. It was too hot not to run the A/C, so I had to just live with it.

If I turn the A/C, it doesn't do it as bad. But it will still do it occassionally.

My mechanic has tried adjusting the tune, and has been able to keep it from doing multiple bounces on one stop, but that has caused the throttle to hang at 1500 rpms when I slow down from a constant throttle situation. He doesn't have any experience tuning bigger cams, so we are just trying trial and error.

Can this be fixed or do I need to go to a smaller cam? This car isn't my daily driver, but I would like for it to be mild mannered enough to serve as my daily driver next Spring and Summer.

I'm going to post this in the Tuning section, as well.

 

I think u may need to try to find another tuner ,yes this can be fixed ,its definatley in the tune

 

It's definitely a tuning issue, and is a very common complaint with larger cammed cars.

This is exactly why so many comment that big cams suck in stop n go traffic, but yes it can be fixed, you just need to find a tuner willing to spend some time with it.

 

What cam are you running? Have you had any issues? Who did your tune? I would love to talk to someone who has tuned this problem away.

 

Rob, I think you know I have a very similar build with a 234-240 112 +0 cam. I don't have that problem at all which tells me that it is a tuning issue in your case.

Contact my friend JACKS996. He had a tuner in Oklahoma do his 346 H/C and is very happy with it.

Good Luck,

Kevin

 

Kevin,

I was hoping you would reply to my thread.

Do you have any problem with the rpm sticking at 1500 when dropping down from a constant throttle? Does your car ever run rough and have trouble idling at cold start up?

I want to have hope that these issues can all be tuned out of my car. I really would prefer NOT to change the cam. I'm very happy with the performance.

How can I get in contact with Jacks996?

 

Rob,

JACKS996 is on here often. Jack is a friend of mine and bought the H/C 90/90 setup off my 346. He moved to Texas and I know he found a tuner he really liked in OK.

My car does not like to idle well until the water temp reaches 120 degrees which is pretty quick. I just need to get back together with Ed so he can take care of that. It's minor. I purposely asked Ed to make sure things were good with the AC on. I had that problem initially with the 346. My idle returns fine and doesn't hang at all.

Check with Jack and let me know.

BTW: Bob K has the same cam you have - I believe and Ed tuned that to run perfectly so it can be done. Just stay with it.

Good luck.

Kevin

 

I am running a Ecs Blower cam ,Not a big Cam ,It will have Nice street manners for the 402,The cam is a comp custom Grind That The boys @ Ecs made up ,The cam is in My 346 right now ,I will be pulling it out & Putting it in the 402 ,I see you are in Broken Arrow ? I would think Ed Wright ,Tulsa , Could tune this car Fairly easy

 

Thanks, Kevin. I appreciate the information.

 

It is definitely the tune and can be fixed. Are you still using a MAF?

 

Hi Rob,
Call Jim at swtuning.com. He can fix any tune. When other places can't get a tune right they send their cars to him. He is located in Ok city. My car is the black vert on his website. Mine had a problem where it would hang up at 1500 and would rev real high when starting and he tuned it and it is perfect now. tell him Jack sent you.