Just wondering something:

If you leave the car sitting for a few days, on initial start up does it have a hard time idling, like it's searching, until the lifters get pumped??? I've noticed that with my car, and I"m not sure if it's right or not. FYI it's a 355 with a big Joe Overton one off cam.

After sitting for almost two weeks, I fired it up and it wouldn't idle, just like before. But, after about a minute of me using the pedal to keep it alive, it settled down somewhat and was a lot better, and the clacking definitely quieted down too.

 

I have a 233/239. Not sure if you would classify that as big or not, but I also have comp R lifters and yes, after sitting for a while, the car needs a little bit of time to idle before I can drive it.

 

Ran a 235/242 for about a year. Ran great, but I worked pretty hard on dialing in the tune. WOT = easy. Part throttle = work .

I'd adjust your valves and play with the tuning/TB blades. Try different tuning (software and hardware) techniques and you should be able to find something that helps fight this problem.

Ryan

 

Mine doesnt do that at all with the 847. It can sit for 2+ weeks and it starts right away and drives. I dont have the R lifters though.

 

That's what I was hoping to hear. My cam in 30's/40's in duration and VERY agressive lobes, so I was expecting to have an issue after sitting for a while. That, and the tune is just a loose baseline to keep the car running, from PCMForless. Once I get this new fuel pump in he and I are going to road tune it, so hopefully it will get better.

Thanks for the replies everyone.

Valves have been adjusted numerous times, see the above post as to tuning. Thanks!!!

 

I have the same problem. (Custom n2o cam, 240ish dur. with Comp Rs) It can be the next day and I have to slightly open the throttle for a minute then it starts to idle right. I also have a baseline tune from PCMforless.

 

Had the same issue - your valve lash is set incorrectly. ONLY way to adjust Comp R's are with the car running and hot. Once they're set right, you shouldn't have the problem anymore.

 

Only way for you maybe. When I adjusted them, for the millionth time , they were hot, and I did the individual valve method. Started it right back up and everything was fine. Two weeks later they have aparrently bled down.

I just have no luck trying to adjust them with the car running. I can't get it that way.

 

My car acts similar after sitting for a week or more. Will start right up but runs VERY rough for 10-15 seconds then smooths right out. I have a little baby cam 242/252.
Steve...

 

Yeah, my cam isn't quite that big.

 

I have recently found out, that I have this little problem too...Sat for over a week, and it idles pretty rough for the first 5 minutes or so..

 

I've done it the same way you did as well and I guarantee that it's still not right. The engine cools down too much by the time you get all them adjusted. I've even gone so far as to use a dial indicator to set them and they were still off. Probably the closest they were ever set is when I built the engine and set them with the oil pan off so I could see the lobes of the cam and used a DI.

I thought the R's would be easier to set since they're supposed to have a big pre-load on them. Seems not to be the case. Best way I have found to set them is with a mechanic's stethoscope, a set of stock steel valve covers with the tops cut off and the correct stepped lash setting wrench/Allen T-handled wrench. Every since I've used this method, the valve train noise is almost non-existant and my dyno runs are very smooth (with smoothing turned off on the dyno software). I have set several people's valve lash using this method who swore theirs were "perfect" and they saw improvements in both noise and on the dyno as well. The majority of the time the lash is set too tight (like the lifters are bleeding down when the engine is off).

 

My car sat for over half a year

Fired right up with just a revolution or two and sat right down into idle though

My valvetrain makes a racket for a short time but that comes with the territory. I lash my lifters cold, fwiw. I find zero lash, tighten the lock, and then give the nut enough torque to lock it in place. I would say that puts my lash at 1/16 to 1/8 turn past 0.

I have spent quite a bit of time with ignition and fuel maps, as well as physical IAC work. I don't ever recall having a big problem with it though. Certainly not having to give it throttle to maintain an idle.

 

Just went home last weekend and mine idled fine. Had been ran for about 3-4 weeks. But, now that I think about it, it almost wanted to die when I first drove it around. I dunno.

 

sure ya dont have any injectors leaking? Thats what it sounds like to me, check for some smoke out the back. I had the same prob. with my 306 cam and stock lifters, turned out a couple of injectors where leaking. just my 2