thomasev

Hi.. I´m a Norwegian corvette owner who just have replaced original cam with a comp cam (XE 08-503-8 cam). I have also melrose headers and BB Tri-flow exhaust (3").. We did not replace valve springs (will do that later), and my question is .. The car is running quite good at full throttle, but I have some problems at idle rpm.. I have to work with it to keep it on idle rpm, and it is kind of hunting up/down ..

Anyone with similar problems? And yes - I have searched the forum ;-)

regards,
Thomas

STL94LT1

If you are still running the stock valve springs they should be changed ASAP!!! You'll need to get the computer retuned (chipped burned) to get the idle right.

neverendingprojects

^^^^ This
Stock valve springs & Full throttle does not sound like a good idea with the cam you mentioned!

bobmic93

Valve springs, 1.6 rockers and a tune and you will be rolling smoothly. At ported heads ASAP for real power with that cam.

pologreen1

agree with above, and do you have stick? I think that cam in an auto might need a slight stall

cv67

Yikes... dont even drive that thing til you get springs!!
Trust me it isnt "fine" even though it may seem like it to you' tuning is a waste til this is done.

You can get a hafl; decent valvespring kit for about $80 uses stock retainers, etc. Get some new seals while youre at it, youll need them.

http://www.speedunleashed.com/comp-c...eries-cam.html

pologreen1

that is one way to a builders heart, tell him your doing this.
cuisinartvette I can only imagine how yoiu reacted to this

thomasev

Thanks for all your comments - I´ll leave the car until new valve springs are in place ;-).. The Comp Cam FAQ says about XE cams "We do not recommend the use of stock valve train..."..

I´ve just drove it back from workshop and once after that.. New valves will be ordered at once..

thanks,
thomas

reoch999

I have the same exact cam, and absolutely would not consider using stock springs. It's not just about the lift (which is too high even for LT4 hotcam springs if you're using 1.6 rockers), the steep ramp rate on the cam lobes need stronger springs to keep the lifter riding on the cam. If you run it with weak springs, you will cause valvetrain damage. Not to mention the negative effects of valve float on high RPM power.

With the right springs and tune, that cam will make good power even with stock heads. But do yourself a big favor and get some decent springs.

If it's an auto, you'll certainly want a higher stall torque converter to prevent it from bogging from a standing start. I'd guess at least 2400, I'm using 3000, and I've heard of guys going as high as 3600 with this cam. I got mine from Pete K, the resident transmission guru on this forum. If you need one, hit him up. He can hook you up with exactly what you want, and he's been extremely helpful with all my questions.

I got my tune mail ordered from PCMFORLESS.com. Pretty good for a mail order tune, considering the person who made it has never even seen my car.

thomasev

I will order new valve springs and rocker arms Monday.. And I have one last question - what about fuel injectors? I´ve also bought 8 new Bosch 3 gen fuelinjectors from www.fuelinjectorconnection.com... The injectors are :

http://fuelinjectorconnection.com/sh...od&productId=5

but they seems to be a a mm or two to long... Bosch injectors are 32lb/min injectors but engine is running to rich. Are stock injectors delivering enough fuel?

Stock injectors are re-installed... Dont know what to do with bosch injectors...(as long as it they seems to be a mmm or two to long and engine is running to rich)

Regards,
Thomas

farscape1a

the reason why the engine is running rich with the new injectors is because you need a tune to get the new injectors to pour the right amount of fuel into the engine. the stock injectors are only 24#. a tune is definitely necessary to get bigger injectors to run right. i would do a tune anyway since you have a new cam and are getting 1.6 RR's.

STL94LT1

Thomas, those Bosch III 32's will work fine in your car with the right tune, or you could contact Jon at FIC to see if you could trade them in on BIII stock flowing injectors to run without a tune.

pr0zac

if you are running a 503 cam, 1.6 rockers or not, on stock lt1 valve springs i would imagine you have probably collapsed a few lifters if not all of them..

thomasev

I will order

GM PP Kit (#12371042) and
Comp Cam Valve springs (#26918)

and re-install Bosh injectors and get a tune... Hopefully thats what required to get the car running OK with new cam.. ;-)

regards
thomas

thomasev

New valve springs are installed together with new set of RR (from GM performance parts). Just drove the car back from workshop, and just by replacing old valve springs with comp cam recommended springs did a great job about idle..

Only two short questions : what is the best chip for my setup (know about pcmforless)? My setup now is 07-503-8 (XR276HR) cam and new valve springs, new RR, melrose long tube headers and bb tri-flow 3" exhaust..

My second question is how to properly break in new valve springs.. Heard about run engine warm and cool down two times..

The sound is great - even better with new cam...

Regards,
Thomas

cv67

Couple heat/cooling cycles is fine, should be ready to "go"