Okay... Here's the situation.

I tore my motor down over the winter after shearing the teeth off of my oil pump drive gear. At that time I pulled the CC306 out and installed a 230/236 cam on a 110ls, running the high energy ~ .598/.608 lift that Combination Motorsports carries.

Installed new valvesprings - Combination Motorsports dual springs - and a rev kit also at this time... I knew the ramps on this cam were pretty steep, so I was trying to take every precaution necessary.

Got it all up and running and the car wouldn't rev past 5800rpms. I put it on the dyno and it pulls nice and smooth and suddenly stopped @ 5800rpms ~ dead in it's track. At that point it was making 10rw more than my 306 did @ the identical rpm. I was totally expecting this cam to pull up to 7k - so I dismissed the problem then as being valve float.

I talked up the problem w/ Seth @ Combination, as well as with Jordon and we all pointed it to being something w/ the valvetrain. Seth hooked me up w/ some crazy springs - not sure what PN# they are but they're dual spring w/ dampners... Supposed to be good up to .700 lift! I installed these at 1.780 - checking and shimming the valve seat on each individual valve. I also installed a new set of stock lifters.

Anyways... Fast forward to tonight.. Took it out for a spin and now it quits revving @ 6400. I floored it in first and the car quit revving - I swear it feels like it's hitting a rev limiter of sorts, but my pcm is set to 9000rpms. After that I put it in second and it was bogging down... kept a nice steady rpm @ 2500 and it cleared itself out. Put it back in second and gave it about 1/2 throttle, seeing just exactly how far up it would rev.. Bam.. 6400.. That's it.

Everything on the car is perfect.. Pushrod geometry is right on. I'm using .050 lash caps, but it's a-ok. Roller wear is dead smack over the center of the oil hole in the cap.

Guess I need more spring?

LOL.

Solid roller soon to come

 

Two questions-
1- do you have any logs of the car?
2- what pcm do you have since you have a 9000 rpm rev limit?

 

obd1 pcm... LT1 Edit. And yes.. I know the car won't rev past 7200, no fuel mapping or whatever

 

stock replacement lifters maybe you're collapsing them... or your tach just sucks and you're at 7k but dont realize it. might be running out of fuel too. but it does seem valvetrain related.

 

Since you have obd1, can you download datamaster and get some logs? That would help us alot.

 

I've a got a 255 intank replacement I'm gonna put in.. I'll get Jordon to log some runs when he's up here next w/e.

 

sounds like a valvetrain issue.

 

Please keep us updated. I'm about to get into a similar boat (large HR).

Ryan

 

I'm gonna pull the intake and replace the lifters w/ some comp r's.. Assuming I have enough seat pressure @ my installed height. No one else has had this problem like I am apparently though. So you just might be okay

 

Sounds like user error to me j/k bro

If you have new lifters, I am doubting that is the problem (not saying that it isnt). Sounds to me like valvesprings. ??

Stop messing around with this hyd stuff and join the solid club
Drop me an email
Jason

 

do the valve spring fit right? cause if bot you might have to machine the guides and seat

 

Take the rev kit off. Problem solved (assuming you have good springs). Trust me.

 

Just a thought. Read second page, first paragraph.
http://www.gowman.cz28.com/guide.html

 

I'm thinking Valvetrain as well, but like Jason said, Pete.

 

Shawn: Any luck?

I am having a similar problem at 6k. Its like the car "hiccups" or "misses" past 6000rpm. It still revs up a little, but it is definitely not smooth.

I can't tell anything from the Datamaster logs - no strange readings that I can tell.

The cam is a GTP6 grind - 235/242 .568/.592 on a 114lsa. I am running stock heads. I expect that the heads are choking my cam down, but doubt the heads are causing the car buckle/hiccup/miss after 6k.

Ryan