I recently installed a Comp 306 cam in my '95 Firehawk and it runs like crap. It won't stay running unless I feather the gas and the engine vibrates like crazy.

I also replaced the springs with the matching Comp Springs on the heads but I did nothing to the valves. Someone suggested to me that I should have had the valve guides milled since the cam has a .540 lift. Is that something I should have done or is the stock valve lift okay with the 306 cam? Please help!

 

Is it tuned?

 

No, it's not tuned. At this point I can't even drive it and the only place in town that will tune it is 45 minutes away without traffic and they want $550. I don't want to spend that kind of money not knowing if that will fix my problem or not.

 

Well between the granatelli and the lack of a tune, I don't think you will ever get it running well enough to say there are no mechanical problems without a tune.

You can not go modifying a car this extensively without IMMEDIATELY addressing the tuning.

Since you made such poor choices and have so little understanding I would bet there is a mix of missadjusted valvetrain too. How did you adjust the lifter preload??

 

The MAF is stock, I never put the Granatelli in, thanks for assuming, and the heads were taken to a shop to have the springs put on so I did nothing physically to the heads myself, however they didn't do anything to the valves.

I know I need to have the car tuned, but it shouldn't run this badly either. So again, do I need to have the valves milled or not. I was originally told that I could run a 306 cam with stock heads minus the springs. Can you help me with this or are you just going to insult me some more?

 

I made no assumption, you put the part in your signature, you gave us bad info.

I was not saying the springs were changed wrong or anything I was saying the rocker adjustment was probably done wrong since it is something most people do wrong the first time thanks to so much bad info out there.

What is it that you think needs to be milled on the valves??? Whomever told you this is wrong I just want to know what they were thinking. Maybe they meant the guides needing to be milled down?? That is applicable to some other heads but not these and even that is not the valves themselves.


The fact you were told you could run the 306 cam on a stock shortblock means you went somewhere bad for info anyway.

I have seen guys snap rocker studs when using stock rockers at LESS lift, seems hit and miss, some get away with it, others have the slot bottom out and snap studs.

 

you can run a cc306 on stock heads, i know because i have done it. my heads aren't stock anymore but the were, and it ran fine without a tune also, but it did run pig rich. it sounds to me like you have another problem

 

CC306 + Stock Tune = Not a good idea!!! Check your O2s as running that rich you have probably screwed them up esp. if they are the originals. As to the rest check your plus (and gap), wires and also let us know if you are throwing any codes as this will help diagnose greatly if it is a sensor issue.

 

Yes, I was referring to the valve guides being milled down, sorry for not clarifying that.

As for the 306 cam, I was given bad information and had I done the research myself and had more time to get the car repaired I would have gone with the Comp 305 cam instead, but at this point that's probably not going to happen; especially since I can't return the 306 at this point. I've just about run out of money, which is one reason for not spending $550 on a tune immediately, and I've spent over $3000 so far with not much to show for it.

Let me backtrack a bit. This job started off as a blown head gasket that evolved into adding some hop up parts since the engine was torn down so much which is why it got rushed (my wife was nagging me to fix it and get rid of it). The person helping me do the job works at a car repair shop, drives an LS1 T/A that he put a cam in and so I thought he new what he was doing. He suggested the 306 so I went with it. He didn't do a bad job, but he didn't do as good a job as I expected based on his experience either. Here's a list of what got replaced during this job:

Fel-Pro Head and Timing Gasket sets
ARP Head bolts
Bosch Water Pump
Delphi Opti-Spark
Moroso Wires
NGK plugs
BBK headers
Comp 306 cam
Comp Springs, Retainers and Valve seals
SLP Airfoil
1 Fuel Injector (the car sat for over a year and this one didn't seem to work)

Couple of other comments: When he adjusted the rocker arms, he did it with the engine running and tightened/loosened them like that. Not really sure how he new what he was doing was correct, but that's what he did.

Also, I thought that perhaps the timing chain/gear could be one tooth off; not really sure though. I thought about taking it off and moving it one tooth to the right, putting it back together, check it and see how it runs like that. If that didn't work, I was going to pull it back off and move it one tooth to the left of the original spot and see how it ran then. I don't know how else to figure that part out since I'm limited on tools.

Well, I think that about covers everything. If not, let me know. Thanks!

 

I'll check the O2's out since they are original, but I know the gapping is good on the spark plugs, they're getting spark and the wires are brand new as well. I've quadruple checked the wiring to make sure they are on the corresponding cylinder from the opti, so I doubt that's it. Thanks for your suggestions!

By the way, do you know of anyone in Houston that will tune an LT1? That's where I live and I noticed that's where you're from too. G-Force had been suggested to me by several people, but when I called them they told me they no longer tune LT1's. The only place I could find is out by Willowbrook Mall just off Hwy 249, but I can't remember their name off the top of my head.

 

i would say the tune is the main issue for this reason....everything as far as sensors is stock. therefore, they arn't used to the set up you have right now. my buddys car would barly idle after his cam...it was custom grind. after the tune...was awsome. have you thought about mail order tune for now to get it running again??

i would think get it tuned first...then worry bout running issues. you can't diag a car that isn't tuned with the work thats done to yours.

 

You can always get a mail order tune from PCMforless, Madz28, etc to get you close and then put it on the dyno to check your a/f and timing, etc...Just a thought, but that would be a cheaper way to get your tuning done..The CC306 is a cam thats been used alot so I wouldnt think that anyone of the good tuners couldnt get you close with a mail order tune...

And not to knock the LS1 guy you are using for advice but the LS1 and LT1s are very different animals when it comes to cam selection...The LS series can support the larger duration stuff while the majority of LTs like smaller duration with high lifts..My advice would've been what you were thinking, the CC503 or the 305...LPEs 211/219, etc wouldve been nice too...But Id definitely get the tuning worked out before I put too many more miles on anything...

--Alan

 

What is the piston to valve clearance like on a 306? The reason that I am asking is that the Felpro gaskets that I have are .014 thinner than the stock head gaskets. Which would mean that you have moved the valve closer to the pistons (and raised compression).

 

If you OP this plan, you may end up bending valves. If you're sweating the cam install pull the cover and ensure the chain is installed dot to dot..... or do the best thing and degree your cam.
If your hurting for cash, why not try a PCM for less tune?

 

Wow, lots of great advice there! Thank you everyone. I will try the mail order tune first and see what kind of results I get from that.

I never thought about the gaskets being thinner than stock, I'll definitely look into that. With that being said I get back to my original question: do I need to get the valve guides milled on the heads for the added lift from the cam?

 

In my last Lt1 I ran the hot cam kit for a while with out a tune for a while then sent it into Ed wright to have it programmed. Car ran good but not great untill I got the tune done. I also had a Gran MAF in it and had no negitive effects that I noticed. actually my car ran 111 mph traps like that. I tried running the car with a stock MAF and the car was slower. Same set up and swapped at the track.
This does not completely apply to your Car/cam since its different but the car should run.
Have you tried turning up the idle?

 

Yeah, you definately need to get it tuned. Its very hard to diagnose or troubleshoot anything when the car doesn't have at least a mail-order tune.

As for the guides: I know of people with a cc306 who didn't mill them and never had a problem. That's not to say it shouldn't have been done, though. I'd go find an engine builder and ask them personally, or someone here could have a definate answer. Definately find out for sure because with your situation, you'd probably rather not waste any time/money on stuff you don't need.

 

You're absolutely correct about that!