LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

cc306 missing its topend

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Old Aug 22, 2005 | 10:43 AM
  #1  
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cc306 missing its topend

My cc306 seems to be missing all its top end. It seems like it pulls good then falls plat on its face at 4000 rpm. If im cruising in 4th i can push on the gas with ease and feel the thing pull you into the seat untill 4k. It will still rev out just without the power. Maybee running lean? I know that others have used the v6's fuel pump as i did without problems and they worked. Its only temp but i think it could be that or my exhaust witch is a temp hack job to. Its only 2 1/2 inch pipe. All my sensors are new and it seems to run realy well now with the exception of slightly hard warm starts.

Any one seen this before?

Hopefully after i swap the FP and exhaust it will run better.
Old Aug 22, 2005 | 10:52 AM
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Re: cc306 missing its topend

http://www.mainstreamtopics.com/foru...p?showtopic=78

My buddy Harlan made this, this can help diagnose stuff.


If it isnt the FP, then look at the ignition/opti.

Last edited by BlackScreaminMachine; Aug 22, 2005 at 10:56 AM.
Old Aug 22, 2005 | 08:48 PM
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Re: cc306 missing its topend

that sucks to lose the cc306 top end since thats all it really has. lol look for fuel pressure
Old Aug 22, 2005 | 10:54 PM
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Re: cc306 missing its topend

excellent link. Im more concerned of a fuel pressure problem now. I think my pumps to weak. The link says it should have 45 +2 or -2 but whats the replace limit?
Old Aug 22, 2005 | 10:58 PM
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Re: cc306 missing its topend

No stock GM F body pump is enough for your 400hp+ LT1, go buy a racetronix kit.
Old Aug 22, 2005 | 11:36 PM
  #6  
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Re: cc306 missing its topend

stock fuel pump is rated to 400 or 450hp. i don't remember. but your also battling with age. i believe my old haynes manual says that the stock lt1 system should be somewhere around 38-44 or something like that. check your pressure with engine off and then check it at idle. it should be lower at idle.
Old Aug 22, 2005 | 11:41 PM
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Re: cc306 missing its topend

The stock v-6 pump is rated for 400-450 hp??? Wow why couldn't we get that kind of excessive strength in our rear ends. I still dont think its enough pump.
Old Aug 23, 2005 | 02:07 AM
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Re: cc306 missing its topend

Originally Posted by 92rslt1
My cc306 seems to be missing all its top end. It seems like it pulls good then falls plat on its face at 4000 rpm. If im cruising in 4th i can push on the gas with ease and feel the thing pull you into the seat untill 4k. It will still rev out just without the power. Maybee running lean? I know that others have used the v6's fuel pump as i did without problems and they worked. Its only temp but i think it could be that or my exhaust witch is a temp hack job to. Its only 2 1/2 inch pipe. All my sensors are new and it seems to run realy well now with the exception of slightly hard warm starts.

Any one seen this before?

Hopefully after i swap the FP and exhaust it will run better.
What kind of lifters are you running?
Old Aug 23, 2005 | 05:55 PM
  #9  
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Re: cc306 missing its topend

i have always heard that when it drops power at higher rpms that it is almost always the lash on the pushrods, to tight.

do a search on setting lash
Old Aug 23, 2005 | 08:53 PM
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Re: cc306 missing its topend

hmm i will re-adjust wich i was planning to do anyway and see what happens. Stock lifters soon to be upgraded to comp. I was told i could get away with the stockers so hopefully they will last for at least a little while.
Old Aug 23, 2005 | 08:55 PM
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Re: cc306 missing its topend

Originally Posted by 92rslt1
hmm i will re-adjust wich i was planning to do anyway and see what happens. Stock lifters soon to be upgraded to comp. I was told i could get away with the stockers so hopefully they will last for at least a little while.
stick with stockers. If you are referring to Comp R's stay away from them.
Old Aug 23, 2005 | 09:57 PM
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Re: cc306 missing its topend

ok well thts good to know. Should i just replace them with oem when i do.
Old Aug 23, 2005 | 10:35 PM
  #13  
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Re: cc306 missing its topend

{in death bed voice> Must Have Fuel!!! <voice off}

Yeah oem is fine, and lighter, not sure what the consensis is on when they are done, mine have 90K and are happy. I'd say 150K should be about it depending on use and abuse and how much spring loads.

I still strongly believe you need more fuel. Do you have bigger injectors? You may be in need of svo 24's or 30's and some tuning.
Old Aug 24, 2005 | 09:42 AM
  #14  
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Re: cc306 missing its topend

nope i have stock injectors with mad z tuning. when i upgade them after i do my FP i will get some 24#
Old Aug 25, 2005 | 03:27 AM
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Re: cc306 missing its topend

Originally Posted by 92rslt1
My cc306 seems to be missing all its top end. It seems like it pulls good then falls plat on its face at 4000 rpm. If im cruising in 4th i can push on the gas with ease and feel the thing pull you into the seat untill 4k. It will still rev out just without the power. Maybee running lean? I know that others have used the v6's fuel pump as i did without problems and they worked. Its only temp but i think it could be that or my exhaust witch is a temp hack job to. Its only 2 1/2 inch pipe. All my sensors are new and it seems to run realy well now with the exception of slightly hard warm starts.

Any one seen this before?

Hopefully after i swap the FP and exhaust it will run better.
What springs are you running? You should pull one before you decide your lifters need to be replaced and have it pressure tested at a machine shop.
I'm about to put CCR lifters in my car because the stockers were looking pretty haggard. I have no faith in those who say the CCR's are junk... especially with not knowing how the valves are being adjusted.
For fuel just by yourself a fuel guage at any parts store, hook it up to the Schrader, put it in your windshield, take the vacuum line off and do a couple of WOT runs. If you see it back off in pressure at all then it needs to be replaced.



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