Author Topic: performance question  (Read 6848 times)

Offline 79c10454

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performance question
« on: March 24, 2009, 07:39:01 am »
Hey guys im new to the carb scene i have question i have 454 cam, headers, intake, holley carb and some more mods. I was wondering what can be the problem i cant get a burnout out of my truck. I'ts a new rebuild 454 i dont have  a clue what could be if you guys can help i would appreciate my total timing 14'.  ??? ??? ??? :(

Offline VileZambonie

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Re: performance question
« Reply #1 on: March 24, 2009, 10:14:51 am »
So where's your question? All I see is a long sentence =P Grammar cop

Are you experiencing any performance issues or just can't fry a tire? If the engine feels strong, pull the meatball cover and find out what gears you have.
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline eventhorizon66

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Re: performance question
« Reply #2 on: March 24, 2009, 01:13:17 pm »
You need to be more specific on your combination.  You could be running a 11:1 CR, a Comp 292 Magnum cam, ported heads, but if your also sporting a stock stall convertor and 2.56's, you'll have issues with quick street starts.  Vile's the man, especially when it comes to 454's, but as far as I know, he's not a mind-reader.

There, that's two snotty comments in respose to your question, LOL.
« Last Edit: March 24, 2009, 10:21:00 pm by eventhorizon66 »
'85 C10 SWB 350 700R4 TKO600

Offline 79c10454

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Re: performance question
« Reply #3 on: March 24, 2009, 06:39:07 pm »
My question was i couldnt spin my tires and i get ugly sluggish start srry if dont know how to write.

Offline 79c10454

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Re: performance question
« Reply #4 on: March 24, 2009, 06:41:30 pm »
Also I have no stall converter and i dnt know what my gears are in the back.

Offline Blue 82

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Re: performance question
« Reply #5 on: March 24, 2009, 08:46:35 pm »
I don't know about you guys, but if my total timing was 14*, i wouldn't be able to do a burn out either.

If you could be a little more specific about your build, we might be able to point you in the right direction.

Here's a tip: your total timing should be more in the 45* to 50* range.

Set your initial timing to 10* and see if you can get 34* @ 3000 with the vacuum advance disconnected.

This should get you in the "burn out" zone.
82 stepside 2wd 355/th350/3.08 posi

Offline eventhorizon66

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Re: performance question
« Reply #6 on: March 24, 2009, 10:20:19 pm »
You know, I didn't notice the word "total" before.  I just assumed it was initial.  Is the advance curve locked out or something?  Is this a factory HEI?

My 350 runs about 14° initial and 35° total (all in around 3000 rpm) with 10° vacuum advance fed off of the full manifold vacuum port (this really helped smooth the idle and increased the off-idle responsiveness).

Like Vile said, you can pop your diff cover off and determine your gearing.  This may be part of the problem.

Is there a stumble or abnormal lack of power when you stomp on it.  Is there a lean surge at a steady cruise?  Does it briefly gain speed immediately after you left off the gas?  Or does the engine just seem weak in general.  What's the condition of your ignition system?  Do you know your compression is good?  Are you sure you have no vacuum leaks? 

Oh and what's your combo?  All you said is you have a cam, headers, intake, and holley.

My truck has a cam too.  A stock one.  That's why it's got no sack.

If all you want to do is a burnout, why not just drag the garden hose out and make your own water box at the end of your driveway, then go to town.
« Last Edit: March 24, 2009, 10:38:27 pm by eventhorizon66 »
'85 C10 SWB 350 700R4 TKO600

Offline 79c10454

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Re: performance question
« Reply #7 on: March 24, 2009, 10:34:46 pm »
Yeah i have an original HEI is no good r what so i can replace with a better unit that you guys recommend. Also its my first Chevy motor I mess with, I use to be a FORD guy so I really don't know what's good r bad. I had my total timing at 12' degrees I would get a sluggish start more than what i get now at 14'. Do you guys know what might be the problem any help i appreciate allot thanks guys for the help. ;D

Offline 79c10454

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Re: performance question
« Reply #8 on: March 24, 2009, 10:54:52 pm »
The motor feels strong but when it try to peel out it moves forward. I have 270 cam from comp cams, performer rpm intake, holley 670 , high flow mechanical fuel pump at 7 psi, ported heads, stock gears, and stock th350 but its good. Also when i try to peel out it kind of loses power. The long lock its new a bought from a friend who never used it has forged flat top pistons. I dont know the compression ratio. Well guys any help i apreciate. I know its a little thing. I have stock HEI

Offline eventhorizon66

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Re: performance question
« Reply #9 on: March 24, 2009, 11:34:13 pm »
When you smack the throttle open, moving foward is a good thing.  It sure beats backfiring or dieing.  LOL.

The main red flag I see is that you say you are running only 14° total ignition timing.  How have you determined this?  What is your timing at idle?  How do you have the vacuum advance hooked up?  I can't imagine how poorly my truck would run if I set my total timing to 14° (putting my initial at 7° ATDC).

The HEI is a good distributor, but can seriously benefit from a quality high performance coil, module, and mech. advance kit, like those from MSD or Petronix.

Also that carb is small for a 454, but that alone shouldn't keep it from laying a little rubber, especially if it's a non-posi.  A hesitation when depressing the throttle abruptly could be the result of an inadequate squirt from the accelerator pump circuit.  Adjusting the idle with a vacuum gauge can also help with off-idle hesitation.  Or the engine could just be a little bogged down by stock stall and gears.
'85 C10 SWB 350 700R4 TKO600

Offline 79c10454

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Re: performance question
« Reply #10 on: March 25, 2009, 11:39:07 pm »
I mean its 14 initial sorry all this time i had it wrong. :-[

Offline Just-speed

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Re: performance question
« Reply #11 on: April 01, 2009, 09:09:17 am »
Also I have no stall converter and i dnt know what my gears are in the back.
No stall converter?  All converters have a stall.     We need way more info here.  What truck is it?  What carb. What heads?
DO you know how to advance the timing?   Does your truck have power brakes?  Do they work good?  A 454 with good heads and beefed cam can not produce enough vacuum to run power brakes with-out a vacuum pump. So if your power brakes work great and they are tied right into a port then I would say you have a close to bone stock 454. Or you have some big issues.   Give us as much info as you can. What parts. Specs etc.   Gears and tire size.     If your running 15 inch wide rims with 44inch tires then you can answer your own question.

Let GM go belly up! I got what I wanted. Thanks for building the best truck ever.