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Engine Tuning issue

  • Thread starter Thread starter nc_302
  • Start date Start date Oct 1, 2019
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nc_302

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#1
  • Oct 1, 2019
  • #1
Hiya, I got a fox with a built 351w. Fun Budget build. 30 over with Forged flat top pistons, h beam rods, Weiand stealth intake, msd everything ignition, Holley 650 dp, comp cams xe268h cam... etc. the car will not stop running rich, I can cut the timing down below 10° btdc and it’ll not smoke as bad but I feel like that timing is too low. Car runs good jus smokes a little. 200 miles on motor
 

General karthief

wonder how much it would cost to ship you a pair
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#2
  • Oct 1, 2019
  • #2
Give it more run time to seat the rings?
is it a lot of black smoke? You may need to tune that carb up. You know carbs very well?
 
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nc_302

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#3
  • Oct 1, 2019
  • #3
General karthief said:
Give it more run time to seat the rings?
is it a lot of black smoke? You may need to tune that carb up. You know carbs very well?
Click to expand...
The rings are moly rings. I heard it don’t take long for them to seat. It’s not a lot of black smoke. It’s just whenever you rev it a decent amount comes out the back. More than I’d like. I can get around a carb good but fine tuning gets me
 

General karthief

wonder how much it would cost to ship you a pair
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#4
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There are a few carb tuning articles from car craft and hot rod, maybe holley has some too. Keep in mind that a carb is not the only part of 'tuning', also a vacuum secondary carb is a little more forgiving that a double pumper.
i should ask stick or automatic?
 
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nc_302

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  • Oct 1, 2019
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General karthief said:
There are a few carb tuning articles from car craft and hot rod, maybe holley has some too. Keep in mind that a carb is not the only part of 'tuning', also a vacuum secondary carb is a little more forgiving that a double pumper.
i should ask stick or automatic?
Click to expand...
I haven’t had the issue before with this carb and I’ve had it for a bit. It might be rings needing to seat. The smoke might be more gray. Any idea of what my initial timing should be at? It’s a stick t5 I’m waiting to break
 

General karthief

wonder how much it would cost to ship you a pair
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#6
  • Oct 1, 2019
  • #6
Here is one by Jeff Smith from hot rod magazine:

Tuning Your Holley Carb Made Easy

With the continued development and popularity of the Holley four-barrel carburetor, knowing how to properly tune one is very important.
www.hotrod.com
Another: https://pitstopusa.com/p-4154-how-to-tune-holley-carburetors.html
I can do pretty good if the carb is on an engine I can lay my hands on, typing something out is something else.
Just make sure the ignition system is working correctly and have a couple sets of plugs handy.
 

General karthief

wonder how much it would cost to ship you a pair
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#7
  • Oct 1, 2019
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I would not be afraid to bump it to 12* or even 14*. I used a vacuum gauge to match timing to the highest vacuum reading, you will have to do some readjustment to the carb.
double pumper carbs work very well with stick cars but I found that a vacuum secondary carb works very well on the street and I prefer them.
 
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nc_302

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#8
  • Oct 1, 2019
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General karthief said:
I would not be afraid to bump it to 12* or even 14*. I used a vacuum gauge to match timing to the highest vacuum reading, you will have to do some readjustment to the carb.
double pumper carbs work very well with stick cars but I found that a vacuum secondary carb works very well on the street and I prefer them.
Click to expand...
Any idea if it might be the rings not sealed yet also? Like a mix of running rich and rings?
 

a91what

SendMeUrDataLog
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#9
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pull a plug and post a picture of it for me..

where do I plug my laptop into a carb???
 
Reactions: Deleted member 215073

General karthief

wonder how much it would cost to ship you a pair
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#10
  • Oct 1, 2019
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a91what said:
pull a plug and post a picture of it for me..

where do I plug my laptop into a carb???
Click to expand...
You're such a millennial, the vacuum port of course!
 
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nc_302

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#11
  • Oct 1, 2019
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a91what said:
pull a plug and post a picture of it for me..

where do I plug my laptop into a carb???
Click to expand...
Ain’t got a pic at the moment but it’s like dry black,
 

a91what

SendMeUrDataLog
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  • Oct 1, 2019
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too much fuel, the porcelain will tell you what its doing at idle.. you want a light tan color with a slightly colored outer ring..

you likely need to back some out of the carb, what size jets you runnin?
 

General karthief

wonder how much it would cost to ship you a pair
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#13
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Is the carb new?
 
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nc_302

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a91what said:
too much fuel, the porcelain will tell you what its doing at idle.. you want a light tan color with a slightly colored outer ring..

you likely need to back some out of the carb, what size jets you runnin?
Click to expand...
I can’t remember the jet sizes. I think it was something stupid. Probably the problem but I don’t see how it did fine before with jus heads and a cam and now it’s got a full bottom end and it’s starting to act up lol. But I’m still hung up on them rings
 
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nc_302

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  • Oct 1, 2019
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General karthief said:
Is the carb new?
Click to expand...
Maybe 5 months old
 

a91what

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#16
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Pull the plugs and get a picture when you can, all of them so we can see if its burning oil.
 
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nc_302

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#17
  • Oct 1, 2019
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a91what said:
Pull the plugs and get a picture when you can, all of them so we can see if its burning oil.
Click to expand...
It’ll be tomorrow but I post one as soon as possible
 

General karthief

wonder how much it would cost to ship you a pair
5 Year Member
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#18
  • Oct 1, 2019
  • #18
Start out by setting your timing to the highest vacuum reading, check your air/fuel and idle adjustment screws with new plugs and drive it for another 3-4 hundred miles at various rpms (nothing high like no higher than 4800-5000) and not a lot of idle time.
you don't want a lot of black smoke, just a wisp maybe.
carb tuning is almost a lost art. A lot of variables,
a vacuum gauge will be your best friend.
 
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nc_302

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#19
  • Oct 2, 2019
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So I feel kind of dumb haha but I changed my oil today. Got the break in oil out. And put regular oil back in. And set my timing to 14°. Plugged up my vacuum gauge and it was the highest there. Messed with the carb some and took it down the road. It missed a bit but cleared right up and now it’s not smoking at all. I used semisynthetic assembly lube. I guess that mixed with break in oil didn’t let the rings seal. Carb idles a like 1300 when I come to a stop and push in the clutch. The after like 5-10 seconds it’ll drop down to idle. So I’m pretty happy
 
D

Deleted member 215073

Oct 2, 2019
#20
  • Oct 2, 2019
  • #20
*cough* fuel injection *cough*
 
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