Tools for tuning

[InfiniteGrade]

Hello.

Currently, my engine is getting around 7-8 mpg and is unmodded. I recently bought it from a guy that replaced the carb with a brand new Holley one. He says he put everything at factory specifications but didn't "put it on the machine." It bucks at idle and blows some smoke. According to the seller, it has about 2000miles on a rebuilt engine.

I really don't know anything about carburetors as I've only dealt with FI since I got into cars. What tools do I need (other than knowledge) to properly bring the engine/carb into tune?

Or is it a good idea to have a professional tune it the first time?

 

[miesk5]

yo!

re:It bucks at idle and blows some smoke

hard to diagnose from here; could be as simple as what Holley advises;

"...If it stumbles and you are getting black smoke from the tailpipe then it will be nessasary to decrease the shooter size..."

see: http://www.holley.com/techservice/FAQ.asp

and

http://www.mortec.com/carbtip1.htm

or a vacuum leak; spray carb cleaner around base, manifold, etc.; if eng speed increases, there is a leak.

some info:

Vacuum Gauge Diagnosis by William R. W at obd-codes.com

Vacuum Leaks, Finding Elusive, general by Jim M at n2performance.com

Also, most holleys (from memory) have diff. springs; found this:

"...If there is a bog or hesitation when the secondaries open, the spring tension is too light, go to the next heavier spring. Holley offers a kit (PN-20-13) which contains one each of the above color springs. When you change springs you'll note that the stock cover over the spring and diaphram is not all that easy to get to. Holley makes a special cover (PN-20-59) that makes spring changes quick. Finally, Holley also makes a completely adjustable thumbscrew operated diaphram cover (PN-20-99). This cover limits the travel of the diaphram and therefore limits how far the secondary throttle plate can open. It makes secondary throttle opening adjustable..."

from http://www.mortec.com/carbtip1.htm

and the Holley Tech Index: http://www.holley.com/TechService/Library.asp

Good Luck!

 

[miesk5]

yo!

Went to a local mechanic/builder that does a lot of Chev dragging; he thinks the shooter size should be decreased. Said the kits are avail all over.

 

[Seabronc]

I would start by getting the setup instructions and follwing them. If it is shooting black smoke at idle, it sounds to me like the idle mixture is too rich and needs adjustment. At idle the jets are not involved on a Holley. Check this site out for dealing with a Holley, lots of good information and you might be a Holley expert when you are done /emoticons/[email protected] 2x" width="20" height="20" /> . http://www.bob2000.com/carb.htm

Good luck,

>-

 

[InfiniteGrade]

I would start by getting the setup instructions and follwing them.  If it is shooting black smoke at idle, it sounds to me like the idle mixture is too rich and needs adjustment.  At idle the jets are not involved on a Holley.  Check this site out for dealing with a Holley, lots of good information and you might be a Holley expert when you are done /emoticons/[email protected] 2x" width="20" height="20" /> .  http://www.bob2000.com/carb.htm
Good luck,

>-

33643[/snapback]

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Thanks for all of the information guys. Just to clarify, I didn't mean it's blowing smoke at idle, sorry. Just when I get on it on the interstate. But it does buck. Somewhere I read of a "trick" where you put a dollar bill behind the exhaust tip to see if it gets sucked in. Supposedly, this can show of a miss or a vacuum leak. The store reciept I used never moved toward the exhaust.

I'll do what I can about tuning the carb. I've printed most of that information and hopefully I can wade through it.