Do carb spacers cause lean condition?

[HT413]

I've read it both ways - some insist spacers don't affect the tune, others say it causes a lean condition so you'll have to jet up. What say you?

Reason I ask is I just installed a spacer to hopefully fix the hard warm start issue I've been having. I put a biggun on (2") just because I had the room under my 6 pack scoop. It's an open spacer on top of my torker II 440 intake.

Thanks.

 

[RustyRatRod]

I guess it could. Since it DOES add plenum space, which means more air volume, but I'm no expert. I DO know that in general a 4 hole spacer helps bottom end torque some, while an open spacer tends to move the power up in the RPM band. At least that's my understanding.

 

[Jeremiah]

More open plenum area will reduce the vacuum signal to the carb so you may need more pump shot and one or two sizes more jet. The only way to find out is get some sticky tires and do some good old fashioned scientific testing. With pictures to share naturally...

 

[Meep-Meep]

Agreed with above posts and the comment about properly documenting you scientific trials! I played around with small spacers a long time ago but didn't notice much difference so don't have much data to share. I'm about ready to mount my carbs in an insulated air conditioned box! Especially on the hemi. @#$%&** new gas.

 

[RustyRatRod]

Yup. Jeremiah makes a real good point. I hadn't thought of the vacuum signal being reduced. That's similar to installing a tunnel ram.....but not quite as drastic.

 

[Supershafts]

I have played with many spacers, they effect many things depending what you want, your open spacer is effecting plenum volume, a 2" spacer like that is usually going to need more pump shot.

If you want to keep your carb cool and have it run nice what you really want is a phenolic tapered 4 hole spacer that will increase signal and keep the carb cool, but there are many spacers out there and only good spacers actually work right.

open usually help peak hp and tq and move it a 100 rpm or a few up, tapered usually help aid peaks but i find they help low end and aid response to the carb more than open.
.

 

[Pops1967GTX]

Spacer Tuning must be consider. Since each spacer will react differently on each combination.....Manifold design ,Carb design , spacer application have cause & effect....

[video]http://victorylibrary.com/mopar/intake-tech-c.htm[/video]

 

[67 coronet]

installing a spacer is akin to changing the intake manifold,just not as drastick.you will need to retune the car,but it shouldnt cause too dramatic of a diff in runability.most of the hp and trq #'s will only be seen or felt on a dyno or in a race cars times(lap or strip)

 

[HT413]

Thanks guys for settin me straight. I'm sure I'll have lots of tuning questions when the time comes.