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am i choosing the correct carb spacer?

5K views 13 replies 7 participants last post by  Super Chevy 
#1 ·
i have read the info in the knowledge base but i just need a confirmation that i am using it correctly. i have a 305 and my peak hp is in the upper rpm around 5500rpm and my peak torque is around 4000rpm, i want to get more low end power and torque, so i plan on getting a 1" 4 hole carb space made from plastic or wood (hopefully ill still be able to close my hood). is this the correct choice?


thanks
 
#3 ·
ok, thanks, oh i forgot to mention i have a dual plane intake manifold.
 
#4 ·
Carb_kid said:
Go with the phenolic spacers... so you limit heat soak. Although the manifold still contacts the carb thru the carb studs and nuts. Do they make phenolic washers? :D
you can get a ph... what he said, at autozone or napa.

a wood spacer would be easy to make, don't know how good that would work though.
 
#5 ·
thanks, now do u think it is worth it?
 
#6 ·
FASTCHEVY said:
you can get a ph... what he said, at autozone or napa.

a wood spacer would be easy to make, don't know how good that would work though.
Even the plywood one has the phenolic resin on the top and bottom surface.

I'm not sure how well wood would hold up. It is cheaper, I agree... and I suppose it would be good just as a test before you invest in a more expensive version, plus you get to check for hood clearance and all. :D
 
#7 ·
thats a good idea, im sure i have some plywood laying around, ill make one first, try it out, if i like it ill go and buy a real one, if not ill just toss it.
 
#8 ·
You will probably have the best results by using no spacer. A spacer adds volume to the plenum. This usually raises the powerband a little and loses some bottom end. The four hole sometimes gains a little metering, but there are no guarantees with spacers. Also, you usually get the most significant gains from the open hole 2" spacers, but that is no the direction you are wanting to go.
 
#11 ·
Carb spacer materials should be non-flammable, wood is not suitable. Phenolic or Aluminum works just fine but your arm chair leg is not suitable.
 
#12 ·
you were just doing you job. a Phenolic spacer kit is around $30 so ill proply just get one of those.

thanks for the help everyone.
 
#13 ·
Spacers

As others have stated a spacer is designed to help crutch or overcome something in the intake system (intake, carb, cam, heads, too big or small for the application).

That being said as a general rule of thumb a 4-hole design spacer will increase the throttle response, bottom end torque, and move the power band down in the RPM. It increases the air speed through the carburetor making the engine think it has a smaller carburetor or plenum. An open spacer will essentially decrease your bottom end torque, and give you more top end power (Moving the power band up in the RPM).

The thicker the spacer you use the more of the affect it should have. ie. if a 1/2" 4-hole spacer helps your torque a little going to 1" or 2" would help it more.

On some race applications it's common to stack a 4-hole spacer on top of an open spacer.

Basically spacers are a great tuning aid, but not an end all be all.
 
#14 ·
i may have clearance issues so i dont think i could use one, but if i come across one at a good price ill try it, and see if it fits.

thanks for the info.
 
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