Phenolic carb spacers

A spacer between carb & manifold to insulate the carb from heat is always a good idea & essential if the intake manifold is heated by exhaust gas.

I've seen 4 hole spacers solve a few problems on both divided plenum & open plenum intakes (erratic idle, fuel distribution). Open spacers are a tuning device for open plenum intakes.

Can't comment beyond that.

thanks for the congrats.

your friend on the DTBB

I've just installed them on my car, but my spacer doesn't have four hole it has one big one.
Haven't tried them yet as I am also putting an electric choke on the demon carbs.
So far so good...
Il let you know if I see any difference in the the power.
Dennis

I put a 4 hole, 1 inch spacer on my dual plane Blue Thunder intake with 600 Holley DP. I got hard starting, rough running until warm and no noticable performance increase.

quote:

Originally posted by bulldog:
I'm sure a lot of you glance over the new products listed on this vendor's website. It's so well presented, you can't help but jump on it every few days to see if you might have missed something!

And what website would that be? Curious minds want...

There are several common types of spacer. Most are alum others Phenolic or Plastic. The idea between the Phenolic or Plastic types is that they transfer less heat to the carb and therefore produce more HP. That is the only difference in the materials.

Spacers also come in Open or Closed version. The Open is where the space is wide open in the center, the closed has four holes to match the butterflies of the carb. The open version is best for large manifolds, cams and big heads. Therefore creating improving high RPM flow resulting in top end HP. The closed version is better for low RPM torque and well suited for dual plane intake manifold.

There is no simple answer other they trying different versions. Their height (1" or 2") reacts differently to each engine, so experimentation is required to find the right match. Often part of a dyno is to play around with spacers to get the right unit.

Insulating the carb from heat is to address/prevent the issue of boiling of the fuel in the fuel bowls.

If you install an open spacer between a carb & a divided plenum intake manifold, you have just redesigned the intake manifold.

your friend on the DTBB

quote:

Originally posted by george pence:
Insulating the carb from heat is to address/prevent the issue of boiling of the fuel in the fuel bowls.

If you install an open spacer between a carb & a divided plenum intake manifold, you have just redesigned the intake manifold.

your friend on the DTBB

George is correct. You've just redesigned the airflow and intake manifold, and it is impossible to say what the impact will be on your engine.

I've read articles that dyno tested a whole bunch of different combinations of spacer height, intake manifold, carb, cam, etc. I don't remember any of the details but do remember the bottom line.

Some spacers added hp. Some made zero difference. None hurt hp (I think). The expert's predictions of the effect of the spacer was wrong as often as it was right, ie it was impossible to draw sweeping conclusions (dual planes will always benefit from one or not, single planes, etc)

As Rover says, the only way to tell on your engine is to buy a bunch of different heights and spend some $$ on dyno time. I'd look very suspiciously at anyone who guaranteed X hp gains.