Carb spacer

[flyinlow]

I have a mild 446 ,eddy heads ,auto 3.54 ,73 Charger

I have both performer rpm and Holley SD. intakes.
Have 4160 holley,750 vac.sec. and a thermoquad.

I was going to try both ( engine new to car)

I have read about spacers under carb to change the performace.
Would a spacer on the SD. with 4 individual holes improve the low end?
Would an open spacer on the RPM help upper rpm performace?

Was considering an 800 holley spred bore double pumper for the SD. Has anyone used one of these ?

[firefighter3931]

I have a mild 446 ,eddy heads ,auto 3.54 ,73 Charger

I have both performer rpm and Holley SD. intakes.
Have 4160 holley,750 vac.sec. and a thermoquad.

I was going to try both ( engine new to car)

I have read about spacers under carb to change the performace.
Would a spacer on the SD. with 4 individual holes improve the low end?
Would an open spacer on the RPM help upper rpm performace?

Was considering an 800 holley spred bore double pumper for the SD. Has anyone used one of these ?

Spacers are combination dependant....some engines like them, some don't. On a single plane like the SD the 4 hole will usually produce a stronger signal to the carb which increases throttle responce and torque. An open spacer is used to increase plenum volume and top end power.

On mine i used an open 1in on top of the SD to increase top end power. We tried 2 different spacers on the RPM intake and it didn't like either...lost power in both dyno tests.  The engine is a pump gas 446, ported e-heads and big solid cam, FYI.

As for the carb....i've had good luck with the Proform carbs and have recommended them to several members here with great results. 



Ron

[MSRacing89]

I can say I have used both the SD and the RPM on a similar combo.  I noticed a significant difference in the throttle response between the two intakes.  The RPM was better.  It lowered the power/torque range around 1500 rpm, and for a mainly street driven car, you notice it.  I do currently have a ½" (4) holed spacer on top of the RPM with a BIGs 750 DP, but now that Firefighter has mentioned the spacer does not seem to help, I can take that off and increase the air cleaner size up to 3".

Bottom line is there is a lot of talk about the SD and the RPM.  Both great intakes, but I was able to tell the difference in drivability.  For mostly street applications you can't beat the RPM.  But keep the SD on the shelf for those track days!!!

[firefighter3931]

Bottom line is there is a lot of talk about the SD and the RPM.  Both great intakes, but I was able to tell the difference in drivability.  For mostly street applications you can't beat the RPM.  But keep the SD on the shelf for those track days!!!

As much as i like the Street Dominator, i have to agree with MSR....the RPM dual plane makes much better torque down low. On mine we noticed a 30ftlb difference at 3500 rpm on the dyno and i know it would be an even larger margin of difference at lower engine speeds. Mine has a 4500 stall and 4.10's so the top end performance was more of an issue and the SD performed MUCH better above 6000 rpm....30 hp better 

On a mostly street driven build with a mild cam and stock e-heads i would probably opt for the RPM for better throttle response and more torque. Just my observations ; with  a 300cfm ported head the RPM dual-plane intake manifold starts to become a restriction on the top end and will limit horsepower....that is a dyno proven fact. Like anything though...it's important to pick out the right parts for your  intended useage. 

I do currently have a ½" (4) holed spacer on top of the RPM with a BIGs 750 DP, but now that Firefighter has mentioned the spacer does not seem to help, I can take that off and increase the air cleaner size up to 3".

Yep, remove that spacer and you can run a 14x3 K&N with a 1.25in drop base and it will clear the stock hood just fine. 



Ron

[flyinlow]

Thanks for the feedback !

I heard the 750 doublepumper mentioned several times. Will that work well wtih an auto/11 inch mopar conv. and 3.54 gears?
Would you be able to floor it from a standstill without it bogging?

[firefighter3931]

Sure...a 750dp will work fine on that combo. A bog can be tuned out 

What cam are you running in that 440 ?



Ron