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Does anyone use intake manifold spacers on their carbed engines? I am looking at puting one on and I wanted to find out what people have experienced with them. Does anyone have any comments about them? Thanks
Not very good for a heavy 4x4 truck with large tires. With the spacer you are increasing the volume of the manifold for higher rpm power. It can hurt your low end throttle response.
Now if you have a lightweight vehicle with a high ratio rear, then it may help a little.
As stated above, he was speaking about a open spacer, a 4 hole will be the opposite and help low end plus give the carb a stronger vacuum signal at a slight loss at top end. To see or feel the difference you have to go in 1" steps like try 1" then go to a 2" spacer if hood clearance allows. Make sure the spacer if 4 hole matches the diameter of the throttle plate bores, not smaller or larger. Most spacers will not match the carb throttle bore.
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On my BBF mustang I have a 1" composite (plastic) spacer. It is the open design. The car has awesome mid and top end, but is kinda soft at low RPM. This seems to confirm earlier posts...
On the 1" Moroso 4 hole spacer the bores are 1.715" up top and 1.725" at the bottom, I believe for mold release. The bore on a 670 Holley SA carb is 1.562" (1.687" for a 770 SA), the spacer is .153" larger than the carb. On a Performer intake there was little difference in low end with this spacer added. With a 2" thick spacer that started out smaller than the carb bores then milled out to 1.562" to match the 670 there was a noticeable low end increase. Far as the upper rpm's loss anything over 5,000 with a torque built 414 it's already beyond its normal operating range anyway.
With the above Moroso 1" spacer and a 770 SA, the spacer is larger than the carb by only .027".
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Last edited by "Beemer Nut"; Apr 12, 2006 at 05:08 PM.
I have a 1" Torq-Swirl adapter on a Edelbrock Performer Manifold on to a stock 460, with a 4160, 600 CFM, Holley carb. I'm not sure I notice any difference. The BIG difference for this engine came when I installed a Cloyes Street Roller Timing Chain Set and advanced the timing at the cam 4 degrees beyond TDC.
I run 2 inch ported (4 hole) spacers on cast iron intakes, nothing but a good insulating gasket on aluminum intakes. Best set ups for me, in my trucks.
I ran a 1/4" spacer once, what a joke as it had heat flooding until I installed a 1 1/2". Will go to 2" after opening up undersize holes to match the carb bores.
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