Wondering if a carb spacer will be beneficial on my stock manifold with my good flowing heads and good size cam? I guess the other option is to cut the divider down in the secondary area. Thoughts?
I have a 1/2" spacer on mine (and two 1/4 " gaskets, for a total of an inch), works well. If this is going in the 66 though, hood clearance may be an issue..
Hi Bob. I have been considering the same thing. There does not seem to be a ton of info on Buicks in particular about this. There does seem to be plenty of discussion on Pontiac forums. I talked to Cliff Ruggle about spacers and plenum dividers and whatnot a year or too back. He has tried lots of stuff along those lines. He suggests to nut cut the plenum divider down for sure. At most just leave a little crossover notch. Here are some links to some discussions as it pertains to Pontiacs. http://forums.maxperformanceinc.com/forums/showthread.php?t=764519 http://forums.maxperformanceinc.com/forums/showthread.php?t=561534&highlight=intake http://forums.maxperformanceinc.com/forums/showthread.php?t=568412&highlight=intake Cliff chimes in on those posts a few times. I have attached some modified intake pictures and spacers to try including Cliff's intake and another fella named Jim Hand. I am going to try modifying one of my intakes like this. I have a few spacers to try too. I made them all out of either plastic or MDF using the router table and a GM 1/4" quadrajet gasket for the template. Greg
Here is a quote from Cliff Ruggle on messing around with the intakes as pertaining to Pontiacs. "I recently switched from an RPM intake and custom Shaker assembly with a filter in the inlet back to a CNC ported HO intake with my plenum modifications. I re-installed all the factory Shaker parts, and stock paper filter/lid, etc. I also installed a choke flap in the carb, electric choke on the carb, and smaller 2.5" mandrel bent tail pipes to replace the 3" "turn downs". The 1977 q-jet was also set up with primary metering rods/jets instead of running straight off the jets. Since I was running well under the roll bar rule anyhow, and doing more street driving, figured I might as well make things a bit more user friendly and more efficient for "normal" driving. I went to or local track recently and low and behold the car ran just as quick in the 1/8th miles with the "stock" components as it did with the RPM and modded stuff! I didn't use a spacer with either intake for fitment reasons, do use a 1/4" thick Chevy style q-jet gasket between the carb and intake. Being a fully open gasket, it allows both sides to see each other and eliminates the need for a "notch" between the secondaries. I've done a LOT of intake and spacer testing over the years, and could write many pages on it here. I'll say as a general statement that using a very well made spacer is REQUIRED on all single plane intakes, or you are going to be down on power some. For dual plane intakes, fully open and 4 hole spacers ALWAYS slowed my car down everyplace. Fully divided with a notch ran close to the same as no spacer at all. For all runs I've picked up MPH using a "semi-open" spacer as close to what Jim Hand shows in his book and prefers on his intakes. I've also played around with divided spacers and removing the divider or lowering it in dual plane intakes. This is NOT a good idea, and all testing I've done to date lowering/removing the divider has hurt vehicle performance. As Jay Delaigle about that deal sometime, as he has dyno and track numbers to show how bad we can hurt power removing the divider from a factory intake. Anyhow, when it comes to this topic, one should consider several things. In most cases we are only chasing a few hundreths of a second here, comparing no spacer at all to a 1" spacer of any configuration used on a dual plane factory or aftermarket intake. Installing spacers reduce hood clearance, and may require "custom" fabrication, drop base air cleaners, and often moving the air cleaner lid closer to the carburetor. Doing that alone can have a TREMENDOUS negative impact on vehicle performance, so something to consider when it comes to this topic. I would also say that my car runs nearly into the 10's in full street trim with a "ported" factory intake and no spacer at all, using all factory Shaker components on top of it. Put up some 7.20's this summer in hot/humid weather just under 96mph. Most folks don't run nearly that quick, yet I see them "hacking" up some pretty nice stuff and going to extremes to put an RPM or single plane intake and 1" spacers to improve vehicle performance. Not saying they aren't making improvements, but one has to ask if it's all really worth a couple hundreths in the big scheme of things, and I'll bet, more times than not, they actually slow down just a bit instead of picking up some.......Cliff "
I used a 1 inch 4 hole spreadbore spacer,qjet style. Picked up 1-2 mph. Think I still have it somewhere if you're interested.
A few years ago I experimented with spacers on a 455 with stock intake & exhaust manifolds and a 228/236 cam, on the same day with the same 2 cars running side by side down the track. We added 1/4 inch at a time by using 1976 Q-jet base gaskets. Each time we added 1/4 inch the car that has the spacers added was better able to keep up with the baseline car. With 4, 1/4 inch gaskets/spacers for a total of 1 inch added the car picked up 1 mph and was able to stay even with the baseline car.
