If your racing seriously,the possibility of any minute improvement is worth huge investments. On the street,you won't feel it.
There are several ways a 2 inch spacer will help you . You will get to meet a lot of new people. The first is when you drop one of the new carb studs down the intake and can't find your magnet. The second is when you close your hood and find out the air cleaner stud is too long. And then there is the rescue squad that picks you up when you throttle sticks because of the weird angle on the linkage. Sorry just had to bust your chops a little. We use them on race cars . A open spacer on a dual runner manifold probably isn't going to help anything . An open spacer on a single runner manifold will help top end H.P. Probably no help for everyday driving.A four hole spacer on an single runner manifold can help the low end torque. In my opinion most street cars would not notice any improvement.Spend your time tuning the carb and ign. chances are you'll get more for your $$.
The one place a composite spacer will help on the street is that it will keep heat from transfering to the carb. Though not felt in the seat of the pants it will help as far as how much timing can be run without pre-ignition. I recommend between a 1" and 2" four hole spacer.
I bought a Holley spacer with an aluminum heat sheild that goes over the intake (about 6" to the front and 6" to the rear) but I haven't put it on yet. Is it worth the effort?
I used to build a lot of 289s and while every little bit helps them, as the other guys have said, it won't knock your socks off. I would go aluminum or composite 4 hole. The 289 can't really make power in a high enough band to take advantage of single plenum intakes or spacers. Use it simply as a heat shield kinda thing. It will provied a minute performance improvement since most of the 289 intakes are so low rise as to be damn near flat, they could all use a little help. But it will cool your air and fuel a hair. I take it that it is going on your Falcon so like somebody else said, watch that hood clearance. It's not as tight as the Mustang of a similar year but it is close. So if it comes down to a space consideration between using a spacer and using a larger element air cleaner, go with the big air cleaner as you'll probably see more efficiency and HP from that engine. As an aside, I don't know if your sportin' headers or not but 289s love to breathe and get a big kick out of a decent set of headers. Big Daddy Eric
I have always used wood spacers because of the heat dissipation, some people say the phenolic spacers dissipate more heat, but I still think the wood four-holers are where it's at. They don't cost too much either if you get a plain jane one.
I think you've got all the info here - I'll try to consolidate it a bit for you. If you're working with a street engine (which it sounds like), a 4-hole phenolic spacer is worth your while. It creates a stronger signal to the venturi boosters in your carb. This is, however, more noticeable on a slightly hopped up engine with a larger cam - if your engine is bone stock, you proabably won't be able to tell the difference and as has been mentioned, very appropriately, if it's a hood clearance issue - take the larger element filter (K&N or something of equal quality) over the spacer any day of the week - and twice on Sunday. If, on the other hand, you've got a high performance engine and you're trying to eek out a bit more, you may (depending on your engine combo & power band) find a bit more 'oomph' (technical term) with an open spacer. The insulating qualities are valuable as the cooler you can keep the fuel in the bowl, the better off you are. And while you'll never keep the carb cold, you can insulate it from conductive heat (not radiant) by using something non-conducive such as phenolic (or wood - although I have my doubts about using wood) or plastic. I'm NOT sold on those old Moroso/Mr. Gasket insulating sandwich set-ups (gasket, metal plate, gasket, metal plate, etc) or even the Holley heat shield for that matter. I think there's too much radiant heat for the heat shield to work & the sandwich set-up is just begging for vacuum leaks & broken base-plate ears. Just my $0.02 worth...
VT, Address is still good - no worries, we all get busy! I KNOW how that is. Thx! BTW, you ain't the only one either...
Sorry dude, I've had both a Fairlane and a Falcon and there might be a slight difference. But they're still FoMoCo baby! LOL But yeah, those headers are gonna make you proud 'cuz you're right, the stock manifolds might as well be solid as well as they breath. Oh and start savin' for some '69 351W heads as those will be the thing you might want next. Ya know, if they'll fit in a Falcon. BDE
any post involving a carb,engine or ANYTHING with wheels is considered on topic in my book.good post/questions,too Creepy
Would that intake heat shield I have be beneficial on my 302? Django..i have used the one your talking about and it does help with keeping the heat off carb..less heat on carb less chance of fuel boil..i hope this helps..
Also, I know all about that under hood space. I can go 1" ....I just checked. von..just cut a hole in the hood it'll fit then,,lol
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