Single planes are the easiest and cheapest to manufactuer. Mopar slant 6 all used single planes.
They are the bottom of the barrel. EDIT the 180hp 425 1977 caddy v8 was single plane! 180 HP! 425CID!
It's amazing single planes ever caught on, for street use by hot rodders!
I too, was almost seduced. There was a dyno guy here Pete76L82 that said Super Victors were worth an extra 10-20 HP on his dyno. True. I was ready to buy!
But its' RPM range is 3500-8000! I can drive all day and not get up to 3500! The Super Vic is a DOG in my street range. And my mpg would drop back to 10-11 from 18-19. And i'd have to downshift every time an old lady makes a right turn. An AWFUL choice for my streets. The AVERAGE HP in my use would be MUCH LOWER!

 

A few days ago you recommended a 1/4 inch spacer under the carb, for better mileage which is better, the1/4 inch spaces or this 3 piece set?

 

I dont know that there is a 1/4" spacer since the industry defines a spacer as 1/2" or greater. i've looked in all my catalogs to learn this.
I've never used a spacer. NEVER.
The question arises as to sealing the base of a carb to an intake. How can this be done properly, as THIN as possible, due to vettes low hood?
They sell 1/4" gaskets and u can make your own from thin plywood. at least i did.
That 3 piece set is an oxymoron. a contradicton. At the bottom there is a heat riser passage to get the carb warm fast in the cold. Then there is the SS sheet to keep exhaust off the carb. Then a 3rd gasket is added to keep the carb cool! Which is it? Do you want fast warmup and better mpg?(cold engines really suck gas,even EFI) Guys that have the carb boil have to add #3 even if mpg is worse on cold starts. Except up north in the winter, shouldnt boil then; take it out if it works for you.
Do u even have a heat riser? I have no idea what anyone has, and how they use the car. Some store it all winter, how am i supposed to know your situation?
In general, as long as the high plane is separated from the low plane reasonably well and the carb doesn't boil over, and the engine gets to 180-195 as fast as possible; then u get the best mpg.

 

I was referring to Cadillac 77-79 425 had a single plane intake & later 368 an al. single plane intake. Normally Cadillac V8s had dual plane intakes.

 

Thanks for pointing that out! I had no idea they stooped so low just to save a few $$.
That 77 425 was 180 HP.

 

It should save ya from telling someone all modern stock V8s had a dual plane intake!

 

I sure wouldn't make that claim. I don't follow other makes.
I don't think there were any factory 1955-1975 CHEVY V8 w/single plane. But i didnt ever look at a 348/409.
Factory single plane is a frugal way to build a really cheap, low HP anything in huge quantity with a weenie cam.
Happy Thanksgiving!

 

When I would run the 1/4 - we'd put the Team G single plane on but for normal use I still prefer the original Lt-1 dual plane. I just can't see spending $ on another dual plane carb that would be significantly better than the original. Now the Team G was port matched but as has been said previously the power kicked in @ 4500 rpm and would top out at 7k - not great for street but designed for the strip by MountainMotor. When I put the original carb on I just smiled at the increase in low -mid range tourque.

 

Aftermarket parts have to be sold/marketed like everything else.
I wonder if some intakes are sold in a less than optimum design to sell better? For example:
What if an Air Gap 1" taller made more power, but was too tall for most applications? What would the mfg do?
Anyway: For most of us we put together the best combo we can depending on money and parts we have to retain for whatever reason.
How many of us have a SB w/cam in 220*, aftermarket 190 heads,
Air Gap, 750 carb? A spacer and perhaps some RRs is about all we can do.
There is also the difference in head flow. My TFS heads flow considerably less than some AFRs ect. Which heads would benifit the most from a spacer, if at all?
As soon as my hood gets fixed and I make up my mind on headers, I will make a trip to the dyno. I will post results of course.
I'm still hoping for some before/after testing?

R

 

R
Driving on the street w/data logger would be very helpful.
Once i stopwatch timed a Fiero v6 before making a simple mod to the headers-removing an obvious restriction at the flange. Very surprising results! The mod killed low end torque-took twice as long to accelerate in 5th-had to downshift out of 5th into 4th where i didnt before. It was 0.4 seconds quicker 0-60. A dyno would not usually show low rpm, like 1200 rpm. So while the mod would look fantastic on a dyno, it required a lot more shifting in actual use. So i rated the mod good, but not great.

 

Just finished some research on the Engine Masters. I find it interesting that they have a spacer rule of 2" max.
No big surprises in the results. Some use them, some don't!
I would like to see a test w/insulator alone just to see what reduced carb temps accomplish? Then play w/spacers to see what they do?
R

 

I installed a insulator, it droped the carb. tempature nearly 100 degrees,
well worth the minor effort. 69VETT

 

too hot a carb and you lose 100%. it boils. it stalls. it's dead.
too cold it ices up. even in the 50F's my carbs get some ice.
Cold air, like cowl induction, really increases HP. Can't measure it on a dyno usually, unless u pipe in cold air.
A cool carb doesn't increase hp significantly like cold air. The air moves thru it so fast, it cant cool the outdoors no way. U just want the fuel not to boil, and it boils at 140-150F

 

http://www.gnetworks.com/v4files/bar...h%20images.pdf


this is from the BG site..... single hole spacer= a little more top end hp
4 hole offers better low and midrange.... according to BG

 

O and I had a HUGE issue with Holly's boiling over and vapor locking....

 

one more thing about cold air induction. it lowers octane requirements LOTS.
my 72 never pings, even in the summer on 87 with 9.7:1 with underhood air it needed 91.
so u can pocket the savings, or raise CR for more power and higher mpg.
so if anyone is still feeding hot air to their engine, shame on you! except in cold winters of course where u may have to allow warm air in to keep ice from forming in the carb. air from the headers is best, with a thermostatic door that closes the flap when it is too hot.

 

I always wondered what temp fuel boiled at. I can see that 140-150 is almost a constant underhood temp? Does that mean near constant boiling?
Hopefully an L88 hood scoop "Not sure about an add on scoop or a new
L88 hood" and the coated Dynomax headers will keep underhood temps down?
Since the L88 hood works so well, just how much comp could be added?
I'm at about 8.4 DCR as I recall. I don't know how much higher I would want to go? I can see that I'm going in the right direction.

I wonder if adding a little rake to the car "17 x 18" wheels will inprove the induction at the base of the windshield? As the windshield gets more vert, how does that change things? I realise this is an aero question, but it is about CAI and underhood temps. Good info all, thoughts?

R

 

R
the same effect in AC goes on in the carb.
An expanding gas cools, so the carb stays much cooler than u'd expect. after a ride, i pop the hood, check the bowl w/IR temp gun, it is usually 120-127F in summer.
The AC effect is why u get ice at 50F.
But at idle in traffic there is not enough flow, and it can heat up and boil. A fuel return line helps.
Even worse, when u shut it off, 10-20 min later it hits peak temps. But w/isolater gasket it is not much higher.
.
No need for rake; plenty of cool air.
.
How r u going to raise CR? Easier said than done.
63mako knows that DCR stuff; maybe he can tell u how much Myself i'd go 1/2 a point w/ iron heads.

 

IM RUNNING 10.5:1 WITH .55 LIFT AND ~240 DURATION AT 50*..... Cam has a lot to do with pinging also......pings in summer, have to run 5 gallons of 100 octane with ~18 gallons 91... but winter or none hot days no problem. I am making a cold air intake currently and should have it done by Christmas... I will post pics

 

Yes,
classic symptoms of a car needing cold air, not race gas.
With a smaller cam it might still ping even with cold air. Then a guy with that problem could try some more tuning similar to
http://community-2.webtv.net/MATTGRU/pv/