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Intake Manifold Advice

J

jmbour66

Member
I'm looking for advice on picking out an Intake Manifold.

The engine: 302 Roller Block
Bored .40 over
E303 Cam
Holley 4 Barrel with Vacuum Secondary 600 CFM
2.5" Exhaust with headers
Ram Air

The engine had a Victor Jr. on it when I bought it, but one of the carb studs was stripped out so I put my old Performer on the engine. I'm really wondering if I should go back to the Victor Jr, and will it make that much difference? or do I go with another intake all together? or??????
 
While I cannot be positive, I'm pretty sure all Vic Jr manifolds are single plane designs. If that is the case, you are much better off with the Performer for your vehicle. Single planes are not great for the street as they are primarily designed to offer performance at mid-range and higher. A good dual plane like your current set-up will prove much better in daily driving. Even the typical "spirited" runs. Leave single planes do applications like drag racing where high rpms are the norm.
 
Re: Intake Manifold Advice

Thanks Terry. At least I won't have to go through all the trouble of swapping intakes.

Any thoughts on Carburetor Spacers and their benefits?

Sent from my DROID2 GLOBAL using Tapatalk 2
 
A phenolic carb spacer can be helpful in keeping the carb and incoming fuel charge denser (lower air temp). The thicker the spacer the better the affect. I used a 1" on my old 83 GT with good success.
Another option, the new Air Gap manifold takes this to a greater level by separating the runners from the hot lower manifold with...yep, an air gap! Just make sure you have underhood clearance whatever way you go.
 
Intake Manifold Advice

I always make my own wood spacers. Pick your thickness and choice of wood, or wood product, at HD, then trace out a carb gasket on the wood. Jig saw it out and you have your own custom wood spacer which does an amazing job at blocking the heat from the intake manifold. Even an 1/8" makes a huge difference in temp.
 
Re: Intake Manifold Advice

I read some where that wood is a great insulator and makes a good spacer.

I have a scrap piece of poplar from a mantel I just built, so I'll give it a try.

The Edelbrock Air Gap looks pretty cool, I might buy one and swap out this Fall if and when the weather here in Iowa starts to cool.

Thanks guys,

Jon

Sent from my DROID2 GLOBAL using Tapatalk 2
 
Re: Intake Manifold Advice

"monkeystash" said:
I always make my own wood spacers. Pick your thickness and choice of wood, or wood product, at HD, then trace out a carb gasket on the wood. Jig saw it out and you have your own custom wood spacer which does an amazing job at blocking the heat from the intake manifold. Even an 1/8" makes a huge difference in temp.
Click to expand...
No issue with fuel saturating the wood? I would think this a probable eventuality and serious fire risk...no? I suppose you could use some type of wood sealer before installation.

Funny story. In a rush one day after spending most of the morning tuning up the carb prior to a trip to an out of town cruise I swapped out my normal spacer for a new "high-tech" plastic one purported to create a distinct flow pattern into the manifold. I was still running a factory 4 barrel intake (83 GT). What I failed to consider was the heat riser port that my new spacer now rested upon. I managed to get quite a ways from home before the heat from that port melted the spacer and left me sputtering and dying by the side of the road thanks to an enormous hole in the side of the spacer. Having left my old aluminum piece sitting on the bench, I ended up buying the only thing available in the small town to which I walked which was just a typical, but very thick, paper carb gasket. Not designed for the heat port I knew I would only burn it out so I sandwiched a piece of a Pepsi can between the port and the gasket and managed to make it home. Lesson learned. Even the simple stuff can burn you if you're not careful.
 
adding a phenolic (or i guess wood in some cases) won't fully isolate the heat from the manifold to the carb (not talking about air flow).

also, don't forget, there is still 200 degree water flowing through an Air Gap type of intake manifold.

i think it would interesting if someone measured the temperature at the carb surface of the manifold and baseplate of the carb to see how much different they are when using some defined thickness insulating spacer.
 
Intake Manifold Advice

"Horseplay" said:
No issue with fuel saturating the wood? I would think this a probable eventuality and serious fire risk...no? I suppose you could use some type of wood sealer before installation.
Click to expand...

Had the same one on the goat for over 10 years, no problems...no wood sealer either.
 
i'll have a thermocouple in my hands in the next few days.

i have a Vic Jr (351W) and a 1/4" phenolic carb spacer. i also run a bypass regulator and return line, so my fuel entering the bowls is really cool.

my plan is to get the water temperature in the 190-200 F range and measure the following locations at a minimum:

1. intake manifold on top of the water jacket

2. intake manifold just below the carb gasket

3. intake manifold lower plate (the bottom part exposed to the lifter valley)

4. carb base plate right next to a screw.

anyone care to take some guesses at the temperature delta's between the various locations?

i have several other spots i would like to measure, but would like to know if anyone else has suggestions on other measurement points? or is nobody else interested in attempting to record some real data?
 
I'd definitely like to see the results, I have a 1" phenolic spacer and wonder how much it actually helps.
 
I will guess if intake is 190*, carb bowl with spacer will be 140* as it's still exposed to underhood heat. If you leave the hood open long it will be lower than just opened temp. I believe.

I did this a few years ago with a 1/2" phenolic spacer and an IR gun from HF but didn't write down the numbers. Without the spacer I could not lean on the carb. as it was the same temp as the intake. With spacer I could rest on the carb, it was warm but not burning hot.
Jon
 
i looked into using an IR gun. the problem i had with it was the measurement spot width i felt was too large. so i decided to go with a thermocouple. hopefully i can get some useful data.

i'll probably measure both bowls, however i'm wondering how the fuel will impact that temperature with my system. maybe the secondary bowl will be an indication.

there will be no hood on the car, nor any air cleaner.
 
sorry for taking so long, but it took awhile to get the thermocouple, i went on vacation and my car has been under some plastic while i've been sanding and buffing.

but today i got it out and thought i would make a few quick measurements. i wanted it to be hotter, but i guess this was a quick sample. i would still like to get some data on a 90 degree day when i can really get things to heat soak.

it is about 72 degrees with low humidity. the shaker assembly was off (so is the hood). i had it basically idling for 20 minutes or so.

as a reminder, i have a Vic Jr, 1/4" phenolic spacer, return style fuel system (fuel is cool).

the water temp gauge was reading about 165F

i made three measurements as shown in the pic (look for green tape).

intake manifold, top, next to water neck: 153F
intake manifold, right below carb stud: 124F
carb base, right next to stud: 89F

IMG_3427.jpg
 
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Thanks for the data. That's a considerable difference between the carb and the manifold, 35 degrees. Measuring right next to the stud, I'd figure there is some transfer up the stud to the carb, so farther away from the stud the temp might be a little less too.
 
buckeyedemon,

What is the bracket attached to the intake manifold and running over the valve cover for???

IMG_3427.jpg

[/quote]
 
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"dm289" said:
buckeyedemon,

What is the bracket attached to the intake manifold and running over the valve cover for???
Click to expand...

support bracket for the shaker. i made my own since a factory part wouldn't work do to the heavy modifications to the shaker.
IMG_2347.jpg
 
Last edited by a moderator:
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