Will Carb Spacer help?

warrenbh · Sep 21, 2011

I have a 289 4bbl with modified cam. Edelbrock 600 cfm thunder series, installed last year.

I have trouble starting the car with the motor hot . . . hard start. I've heard that gas vapors have something to do with it and that a carb spacer would help.

Is this true? If so, what's the best spacer? wood? synthetic material?

And what about the opening? 1 hole, 2 or 4?

Thanks in advance.

Warren

robbz28 · Sep 21, 2011

First thing you need to make sure is that its vapor lock and not something else, like maybe your starter is old and gets weak when it gets hot....it happens. Also your timing may need adjustment. If you do find out that it is vapor lock then a spacer may help. If you have a dual plane intake then you need a divided spacer (or a 4 hole), otherwise you will lose some low end torque.....but may gain some top end...but for the street you want the torque. Wood is the best insulator against heat, but i think you would probably be fine with an aluminum spacer....probably the cheapest too. Just my opinion...maybe someone else can chime in as well.

Edit....One more thing to check is where your fuel filter is...if you added a filter before the carburetor, make sure it isnt just lying on top of the intake, that would be like heating up the fuel before it gets to the carb and adding to your troubles.

Slobin3d · Sep 21, 2011

if your getting that hot, maybe you need to look into your cooling system too?

blown65 · Sep 21, 2011

If you were to do a spacer I would not do an aluminum. Keep the heat away from the carb with a wood or poly spacer. 4 hole would be my choice either way.

X2 on checking your timing. Does it want to kick back when you crank it? Or just not want to start?

Rmoore45 · Sep 21, 2011

I have same problem, I bought the wood spacer and it helped it, but that's all it did. After an 45 minutes or so, its still difficult to start but like it was before. Its not vapor lock, that's in the fuel lines, its boil over the carburetor gets so hot that the fuel in the bowls boils and goes into the intake flooding it. I pulled the carb off mine after letting it set for an hour, the intake was wet with fuel.

I don't know what to do, the cheap made in china aluminum intake may be a problem. I think that the carb heater is doing too good of a job, the heads and intake have a port built into them to run exhaust gasses through the intake to heat it up, I'm thinking about plugging the passage and seeing what happens.

2+2GT · Sep 21, 2011

Plastic, with 4 holes, would be your best bet.

warrenbh · Sep 21, 2011

Robbz - I think you might have a point with the starter . . . .

Could someone help me understand single plane, dual plane?

warrenbh · Sep 21, 2011

1/2 inch, 1 inch, 2 inch??? Anyone?

warrenbh · Sep 21, 2011

Rmoore? mine's a 66. Would it have a carb heater??

JonK · Sep 21, 2011

Single plane is one big hole in the intake opening - for top end speed/breathing like a car that runs 7,8K RPM steadily at the track. Dual plane is perfect for street and modded to run up to 6K+ range, it will have a divider down the midde and one plane will be half way up and one down low.

I installed a 1/2" phenolic spacer (4 hole) on my 4bbl. with a highrise dual plane. It made a huge difference in how hot the carb. got, I did take IR readings but forgot to write them down. Before the spacer it was alum. int.> thick gasket/paper gasket> carb. base and I couldn't hardly touch the carb., it was just as hot as the intake. After the 1/2" spacer (all I had room for) I could lean on the carb with it running, it was warm but nothing that would burn you if you left your hand too long like before.

1" is plenty if you have the room under the hood.

As your starter gets older the windings will swell from exh. heat and it will slow the turning. Eventually the starter will die but when it's swelled it is putting a huge load on your battery/cables to turn.
Jon

blown65 · Sep 21, 2011

1/2"-1" is all you need. Really your just trying to keep the heat off the carb and its not really going to make a whole lot of difference between the two thicknesses. 1" or more will pull differently on your carb and you might need to go up one jet size, but that would be if you were already at the right jetting to start with.

robbz28 · Sep 22, 2011

warrenbh said:
Rmoore? mine's a 66. Would it have a carb heater??

If you have the factory intake you probably do....if its an aluminum aftermarket like and edelbrock or something you may or may not.

jerthemost · Sep 23, 2011

Problem solved

I have the same engine in my 68. 289 with edelbrock cam and performer intake with 500 cfm 4 barrel. I am in Houston where we have had 100 + temps all summer. My car would crank fine cold but would not crank after running a few miles and warming up, was flooding etc. It even affected my starter. I went thru 2 start relays, they were sticking. I called edelbrock and they sent me a synthetic spacer said I had fuel boil over. I installed the spacer and have had no problem since. It's about 3/8 " thick. If you go much thicker you may have a problem closing the hood. I use the thicker air cleaner from edelbrock.

Call edelbrock they will advise you properly, ask for Smitty he really knows cars.

warrenbh · Sep 24, 2011

Thanks Jerthemost.

Realmongo · Sep 25, 2011

Have you already tried a heat insulating gasket and heat shield?

warrenbh · Sep 25, 2011

Thank you all.

warrenbh · Oct 6, 2011

Spacer Size

I have narrowed it down to plastic or wood, 4 hole.

I measured the clearance between the airfilter and the underside of the hood (with a piece of clay) and arrived at 2.5 inches.

i'm looking at 1/2 inch to 1 inch. Any difference in engine performance??

Also I see some with "tapered" openings . . . does this help?

Thanks in advance!

blown65 · Oct 6, 2011

warrenbh said:
I have narrowed it down to plastic or wood, 4 hole.

I measured the clearance between the airfilter and the underside of the hood (with a piece of clay) and arrived at 2.5 inches.

i'm looking at 1/2 inch to 1 inch. Any difference in engine performance??

Also I see some with "tapered" openings . . . does this help?

Thanks in advance!

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