Question: will vortec heads/manifold work with L48 hood

[lalo]

Hello. I looking into a pair of vortec heads for my 73 vette with a standrad L-48 hood. I've been told the manifold will be too tall and the hood will not close. Any suggestions? I there a vortec manifold that will work with this hood? Or is the L-88 hood the way to go. Thanks.

 

[Crimson Thunder]

The Edelbrock catalog says it will not fit Corvettes,but if you use a LT-1 drop base air cleaner it might fit.

 

[lalo]

Thank you. I heard the Edelbrock #1002 drop base air cleaner might work. I'm not sure if that's the same as the LT-1 drop base air cleaner, but will look into it. Thanks again.

 

[Crimson Thunder]

If you are using a 14 inch open air cleaner you can try to get a shorter air filter. I know K&N makes 2 3/4 inch tall filters.

 

[lalo]

I do. I purchased the Edelbrock drop base air cleaner, but it looks like it measures higher that my K&N 14" air cleaner that I have right now. I will return the Edelbrock and will try out that 2 3/4" filter that you mentioned. Thanks for your help.

 

[Glensgages]

a buddy had vortec heads on his '80, which 'appears' to be a lower-profile than the '73 (underside may be another story), with an RPM AirGap intake, Holley carb, and a drop-base air-cleaner

 

[Hib Halverson]

I will be surprised if you can get that manifold under the hood in a manner which will have the engine not being restricted for air flow.

Keep in mind that you can only go so far in drop-base-air-filter-assemblies and shorter fulters until you decrease horsepower due to restricted space between the carb air horn and the hood or between the air filter top and bottom.

Once you start restricting that, then the purpose of the intake manifold is defeated.

The typical performance modified 350 is going to need at least a 3-inch and preferrably a 4-inch air filter element and at least a full inch between the top of the carb choke horn and the hood.

 

[Crimson Thunder]

I can tell you right now that my LT-1 drop base air cleaner (with a three inch filter) on top of my Holley Street Avenger carb has nowhere near an inch above the choke tower and the front vent tube is very close to the top of the air cleaner. I've often wondered how much HP I could be losing with this setup.

 

[lalo]

the vortecs are out

I can tell you right now that my LT-1 drop base air cleaner (with a three inch filter) on top of my Holley Street Avenger carb has nowhere near an inch above the choke tower and the front vent tube is very close to the top of the air cleaner. I've often wondered how much HP I could be losing with this setup.

I decided to do away with the whole vortec idea and leave it maybe for another vehicle. It was just going to be too much of a risky expense of purchasing a high rise or L-88 hood, plus shipping and paint. I searched for different filters, manifolds, talked to people, researched online, and read all of your posts. I decided to purchase a pair of aluminum heads instead for a moderate price (without having to worry about the space issue). I'll keep my current manifold and with minor adjustments, these heads should do well and should have plenty of air space. Thanks everyone. I think I made the right decision and couldn't have done it without your feedback.

 

[Hib Halverson]

I can tell you right now that my LT-1 drop base air cleaner (with a three inch filter) on top of my Holley Street Avenger carb has nowhere near an inch above the choke tower and the front vent tube is very close to the top of the air cleaner. I've often wondered how much HP I could be losing with this setup.

There's an easy way to find out.
Take the car to a chassis dyno. Remove the air cleaner top and filter but leave the base plate on the carb. Leave the hood open and make three passes and average the results.

Reinstall the filter and top then close the hood and make three more runs and average.

The difference will be skewed a little bit because of underhood temp but it will give you an idea of how much restriction develops due to insufficient space between the bottom of the hood and the choke horn.

 

[Jack]

The heads themselves have nothing to do with how high the carb sets ... the intake manifold does. Matters not whether L48 heads, vortec heads or afr heads ... it does matter what the intake manifold is.

FYI:
Years back I checked Intake Manifold from '71 L48
OE Intake Manifold, Cast Iron c/n 3973460 F = 2.69”, R = 4.375” (~35 degrees down in front)

very likely '73 L48 manifold has about same dimensions as '71.

compare those dimensions to whatever manifold you plan to use.

Measure method: lay straight edge across carb flange, drop lines down from straight edge to china rails ... most manufacturers post some specs-dims on their sites ... some show both F&R (A&B) ... some average the two.

The way it works out ... a perfomer vortec 2116 is about 1/2" taller than plain old performer 2101. Measure between your closed hood & your air cleaner assembly (wad of tin foil) ... then figure how much more room you'll need ... leaving some wiggle room as motor torques against mounts.

NOTE: The angle is just as important to fitment as height is.

http://www.edelbrock.com/automotive_new/mc/manifolds/lb/ab.gif