Dispelling the Edelbrock Performer RPM "Won't Fit Myth"

[krscholz]

Yesterday, I fitted the hood on my 75 C3 with the Performer RPM and this is what I found. There was 1 ½” space at the front of the air cleaner and 3” at the rear after the hood was closed. To check clearance yourself, take a wad of aluminum foil and compact it loosely into two balls and place one ball on the front and rear on the air cleaner. Then close the hood carefully. Open the hood, assuming that the hood closed all the way. Take out the foil balls and measure the compacted area. This was done using the full size 14” Edelbrock Elite air cleaner, but in all fairness, I must say that I used the flat air cleaner gasket instead of the ½" plastic spacer that Edelbrock recommends when you have an electric choke. The way to get around the electric choke problem, is that I took a small ball pein hammer and created a little more space on the lower lid where the choke tucks-up under. This gave me the space I needed so that the lower lid could sit flat on the carburetor and it is impossible to see when the air cleaner is installed.

For even more space, I’m going to use a NAPA Gold #6037 filter element instead of the Edelbrock element because it is 2 5/8“ compared to Edelbrock’s stock 2 7/8”. When you call Edelbrock and ask about the clearance, they will say that the Performer RPM will absolutely not fit Corvettes. Here is the reason I believe for the misinformation: early C3 Corvettes have flat cowls/hoods except for the high performance factory set-ups. Later mid-year models have a substantial cowl for their air induction system that was later developed like my 1975. The newer cowls give more clearance that works just fine with the Performer RPM. If you're nervous about the engine torquing too much, you may also switch to a pair of Poly motor mounts that give la little more rigidity to the engine. Feel free to contact me at www.c3corvettegrilles.com for any questions. I hope this helps.

One other point. . . If you are going to an Edelbrock Performer RPM intake, you won't want to use the stock air cleaner, this may add to the compatibility problem that Edelbrock is talking about.

UPDATE: I just changed the air cleaner to allow for the electric choke clearance. This Eldebrock part is slightly higher and still fits fine (model #4221).

 

[catbert]

Great input - thanks

 

[Hib Halverson]

You are right in your assessment of Edelbrock's fit information for Performer RPM on an engine in a C3 but you're only right if you mean "fitting without interferring."

If you mean "fit in a manner that works well." you may be disappointed.

Two problems. One is you can't use a air filter which is tall enough to allow the airflow that a small block which can use that intake manifold will need. You need at least a 3-in. filter element.

Secondly the aforementioned choke horn. If you run a Holley with a choke, you end up with not enough space between the top of the choke horn and the bottom of the air cleaner top such that airflow is restricted there, too.

So, yes, a Perf. RPM may fit under a 73-up hood but it's not going to work well at high rpm unless you have more space under there.

 

[krscholz]

Size Does Matter

Hib you're right on the money about size. The Edelbrock Elite has a 3" filter which is a fairly large size (really 2 7/8") and is the one I experimented with - it will work. I looked into all the air filters available with low profiles and found the Mr. Gasket's "Low Rider" has a 2" filter. I steered away from this choice because of the air flow volume.

 

[Tepot]

Solution? Maybe?

Hib you're right on the money about size. The Edelbrock Elite has a 3" filter which is a fairly large size (really 2 7/8") and is the one I experimented with - it will work. I looked into all the air filters available with low profiles and found the Mr. Gasket's "Low Rider" has a 2" filter. I steered away from this choice because of the air flow volume.

If the only problem here is the size of the filter, would a K&N X-Stream-Top-Filter fix the issue? I have one on mine and will probably go fetch that extra air required. Also my hood on my 74 is a fully fonctional cowl induction hood, air will flow to the top of the filter.

thoughts?

 

[Hib Halverson]

Hib you're right on the money about size. The Edelbrock Elite has a 3" filter which is a fairly large size (really 2 7/8") and is the one I experimented with - it will work. I looked into all the air filters available with low profiles and found the Mr. Gasket's "Low Rider" has a 2" filter. I steered away from this choice because of the air flow volume.

There's an easy way to test this issue.

Put the car on a chassis dyno, open the hood and install your typical open element Chevrolet air filter assy that fits a Holley. Make three runs and average the result.

Then put your low profile base short filter and flat air cleaner top on, close the hood and run again.

If you loose power, you need a better air filter base, a taller filter and more hood clearance.

 

[glen242]

Yesterday, I fitted the hood on my 75 C3 with the Performer RPM and this is what I found. There was 1 ½” space at the front of the air cleaner and 3” at the rear after the hood was closed. To check clearance yourself, take a wad of aluminum foil and compact it loosely into two balls and place one ball on the front and rear on the air cleaner. Then close the hood carefully. Open the hood, assuming that the hood closed all the way. Take out the foil balls and measure the compacted area. This was done using the full size 14” Edelbrock Elite air cleaner, but in all fairness, I must say that I used the flat air cleaner gasket instead of the ½" plastic spacer that Edelbrock recommends when you have an electric choke. The way to get around the electric choke problem, is that I took a small ball pein hammer and created a little more space on the lower lid where the choke tucks-up under. This gave me the space I needed so that the lower lid could sit flat on the carburetor and it is impossible to see when the air cleaner is installed.

For even more space, I’m going to use a NAPA Gold #6037 filter element instead of the Edelbrock element because it is 2 5/8“ compared to Edelbrock’s stock 2 7/8”. When you call Edelbrock and ask about the clearance, they will say that the Performer RPM will absolutely not fit Corvettes. Here is the reason I believe for the misinformation: early C3 Corvettes have flat cowls/hoods except for the high performance factory set-ups. Later mid-year models have a substantial cowl for their air induction system that was later developed like my 1975. The newer cowls give more clearance that works just fine with the Performer RPM. If you're nervous about the engine torquing too much, you may also switch to a pair of Poly motor mounts that give la little more rigidity to the engine. Feel free to contact me at www.c3corvettegrilles.com for any questions. I hope this helps.

The 'Myth", as you call it, is really true! Performer RPM will NOT fit under a stock hood when using the stock air cleaner.

You can attempt to use after market/modified air cleaners to get a fit, but I have not heard of anyone running stock, from the factory, components and having it fit. This is what Edelbrock means when they say it will not fit. STOCK COMPONENTS!

I had to use a drop base for the air cleaner along with an open element top, to get the hood closed. I did not like the lack of 'cold air' intake on my 383 but I put up with it until a guy designed and built a 'cold air' intake that actually works, picking up cold air from over the top of the radiator. Works well with no clearance issues. The last I heard, he only made a limited run of these, and they were sold out. Workmanship was excellent. He is just a enthusiast, not in the parts business, as his vocation is a school teacher.

He posts on the 'corvette forum' with a user name of Paul Dana.

Not cheap, but worth it to me and a lot of others.

 

[krscholz]

The 'Myth", as you call it, is really true! Performer RPM will NOT fit under a stock hood when using the stock air cleaner.

You can attempt to use after market/modified air cleaners to get a fit, but I have not heard of anyone running stock, from the factory, components and having it fit. This is what Edelbrock means when they say it will not fit. STOCK COMPONENTS!

I had to use a drop base for the air cleaner along with an open element top, to get the hood closed. I did not like the lack of 'cold air' intake on my 383 but I put up with it until a guy designed and built a 'cold air' intake that actually works, picking up cold air from over the top of the radiator. Works well with no clearance issues. The last I heard, he only made a limited run of these, and they were sold out. Workmanship was excellent. He is just a enthusiast, not in the parts business, as his vocation is a school teacher.

He posts on the 'corvette forum' with a user name of Paul Dana.

Not cheap, but worth it to me and a lot of others.

Perhaps you are correct about using the stock air cleaner. I didn't use it and got plenty of clearance with the Edelbrock Elite air cleaner. If you are going to use the Performer RPM intake and change the performance and look, then I would use an Edelbrock air cleaners as well.

 

[Peer81]

Yes use a performer rpm intake for some extra hp and torque but loose it all together and even more with a aftermarket hot air intake in favor of the oem cold air intake. I would say read a few books and see how much hp gain you have with a 5 F intake temp drop compared to a better intake. Not everything with performance written on it is truly an improvement. Just my 2ct.

Greetings Peter

 

[spikebot 81]

I'll agree that the stock air cleaner will not fit. I just installed 7101 rpm edle intake and 1411 750cfm edle carb on my 81 with the stock hood. With a edle air cleaner assm and a 3" filter the highest point has 1/2 inch clearance. Not too sure I buy into the stock cold air intake setup making more power. On a turbo Subaru, yes but normally aspirated engine I'm not convinced. The stock 81 air assm has 2 snorkel intakes that measure 2X6 inches each. The 14X3 paper air cleaner element is 44" X 3" of surface area. Is the engine bay really that hot while at speed? I can say that the edle 2101 intake and 1406 edle 600cfm carb with the stock air cleaner performed just fine. Now that I have made the swap the power difference is more than noticeable. The engine seemed to run out of breath at 5000rpm and now still pulling hard at 5700.
180cc rhs iron heads
9.48 to 1 compression
60103 luanti cam
long tube ceramic headers
true duals with dynomax super turbo mufflers
2004r trans with 2400 rpm stall converter

 

[Vette79]

Good read and a lot to consider when making the switch. I am currently finishing my install to the Performer RPM 7104 from the Performer. There is a .70'' increase in height difference from the Performer to Performer RPM. Stock setup will not fit under the stock hood which has already been covered. I am using a Holley 0-9895 and had to use a Holley drop base air cleaner with a K&N 2.3'' filter element and to adjust for loss of filter and air flow I am using K&N Filters 66-1401XP Air Cleaner Top. The only other modification was to trim the stud that secures the air cleaner assembly in place on the carb. The only other option for clearance was to purchase another hood which was much more costly. I'll know more once I finish up and do a butt dyno but for now this seems like the perfect upgrade for my configuration.