Hood to Air Cleaner Gap

[Jim S]

I'm to the point of installing the hood on my MkIV. I have the hood installed with the hole for the hood scoop cut and the hood gaps adjusted all around. I cut the hole for the scoop using Jeff K's suggested dimensions on the underside of the hood. When installed, I have 1/8" of clearance at the air cleaner on the passenger side. While I don't think an 1/8" of clearance is enough to account for engine rocking, how much clearance is everyone else allowing?

I have a BluePrint 427 based off the 351W. The hood must be cut and the scoop installed to clear the air cleaner.

Are there any other tricks or adjustments I haven't thought of to get more clearance? I have made sure the body is centered on the chassis. To get the 1/8" of clearance I have, I set the driver's side gap by trimming the passenger side of the hood. That allowed me to shift the hood to the passenger's side.

It seems the recess on the underside of the hood is offset quite a bit to the driver's side. The hood scoop hole is centered in the recess in the underside of the hood so that it looks centered when the hood is up. When the hood is down, you can see in the following pictures that the hole is shifted towards the driver's side by 1/2". (The white line in the picture is a string down the center of the car.) It won't be noticeable once the scoop is on but I believe it is causing the air cleaner clearance to be tight.

189431189430

[Jeff Kleiner]

The entire drivetrain is offset to the passenger side by design and the hood is not centered on the body (not by design ;)).

Jeff

[Jim S]

I agree Jeff. The drivetrain offset is easily seen at the IRS. It looks like the hood (at least on my car) is offset by a 1/4”.

Given that, the what is a practical amount of clearance between the hood and the air cleaner? Is 1/8” enough? Seems too small.

[Jeff Kleiner]

I can't tell you what a "practical amount" is but I can tell you that this is what happens when using the combination of a high deck 351 based block, a tall intake such as the Performer Air Gap and the oval air cleaner. I've had multiple cars come through my shop with exactly the same issue. My recommendation for those was to either swap to a lower profile intake or ditch the restrictive oval air cleaner and replace it with a drop base 14 K&N with an X-Stream top. A third option is Gordon Levy's solid lowering engine mounts however that opens up the potential for other complications with oil pan clearance and header/sidepipe/body cutouts.

Jeff

[CraigS]

The engine rocks on accel to the passenger side. I can't tell for sure is the RF corner of the air cleaner above the fiberglass? Or would it rock sideways and slip under the hood? Would the scoop cover the hole if you widened it some? A lot of front wheel drive cars w/ the engine mounted sideways have a dog bone shaped strut to keep the engine from rocking too much. I wonder if you could find a spot to install one on an FFR. This is what I am thinking of.
https://ic.carid.com/pioneer-automotive/items/635379_1.jpg
Search this "automotive engine torque strut" for a bunch of varieties.

[Jim S]

The engine rocks on accel to the passenger side. I can't tell for sure is the RF corner of the air cleaner above the fiberglass? Or would it rock sideways and slip under the hood? Would the scoop cover the hole if you widened it some? A lot of front wheel drive cars w/ the engine mounted sideways have a dog bone shaped strut to keep the engine from rocking too much. I wonder if you could find a spot to install one on an FFR. This is what I am thinking of.
https://ic.carid.com/pioneer-automotive/items/635379_1.jpg
Search this "automotive engine torque strut" for a bunch of varieties.

Craig,

The right front corner is above the fiberglass by about 1". I too was wondering if the air cleaner would slide under the hood when the engine rocked but I decided it would probably hit first. The fiberglass may deflect and let it slide under the hood but then the hood and probably the air cleaner would get marked up a lot. The fiberglass may even crack.

There is room to widen the hole on the passenger side... see the picture below. I'm thinking I probably need to open it up by another 1/4" to get enough clearance. Unfortunately, I can't open up the hole by much on the driver's side and still have the scoop cover. Only opening up the passenger side would leave the hole in the hood looking off center when the hood is opened. At least I think a 1/4" would be noticeable. While a possible solution, it is not one I am ready to pick.

189451

Your idea of restraining the engine from rocking is interesting. I need to consider that for a bit. The only place I can think of that would have enough strength are the 4" round tubes. I'm afraid the 3/4" tubes would bend. Maybe I can get something to run down from the lower, front corner of the cylinder head or engine block to the 4" tube. I can remember seeing people doing this with a chain on old muscle cars because the engine mount wouldn't restrain the engine enough.

From Jeff's reply above, I can see some other possibilities as well that I am going to look at.

Anyone else out there come up with a different solution? Does anyone know if a wider scoop?

[CaptB]

I was advised to use different motor mounts which lowered my engine a few inches. If you have FFR motor mounts they are taller. Got them from lmr.com:

https://lmr.com/item/LRS-6038DS/1979-95-Mustang-351W-Drop-Solid-Motor-Mounts

I checked and had an alignment shop check my pinion angle, all was well with these motor mounts.

[Norm B]

Looking at pictures of my car sitting still and under hard acceleration the passenger side header moves down about 3/4 inch at the body opening. That’s on stock Mustang convertible motor mounts. Here’s a picture showing how high my air cleaner is on a 302 block. High rise dual plain manifold, 1/2 inch open spacer, Sniper unit, 3/8 inch air cleaner spacer (stops the oval air cleaner from choking the airflow) and the air cleaner. There’s about 3/8 inch clearance at the rear cowl off the hood opening.

HTH

Norm

[Jim S]

I was advised to use different motor mounts which lowered my engine a few inches. If you have FFR motor mounts they are taller. If you need a PN let me know.

I would like the PN please. I would like see what they are like.

[Jim S]

Looking at pictures of my car sitting still and under hard acceleration the passenger side header moves down about 3/4 inch at the body opening. That’s on stock Mustang convertible motor mounts. Here’s a picture showing how high my air cleaner is on a 302 block. High rise dual plain manifold, 1/2 inch open spacer, Sniper unit, 3/8 inch air cleaner spacer (stops the oval air cleaner from choking the airflow) and the air cleaner. There’s about 3/8 inch clearance at the rear cowl off the hood opening.

HTH

Norm

Norm… I just went out and measured my car. I have 3/4” of clearance at the cowl on my car. How much clearance do you have between the air cleaner and the hood where the air cleaner transitions from straight to round at the front? I know that is a difficult measurement with the scoop on. Maybe you could look inside the scoop with the hood closer to get a measurement? I’m thinking you must have more clearance than I do but I’m not sure why given the cowl measurements.

[Norm B]

Away from home until 1 September for work. Will measure then.

Norm

[Rdone585]

You could also consider solid motor mounts. That will fix the engine to the frame. You will feel the engine more with them than you would using traditional mounts. If you do go with solid mounts consider two things; 1) do not use a solid mount for the tranny, use an energy suspension mount or similar, 2) Your engine may lower a slight amount, thus changing the exit point on the body for side pipes. There are (or at least use to be) multiple vendors with solid mounts, each may have a different spec for change in engine position.

[Jim S]

I think looking for some solid engine mounts may be the way to go to stop the rocking.

The LMR mounts that CaptB suggested drop the engine 1-1/4". While that would fix the clearance problem, it creates another problem. It puts the oil pan below the 4" tubes by 3/4". I'm not a fan of that.

[haak60]

189475189476189475189476mine is the same, never had a problem. Probably going to get a better breathing air cleaner though

[Jeff Kleiner]

I think looking for some solid engine mounts…

The LMR mounts that CaptB suggested drop the engine 1-1/4". While that would fix the clearance problem, it creates another problem. It puts the oil pan below the 4" tubes by 3/4". I'm not a fan of that.

Wow, just like I told ya’ several posts ago. ;) Change the air filter and be done with it. Yeah, I know, the oval looks cool but like I also said earlier, it’s restrictive and will choke your engine.

Jeff

[CaptB]

I would like the PN please. I would like see what they are like.

https://lmr.com/item/LRS-6038DS/1979...d-Motor-Mounts

[CaptB]

I think looking for some solid engine mounts may be the way to go to stop the rocking.

The LMR mounts that CaptB suggested drop the engine 1-1/4". While that would fix the clearance problem, it creates another problem. It puts the oil pan below the 4" tubes by 3/4". I'm not a fan of that.

I had a Forte built 427 and the oil pan didn't extend beyond the frame. But your point is well-taken on that, it would make me nervous too.

[Norm B]

Do you have a spacer under the air cleaner? If you don’t, then your problem is much worse than you thought. The oval air cleaner top will be very close to the carb or throttle body air intakes and will choke your engine. Needed a 3/4 inch spacer for an Edelbrock carb and can get away with a 3/8 with a Sniper.
Maybe a nice round air cleaner with a turkey pan like some of the originals is in your future.

[Jim S]

Maybe I am analyzing this to death.

I have looked up a lot of air cleaners. The only drop base that I can find to fit a Sniper EFI is from Holley with a 1" drop. Using a 2" tall filter element and a K&N X-Stream top at 3/4", I find that I need a 12 inch air cleaner to clear. Holley doesn't make a 12" Sniper drop base. (I can bore you with crude CAD drawings if you like.) Has anyone got a round air cleaner installed on the same combo and found anything different? My combo is a Sniper on a 351W Dart block with an Edelbrock Performer Air Gap manifold, no spacers under or above the carb. If you do have something that works, could you please share what the combo is?

On the restriction aspect of the Cobra oval air cleaner... I'm not getting it. The filter element is 2" tall leaving the lid 2" above the carb mounting flange. Ford used this same dimension air cleaner / filter on engines with 750 CFM carburetors. Is it opinion that this air cleaner is restrictive or has there been some testing done to show that it is? I know K&N makes a replacement filter and no doubt it will flow better than a Motorcraft filter but I haven't been able to find any actual tests listing the CFM flow rates or engine dyno test results. Would a shorter turn radius into the carb be better? Sure. I'm trying to sort out facts from it could be better if....

Haak60... I'm encouraged by your post. How many miles have you driven it and how hard? Maybe the engine doesn't move that much.

[Norm B]

Take the top off your air cleaner, leave the base and the filter on, put a straight edge across the top of the filter element over top of the Sniper ports. You will see where the restriction is. The Sniper is way better than a carb where the barrels stick up well above the air filter flange. My old Edelbrock carb with electric choke had the primaries almost touching the air cleaner cover. Here’s a screenshot of a Sniper. See how far the ports stick up above the filter mounting flange.

Norm

[CraigS]

One other thought; I know that the air gap is the better of the two but I had a Performer RPM intake before the air gap came out. Maybe you could research the height difference to see if swapping would be worthwhile.

[ggunter]

I went through all that crap with the oval air cleaner and the Edelbrock air gap intake. The air gap looks cool with the oval intake but let's be practical for a second. The intake that does fit is an Edelbrock 2181 low rise intake. With the engine you have you will never feel the difference in the power which is only there at high RPM for the second or two your are in that RPM. You will spend hours and hours in the RPM range the 2181 will be working in and it still pulls great to 6000 RPM. I have the 2181 with a 1/2" phenolic spacer under the carb and an Air Cleaner from Blue Print 189496 engines that came on my 347 and everything fits under the hood with room to spare.

[ggunter]

I forgot to mention my engine is a 427 also. And by the way Jeff told me that combination wouldn't fit but I had to find out for myself.

[Jeff Kleiner]

...And by the way Jeff told me that combination wouldn't fit but I had to find out for myself.

Kinda' like touching a hot stove aint it ;)

Jeff

[ggunter]

Yep.

[ggunter]

I give credit where credit is due.:cool:

[Jim S]

ggunter... Based on what I can find on intake manifold carb flange height, I can see why your set up would clear the hood.

Your Edelbrock Performer 351W #2181 carb flange height: 4.12"
My Edelbrock Victor Jr 351W #2981 carb flange height: 5.75"

Your Performer manifold is about 1.5" shorter. I have a 1" hood clearance problem so the Performer 351W should fix the problem with a 1/2" to spare.

[CraigS]

The good news is that the air gap is very popular so you should be able to sell yours fairly easily.

[Jeff Kleiner]

One of my customers got rid of the Air Gap to solve the clearance issue…added benefit was the car actually became drivable. With the Air Gap he had to keep it wound up above 2,000 just to drive it out of the neighborhood. Said that after changing to the Performer his neighbors don’t think he’s just being an a**hole anymore :D

Jeff

[ggunter]

I have another project for the Air Gap manifold where clearance is not an issue.

[GoDadGo]

My take is that "Big Inch Small Blocks" deserve a single plane intake.

Yes you will lose some bottom end torque and low RPM drivability, but a Torker-II will fit where taller dual planes won't. The good news is your engine won't be nosing over after 5,000 R.P.M. and the torque curve may be wider and flatter.

https://www.edelbrock.com/torker-ii-small-block-ford-351w-intake-manifold-5081.html

[MPTech]

I'm trying to figure out which air cleaner would be the best fit for my setup.
I too had the popular (better looking) Cobra Oval Air filter, but was also concerned with it rubbing the scoop opening (and I've heard the oval base can cause problems with the Sniper / Hyperspark electronics)
Looking at the K&N 14" X-Stream Assembly offerings on Jegs, I see multiple combinations.
There's a 1 1/4" and 7/8" drop base available with 3", 4" or 5" filters.
Which is recommended for a Holley Sniper / Edelbrock Victor Jr intake on a 347 SBF?
I want to avoid a trial&error fit.

[Jim S]

MPTech,

Some feedback for you. Keep in mind that my engine is based on a 351 Windsor (Dart block) with an Edelbrock Victor Jr manifold (part #2981). The carb flange height is 5.75". That causes the front of my oval Cobra air cleaner to stick above the hood by 3/4 inch. I'm not sure how that compares with your engine / intake combo.

1) When I looked at this last year, the only company that made a drop base air cleaner that fit the Sniper was Holley (at least that I could find). The issue is the fuel line inlets and outlet. Even with Holley's air cleaner, 90 AN fittings had to be used to get the fuel line clear of the drop base air cleaner. Maybe this has changed since then but I would check closely to make sure any air cleaner you pick will fit the Sniper. (Sometimes the air cleaner specs fine print section will tell you what it fits / won't fit. Sometimes you find it in the Q&A section.)

2) With some crude CAD drawings, I found using a 2" tall filter element and a K&N X-Stream top at 3/4" high combined with a 12 inch, 1 inch drop base air cleaner would clear. Holley doesn't make a 12" Sniper drop base.

3) What I ended up doing was far simpler. I rotated the oval Cobra air cleaner. Instead of having the Cobra text at the 6 o'clock position, rotate the Cobra text to the 4 or 5 o'clock position. It clears just fine this way. Sure it looks funny that way but if it bothers you, just twist it back when you have the hood open.

Hope this helps.

[Mag]

I'm running a 427W with a Victor JR intake which is quite high. I installed a torque strap to limit engine movement. Used one for years on my 70 Hemi Roadrunner.
Back in the 80's a lot of guys were using them on street/strip cars as it limits torque movement without the noise of solid mounts. The turnbuckle allows you to adjust
how far you want the engine to move. Takes stress off the mount also. Works like a charm.201176201177