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Not a nickels worth of difference between the air-gap and RPM or the Victor jr. in the overall scheme of things. Not enough to "feel" anyway...(on the butt-o-meter scale)
That leaves...which one looks the coolest when I raise my hood!? Single plane Victor gets my vote for that.
Unless you abandon the...."no-hole-in-da-hood-theme". Then spring for a tunnel ram.
6sally6
PS...Keep in mind on the cam.....tight LSA(107-110*) gives killer torque at the expense of lower(er) vacuum and slight drop in fuel mileage. With 427 cubes...you AIN'T worried too much about fuel mileage. Don't be afraid of tight LSA's and plenty of duration!
You have...1. light weight
2. big cubic inches
3. good stiff gears
in your favor.
Put a nice size cam in it and worry about rear tires!
not even close to correct.
 

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Although the RPM or Stealth dual planes are great intakes, they will be more restrictive as the design RPM's go down as the cubes go up. That correlation also plays well into the hands of the Vic Jr and its streetability. The big stroker motors have more than enough torque to make the Victor Jr street friendly.

There is a way to put a Vic Jr under a STOCK Mustang hood. Had one under my street/strip 65' with a 393w that ran 11 flat several years ago. Here is how I did it:

A Vic Jr's carb flange can be angle milled. I removed .300 from the front of the carb pad and tapered it to near zero removal at the rear. That substantially drop the front of the modified 14" air cleaner I used.

Used dropped motor mounts. At the time mine where stock 65' Mustang 3 pc units but they really aren't strong enough for long term performance use (even with a through bolt.) I now use Ron Morris drop mounts similar to what Juiced Coupe mentioned. With either mount the Canton oil pan I used just touched the tubular cross member so that should give you an idea of how low the motor is in the engine compartment.

Carb selection. Use a "chokeless" carb such as the original Holley HP series (not one that has the choke removed.) The chokeless carb's air cleaner mounting location if somewhat lower than the choked type. I had used both a Holley 750HP and later a 950HP.

Modify a drop base air cleaner. I've modified 14" "Holley" brand drop air cleaners. Basically cut the carb flange ring area off of them which drops them substantially. If this is done the float adjusters of the Holley will be the next interference. I drillled 3/4" holes to allow the adjusters to pass into the air cleaner and then cover them with 3/4" EMT electrical conduit extensions, capped with knock out plugs from an electrical 4x4 box.

There is always a chance that your 67' hood has more of a crown than the 65' hood since it could also house an FE motor.

Although the milling of the intake and the severely dropped air cleaner base were not an ideal situation, the 393w had no problems screaming to 6600+ rpm's at the track and I did get it down to 11.0x (full weight car and driver) before I started using other combinations that needed a hood scoop.

Photos of said 393w:



The fancy 3 bar air cleaner hold down nut would not work under the stock hood. There are shorter hold down's available.





 

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For 90-95% on the street, I'd run the Weiand 8023 Stealth. If it was more for the track, I'd run the Victor Jr, unless someone had an original Torker for sale.
 

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If the intake doesn't flow a bit more than the inlet side of the heads, it's a restriction. You can have almost any intake ported (which can make a big difference) and there are some great/ clever ideas on getting intakes to fit under the stock hood in this thread.

That said - if you're not chasing every last bit of performance, get what you like/ fits easily enough!
 

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I called Edelbrock to ask about the Air Gap and their response was if you are buying a manifold, buy the airgap, if you have an RPM its not worth the money to upgrade. That said, there was a guy posted on this site with a performer RPM top end (no airgap) on a 408 that pulled a clean 500/500 across the RPM range dyno run. to me, a working man's stroker by definition is a mid-range motor unless you spend some big money on the lower end and top end to feed it. Most of us can't afford to grenade a motor at 8K so we chip to a modest "safe" number.

Most people I've spoken to with 408s already have a few stories of incidents and quite a bit of respect for them. I believe it was Dodgestang that said something to the effect; my 351 is a blast to drive but my 408 requires respect. So my bet is you will be find that even with an RPM, the car will not leave you wanting for power unless you are seeking single digit 1/4 times. Perhaps spend more money on putting that power to the ground which appears to be the biggest issue 408'rs have.

Such problems to have...

Happy new year...
 

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Discussion Starter #27
I called Edelbrock to ask about the Air Gap and their response was if you are buying a manifold, buy the airgap, if you have an RPM its not worth the money to upgrade. That said, there was a guy posted on this site with a performer RPM top end (no airgap) on a 408 that pulled a clean 500/500 across the RPM range dyno run. to me, a working man's stroker by definition is a mid-range motor unless you spend some big money on the lower end and top end to feed it. Most of us can't afford to grenade a motor at 8K so we chip to a modest "safe" number.

Most people I've spoken to with 408s already have a few stories of incidents and quite a bit of respect for them. I believe it was Dodgestang that said something to the effect; my 351 is a blast to drive but my 408 requires respect. So my bet is you will be find that even with an RPM, the car will not leave you wanting for power unless you are seeking single digit 1/4 times. Perhaps spend more money on putting that power to the ground which appears to be the biggest issue 408'rs have.

Such problems to have...

Happy new year...
So they say it isnt worth the upgrade, but I dont have either yet..... But I can buy a regular RPM for a hundred bux from a friend.... And I could easily mill out the center a bit on the rpm like was done in the above video. I could also atleast gasket match any of the intakes......

I guess unless the RPM is a fantastic deal, I will hold off, and buy something better. if it is a great deal, well that might change things some.....
 

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So they say it isnt worth the upgrade, but I dont have either yet..... But I can buy a regular RPM for a hundred bux from a friend.... And I could easily mill out the center a bit on the rpm like was done in the above video. I could also atleast gasket match any of the intakes......

I guess unless the RPM is a fantastic deal, I will hold off, and buy something better. if it is a great deal, well that might change things some.....
If starting from scratch the Air gap is the better choice. I have seen dyno numbers on both intakes on a 351W and they were within 8-10 HP. So not a huge gain but it is a better intake. Like some others have said your big issue will be hooking up with whatever intake you use. Use the RPM and with the money saved have it port matched to your heads by a good machine shop and you will gain back some of the power you lost from not using the Air Gap and not have any clearance issues with the hood. If you have some extra clearance install an open carb spacer as they will almost always add a couple of horsepower.
 

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Discussion Starter #29
If starting from scratch the Air gap is the better choice. I have seen dyno numbers on both intakes on a 351W and they were within 8-10 HP. So not a huge gain but it is a better intake. Like some others have said your big issue will be hooking up with whatever intake you use. Use the RPM and with the money saved have it port matched to your heads by a good machine shop and you will gain back some of the power you lost from not using the Air Gap and not have any clearance issues with the hood. If you have some extra clearance install an open carb spacer as they will almost always add a couple of horsepower.
I guess I could pick and run it to get the car going, then if I'm not happy or want for more, I could upgrade later. Atleast itd be running and I could use it for a baseline on what might fit later on.
 

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I guess I could pick and run it to get the car going, then if I'm not happy or want for more, I could upgrade later. Atleast itd be running and I could use it for a baseline on what might fit later on.
The RPM Intake can support close to 500HP give or take. You will be just fine with it. Is it Ideal? No, but it will get the job done.
 

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Discussion Starter #31
Im sure I will eventually upgrade, but I can go for the air gap or vic jr and do lower motor mounts at same time. or a cowl hood. Get me by for now, and the car currently has a stock block 302 in it now, so its gonna be way better than that
 

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Im sure I will eventually upgrade, but I can go for the air gap or vic jr and do lower motor mounts at same time. or a cowl hood. Get me by for now, and the car currently has a stock block 302 in it now, so its gonna be way better than that
You will be amazed at the difference even a mild 408W will make. It will have an insane amount of Torque. You will probably not feel the need to upgrade.
 

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Discussion Starter #33
You will be amazed at the difference even a mild 408W will make. It will have an insane amount of Torque. You will probably not feel the need to upgrade.
The 302 was also pushing 2.80 gears, now its got 3.70... never drove the 302 with 3.70, so its an all at once upgrade lol
be like a whole new car
 

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Discussion Starter #34
How much hp should I expect to make? with port matched rpm, hydro roller cam custome built (not ordered yet) and a 770 cfm street avenger? 10.2 to one c/r. Hooker 6208's
 

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How much hp should I expect to make? with port matched rpm, hydro roller cam custome built (not ordered yet) and a 770 cfm street avenger? 10.2 to one c/r. Hooker 6208's
The 2400 stall converter is going to limit your cam choice a little but 500Hp should be easily attained even with the RPM intake and small carb. It takes some real work to get a 408W to dyno under 500 at the flex plate.
 

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Discussion Starter #36
The 2400 stall converter is going to limit your cam choice a little but 500Hp should be easily attained even with the RPM intake and small carb. It takes some real work to get a 408W to dyno under 500 at the flex plate.
I dont mind bumping up the stall a bit, just trying to keep stall speed just under cruising rpm to not heat the trans up during car club cruises. The intake will eventually go away for a big single plane, but I gotta save up for either a cowl hood or ron morris motor mounts..... trying to do it all at once will kill the build. I'm already over budget lol. Been trying to buy the best I can even if I have to save for an extra couple weeks.
 

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I have a Victor Jr intake on my 427w and I wish I woulda went bigger. I also do run a 1/2" carb spacer. For a 408, I'd go Victor Jr. at the minimum.
 

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I have a Victor Jr intake on my 427w and I wish I woulda went bigger. I also do run a 1/2" carb spacer. For a 408, I'd go Victor Jr. at the minimum.
I see you are running your air cleaner up into the Mach 1 scope. I have debated if I want to cut the stock hood up in my 69 and run the air cleaner up through the hole so I can run a taller intake on my 408w as well.


Do you have stock height or drop motor mounts?

Sharp looking 69 by the way!
 

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I see you are running your air cleaner up into the Mach 1 scope. I have debated if I want to cut the stock hood up in my 69 and run the air cleaner up through the hole so I can run a taller intake on my 408w as well.


Do you have stock height or drop motor mounts?

Sharp looking 69 by the way!
Thx!

I just installed some 1/2" drop mounts recently, so I have room to run up to a 1" spacer now. But otherwise, without the 1/2" drop motor mounts, I was able to fit everything in there with a 1/2" spacer with zero issues.
 

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Thx!

I just installed some 1/2" drop mounts recently, so I have room to run up to a 1" spacer now. But otherwise, without the 1/2" drop motor mounts, I was able to fit everything in there with a 1/2" spacer with zero issues.
Cool thanks, and your hood scope is still the stock Mach 1 scope?

I might have to really think hard on running a Vic Jr then.
 
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