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FE Power Forums => FE Technical Forum => Topic started by: unclewill on December 31, 2016, 11:21:22 AM

Title: 2105 vs. 7105
Post by: unclewill on December 31, 2016, 11:21:22 AM
Greetings,
I'm getting ready to start assembly of my 482 S.O. stroker, bought a 390 donor for some sheet metal and spare parts/cores, it has an Edelbrock intake which I assumed was a 7105 but, upon further inspection, appears to be a 2105 (stamped "Performer 390").
What am I giving up by using this intake?  Can it be easily modified to perform more like a 7105?
Heads = BBM alum, Comp 292H cam, ~10.4:1 comp., est redline = 6200.
1969 Torino Cobra, ~3500 lbs, CR 4-speed, 3.50 rear, hp street cruiser/some strip, looking for BIG midrange torque 2500 -5500rpm.
Thanks ahead of time!
Title: Re: 2105 vs. 7105
Post by: bn69stang on December 31, 2016, 12:40:01 PM
you would giving up a lot , you need to step up to a blue thunder intake , or a performer rpm .. the regular performer is not for making power imo , i think you would choking your 482 inch motor .. Bud
Title: Re: 2105 vs. 7105
Post by: My427stang on December 31, 2016, 12:57:06 PM
At least 40 hp IMHO, maybe more
Title: Re: 2105 vs. 7105
Post by: unclewill on December 31, 2016, 01:13:43 PM
I also have a brand new Blue Thunder (or Dove?) 4X Weber manifold sitting in the closet.  It will probably cost me at least $3k to get it set up to run, I doubt it will fit under the ram air hood, and it may be a pain to tune...but Jees, it is tempting to run the 2105/850 dbl pumper until I sell my S.O. long block then take the plunge on the Webers...I read somewhere the Webers can't support 482 cubes - anyone care to chime in on that one?

Also, the car is relatively heavy and midrange torque is my goal.  Perhaps the high rpm hp loss would be mitigated by higher port velocities boosting torque?
Are the heads the limiting factor or the intake sub-6000 rpm?
Title: Re: 2105 vs. 7105
Post by: jayb on December 31, 2016, 01:20:27 PM
On the Webers, there is some truth to the cubic inch statement.  However, its not so much a cubic inch limitation as it is a horsepower (airflow) limitation.  The 48 IDAs will start to loose out in horsepower over about 550, to something like a Victor with a Dominator.  Having said that, the Webers are FABULOUS for midrange torque.  If you have a copy of my book, take a look at the graphs.  The Webers slaughter anything else in the midrange, even with a big cube motor.
Title: Re: 2105 vs. 7105
Post by: cammerfe on December 31, 2016, 03:29:11 PM
As an additional comment, it is entirely possible to use your manifold and install EFI units instead of carburetors. The EFI units come in various sizes so it should be possible to 'have-your-cake-and-eat-it-too'. I have switched from regular carbs to Webers to FI several times, and can attest to the mid-range torque available. And switching to fuel injection removes the 'hitting-the-wall' limitations of the Webers.

You may find it necessary to open up the runners on the manifold to get air-flow capacity to take full advantage of the EFI.

KS
Title: Re: 2105 vs. 7105
Post by: unclewill on December 31, 2016, 04:42:41 PM
I just pulled the 2105 off the donor 390 and man does it look wimpy!  I guess I'll be ordering a 7105 tonight...oh well, another $500 down the tullet!
Hopefully I can get a few bucks for the 2105 + other unneeded parts from the 390 - anyone want a pair of C8AE-H heads?  LOL!!

I'm stuck between selling the Weber manifold and taking the plunge.  They just look so cool!  EFI is tempting too but the cost starts getting ridiculous!  The car is a factory R-code Ram Air car and I still have the air cleaner assembly installed...it's hard to let go...

Thanks for the advice, guys, much appreciated!

Here is some side oiler noise to make your day:
https://www.youtube.com/watch?v=N5w1c6CMk80
Title: Re: 2105 vs. 7105
Post by: My427stang on December 31, 2016, 05:08:47 PM
Smart move for a new intake, but if you go RPM realize that it puts the carb to the rear a bit.  Not sure how the Ram Air will work, may want to consider Blue Thunder or getting a Holley Street Dominator and working it a bit.

As far as the "more torque with smaller ports" unfortunately the Performer just is old tech and small stuff, it doesn't win anywhere on anything over 360 cid in my opinion.
Title: Re: 2105 vs. 7105
Post by: bn69stang on December 31, 2016, 06:33:22 PM
Keeping the carb in the factory location is why i opted for the blue thunder , i have a shaker and the hood was cut already . so go over your ram air stuff before you buy .. Bud
Title: Re: 2105 vs. 7105
Post by: unclewill on December 31, 2016, 08:08:42 PM
Thanks for the advice guys, I'm actually more concerned with the height of the carb than the fore/aft location.  I will need to ponder the choice of intake over the next couple of days...
Title: Re: 2105 vs. 7105
Post by: bn69stang on December 31, 2016, 08:12:56 PM
The blue thunder is slightly taller than the ford aluminum p i intake , i am able to run a small insulating spacer between intake and carb , and not push it into the bottom of the hood , my shaker set up that is ..Bud
Title: Re: 2105 vs. 7105
Post by: unclewill on December 31, 2016, 11:13:01 PM
How about the RPMs carb pad height?  The 2105 has a 1" spacer which I'm saving for another build.  The Offy 360 on my 427 has a ~3/8" phenolic spacer which I will use if there is room.  Is carb heat soak a big problem without a spacer?  I'm planning to put the splash tray in the lifter gallery to keep the oil under control.
Title: Re: 2105 vs. 7105
Post by: bn69stang on January 01, 2017, 09:20:20 AM
If i remember correctly , the rpm is slightly taller than the blue thunder . the rpm is 5.46 inchs tall .. Bud
Title: Re: 2105 vs. 7105
Post by: unclewill on January 01, 2017, 10:36:30 AM
Thanks for the info, Bud.  I just found a street dominator in my local paper, going to make an offer later today...
Title: Re: 2105 vs. 7105
Post by: My427stang on January 01, 2017, 10:38:48 AM
Thanks for the info, Bud.  I just found a street dominator in my local paper, going to make an offer later today...

I really like those intakes.  Should work well for you, but could benefit from some well thought out porting.  Regardless, should be within spitting distance of the RPM and well above the Performer 390 intake even as cast
Title: Re: 2105 vs. 7105
Post by: bn69stang on January 01, 2017, 11:40:38 AM
Nice intake , pick it up for sure .. i have a streetmaster that is untouched and would love to send it to joe d craine so he could massage it , and then put it on a 463 build . that street dominator will allow you to use your spacer as well .. Bud
Title: Re: 2105 vs. 7105
Post by: unclewill on January 01, 2017, 03:23:34 PM
I offered $200 for it and the lady acted like I was nuts - anything above that I'd just as soon buy a new RPM.  AM I NUTS?
Title: Re: 2105 vs. 7105
Post by: 1967 XR7 GT on January 01, 2017, 03:33:47 PM
48mm Webers can be opened up to 51.5mm (JayCee Enterprises)  and run as large as a 48mm Venturi which support additional flow requirements, that is if you already have the 48mm IDA Webers, there are also the Gene Berg Carbs ranging from 52mm up to 60mm carbs, but at a substantial cost, another option for your Weber manifold is Fuel Injection, Borla has a nice setup.

I also have a brand new Blue Thunder (or Dove?) 4X Weber manifold sitting in the closet.  It will probably cost me at least $3k to get it set up to run, I doubt it will fit under the ram air hood, and it may be a pain to tune...but Jees, it is tempting to run the 2105/850 dbl pumper until I sell my S.O. long block then take the plunge on the Webers...I read somewhere the Webers can't support 482 cubes - anyone care to chime in on that one?

Also, the car is relatively heavy and midrange torque is my goal.  Perhaps the high rpm hp loss would be mitigated by higher port velocities boosting torque?
Are the heads the limiting factor or the intake sub-6000 rpm?
Title: Re: 2105 vs. 7105
Post by: bn69stang on January 01, 2017, 08:44:59 PM
I dont think i would pay more than that , maybe up to 250.00 , but no more .. Bud
Title: Re: 2105 vs. 7105
Post by: unclewill on January 02, 2017, 08:49:24 AM
Thanks, Bud, the RPM is $400 including rebate so 1/2 of new sounds fair to me.
Title: Re: 2105 vs. 7105
Post by: My427stang on January 02, 2017, 11:29:34 AM
I am all for getting used cheap but:

If the RPM costs 400 and potentially does not allow the use of Ram Air due to carb location, and the SD is in very nice shape, it has value that the RPM doesn't.

That being said, nice ones bring 250-275 and potentially more on Ebay, so I am not saying pay 400, but if it's nice, don't let 50 bones keep you from solving the problem on a nice engine.  Look real close for pitting, cracks/stripped threads, etc, and then if it's nice enough, I wouldn't let a 50 dollar bill stop you
Title: Re: 2105 vs. 7105
Post by: jayb on January 02, 2017, 12:58:38 PM
The Mustang shakers have some elongated bolt holes to allow for a small amount of movement at the scoop.  Pretty sure that the RPM with shaker could be made to fit the factory hood; it seems I've seen a post or two where people have done that. 
Title: Re: 2105 vs. 7105
Post by: unclewill on January 02, 2017, 08:27:45 PM
Mine's not a shaker, the Torino Cobra uses a thick foam gasket to seal to the hood.  I think I have enough leeway to use either.  I'll talk to the guy tomorrow night but I'm about sold on the new RPM - no worries.  Another friend talked me out of the Webers - and he has 4 sets of IDAs in his garage!
Title: Re: 2105 vs. 7105
Post by: BH107 on January 03, 2017, 12:09:26 AM
With that kind of build I would definitely recommend stepping up to a hydraulic roller cam too. You are doing the displacement and great top end a huge disservice by going with that hydraulic flat tappet cam. I have a local friend that just went through the same process with an engine for his truck. He went with a 482 and BBM heads, and then had Brent spec a custom hydraulic roller cam. It made 550hp and 640ft/lb of torque with a pretty basic bolt together package.
Title: Re: 2105 vs. 7105
Post by: bn69stang on January 03, 2017, 05:15:00 PM
sounds like a nice package for sure .. Bud
Title: Re: 2105 vs. 7105
Post by: unclewill on January 04, 2017, 12:57:30 PM
I already have the cam, so in it goes!  I also ordered the RPM today.  The seller of the Holley manifold did not want to sell it separately from a pair of built up Edelbrock heads and a POS Holley carb.  Bad JuJu came through the phone line from these people too, so I'll spend my money elsewhere!
Title: Re: 2105 vs. 7105
Post by: My427stang on January 04, 2017, 03:53:03 PM
I ran my 489 with a very similar combo, Erson solids at 242/248@.050, ran a 1000 vac sec Holley on an RPM with a 1 inch open spacer. Heads are ported Edelbrocks and the intake was ported too.

It was very strong.  It got stronger with the ported Victor and EFI though.  Either way you'll have a strong running combo
Title: Re: 2105 vs. 7105
Post by: unclewill on January 04, 2017, 07:35:42 PM
Thanks Ross!  It's gotta be stronger than my current iron head 427, there is no replacement for displacement!