Blue Thunder 427MR intake - power increase over stock 390 2V?

[482supersnake]

In it's current state the motor would probably benefit the most from either an Edelbrock Street Master or a Holley Street Dominator but would look more stock with the Blue Thunder.

[WerbyFord]

I purchased a Blue Thunder 427 MR 4V intake shortly after purchasing a 68 Cougar with stock 390 2V motor…X code @ 10.5CR.  I haven’t installed it yet as I’m a bit paranoid installing it correctly with out vacuum/oil leaks.  Every project seems to take longer than expected, although it appears to be fairly simple when taking time and checking fit…bit harder looking at rear while in car.  I already have an old Holley #80457 600 CFM carb I was planning on using after I rebuild it, but open to purchasing a new carb.

I’m curious in what I could expect from a power bump in this configuration…30-35?

We had SO many 2bbl intakes, all went for scrap, never measured any of em. Same attitude - the 2bbl intake was the 3rdd thing to go, right after the IMCO air cleaner and the single exhaust.

Is there a way you can get
1. Your intake's casting number (should be easy)
2. The carb pad height as Edelbrock measures it in their catalog: Lay a straightedge on the carb pad with the carb, spacers, gaskets OFF: Then
A=distance down to the intake's china wall at the front, measured vertically at the front
B=same, measured at the rear
For example, Jay lists A=4.875 and B=6.500 for the BT 427 (CJ ie tall port) intake

The 4v iron low-perf FE intakes got taller in 1966 but with smaller ports.
But I never measured a 2v intake, just didnt seem worth it.

Maybe Brent has the same info from the Project JJ 352?

[Rory428]

I have had similar experiences as Gerry, I had a bone stock 302 2 barrel Fairmont, with a C4 and factory 2.47 gears about 25 years ago. I started doing a few bolt ons, bone stock it ran a best of 17.2 ET at 78 MPH in the 1/4 mile, first modification was a set of 3.55 gears and Traction Lok 8.8, and a pair of 1 1/2" long tube Hedman headers with a factory dual exhaust system from a 5.0 Mustang. (No cats, straight pipe from the collectors to the Mustang mufflers). HUGE improvement, 2 full seconds, best of 15.2 and 84 MPH, with the stock 2 barrel engine. next step was a factory aluminum 4 barrel intake from a 84 Mustang 5.0, and a 600 Holley. Expecting big things, the ET was exactly the same, up a mere 1/2 MPH. Figured it needed a cam, I swapped in a popular .448/470", 204/214@ .050 hyd. cam. Imagine my disapointment  when it only picked up another 1/2 MPH, but actually ran slower ET, and lost over a tenth in 60 feet. Only after I installed a higher (2400 ) stall speed converter, did it run much quicker, and then a pair of early 351W heads picked it up another 1/2 second, likely more from the over a full point of compression than the slightly larger ports and valves. It`s all about combination.  Even the 428 CJ in my 59  liked less carb, When I ran it last weekend, it ran 14.07 with a Holley 600 vac, when I swapped to a 780 Holley, it lost ET, MPH, 60 foot, as well as part throttle drivability to the 600. I am shifting this 428 at 5400 RPM, (on the dyno, it actually made peak HP at 4600 RPM, peak torque at 3800), with a bigger cam and more RPM, the bigger carb may help, but not here.And as I said before, even my Fairmonts 454 FE ran quicker with a 780 than it did with 850DP, 1030 3 barrel, 950 HP, or a 1050 Dominator (with an adapter). More ain`t always better.

[cheeser]

We had SO many 2bbl intakes, all went for scrap, never measured any of em. Same attitude - the 2bbl intake was the 3rdd thing to go, right after the IMCO air cleaner and the single exhaust.

Is there a way you can get
1. Your intake's casting number (should be easy)
2. The carb pad height as Edelbrock measures it in their catalog: Lay a straightedge on the carb pad with the carb, spacers, gaskets OFF: Then
A=distance down to the intake's china wall at the front, measured vertically at the front
B=same, measured at the rear
For example, Jay lists A=4.875 and B=6.500 for the BT 427 (CJ ie tall port) intake

The 4v iron low-perf FE intakes got taller in 1966 but with smaller ports.
But I never measured a 2v intake, just didnt seem worth it.

Maybe Brent has the same info from the Project JJ 352?

I don’t have an easy way to pull the measurements right now as I have to keep this car at a different storage location…lack of storage for my toy.

I will check for a casting number when I bring it home next, and also capture those measurements when I make the manifold swap.  I currently have a Holley street avenger 350 cfm two barrel on it.  The previous owner swapped out the original Autolite sometime in early 70s with another two barrel Holley.  It was leaking when I bought it last year…just easier to replace as I also wanted an electric choke.

I went for the Blue Thunder manifold as it has more of a stock look, port on the rear for power brakes and rest of the cougar vacuum maze, and of course aluminum to drop weight.

Looks like I’ll probably go ahead with the intake/carb swap and install the rebuilt / recurved distributor I obtained from Faron Rhodes.  I still have to explore an FPA header swap…just concerned with an in car swap, breaking off exhaust bolts, and correct fit as my heads may or may not have been modified for the current CJ manifolds.

[My427stang]

I think headers are beneficial and should be done during the intake swap for a couple of reasons

1 - Pull the heads and replace valve seals.  With some smart shopping you can put a viton seal on the stock guide.
2 - You can fix any broken bolt easily and make sure exhaust flanges and gaskets match on the bench
3 - You can likely set the headers in before the heads
4 - The headers will make the other parts work significantly better

Then once the heads are back on, finish the intake install.

Of course you could ignore the manifolds, but if you go to do it later, I'd expect you'd have to do it all over, and/or pull the engine.

[67xr7cat]

I think headers are beneficial and should be done during the intake swap for a couple of reasons

1 - Pull the heads and replace valve seals.  With some smart shopping you can put a viton seal on the stock guide.
2 - You can fix any broken bolt easily and make sure exhaust flanges and gaskets match on the bench
3 - You can likely set the headers in before the heads
4 - The headers will make the other parts work significantly better

Then once the heads are back on, finish the intake install.

Of course you could ignore the manifolds, but if you go to do it later, I'd expect you'd have to do it all over, and/or pull the engine.

On a '68 Cougar if I had to pull the heads I think I'd pull the engine. Not saying cannot be done in the car, but is a bit of a PITA! Of course swapping intakes is n fun either.  the factory shop manual tells you to use a hoist to lift the intake manifold which I can understand as it is what 80 lbs?  Headers are best, but if he is not looking to get into a whole rebuild/remake project and it is running good, just swap the intake/carb. The CJ manifold are not as good as headers, but are decent and headers can be a pain. OP has not stated a goal so guess just wants a bit better performance.

[WerbyFord]

Another one that gets a little complicated!
From what I can glean from history and MPC, there may have been TWO different cams for the X-code 390-2v premium in 1968.
Urban Legend has it that most got the 192-199-112.3 .427 .431 cam.
But Mustangs mid-year got the 200-200-110.5 .438 .438 cam, same cam as the "hot" Z-code 390/315hp.
Maybe the Cougar got the "hot" cam too? No idea.
The lifts are so close, I doubt you could tell the difference given a little wear. Degreeing the cam would answer it.

Thanks for looking in to those 2bbl intake measurements when you can. I’ve found several post-1966 2bbl intakes.

Any known dimensions (ports or “A” or “B” or even volume) much appreciated!
Anybody have any 2-barrel intakes out in the scrap pile they can measure?
C7TE-F pictures show a “T”
C7TE-G NHRA listed for 1968
C8TE-A NHRA listed for 1969
C9AE-B pictures again show a “T”
D3TE-A1A pics looks like low “early” version, cant tell if it has “T” or not

MPC lists only 2 service intakes for those years:
C6AZ-D 1965-66 2bbl (Muscle Parts says 1.16 x 2.75 ports. Unless it’s a HiRiser 2bbl I think they mean 1.16 x 1.75)
C9AZ-E 1967-71 2bbl (Muscle Parts says 1.16 x 1.82 ports.)
Muscle Parts also lists the C9AZ-E 2bbl and the C9ZZ-A 4bbl (390 IP?) as “Equal Length” intakes, along with the C6AZ-M Sidewinder. I found that an interesting comment, hadn’t noticed it in all the years I’ve seen that table.

Meanwhile, with what I THINK is a decent 2bbl intake model:

Here is what the Gonkulator said:
CJ exhaust iron added about 5 ponies to each "cam" for:
192-199 cam
Torq 353 at 2000
Torq 388 at 2600
Powr 262 at 4200

200-200 cam
Torq 358 at 2000
Torq 391 at 2600
Powr 271 at 4200

Now with the big BT 427MRCJ intake and 600 Holley:
192-199 cam   
Torq 350 at 2000   -3
Torq 389 at 3000   +1
Powr 307 at 4800   +45

200-200 cam
Torq 345 at 2000   -13
Torq 381 at 3300   -10
Powr 307 at 5000   +36

Some unexpected stuff going on there. Sure, peak power is going way up, bot on the low end, it just depends, too close to call.

It’s always been my experience that when you ditch a 2bbl and add a 4bbl, the car will go faster unless it’s jetted wrong or the secondaries are flopping open too early (or not at all) etc. But you can see where, with a big intake, if you give up any low end on a tight converter, you can spend the rest of the 1/8 mile just catching up with your own car!

Here’s the last one, but Gonkulated with the boat anchor iron “S” “390 GT & friends” stock intake instead of the BT427MRCJ:
200-200 cam
Torq 367   +9   
Torq 403 at 2800   +12
Powr 307 t 4500   +36

I was surprised how good the old “S” boat anchor did here. Gains across the board. Pretty good for what FoMoCo intended it to do, at horsepower levels in the low-300s like “civilized” people use. But with future plans in mind I’d throw that big aluminum thing on there and go for it!

[cheeser]

I think headers are beneficial and should be done during the intake swap for a couple of reasons

1 - Pull the heads and replace valve seals.  With some smart shopping you can put a viton seal on the stock guide.
2 - You can fix any broken bolt easily and make sure exhaust flanges and gaskets match on the bench
3 - You can likely set the headers in before the heads
4 - The headers will make the other parts work significantly better

Then once the heads are back on, finish the intake install.

Of course you could ignore the manifolds, but if you go to do it later, I'd expect you'd have to do it all over, and/or pull the engine.

On a '68 Cougar if I had to pull the heads I think I'd pull the engine. Not saying cannot be done in the car, but is a bit of a PITA! Of course swapping intakes is n fun either.  the factory shop manual tells you to use a hoist to lift the intake manifold which I can understand as it is what 80 lbs?  Headers are best, but if he is not looking to get into a whole rebuild/remake project and it is running good, just swap the intake/carb. The CJ manifold are not as good as headers, but are decent and headers can be a pain. OP has not stated a goal so guess just wants a bit better performance.

At this time, I have two goals....near term and long term:

- Near term - Some are purely aesthetics I wanted to dress it up a little with an aluminum intake (cars and coffee, etc.), while also dropping a bit of weight from the front end.  I also wanted to bump the power a bit to give it a bit more acceleration when wanted.  The Denver altitude has already taken some of that power away, and would like to address that.  The car is primarily just used for fun at this time...haven't really had a chance to drive it too much due to work and such.  Since the engine runs well, I'm trying to see if the intake/carb/distributor, and maybe headers is simply enough at this stage.  The car has 2.73s at this time...was thinking of going to 3.25 as I want to still drive it on the interstate out here....70-75 mph seems to be the min sustained speed I need and didn't want the revs too high on those drives.

- Long term - That depends on how the other efforts work out and if I'm satisfied with the power level for simply driving around in town / interstate, and the yearly blast down the dragstrip.  I'm not expecting a competitive drag car, but would like one that is respectable...low 13's here in Denver.  My427stang has provided me advice for some of this.  I would love to jump on a mild 445 with 500+ HP, but as the engine runs well and the associated costs hold me back at that.  However, if the engine was to take a dump, I would like to do more than a simple rebuild as I only want to do it once.

My current storage / working environment for this Cougar is fairly limited at this stage, so I don't really want to do anything where the car is blown apart for more than a week or two.  This is another reason I'm keeping the current changes somewhat small.  If I ever had to pull the engine, I would have to find one of the DIY garages around here...can't do it at my house as I have the normal family cars to keep in the garage...damn Denver hail.

I am fairly good in being able to remove/install stuff, but would probably rely on an engine shop for heads and engine mods. 

I came from a 2013 Mustang GT with TVS style supercharger....609 RWHP.   That car was extremely fun to drive, but I'm not expecting that level of performance.  I had to make the adjustment in how the cars drive.

If I was to install headers, I was hoping to have enough room by jacking up the engine via the oil pan....I recognize pulling the engine / heads may be the best option though.  I am a but concerned if I buy the headers with the CJ flanges (assuming my heads have been modified - will check to see if all bolts are in) only to find out they don't seal well on the lower port.  Isn't the only true fix a new set of heads with the right configuration as I can't go back back to a regular 390 header (assuming my heads are modified)?

I was tempted to buy a new set of heads and cam and install while in the car, but have read somewhere that the heads should be gone through and rechecked.  If that was the case, then I was probably back to letting a professional go through it and doing it correctly the first time.

So I seem to be in a catch 22...going ahead with the just the intake/carb/distributor or just leave it alone (as engine runs well) and save up the funds to perform a decent upgrade that involves pulling the motor.

[67xr7cat]

I'd swap the intake and get a good 750 VS carb like a Brawler. See how you like it. Going to a 3.25 and a limited slip diff will help without revving too high at 70.  I'd spend some time tuning it too. Get a wide band O2 and a G-techpro or similar to measure 0-60.

[cheeser]

Brought the car out of storage last night and found two things:

Intake:  C9AE-9425-B. Seems to be a 69 part on my 68

Heads:  C8AE-H.  The top rear drivers side was drilled/tapped for the exhaust bolt, but the bolt hole just below it doesn’t seem to have been filled with another bolt.  I thought that was a required practice? 

Based on the heads, it seems I would need to buy headers for the GT heads to ensure flange compatibility and sealing, but then would have to buy another set of CJ style headers if I was able to have a better build down the road involving newer aluminum heads.

The Blykins 352 build has me rethinking things a bit for long term if I was able to pull motor for a quality rebuild.  Curious in whether it be cost effective to go down that 352 path with modern internals, port heads, and my BT single 4V…the 352 build seemed to show there is a lot that can be done without going stroker/aluminum head route.

While I’m thinking about that, believe I will stick with intake/carb/distributor swap with parts I have for now.

[My427stang]

You don't have to go with a stroker or alum heads, but I would say you "should" lose the C8AE-H unless you really want to keep them

Some examples

I just did a 397 inch FE, budget build aside from machining.  Not dyno'd but readily in the 420 hp range.  Stock C3 heads, 11/32 CJ valves, hyd roller, pump gas, low riser dual quad.  That 4 speed Galaxie downright flies and does everything the owner wanted it to do and was a cheap build in pertspective.  Yours could be done the same way with C6AE-R heads and run very well and use CJ headers if you wanted to keep options open later

If you wanted to keep C8AE heads, my own F100 has a stroker that made 490 HP, now it's 461 inches, but, we did it with al old tech mild cam (280 Magnum intake, 286 Magnum exhaust on 112)  It runs on mid grade and has 17 inches of vacuum. The key the power was porting the D2 heads (almost identical to yours)  I did that because I had C8/D2 truck headers and a fresh 3 inch mandrel bent exhaust.  So aluminum isn't a must do, but C8/D2 without porting will be real tough to make power

The key is, spend the time thinking about exactly what you want you car to do, most of the time, and when feeling your oats.  After that, the path will be easier to choose after you decide how much money you are willing to spend

That being said, after hearing a ton of owners over the years, I "hear" that you want to try the 4 barrel swap.  Go ahead and do it, no big deal, cheap to do with parts you have, add the new distributor, forget the headers, and see what you think.  It's more data for the later decision (if there is one)

[67xr7cat]

Problem with factory iron heads is to do them up right and port them cost what an aftermarket aluminum head will. Now if you want a killer iron factory head Blair Patrick can CNC a head for you. Is what he use to win the emc.

400 inch FE.  He made peaks of 597 horsepower and 510 torque with iron heads, 10.5 compression and .600 valve lift. Have say pretty impressive considering made it with just a 4v carb and still crank driving the water pump.

[My427stang]

Problem with factory iron heads is to do them up right and port them cost what an aftermarket aluminum head will. Now if you want a killer iron factory head Blair Patrick can CNC a head for you. Is what he use to win the emc.

400 inch FE.  He made peaks of 597 horsepower and 510 torque with iron heads, 10.5 compression and .600 valve lift. Have say pretty impressive considering made it with just a 4v carb and still crank driving the water pump.

Amen on the alum head cost brother!

However if you want a truck header, there isn't any choice.  Blair's program won't do a low exhaust port GT head, Craft offers CnC, but its 25 or so CFM off a hand port with 3/8 valves, more if 11/32 or 5/16.  If we could only get a manufacturer to provide a TFS-like intake port with a good flowing exhaust with a high floor / low roof that would fit both trucks and car headers, or allow you to grind a lip off of either if you want, it'd be desirable for any application.  Maybe Blair could pull that off on the next BBM iteration?

Unfortunately, although you can slot the header bolt holes, it won't get you .200-ish . 

[Rory428]

If you were to only do one upgrade, in my personal experience, a pair of headers (with a decent exhaust system behind it) , will make a more significant improvement in performance that a 4 barrel carb over a 2 barrel will. Plus that improvement is there at pretty much all across the RPM range, where the 4 barrel only helps at higher RPM.

[cjshaker]

If you were to only do one upgrade, in my personal experience, a pair of headers (with a decent exhaust system behind it) , will make a more significant improvement in performance that a 4 barrel carb over a 2 barrel will. Plus that improvement is there at pretty much all across the RPM range, where the 4 barrel only helps at higher RPM.

I agree headers should be the first move. But in all honesty, unless someone wants a stone stock build with factory tires and all, it'd be kind of embarrassing to have a 2 barrel on any big block engine. If it did, and it was mine, I think I'd keep the hood closed, or at least have an air cleaner big enough that you couldn't see the carb.