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

[frnkeore]

I agree with Rory on the headers. Every car that I've put headers on, has had a very noticeable power increase.

So, here is my suggestion, based on you goals:

1. Use your BT & carb
2. Get headers for your heads
3. Pull the heads to install the headers and take to to a place that you know does good high performance head work. Get min seat width (.050/.080) 3 or 4 angle valve job and back cut valves.

That would last you years or, until you want to change out the engine.

You'll notice the difference!

Warning, it can be a slippery slope, once you tear into a engine!!!!

[cheeser]

I'm open to swapping better aluminum heads and installing the CJ style headers if it was as simple as replacing parts.   From my understanding, it isn't that simple as I would then have to work other issues like pushrod length and other measurements...areas where I'm not skilled / lack experience.  My main reason for sticking with the C8AE-H heads is I (in theory) wouldn't have to worry about those things...but probably not cost effective by the time I paid a shop to port.

As I mentioned earlier, I'm hesitant doing headers now with the current GT style heads, and then have to pay for another CJ set later on if I go with better build using aluminum heads.  If I was never going to install better heads in the future, then it wouldnt matter, but want to leave the option open for now.

Members here have already hit the nail on the head...I have to figure out what I want.  This is probably a common problem where folks with these cars are going to be primarily cruisers with an occasional throttle blast...we all want as much HP as we can, but would probably live with a more modest build (425-450 hp) which is still respectable.

frnkeore pointed out the slippery slope perspective in opening up the engine which I'm trying to avoid to some degree.   If I went with pulling the heads, then Id probably prefer to do this once and put on a good set.

Thanks...I appreciate the constructive feedback.   Looking forward to tackling the things I can do myself, but see myself working up towards a modest quality build in the future.

[67xr7cat]

IMHO I think you are on the right track.  Install the intake, re-curve the distributor, and get it tuned right. then swap in some 3.25 rear gears. 

Headers on these engines certainly made a big difference, but as I said before you already are about 1/2 there as you have the CJ manifolds and a decent exhaust system. A lot of guys go that way as they don't want headers and they are an improvement over the stock manifolds.  Know some who pulled the headers off and went back to the CJ manifolds.  Not everyone likes some of the things that come with headers. 

If you decide you want more I'd plan that deal out and do it all in one shot. Is all too easy to end up in a big project and have a car in pieces instead of running. 

[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.

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 .

LOL was not thinking of the smog heads.  They never were considered a performance head. Perhaps is why most headers used the CJ flange. As for the headers fitting the smog heads is what die grinders and welders is for...

[cheeser]

I'm doing a quick check to make sure I have everything before tackling the intake swap next month....some parts I can pull off original intake, while buying new pieces where needed:

• Mr. Gasket 202A intake gasket
• Dow Corning 732 or Ford TA-31 silicone
• Stant Superstat 180 degree thermostat...after testing it in hot water
• New water pump to intake hose
• New intake fitting for heater hose connection

[67xr7cat]

I'm doing a quick check to make sure I have everything before tackling the intake swap next month....some parts I can pull off original intake, while buying new pieces where needed:

• Mr. Gasket 202A intake gasket
• Dow Corning 732 or Ford TA-31 silicone
• Stant Superstat 180 degree thermostat...after testing it in hot water
• New water pump to intake hose
• New intake fitting for heater hose connection

Add valve cover gaskets and of course a torque wrench if you don't have one.
May want an engine hoist to remove the old intake or at least a 2nd person, unless you are real strong and have a good back!

When you get the old intake off and everything cleaned up lay the new intake on the heads and check the fit.  Should be parallel on the head sides and sit even with the valve covers and have abut 1/8" - 1/4" gap on the china walls. Of course the last two want to check with the intake gaskets in place. If you do not drive in cold weather may want to block the heat riser passage. 

[1964Fastback]

I use a hoist as well.  If for no other reason than to be able to lower the new intake down without sealer for a test fit, move the hoist around until I can raise and lower it straight up and down, then raise it, put sealer on the gaskets, reinstall and then drop straight down.

A tip I learned awhile back on the water pump hose:  For removal, just cut it and forget it (pretty obvious).  On installation, leave it off until the intake is installed, then measure and cut a short piece, bend it into a U and work it on.  You wouldn't think there would be enough room but there is.  If not (I haven't encountered this but I have limited experience), I'd just trim a bit off one or the other of the tubes.

Pat