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MG MGB GT V8 Factory Originals Technical - Which Ford small block intake to use?

I'm about to purchase an intake manifold and carburetor setup for my 289 Ford installed in a 1970. I am looking for advice.
My engine is set way back and low, so clearance is not an issue. (Unless I use a tunnel ram or Vic Jr. or something along those lines)
The engine is stock .030 over with cast iron manifolds and 2" dual exhaust. I have a Comp Cams 31-218-2 cam with a 218 duration and .456" lift. I live and plan to run this car in Colorado at an average sea level of 5000 ft. I have stock 58cc cast iron heads and was planning on running a 500 cfm carburetor, due to the elevation here, and because I don't think this engine needs anything bigger.
Now the question is... which manifold. Will the taller manifolds such as the Edelbrock RPM or RPM air gap give any benefits over say the Edelbrock 2121, which is designed for stock engines? What about using a 500 cfm carburetor with a manifold designed for 600+ cfm carburetors? Will the larger intake runners on such an intake just slow down the velocity of air entering the engine, given the small dispacement and elevation of my engine?
My plan is to use the Edelbrock 2121 with the Edelbrock 500 cfm carburetor, but because there is so much clearance for a taller intake, it seems like a waste to not use it....

I am not completely biased toward Edelbrock either, I am simply using them as an example.

I want a car with good driveability above all with excellent mid range torque. I intend to drive mostly on the street with an occasional vintage race thrown in just for fun.

Any thoughts, educated or not welcome. I am ready to buy and would like some input from this crowd.

Thanks.

Scott
Scott Wooley

depending on motor placement, the 2121 will fit under your hood. none of the other will without hood mods. I ran the 2121 and ran out of valve spring before I ran out of power. The car ran high 13's with stock rear end and tires which had me using 5th gear by 1000ft.. LOTS of power, and ran quite well..

The other intakes are high rpm, unless you build your cam and heads to flow up past 6k rpm, they are not of much use. Yeah they will give more power, but it is not truly realised till upper rpm and for a street car how often is that achieved?? Based on your heads and exh I think the 2121 with a matching vac secondary edelbrock carb would be a great combo. or get an older Carter AFB carb, I ran one of those and liked it..
Larry Embrey

Scott, I used a 2101 (I think) Edelbrock Performer 289 manifold on my 302 - it worked well but with the iron heads you could feel the power falling off after about 5000 RPM. This was with a 600cfm Edelbrock carb (Carter AFB)and standard HO cam and 1 1/2" tube headers. I then bought a set of AFR 165 heads and they really transformed the motor - it would pull much more strongly after 5000 than before. I think the iron E7TE heads with their small exhaust ports especially, give good mid-range torque but aren't really best for performance. Fuel consumption does climb alarmingly if you use the revs the motor can now function at! You will need leaner jets and/or needles at your elevation but ease of adjustability of the AFB series seems one of their stong points. Save 40lbs with alloy heads too! Good luck, Bob Elwin
Bob Elwin

yeah Edelbrock probably makes a kit I would think.. intake, came, heads, carb..?? I forgot to mention that!!
Larry Embrey

Scott:

How did you make out with the exhaust and engine set-back? If I recall, your plan was to move things back far enough to clear the frame rail in the engine compartment. How much is left of the firewall and interior leg room? My measurements show a lot of heat being transfered into the passenger leg area due to the proximity of the manifold to the inner footwell panel.

Pete
Pete

Pete,
I ended up using cast iron manifolds. The driver's side is stock from a 65 full size sedan. The passenger side is one I created using 3 manifolds, lots of preheating, nickle welding, peaning and cursing. It allows the exhaust to dump straight down between the engine mount, frame rail, and the mini starter. I'm having both manifolds jet hot coated, as well as the front downpipes. I'm insulating on both sides of the sheet metal. Heat transfer into the car is yet to be determined, as the engine won't be ready to run for some time to come. I'm closing in the footwells as we speak and hope to have them completed in the next 2 weeks. It looks as though there will still be plenty of room in the footwells, although you will lose some width for sure. Once I get the pedal brackets all done, I'll have lots more answers on this particular engine setback. At this point, I can't recommend this method to anyone unless you're not all there. It is an incredible amount of work. Probably not worth it to 99% of the converters out there.
The engine setback looks nearly identical to the Sunbeam Tiger, and I have to make access doors for the rear spark plugs just the same.
As far as the intake... I think I am just going to go with the 2121. At least I know this one will work great with a small cfm carb and mild cam.

Scott
Scott Wooley

This thread was discussed between 19/11/2005 and 22/11/2005

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