upgrading intake/carb on 256 Mercury

S

steve fritz

Well-known member
Question for y-block experts...... can I replace the stock intake manifold on my stock 1954 Mercury 256 cu in y-block engine with a later model, like 1957 292 intake manifold ? Will there be any issues with matching the surfaces of the 256 heads and the 292 intake manifold ? I want to then use a more modern carburetor, like a stock 1957 and up Holley or autolite carb, which bolts up to the 292 intake manifold. This will eliminate my troublesome "Teapot" carb on the original 256 engine.
I appreciate any first hand experience with guys who have replaced their "teapots" with a later model, more trouble free carb.
 
Easiest way is to buy an adapter from Speedway that lets you bolt a Holley based carb to your intake. Of course then you will need to replace your distributor and oil pump to a '57 or newer because the earlier distributor can't use the signal from the carburetor for the advance. The later model intakes are very difficult to mate to the smaller intake ports on the head without creating a leak. I changed the distributor and oil pump on a 239 I had and used the Mercury 256 intake with a 390 Holley carburetor. Made a world of difference. EDIT Also, used the Speedway adapter.
 
When replacing the distributor to a 57 or later (and oil pump to a 55 and later), you must change the gear to the 54 gear as the no of teeth differ between 54 and later. The 55 and later gear will not match up with the 54 cam.
 
Thanks for the replys.

Noswal, I am leaning toward what you did with your 239. Except I would want to go 2bbl instaed of the Holley 390 4bbl. Do you think Speedway or somebody else have reproduced an adapter I could use on my 256 intake manifold that would adapt to a later model 2 BBL carb?
I really like the autolite 2100 2bbl that was used on the 292's from 57 on into the 60's, even on the 289's. It would have to have the square 4 bolt base to fit on the 256's stock 4bbl manifold, then have the 2bbl spacing bolt pattern on the top side, to mate to the 2bbl carb.
Changing the oil pump and distributor should be an easy upgrade. I can press off the cam gear from my 54 Distributor and press it onto the 57 distributor, then use the 57 oil pump shaft at the end to go into the newer oil pump.
 
steve fritz said:
Thanks for the replys.

Noswal, I am leaning toward what you did with your 239. Except I would want to go 2bbl instaed of the Holley 390 4bbl. Do you think Speedway or somebody else have reproduced an adapter I could use on my 256 intake manifold that would adapt to a later model 2 BBL carb?
I really like the autolite 2100 2bbl that was used on the 292's from 57 on into the 60's, even on the 289's. It would have to have the square 4 bolt base to fit on the 256's stock 4bbl manifold, then have the 2bbl spacing bolt pattern on the top side, to mate to the 2bbl carb.
Changing the oil pump and distributor should be an easy upgrade. I can press off the cam gear from my 54 Distributor and press it onto the 57 distributor, then use the 57 oil pump shaft at the end to go into the newer oil pump.
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Even if you could find an adapter to go from a 2100 to a tea pot 4 bbl intake it would be a very bad idea as it would be very restrictive as far as flow goes,the adapter used to adapt a later 4 bbl will align with the 256's ports and not create a restriction.The 390CFM Holley works great and would be good for MPG also the EDL-1403 500CFM Edelbrock works out good too.This adapter has the correct tapered ports:http://cgi.ebay.com/ebaymotors/Carb...QQptZMotorsQ5fAutomotiveQ5fTools#ht_500wt_956 these are getting hard to find.
 
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If you are leaning toward a 2100, do youself a favor and get a 4100. As JeffB2 said, the flow is too disruptive. A 4100, when in proper operating condition, is the best 4V carb for the job
 
Listen to Jeff. If you are going to go to the trouble of making the changes, go with the 390 CFM. Worked great on mine and got pretty good gas mileage. I don't think you will get an adapter/2 barrel set up to give you the flow/performance/mileage you may want.
 
I love 4100's and constantly spead the word. However, in your case, if your car was in my shop I'd strongly suggest an intake from a later model 292 2bbl motor that takes a 2100 ford 2bbl carb. Use one from a 289 or 302, or ideally, from an early 260. Your driveability will be much more rersponsive with the smaller 256 motor.
 
streetdreams said:
I love 4100's and constantly spead the word. However, in your case, if your car was in my shop I'd strongly suggest an intake from a later model 292 2bbl motor that takes a 2100 ford 2bbl carb. Use one from a 289 or 302, or ideally, from an early 260. Your driveability will be much more rersponsive with the smaller 256 motor.
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Wise stuff. No way a 256 will do well with a 4100. I like the 4100s too. You may be able to slot out the 256 intake manifold to improve remove the obstructions for a 2100. The early 260 SBF has a 1.01 venturi which would match up real well to the 256 displacement. So would the 1.02, since Ford had a tendency to match smaller than needed 2100s to engines early on. An adaptor would still be needed. It might be a better idea to make the adapter so that there is less space between the carb base and plenum, producing improved throttle response. The available commercial adapters have a significant amount of volume underneath the carb.

It still needs to be determined if a set of early intake gaskets will seal to a 57 up manifold. Late model intake gaskets wont seal to a 256 head. At least not for very long.
 
The problem with replacing the 256 intake with any intake later than '56, whether it is a 2 or 4 barrel, is sealing of the intake ports. The ports on '57 and newer are larger and it's very difficult to position the intake on the smaller ports of the 256 heads with a good seal. Still say the best bang for the buck is the adapter/small Holley or Edelbrock and oil pump/distributor change.
 
You all can say what you want, but I still vote for the 1.08 4100. I have run it on a stock 239 Y-block and currently run one on a 255 Flathead. I had a new 390 Holley on the flattie, but the car runs better, leans down better and produces less H/C with the small 4100. I don't have to worry about warped, leaky metering blocks either
 
The 2 bbl intake from a '60 to '62 Ford 292 may be different. I'd have to double check one I have on the shelf, but it may have a 1960 ( COAE ) P/N on it. If so, it may have the intake runners downsized to fit the '60 -'62 heads. Ford went back to the early, smaller intake valves for those years, and intake ports changed also. There may not be an issue with match up.
 
craig....if you ran a 4bbl intake on your 239 engine, what intake manifold did you use? Did you have any problem matching the later model 4 bbl intake to the smaller ports on the 239 heads? Did you get it to seal up and not have vacuum leaks?
 
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