351w heads
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351w heads
i have a 79 351w that i am rebuilding it was a 2 barrel engine. i bought a edelbrock preformer intake. I noticed the ports are bigger on the intake than the heads. Will that hurt anything. Does it have something to do with 2v or 4v heads.
bulldog
bulldog
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From: Topsfield, MA
If the ports are bigger on the intake than on the heads...theres a problem that will arise. Basically, it's just not going to flow very well. The air is going to run into that smaller port, bounce back and disrupt the flow of air. It should be port matched, but it sounds like you're onto something with the 2v or 4v...I'm not sure on that because I am not as informed about them. It makes logical sense though...
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From: Southern New Hampshire
I noticed similar when I pulled the 77 351W out of my 79 E350 (came with a 302).
Replaced the engine with a 4V 86 block/heads. Got the Performer and 1406 carb but havent installed as yet. Hope it matches up!
Replaced the engine with a 4V 86 block/heads. Got the Performer and 1406 carb but havent installed as yet. Hope it matches up!
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The effects of port mismatch
The effects of the port mismatch is not a big deal. Ford did this stock for many marine Big block engines engines when they put the SCJ 429 intake on Small port passenger car heads. The mismatch was huge. The engine still picked up about 20 hp over the stock small port intake.
Thinking there must be a huge loss there, the heads were removed on one project and ported to match the heads. There was no noticable gain.
But what your sayin is funny. My last experiance with a Performer intake on a SB was that the intake was noticably smaller than the head entrance. But this was an old Performer 289. Maybe they changed the newer ones.
Thinking there must be a huge loss there, the heads were removed on one project and ported to match the heads. There was no noticable gain.
But what your sayin is funny. My last experiance with a Performer intake on a SB was that the intake was noticably smaller than the head entrance. But this was an old Performer 289. Maybe they changed the newer ones.
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From: Northern California
You should be able to port match those heads with a die grinder bulldog.
The effects of a large port mismatch IS a big deal, your cylinder heads, and in particular the ports is where a large amount of HP can be gained. There should be a fair amount of difference in power due to the better flow. I would do a little pocket work under the valves too, as long as the heads are apart.
The effects of a large port mismatch IS a big deal, your cylinder heads, and in particular the ports is where a large amount of HP can be gained. There should be a fair amount of difference in power due to the better flow. I would do a little pocket work under the valves too, as long as the heads are apart.
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The early 69 351w heads are the same 4v or 2v. intake ports are large and exhaust ports are small, 60.4cc chambers, 1.84 and 1.54 valves. If you are using newer style heads the ports and valves are smaller. Gasket match the intake and exhaust. Start with the intake and if you do pocket work do that first. If when working on the pocket and you hit the valve seat the heads might become unusable, so start there. If you start there and nothing goes wrong move on to other areas of the head. The intake ports porting neads to be steady flowing but not glass sooth, finish the ports with 80 grit paper. The exhaust ports porting can be glass sooth.
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Hi Bobsbigworld, and welcome to FTE! Please take a moment to check out the Guidelines, they contain important info that you'll need when posting here:
https://www.ford-trucks.com/guidelines.html
Good first post, BTW, even if this thread you brought back is a little old!
https://www.ford-trucks.com/guidelines.html
Good first post, BTW, even if this thread you brought back is a little old!
Last edited by TigerDan; Jan 2, 2006 at 12:22 PM.
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From: Northern California
Originally Posted by bobsbigworld
If when working on the pocket and you hit the valve seat the heads might become unusable
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If you have to start putting in new valve seats why not put in new guides or larger valves. If you completely redue stock heads due to porting mishaps you are better of buying aftermarket they will flow better and they are better engineered. my first reply was to let people know that if you intend on doing pocket work that is where you should start and to be carefull of the valve seats even if you are going oversized.
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Does any one have any pictures of the intake and exhaust valve bosses and how much can be cut out of them. I know how to gasket match, chamber matching and polishing on chevy SBC and SBF, but I don't know how much can be done on the bosses on a set of 1969 351w heads, that is what I am working on. Thank you
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From: The hills of No. Calif.
I came across some cutaway pics of some E7 heads on the 'Net, but I haven't seen any on the old 351W heads. I have a cracked C9OE 351W head that a guy gave me years ago just to make a cutaway out of, but I never got around to it. I have two sets of them, one set is stock and untouched and the other has 1.94/1.60 valves, bronze guides, screw-in studs and guideplates. I started porting them several years ago but never finished as my needs and priorites changed. When I have a shop set up again I'll finish them but for now, they just sit.
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Originally Posted by bobsbigworld
If you have to start putting in new valve seats why not put in new guides or larger valves. If you completely redue stock heads due to porting mishaps you are better of buying aftermarket they will flow better and they are better engineered. my first reply was to let people know that if you intend on doing pocket work that is where you should start and to be carefull of the valve seats even if you are going oversized.
If you only have to put in one valve seat, it sure is alot cheaper than a new set of heads! The option of grinding the seat deeper and shimming usually does the trick for most porting mishaps. If going with oversized valves, small nicks wouldent be anything to worry about.