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95 Bronco, 351W, E4OD, 4.56 gears, 35x12.50x15 Patagonia MTs. 94 Bronco 5.0/E4OD/1356/3.50 gears.
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There are many great ways to resolve this, however, not all are equal. During a rebuild, you can have the head, intake, and exhaust port matched for a fairly reasonable fee. I've always noticed gains in power and fuel economy from a good port match and cleaning up where the valve seat meets the casting.

I've been doing my own porting for years now, it's easy as long as you remember less is more, avoid sharp transitions, and do NOT hog out the passages. That being said, I still pay my machinist for an hour or so of finish porting. The results speak for themselves, we got a full interior, fully optioned 240SX to run 14.6 in the 1/4 mile, on 15 year old 185 width all season tires and a passenger. Oh, I forgot to mention that was after I bent a valve. So yeah, porting gives you a lot of bang for your buck. I also gained a mpg or two.

The 4.9 in my 1992 F150 was rebuilt before I got it, It atleast had the standard cam timing set, possibly higher compression, it got 17 mpg and ran great even with a blown head gasket that was drinking water.
 

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There are many great ways to resolve this, however, not all are equal. During a rebuild, you can have the head, intake, and exhaust port matched for a fairly reasonable fee. I've always noticed gains in power and fuel economy from a good port match and cleaning up where the valve seat meets the casting.

I've been doing my own porting for years now, it's easy as long as you remember less is more, avoid sharp transitions, and do NOT hog out the passages. That being said, I still pay my machinist for an hour or so of finish porting. The results speak for themselves, we got a full interior, fully optioned 240SX to run 14.6 in the 1/4 mile, on 15 year old 185 width all season tires and a passenger. Oh, I forgot to mention that was after I bent a valve. So yeah, porting gives you a lot of bang for your buck. I also gained a mpg or two.

The 4.9 in my 1992 F150 was rebuilt before I got it, It atleast had the standard cam timing set, possibly higher compression, it got 17 mpg and ran great even with a blown head gasket that was drinking water.
@twofortyz well said. My 300 has already got the port matching done and intend on getting the head flowed so I can make good use of the power of the cam and motor itself. Sage advice... 6=8, all day long.

Sent from my Hush-98 comlink
 

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Addicted to Junk
85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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Porting a u-port 300 head is not as straight forward as a crossflow v-8 head. For the 300, do not touch the floor of the runners. Only the sides and roof. The exception is the radius dumping into the valve bowl can be smoothed out a small bit. More can be accomplished with going to larger valves and enlarging the valve bowls. In fact, my 85 head has no work done to the head runners. It does have larger valves and valve bowls were enlarged and smoothed out. The head is the choke point of the 300. But the runners themselves are quite adequate. The issue is the extremely sharp 90° turn the air has to make to pass through the valves. Making that turn as lengthy as possible is the best solution.

SI sells the enlarged valves. But a machinist will have to do the work.

The 300 is so choked from the factory in 85, its not even funny. What other engine can add 50% more power just with an intake and carb swap? Add a cam and some compression, and you can add 100% of the factory HP rating.
 
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I already have oversized valves, so I wouldn't have much headwork to be done as it is. I really lucked out when I found and purchased this motor from the PO who had wrecked his truck by getting t-boned. Motor hasn't even passed the break-in period yet.

Sent from my Hush-98 comlink
 
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