Just got back into Fords. Trying to sort through the various "shortcuts" and general butchery done during an engine swap. I'm scratching my head wondering what goes in the hole on the back of the drivers side head of a 351w in a 94 F250 4x4 E4OD truck. It currently has a spark plug in it but I'm pretty sure thats not OEM, LOL. The air pump and associated tubing has been gutted along with the egr. Tried to search but no immediate luck. Thanks for any help. Brad

 

That is where the air injection(smog) tube would connect on a 1/2 ton motor. For some reason Ford chose to connect it directly to the exhaust manifolds on the HD trucks, so that means either the heads were changed on your motor or the whole engine was. But since you have removed the smog system just plug these holes with 5/8 x 1" coarse thread bolts or pipe plugs.

 

Okay. That makes sense. I know the motor came from another truck but it's been at least ten years since my last heavy duty 3/4 and I've never seen a 1/2 ton 8 since my 150 was a si loved that one ) Thanks for the quick replies everyone

 

Thank you!
One question... Will just a bolt be good or should I use a copper washer or some type of sealant?
I am having this same problem right now. I have spent the last few weeks thinking my stock exhaust manifolds were cracked because we couldn't seam to get the leak to stop. Actually went and bought some shorty headers to eliminate the possibility of the manifold. (an excuse to upgrade) Got it all together and still an exhaust leak! That led me to believe the tube that comes off the driver side header collector was cracked. Took that off today and only saw the evidence of something leaking onto it and no crack. Got an inspection mirror out and saw a big bolt hole in the back of the driver side head right where all the black mess had been collecting on the fire wall. Called my mechanic buddy to confirm. Made two trips to Napa to find a bolt or plug that would fit. After two failures I gave up for the night. Thanks to this post, I now know what I need to get my truck on the road. 5/8 x 1" coarse. Thanks again!!!

 

I would just get the bolt, with a good thick washer, put some RTV under the washer, and tighten the bolt in the hole.

I took the smog off my F150, but I got the factory insert that is 5/8 x 1" course thread on the outside, and 7/16 x 1" on the inside and closed end. (I think it is 7/16, can remember course of fine thread). Cost my $2 each.

 

I got rid of the air pump on my 1990f250 heads and i believe the hols were just plugged.
Wondering if anyone knows what specs these heads are on the 351w.
valve, chamber & port sizes?
Looking into getting a set of aluminium heads for the old girl but dont have the info to compare what is there atm.
Cheers
Joe

 

A copper washer is a good idea for these smog plugs, RTV sealant will get burned off rather quickly with the temperatures these things will be exposed to.. about 1200 deg F.

 

Well I was talking about putting the RTV between the washer and the head, to seal it off. Kinda just for extra security. Would it still burn it off?

 

The quick answer is too small, too big, and too small, but if you want to be more specific these heads have 1.78"/1.45" valves, 62-64cc chambers, and 125cc/45cc ports that flow about 155cfm/105cfm. GT40 heads are a healthy improvement with 1.84/1/54" valves and ports that flow about 190/125cfm, staying with irons Windsor Jrs are slightly better at 185/145cfm but considering the fact these would cost about the same as Dart or RHS irons they're not good value, those heads flow about 250/180cfm and can be had for a little over $1000/pr fully assembled.

 

Sweet, no more exhaust leak! Got the 5/8 x 1" bolt's, one for each side, used a copper washer and tightened down as tight as I could get it with the limited space. Fired her up and finally after weeks of searching for an exhaust leak it's gone. Still seam to have a check engine light though. I'll search in other posts or maybe post in another thread that is more on subject.
Thanks!

 

I have a 95 ,5.8H that has been hard to start when warm ,put new fuel filter ,has good fuel pressure but has a exhaust leak on the air injection pipe which blows out right on the fuel line to the fuel pressure regulator. I know I have to change it but could this be causing my hard to start when hot condition.167,000 miles and my first problem with it.Love my old truck an don't want to trade!

 

Do you have any links to where i can buy these heads.
I'll have to get them shipped over so not sure which would work out the best value.
I've been eyeing off a set of 175 trick flow twisted wedge heads with a 2.02/1.60 valves for around the 1100 mark.
Either those or spend a few more $$$ and get the cnc port set.
Any recommendations on pros and cons ?

 

Summit racing has some of the best prices on heads. IMO an engine should be able to make 1hp per cu/in at or below 5000rpm with a mild cam and to do that with 351 odd cubic inches it takes heads that flow 230-250cfm. But before you run off and spend a grand or more on heads you need to understand something, as sweet as that would be... to get that to run on the EFI system in your truck you're gonna be replacing or upgrading just about all of it since the stock intake, fuel pumps, and injectors are too small to support that power level and the computer isn't easily tuned for the bigger parts needed, so you're also looking at converting it to mass air with a mustang EEC and then adding a tuner module like the Moates Quarterhorse.

 

Should have mentioned that the injection setup and manifolds have been replaced with a RPM airgap manifold and LPG gas carby running dedicated LPG.
Got the option when heads are fitted of running the same carb and manifold or changing to the twin carb rpm airgap manifold and running twin 425 gas carbs.
With the petrol price at $1.60 a litre at the moment LPG is the only way i can afford to run it over here