Ok so I have a question about smog. I am replacing the engine in my 1968 ford f100. It currently has a 351 windsor from a 1979 cougar that is shot! I am ordering another 351 windsor from an auto parts store. They have two options that I am looking at. One is a 351 windsor without smog for about $1500, the other is a 351 windsor with smog for about $1200. From what I understand this simple means the heads do or do not have smog ports in the heads. So my question is, can I buy the 351 windsor with smog and simply plug the smog ports. Would this hurt the engine or performance in anyway. That would save me about $300 dollars but I dont want to do something that would have a bad effect on the engine. My 1968 f100 does not have any smog currently so I do not see any reason plugging the smog ports would hurt anything. Thanks in advance and any input is appreciated!!!

 

Earlier 351W (and 302) heads were plumbed with thermactor passages for the purposes of running smog pumps --extra air pumped into the exhaust ports of the heads for emissions reasons.

There will be a 'smog knot' sticking down in each of the exhaust ports with an air passage running through the middle of it. These smog knots are restrictive to air flow out of the heads. They can be removed with a die grinder and a carbide bit.

The intake and exhaust ports can also be port matched to the openings of the gaskets (Fel-Pro gaskets are best for using as a template for doing this). It's best, if you haven't ported a set of heads, not to get too crazy with opening them up. From the port openings, only go back into the head about 3/4". Opening the ports too much can grind into the water jacket of the heads. There's plenty of information on the internet of how to do this.

However, later model E7TE heads from an '87-'93 5.0L Mustang would be an improvement over the stock 351W iron heads.

The ultimate Ford factory small-block iron heads would be the GT40 and GT40P heads from the 5.0L Explorers. They aren't going to flow as well as a set of aluminum heads but, they were the best factory small-block iron heads available.

Five.Oh Info : The Ultimate Ford GT40 and GT40P Cylinder Head FAQ

This is a set of 5.0L Explorer GT40P heads I have. These pictures were taken of the heads fresh from the wrecking yard.





As with anything, always thoroughly research the subject of whatever it is you're doing, BEFORE hand.

 

Looks like the intake bolts broke off at EXACTLY the same spots mine did!