5.0 SO upgrade using 351W heads March 16, 2006, 03:14:55 AM So I've been talking to this guy at work, and he said a pair of '69 or '70 351W heads would give my motor some pep. Keeping in mind that this is the stock engine, I am wondering about the piston clearance - would there be a problem ?Also, would these heads be a better choice over the E7TE from the HO ? I'm asking because there's a chance I might be able to get the 351W's for about a hundred or so dollars, whereas I haven't been able to find a good deal on the E7TE's yet.Could I use the stock/HO intake manifold with the 351W ? (I know I have to use 351 gaskets and bolts)Any other issues that you can think of ? Has anybody here done this ?I have an '87 Thunderbird LX with the stock 5.0 SO. Quote Selected
5.0 SO upgrade using 351W heads Reply #1 – March 16, 2006, 09:49:56 AM Quote from: siscrewAlso, would these heads be a better choice over the E7TE from the HO ? I'm asking because there's a chance I might be able to get the 351W's for about a hundred or so dollars, whereas I haven't been able to find a good deal on the E7TE's yet.Probably - A 69-70 351W head has 1.84/ 1.54 valves and 60cc chambers. A 87-93 E7TE head has 1.78/ 1.46 valves and 62-65cc chambers. Looks like the intake ports are a bigger on the 351 head (1.94x1.76) than the E7 (1.94x1.04), but exhaust port size is the same (1.24x1.00)So, by the books it looks like a win/win situation - bigger valves and more compression. As long as you can figure out if piston-to-valve clearance will be a problemYou'd have to get a 351W manifold base but you could reuse your upper. Quote Selected
5.0 SO upgrade using 351W heads Reply #2 – March 16, 2006, 10:05:28 AM Quote from: 302FairmontYou'd have to get a 351W manifold base but you could reuse your upper.NO NO NO!!! The engine determines the intake usage NOT the heads(at least in Windsor applications). Plus there are no stock 351 lowers that mate with any of the 5.0 uppers(other than Lightning/GT40/ Cobra/Explorer and they don't mate to any stock 5.0 upper or lower). Quote from: 302FairmontSo, by the books it looks like a win/win situation - bigger valves and more compression. As long as you can figure out if piston-to-valve clearance will be a problem.Also the old 351 heads do not have hardened exaust valve seats for todays unleaded fuel(could have been added). If they are not installed the valves will burn in 8-10K mi. They are good heads otherwise, the iron GT40s are updated versions of the early 351 head. Quote Selected
5.0 SO upgrade using 351W heads Reply #3 – March 16, 2006, 10:14:30 AM Quote from: TurboCoupe50Also the old 351 heads do not have hardened exaust valve seats for todays unleaded fuel(could have been added). If they are not installed the valves will burn in 8-10K mi. They are good heads otherwise, the iron GT40s are updated versions of the early 351 head.Isn't there something you can add to the fuel to prevent this from happening? I know my father-in-law adds something to his fuel to allow him to run unleaded in his 1963 390. Quote Selected
5.0 SO upgrade using 351W heads Reply #4 – March 16, 2006, 11:44:02 AM yea hes adding a lead addictive since there was leaded gas back then, Id rather just spend the money on redoing the valves/seals and not have to buy cases of the stuff and just goto the gas pump and be done with it. Quote Selected
5.0 SO upgrade using 351W heads Reply #5 – March 16, 2006, 12:02:24 PM Since the heads are off, it would make more since to get them done so he can run unleaded fuel. Quote Selected
5.0 SO upgrade using 351W heads Reply #6 – March 16, 2006, 12:35:36 PM Thanks for the answers guys, I'm hoping the deal goes through ! Does anyone know about the piston clearance - would they work with the stock pistons ? Quote Selected
5.0 SO upgrade using 351W heads Reply #7 – March 16, 2006, 01:11:55 PM Um you have another issue. 351's use 1/2 head bolts. 302's use 7/16 head bolts. You will have to buy a set of ARP head bolts designed for this swap to make up for the difference. Quote Selected
5.0 SO upgrade using 351W heads Reply #8 – March 16, 2006, 03:27:17 PM I've heard of spacers you put in the holes on the heads to make up the diff so you can use the 302 bolts. Quote Selected
5.0 SO upgrade using 351W heads Reply #9 – March 16, 2006, 07:01:55 PM Quote from: TurboCoupe50NO NO NO!!! The engine determines the intake usage NOT the heads(at least in Windsor applications). Plus there are no stock 351 lowers that mate with any of the 5.0 uppers(other than Lightning/GT40/ Cobra/Explorer and they don't mate to any stock 5.0 upper or lower). Bad goof - I totally ****ed that up. Seeing 351W so many times, I was in tall deck mode and thinking we were talking about a 351 block. :flame: on me. Quote Selected
5.0 SO upgrade using 351W heads Reply #10 – March 16, 2006, 09:17:13 PM The heads wont give you much power, the biggest improvement would be the cam, and youd be better off going right up to a full HO swap. Quote Selected
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