[89mustang_gt]

i have a 1989 mustang gt convertible and i have been considering a nice set of aftermarket heads for quite some time and i am thinking of buying a set and installing them over this winter. it has only 91k original miles but it has been burning oil for the last few summers and my buddy that was following me the other day told me that he was seeing some blue smoke when i jumped on the gas. i have not done a compression test or anything because the car runs and idles great otherwise. could my valves be worn or sticking and be causing this and would a new set of heads/pushrods/roller rocker arms fix this? which set-up should i go with? i dont want to have to change or modify pistons or anything that drastic. i would like something that is a direct bolt-on that would compliment the gt40 upper/lower intake and other mods (see SIG) that are already there. i also plan on keeping stock cam in place.

[EagleAutosports]

Hiya and welcome. Glad you joined us.
Based on your current parts, and your position on everything else, I'd recommend one of these:

AFR 165, TFS Twisted Wedge, Holley Systemax, Edelbrock Performer, Ford Racing GT40X.

Any of those would compliment that intake and stock cam very well. They would also give no trouble with the stock pistons and valve reliefs. I included the TFS TW head because you'll have the stock cam. If it goes above .500 lift, then it'd be time to look for TW specific pistons.

[89mustang_gt]

thanks for the warm welcome and quick reply. i was paging through my old issues of 5.0 mustang last night and read that the AFR 165 were looking like my best option. couple more questions: what is the easiest way to check valve clearance? and is it best to replace pushrods when installing new heads? i have heard both sides on this.

[The Greek]

You oil smoke may be caused by old hardened valve seals. They're cheap, Ford Racing has them, and there's a procedure to install them without pulling the heads.

If you're interested, check out Racing Head Service - RHS Performance Cylinder Heads , they've just updated their site and there's info that may help you make a decision on which type of heads will work best for you. I've seen their cast iron heads and the casting quality is the best that I've ever seen. ---Chuck

[The Greek]

The only true way that I know of is to pull the head and place modeling clay, not Play-Dough, into the valve reliefs. Using an old compressed head gasket, the same thickness as what you're going to use, install the head and set up the valve train for that cyl. Then bar the engine over, remove head and measure thickness of clay indentation caused by the valve.

As for pushrods, I would replace them. For what they cost, using old pushrods doesn't help in the reliability factor. With some cyl heads hardened pushrods are a requirement because of the use of pushrod guide plates.

[89mustang_gt]

please forgive me as i am new to this site and pretty green when it comes to heads and valvetrain. i have never actually seen a 302 with the heads taken off. i have only gotten as deep as replacing the lower intake. i have read a million magazine articles about a head swap and honestly, i am a little intimidated about doing it. magazines make everything look so easy (probably because they want you to buy the stuff they are advertising!). arent the stock pistons flat on top (ie, no valve reliefs)? and i have read in the service manuals that you can check vavle clearance by measuring the gap in the spring coils at TDC to ensure that the spring is not "bottoming out". is this just another way to do it instead of clay? and how do i know that a cylinder is at TDC and what is the easiest way to rotate the engine to get each cyl. at TDC?

[fast8903]

Hey there, the pistons on stock bottom end 302 have valve reliefs... at least on my 89 gt they do. I have run as high as a .533 lift Lunati cam and haven't had any issues. You are right on the money with using your stock cam, I put mine back in there and it does great! I am using Windsor 200 heads, they flow pretty good for the price. But you can't go wrong with the AFR 165's. as far as the TDC goes, take off your valve cover first and remove #1 plug. While rotating your motor (manually) watch your rocker arms and when the intake side goes down you'll be close to TDC. then shine a light in the plug hole and rotate some more until you are at TDC.

[The Greek]

The only 5.0 that came with pistons that were completely flat with no valve reliefs was the 1986. These pistons were forged instead of cast or hypereutectic. The reason this was the only year for the completely flat pistons is that the 86 cylinder heads were a one year design. Ford was experimenting with a lean burn combustion chamber, which didn't do a thing for performance. The valves were completely shrouded and made air flow very poor. Stay away from any E6 cyl. heads.

I suggest that you get some books and read up. Magazine articles tend to skip a lot of details and will at times make a major project look like a 2 hour job. ---Chuck

[89mustang_gt]

my neighbor thinks i am nuts for putting higher flowing heads and new roller rockers on the car and not replacing the piston rings and cam. he seems to think the higher compression heads will proabably kill my piston rings in no time at all. he thinks the cam should be replaced too because it is probably already worn out (after 91k miles?) and a new set of heads is no good if your cam is worn. i dont think the engine is ready for a rebuild yet. i definitely dont have the budget for that. it still runs very strong and should have plenty of life left, although it has been using some oil, but that sounds pretty common for 5.0's. do you guys think my neighbor is nuts?

P.S. i was leaning towards the AFR 165 pedestal mnt. and putting some 1.7 cobra Rockers to get some extra lift out of the stock cam. wise choice?

[fast8903]

Definitely a wise choice in the heads and rockers. Your neighbor isn't too far off there, a fresh set of rings is a good way to go. And you might as well bore it out .030 while you are at it. It all depends on your wallet though, there is all kinds of possibilities. Stroker kit?