daily driver,once and a while strip,mostly tire turning torque.I was going to keep the stock heads cause the motor only has 20k since total rebuild including the heads.and upgrade to a gt40 intake,keep the SD for now.70mm TB,and egr block off plate.24lbs injectors and run a the maxx cam the stock heads will handle.the car has headers,magnaflow x-pipe with gutted cats and catback flowmaster and CAI.someone I talked to has a TF stage 1 cam on stock heads and he said he didnt run into any problems.then was told to change the heads cause the 86 heads are the worst flowing heads ford made.
Yes, the '86 heads are the worst of the 5.0 heads.
No, a cam won't do jack for your engine with those heads.
If you still have the original '86 pistons, your cylinder head options are easy: You can only run TrickFlow heads. Standard, inline-valve heads will cause valve to piston interference issues with those pistons because they do not have valve reliefs. TrickFlow heads have a different valve arrangement that supposedly allows clearance even with the '86 pistons.
cam timing determines piston to valve clearance. the difference in valves diameters really doesnt mean much in the grand scheme because even if you take the difference radius between a 2.02 and a 1.90, which is .06; its only .06" if the valves were at 90*. none of them are at 90*, they are at 20*. or in the case of the tfs tw 15*. another thing about the tfs tw is that in OOTB form it has more free drop. while that is good for piston to valve clearance, a lot of people mill their heads down to get the free drop out because it hurts power production.
but the TFS TWs are excellent heads. pick the heads you want and the best cam for the application, check the PTV clearance and notch the pistons if you have to. it aint no big deal.
A good option would be the TFS heads and an E-cam (or equivalent).
clement makes some great points but you will discover that with the 86 flatop pistons that, that .06 extra clearance can make you or break you when you're talking about the 86 flat tops.
If you're on a budget and/or time contraint, I'd toss the TFS heads and letter cam in and call it a day. You're going to have to switch over to mass air for the cam unless you can find somone still able to cut a chip for the SD computer (good luck with that... if there is someone, I can't find them).
All is not lost though... There are still some great gains to be had by reusing the stock cam! The 86 (comparitive to the other 5oh HO OEM cams) is pretty nasty. You'll get a great SOTP woody just by swapping out those heads! If you decide to add boost later, all the better as both the OEM cam and the SD respond awesomely to being boosted or juiced or both (think wet system adapter plate between upper and lower)! The only downside to this option is that you need to do what you're going to do within the confines of the 19lb injectors and an FMU (again with lack of options for chipping the EEC).
With the stock cam and TFS heads though... there's no PTV clearance problems. Other cam (including letter)... it's hit or miss. You can be clear on P2V but inside of the acceptable safe range (this is what I was referring to about the afrementioned .06 clearance above).
I guess my point is that even though the heads suck... there's nothing short about reusing that stock cam.
Anyone have the specification for the 86 and 87 cam profile that they can post up side by side?
cams can be made to clear, but you really need to mock it up to determine PTV. everything can come into play....
how far the valves are sunk into the seats
how far in the hole the pistons are
how thick of a HG is being used
if the right valvetrain parts are being used (and not some junk that wont control the valve.)
and most importantly, the valvetiming.
its not about total lift, its about the location of the valve at the points where the intake valve is chasing the piston or when the piston is chasing the exhaust valve.
i say forget the cam [unless you want to do a custom grind. and if you do that i would notch the pistons (if it were mine) so the cam could be optimal for the combination instead of having to lose power simply because you wanted it to clear.] and put a set of heads and a decent intake on top of the stock cam. if that wont run low 12s at 3200lbs something is very wrong.
the explorer/gt40 top end combo is very well suited a DD. Unless you are ready for a tune or to convert to mass air I would skip the cam.
FWIW I have a stockish 306 rotating assembly, stock cam, with gt40 heads and an edelbrock performer(flows very close to the explorer) and I have no problems driving through traffic and it will pull hard from idle all the way to 5400 rpms.
I guess the OP didn't read anything about switching cams and speed density. You can do it, it just won't run for crap. And 24lb injectors on SD would flood then engine with fuel. Do everything else you want to, BUT SWITCH TO MASS AIR before you do it. On stock heads you are not going to get much above .500" lift. If even .500". The high swirl E6's are junk, yes the car runs great stock, but keeping those heads and changing anything is like wiping before you poop.... just does not make good sense.
Do a mass air swap, get a 70mm MAF from a 94-95 Mustang (or one of the other compatible cars), do your 70mm TB, intake, heads and what ever cam you like. I would not go to 24's until you get over 300 crank HP. And then you are going to need a tune to run them unless you get a MAF with the proper transfer function to give the computer the right signal. Or swap in a 93 cobra ECU and MAF then you can have the 24's. If you think about it a 24 flows around 20% more fuel. If the ecm isn't tuned or the MAF tells the computer the wrong amount of air your car will run pig rich and possibly fuel wash the cylinders causing all kinds of bad things. because it is going to provide that 20% increase over the duration of the pulse width....
You can reuse your CURRENT harnes. There are a couple of splices you need to put in and wire or two that you have to swap from one terminal at the EEC to another. The whole thing is pretty simple so long as you pay close attention to the pin orientation etc. SOLDER EVERYTHING!!!!! Do not rely on mechanical splices of any kind.
Do to it's importance, I'll say once again SOLDER YOUR SPLICES! It will save you from having to track down that one weak splice and chasing your tail to discover what the problem is.
There a lots of "How To" articles on doing the conversion both with and without swapping the harness out. If you have difficulty finding a good one, post that here and someone will find you a link to a good one.
CHROME RUST brings up a great point about the Cobra EEC. If you can find one for a reasonable amount of money, that is the way that I would go. Cobra EEC + 24 lb injectors = Happy feul injection system with room to grow. I would say that it would cover just about all of your normally aspirated dreams short of the extreme (which you're unlikely to accomplish without swapping out the pistons anyway).
Even though the 86 flat tops are kind of a pain in the rear for cam/head selection etc... one thing to keep in mind is that they come with one small advantage... a slightly higher end compression ratio than the E7 era pistons... and they're forged! With a set of E7 heads (unmodified) you can expect a final compression ratio of at or around 9.8 (nature of the beast) IIRC. I don't have a reference for the TFS heads but you get the idea.