OK guys, I need a little advice. When I built the 302 for my '87 F-150, I used '69 351W heads with the bigger valves because 1. I had them. 2. Hey, bigger is better, right?!? :-X23 Well, I have since learned that this setup apparently requires an adjustable valve train to compensate for some funky problem with pushrod length. Consequently, we are now pulling the lid back off to deal with a burnt valve. I was never satisfied with the performance to begin with (not a bit different than my 170K mile bone stock '90 except uses a lot more gas), so I have decided to go back to a set of 302 heads and forget about being tricky. HA! I scrounged through the shed and I've got three sets of 302 heads and they're all different. One set is off a late 70's "smog" motor with combustion chambers big enough to park a Volkswagen in, one set has "average" sized chambers and I think they came off of a '72 Torino, and one set has really small triangular combustion chambers. That last set is cast "302" but I don't know but what they didn't come off of a 289. Here's the deal: I have rebuilt a lot of engines, but always in their stock form. I've never made any major changes except maybe a 4BBL intake or mild cam. I realize that smaller combustion chambers = more compression = more "theoretical" horsepower, but I have no idea which set to use. I guess what I want is more information on how combustion chamber and valve size affect horsepower AND torque. I realize that being a short-stroke 302, it'll never make good torque, but surely I can do something to give this boat anchor a little git-up-and-go! Would I be better off with the smaller chamber heads assuming that the additional horsepower at a higher RPM will be worth the effort? I'm obviously way over my "head" here. Any help or source of info is greatly appreciated! I can't afford another mistake!

'87 F-150 4x4
3.55 gears
4 SPD trans. with no OD
EFI 302 with mass air conversion
Ford Motorsport A-311 cam

 

Basically, Ford never made a "good" head, except maybe the cleveland heads, and they are not perfect either. You can't fault them for this, because I guess they designed their engines with certain goals in mind, and they do it quite well(grocery getting comes to mind). Your goal of high rpm power will never be fully realized with a stock ford head. The valves are small and they don't flow well stock. The aftermarket heads are what you need, but they aren't cheap. But you may want to figure how much it's going to cost you to get a set of heads you have now, redone, and see if you can spring a little more for some cast iron aftermarket ones.(aluminum would be even better)

But, if you want respectable horsepower, and good gas mileage, I would use the heads you have, that have the smaller chambers, and the largest valves. If you have flattop pistons in your engine, it would probably be around 9.0-9.5 to 1 compression ratio.

Or, you could have your 351w heads redone again, and get the machine shop to modify them for an adjustable valvetrain.

 

[updated:LAST EDITED ON 30-Jan-02 AT 00:10 AM (EST)]you made a comment about the clevand i would like to hear more i have on me and my brother inlaw got drunk one night led to brainstorm we put it in 1985 ford ranger this would be a 351 clevland 4v heads 4bolt mains c-6 and 205 transfer case i would like to hear more about the heads it is great put it in drive and stomp on the gas and all it dose is search for road all the way thru drive i think we are on are 2nd or 3rd driveline she is a little heavy in the nosebut what do you expect



mike
:-X11

 

Hey Mike
Just how much room did you have left with that 351C in there .. I have a 650 H.P. 400 sitting on the floor in the shop I'd like to stuff in one of those rangers, Put a narrowed Dana 44 in front and a narrowed Dana 60 with a locker in the rear and take it to the dragstrip and in 4 HI run a few passes to see how quick it is ..
I'm thinking 11's.

As for the Clevland heads with a little work the can be made to really breath.

 

the most difficult part is the exuast and the fiberglass housing for the heater motor we just had a front sump oil pan so we were pretty limited on how low and the best placement but sorry i forgot the pickup had a 3 inch body lift befor we did this and it helps alot you really cant tell there is a larger motor in there the front only droped about a inch without a body lift this could be a real job and with the lift we put motor tranny and transfer case all in one shot



hope this helps mike
:-X11

 

BlueOvalRage,
I may be too late, you may have already installed heads, but my suggestion would be to pick the middle of the 3 sets of 302 heads you have. This is the reasons(s): First, smog heads are just that, toss them. Second, the small chamber heads are going to ask for more conservative timing and better grade fuel to avoid detonation. Less advance timing means a drop in horsepower, but compression "might" make up for it. Third, and most importantly, the smaller chambers will really "shroud" the intake valve, limiting flow "under the curve". Less air/fuel in means less power, no matter how much compression you have. They might be worth it with some port work, but the mid-size set of heads you have are really your best "real world" choice.
Just my opinion.......think about it.

 

[updated:LAST EDITED ON 06-Feb-02 AT 08:13 PM (EST)]Ohhhhhh, my dear Mr. Motorsport. I do SO appreciate your very informative reply. Unfortunately, I read your post about 4 hours too late. I went with the smaller combustion chamber heads and I dropped them off at the machine shop after work today. I do whole-heartedly agree with your opinion of the smog heads. Horsepower from a 302 in the late 70's was down around 115-120. PATHETIC! I did a little more research though, and found out some more about what I had to work with. The above mentioned heads were 1979 69cc castings, the middle set were '69 62cc castings, and the smaller set, which I chose, were 1975 58cc castings. I was, however, going to use the 62cc heads (decision made after studying horsepower/torque charts from these years) , but a closer inspection revealed that the engine they were on had obviously been thrashed quite hard on unleaded fuel. All of the exhaust valves had recessed into their seats, two of them well over a quarter inch! As I only plan on driving this truck after it's fixed for a couple of months before I sell it, I really didn't want to invest the extra cash in having all the seats cut out and replaced with hardened. So, I went with the smaller chambers. We'll just have to hope for the best. As I said before, I really do appreciate your input. That is exactly the response and explanation that I was looking for. I am extremely interested in any information regarding Ford small block heads, as this is an area I'm kind of vague on. If you know of a web source or Ford specific book (screw the bowties) where I can study up some more, please let me know! Thanks again!

 

I think you made the right choice. The 75 heads do have hardened seats for unleaded fuel.

 

Well, just an update for anyone who may be interested. I finally got this thing put back together. It still doesn't have any torque, but when you get it spun up past 2500 RPM, it REALLY pulls! The valve train is infinitely quieter than ever before, too. It's still a mystery why I burnt that valve with the 351W heads, though. I checked everything out and the valve stem length and valvetrain geometry were OK after all. The burnt valve DID have very heavy stem wear on the upper half of the stem on one side and the lower half of the stem on the opposite side. Heavy enough that there was guide material embedded in the stem and the guide is trashed. Makes me wonder if the seat got cut off-center or some such thing. I can't think of anything else that would have sideloaded the valve like that. Anyway, thanks for all the replies!


P.S. Never bolt an EFI intake to earlier heads unless you need a water-cooled alternator. The water ports aren't the same size and don't exactly line up. With a little epoxy and some creative filing, though..........

 

Too funny! (your sense of humor regarding the water jacket)
If you ever need any help, advice, opinions, specs, etc, feel free to ask. I'll share what I know, and what I don't know, I'll find out for you. - Don