Another Cylinder Head Build Reality Check Please

T

TrickSix

Well-known member
Hello. They say there's no teacher like experience, thanks for letting me take advantage of yours. And I'd like to apologize in advance if it seems like I'm trying to tell you something you already know, or if I'm preaching to the choir. But I want to clearly depict my thought process, so If I've gone off track you can let me know where. Let me start with the car - I have my first car yet, from 1973, a 1966 Mustang convertible. It has the original 200 I6 and C4 transmission, and the 2.83 rear end. The engine received a quality stock rebuild back about 40 years ago, and is still in good condition. It was bored I think .030 over and was balanced. The only engine mods I have done are an 1101 carb on a homemade adapter, and a 1970 distributor. The exhaust manifold has been changed to the larger 2" outlet style, and the standard configuration exhaust system is also 2". For something to do and to spend some money to help out local businesses, I've been putting together a big log/big valve head for it. I'm not trying to make a race car here, just pick up a little low hanging performance fruit. The head is a late '69 model, (the '77 I found had some cracks) but does have the larger carb inlet. I've had new valve guides installed, the later 1.75 intake valves, and 144 intake valves used as exhaust valves. The valve pockets have been enlarged and smoothed a bit, and an exhaust port divider has been installed. I even scrounged some 221/early 260 retainers. Yes, all by "The Book". It hasn't had the final valve grind done yet, just the new seats installed, but I plan on a 3 angle valve job, with back cut intakes. Just for fun, other than seals and gaskets I've been finding NOS parts for it, the newest things on the head are the intake valves, they didn't come out until the late 70s. I've measured the combustion chambers at 62 cc, so any past milling must have been limited to just a close shave to true it up. The general, conservative consensus around here suggests that I take off about .060" to get the compression up where it should be. I just had the original head off a couple years ago, it's running good and I don't feel like pulling it again just to check measurements for an exact comp ratio calculation. So that's all the easy stuff. Now I need to make a decision about valve springs and the possible installation of an aftermarket camshaft. But before we talk about camshafts, I'd like to talk about my transmission. Although I've preferred a manual tranny through my life, the C4 is here to stay, I'm not changing it. I've never had a tach in the car to check RPMs, but from what I've seen around, screaming wide open throttle shift points are still only in the low 4000s. And at the top end, even if I put in some 3.20 gears and drove 100 mph, it would still only be turning in the low 4000s. So I don't see any point in installing a cam tuned for anything over that. There are a few out there with an RPM range 1000 to 4500, and valve lifts from about .400 to .425. So, given those two constraints, low rpm and low lift, how much valve spring do I really need? I see spring ratings up close to 300 pounds for some cams, it seems like a way big jump. Valve spring selection for these engines is not great. The short, small diameter stems limit retainer choices, and make it hard to fit in much of a spring without coil bind issues. At least the thinner one piece V8 retainers help out with installed height, I measured 1.64", and that may go up a bit with the final valve grind. However, if you use the V8 retainers with the stock springs, you have to shim the short out of them just to get back to the spring pressures you had before. There aren't a lot of spring choices with a solid height comfortably under the 1.222" open (stock cam) height, much less a higher lift cam's. There's a stiffer, short enough 289 spring, but it has a smaller diameter, which raises some issues. The 240 police/taxi exhaust valve spring looks like a good alternative to the stock springs when used with the thinner, lighter retainers. There's also a 302 exhaust valve spring that's just barely short enough with the V8 retainers and a .425" lift, and is about the stiffest I see that will fit. So, with all that being said, (sorry) here are my questions - First, in your opinion, would it be worth the trouble to install one of those mild camshafts? If most of any power improvement seen is from the new head, not the cam, I may pass. Second, given one of those mild cams, would the 302 springs be stiff enough? I'd rather not machine the head to fit double springs. I apologize for this thesis length dissertation, but I wanted to make sure you had all the information you needed. Thanks again, I hope you're having a good day.
 
Welcome aboard. For valves i would get the SI valves from Matt at vintageinlines.com
You are going to have to mill .060"-.070" to get your compression back to normal.
You really would benefit from a new camshaft. Stock cams are junk.
Call Schneider cams & ask for Jerry. He can fix you up with what you need for your type of engine & driving.
If you need a distributor check my listings in the small six for sale section. Bill wsa111 billythedistributorman@live.com
 
Hi, while I like to learn about my engine and the improvements I think about, I am glad my new cam kit came with new springs, that work with the old retainers. What was a problem for me was cam timing. I needed the variable timing chain set from Vintage Inlines and help from the guys here to properly degree my cam. If you install a new cam DEGREE IT. As Bill mentioned, a new performance cam is light years in performance better then stock.
Watch the very good "Echo videos" right here, especially how he degrees his cam, and get the Ford Falcon Performance Handbook. Good luck
 
consensus here might B "build the engine around (a modern) cam".
That is chosen by application, use, RPM, octane choice. U seem to B sayin: tops 4K. - OK, well then, go w/that, nuttin special.
(Not sure Y U pick that but U seem to. $?, use? amount of understanding?, etc)?
So the cam comes w/its own recommended springs/retainers, etc. Again nutting special. Y all the worry? Caculations? I must be missin something...

Glad U gota Handbook, have been lurkin here. CK the tech archive ('cover to cover') too:
https://fordsix.com/app.php/page/archives
(y)
 
Last edited:
That’s a good plan covering most of the very important items. I will add this bit of info for you, the stock 1966 200 engine has a 8.7 to 1 compression ratio with a 52 CC chamber this engine also used a steel shim head gasket with a .022 thickness. To be able to restore the engine compression ratio back to stock specs plus account for the newer style head gaskets we have today such as a FelPro composition which is .050 thick would take approximately a .075 mill cut a .010 cut decreases the chamber about 2 CC less. This is works out to a .050 cut to bring the chamber down to 52 CC and a .025 cut for the thicker head gasket:

If the heads log doesn’t have the 1 3/4 carb hole then it helps flow to opened up. The 289 or 302 valve springs really only work fair are ok when using the stock cam. So if you go with a much better aftermarket cam then there are better springs, the cam supply’er can help you get the right spring. For most street cars like yours with a stock auto trans there should be no need going with a duel valve spring. A TransGo shift kit in your C4 would help it shift better and last longer, better still is to install a 1967 to 1969 (Select Shift) valve body with a shift kit then add a small accessory trans cooler. Best of luck :nod:
 
A big collective thank you to all the replies here. Most other Ford/Mustang sites are all about the eights. And I miss Mustangs Unlimited, seems like they had more of the six specific parts than the other vendors.
 
You actually have a wider spring selection with the Crane 99950 retainer and the 99093 lock.
The Crane 99833 spring will work for most cams.
If you need a little bit more spring use the Crane 96803 spring.
 
You must log in or register to reply here.
Back
Top