Head Selection

ski4evr

Well-known member
I have a 200 cid. It is a '68 block with a '66 head. I've gone through several Autolite 1100's. Some have been rebuilt through auto parts stores and the one that is on the engine now was rebuilt by myself. It was running really good, but... For no apparent reason, it wont idle now. It dies as soon as it starts (unless I keep my foot on the gas - alot). I'd like to switch to a later model head and move up a decade or two in technology to a 2-barrel carb. I found a head at a local shop. The casting number starts with D0. This link:

http://www.geocities.com/mustang_man_19 ... coder.html

shows the head belonging to a 170 cid. Is it the same head that was used on the early 200/250's? I'm assuming it has the smaller intake valves and the lower cc volume like the early 70's head. It definitely has the larger intake log (relative to my '66 head).

The shop is asking $350 for it. It has been rebuilt (3-angle valve job and hardened seats). Good? Bad?
 
D0 is a 1970 head and should be either for a 250 or 200.

As far as your carb, check your idle air mixture screw. I once had my idle air mixture screw rattle closed because the spring on the screw was the wrong one.

Slade
 
I had a piece of rust in my carbs jet that made it not run unless I would pump the throttle. I had a rusty fuel line to the carb. It gave me worse troubles a couple times. Now the line is rubber until I find or make a new metal line from the pump to the Holley carb.

Steve
 
HELLO SKI4EVR

....THE HEAD COULD BE A VERY GOOD BUY OR A BIG DROP OFF IN POWER.

....WHAT YOU NEED TO CHECK IS THE LAST LETTER ON THE HEAD. YOUR DO?? 6090 A OR B. THE A WILL GIVE YOU A GOOD JUMP IN COMPRESSION. YOU WOULD BE IN THE AREA OF 9.25 TO 9.75. WITH JUST A BOLT ON. THE B WILL DROP YOUR COMPRESSION TO 8.0 TO 1. THAT WOULD BE A BIG DIFFERANCE THAT YOU WOULD FEEL. I KNOW THIS FROM EXPER.

....I HAD A 170 HEAD (EARLY) ON MY 1970 200 CU. IN. MOTOR WHILE I REBUILT THE 200 HEAD. WHEN I PUT THE 200 HEAD ON THE MOTOR LOST ALMOST ALL OF THE HEAVY TORQUE IT HAD WITH THE OLD 170 HEAD. I THEN WENT AND FOUND THE 170 HEAD FROM A 1970 FALCON. THE HEAD WAS DODE 6090 A. WHEN I PUT THIS HEAD ON I GOT BACK THE STRONG TORQUE I HAD LOST.

....I ALSO WAS ABLE TO PUT ON A LARGER CARB. THIS HAS BEEN THE ONLY THING I'VE DONE TO THIS MOTOR TO MAKE IT GO LIKE IT SHOULD!!

.... THE HEAD SOUNDS LIKE A LOT. MY 1970 170 HEAD REBULD WAS OVER $480.00 WITH ALL NEW VALVES AND SEATS. THAT SOUND LIKE A GOOD DEAL IF YOU KNOW THE WORK WAS GOOD WORK! DON'T BUY IT IF IT'S A DO?? 6090 B.

.... THE HEAD FROM A 1970 170 WOULD GIVE ABOUT A 7 OR 8 HP JUMP OVER THE 200 HEAD YOU ARE USING NOW.

.... HAPPY MOTHERS DAY EVERY ONE......!!!! IT MIGHT NOT BE TOOOO LATE......!

LIVE IN GRACE

LEROY POLL[/b]
 
Thanks for the information and first hand experiences.

:arrow: Would the drop in power between the "B" head and the "A" head be a difference in chamber cc ("B" being the 62cc chambers and the "A" being the 52cc chambers)?

:arrow: Is there any other reason for a drop in power when swapping heads - other than chamber cc?

I intend to cc the chambers knowing that I could kill the compression ratio if I'm not thinking ahead (compensating by milling for the newer head gasket thicknesses and cc differences).
 
The head at the shop is an "A." I guess this means revision number one from what I have seen in the postings.

The guy at the machine shop was trying to talk me out of putting in an exhaust port divider - saying that it's effect would be negligable. Everyone here gives it a thumbs up, so I'm going to add one. What is the best way to put it in? Tac weld? Epoxy? Would the expoxy even last a few hours at operating temps? Or should I simply just wedge it in?
 
There are some cars with siamesed ports (like Minis) that run amazingly. The divider is not a bad thing; is probably worth fitting. Bear in mind the old adage of not making a tradesman do something he really doesn't want to. The best conclusion about fiting has been pinning it with set screws or similar. Don't expect epoxy to hold forever.

Guys here used to make their own, welded to the header flange - another way of thinking.

Cheers, Adam.
 
HEY SKI4EVR

....THE "A" STANDS FOR THE 170 CUBIC INCH MOTOR. THE SMALLER CHAMBER. THE "B" WAS ON THE 200 AND 250 CU.IN. MOTORS, BIGGER CHAMBER.

....THE HEAD HAS THE LARGER VALVES. THEY'RE THE SAME ON BOTH THE "A" OR THE "B" HEAD IN 1970.

.... YOU SHOULD SEE AND FEEL A GOOD JUMP IN THE TORQUE WITH THIS HEAD.

....YOU SHOULD ALSO RUN 2 NUMBER COOLER PLUGS ON THIS HEAD. THIS WILL HELP ON THE PINGING ON HOT DAYS.

....TELL US HOW IT RUNS WHEN YOU GET IT ALL TOGETHER.

LOTS OF LUCK.....LOL.

LIVE IN GRACE

LEROY POLL
 
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