So I made a nice purchase this weekend. Got a flat-top and a hex-top head for next to nothing. Grabbed the distributors and a few misc. parts too. I didn't really need them, I already have a flat-topped log head I've been working on. But for the money, and to save them from being scrapped I had to take them home. There's a real nice low-mount starter 200 and a 250 block left behind, dirt cheap or even free to the first guy that gets there soon enough. There's more details in the eBay deals. Anyway, after looking at the two heads, I'm wondering what to do with them. The hex-top has an obviously larger log, the end plugs are 1-1/4" vs just 1" for the flat-top. Someone said in another posting that despite that, the hex-top head has smaller ports than the flat-top head. I'm not sure why Ford would do that when all the other changes were about easier flow, maybe to get the air velocity back up after slowing down in the big log passage? And there doesn't seem to be enough material on the top of the hex log to support milling it off to add a two barrel carb mount. So what I'm thinking, and looking for correction if I'm wrong, is that the hex-top log might be better if you're planning to stick with a one barrel carb, or maybe a one to two barrel adaptor. But the flat-top log is better for a full two barrel adaption.
All Small Six Hex-Top Vs Flat-Top Large Log Heads
- Thread starter TrickSix
- Start date
This relates to all small sixes
For living in a small town, I've had pretty good luck finding these large log heads. I've bought four of them for an average price of about forty bucks. The most expensive one I bought at a junkyard, and it had a crack, so they took it back. The cheapest one was $20! I coulda shoulda woulda bought the Maverick 4-lug 8" rear axle for $50 a couple years ago.
Ba Mustang
Well-known member
Probably what I’m going to do with my spare head.
So, the vacuum port on the hex-log head is up at the top front of the manifold, instead of back below the inlet like the older heads. Is that an issue, or is it still okay for my C4 and distributor? I'm not sure how much of a vacuum gradient there is inside the log between the center and the ends.
Depending on what you are doing, if you are thinking of cutting off the log it may be better using the small log that way you get the better 52cc chamber and the same size valves as the early large log but not as large as the later large logs. The small logs have a straighter high port that is rounder and makes doing round tube runners easier. The large log the ports are upside down cathedral and harder to fab new runners. Save the large log for tri power, hex power or a two barrel, on top. Save yourself a lot of trouble and leave the exhaust as is. Well, that is my thinking.
Is there not a spot by 3-4 on the side of manifold for smog that won't be used, something could be done there no.
yeah, nota easy project. If attepmting I'd come along for the ride. Need special facilities for "1/2 measures". More from there~
"sm log", 'large log', 'hex' etc... not easy 4 me to follow. Castings (ltr/#) are easier. (as early'n late come in here too).
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There is a hole directly below the carb, I suppose for the EGR inlet. It is not tapped, and the wall is kind of thin to support threads for a plug. I will probably just bolt a little plate over it.
Make a plate thick enough to drill and tap a pipe fitting.
Whatever you do, do not put the PVC at the end of the manifold we have seen where that could lean out the nearby cylinder.
Whatever you do, do not put the PVC at the end of the manifold we have seen where that could lean out the nearby cylinder.
No, I won't be doing anything too radical. I like keeping my car mostly stock looking. For instance, my exhaust looks stock but is a 2" diameter instead of 1-3/4". My original engine has few miles but many years since a good rebuild. It's getting a little leaky now, and I'd like to pull it for a while to refresh it. I'd like to drop in a temporary replacement so there'd be no hurry. I thought it might be interesting to try a newer head with the bigger valves and intake to see if the difference was noticeable. I've got an 1101 carb, that looks enough like an 1100, and the newer heads look enough like the old to suit me. My car has a C4, and will be keeping it, so the engine rarely gets much over 4K rpm. A big cam and a lot of porting probably wouldn't be real cost effective, I wouldn't realize their full potential. Tha's why I was asking which of the stock cams is better, I can get a NOS cam fairly cheap, and maybe they're made of better steel. All you see is complaints about bad cams and lifters these days...
DSII is worth it (motor '65 +), looks stock and in place of the lill alu brain box one can run hybrid - a gm 4 pin fits right in there (https://www.gofastforless.com/) can be hid easily, spare in glove box 4 breakdwn, cheeper, etc. I'd try these as an incremental approach (U suggest that) rather than cam, valves, compression, etc. (higher ratio rockers would B nxt w/carb if still not satisfied).
TrickSix, following up on chad's post- I recently installed a DS2 with the GM 4 pin module on a 300, and it is performing perfectly. Including factory tach.
That's a good plain TrickSix, and just bolting on one those 1980's Late Log Heads is going to be a very big improvement in flow over any of the 1968 and older Log Heads. All you need to do to Maximize one of them is to Mill them to get the average 62 CC's Combustion Chambers down to 52 CC's matching what your early head was or better still going a little more and or Zero Decking the Short Block to take it to a 9.1 to 9.2 to 1 Compression Ratio if you want to still run on 87 Reg Fuel. There are some other do it yourself Mods that you can also do. Good Luck
D7 head is flat. D8 is hex or more round. I pulled both from 78 Fairmonts at Pick'N'Pull.
I run the D7 with .060 milled off it on a 78 block. I run the cheapest gas.
Both will run good with a cheap China made elec. choke Carter YFA carb.
A Rochester 2V small base carb adapter shouldn't be too hard to make.
NOS Rochester 2V small base carbs were available on ebay the last time I looked.
The large log weber adapter looks like it could be adapted to fit a Rochester 2V small base carb.
Both the carb adapter bore and the log intake bore could be enlarged.
I run the D7 with .060 milled off it on a 78 block. I run the cheapest gas.
Both will run good with a cheap China made elec. choke Carter YFA carb.
A Rochester 2V small base carb adapter shouldn't be too hard to make.
NOS Rochester 2V small base carbs were available on ebay the last time I looked.
The large log weber adapter looks like it could be adapted to fit a Rochester 2V small base carb.
Both the carb adapter bore and the log intake bore could be enlarged.
The "small base" Rochester 2G carb is an excellent carb, @280 cfm.
Looks like C9 to me.
