All Small Six 68 small log head porting

This relates to all small sixes

clochard68

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Hello,

I'm currently working on my 68 small log head.
First, I just wanted to state that I am fully aware that the small log head isn't worth porting/upgrading/throwing money at it, that the large log or aluminum or OZ 2V would be better choices. Two things make it hard for me to upgrade to one of the mentioned heads: I live in europe and they are hard to find online and I am obligated to keep my L6 as stock locking as possible to keep my vehicle registration (my 68 Mustang is registered as a classic car).

So I want to get as much out of my small log as I can, with porting, back cutting of the intake valves, 1.65 roller rockers, higher compression (it will run on 98 octane fuel only) and a progressive weber 32/36.
My head already has hardened seats on both intake and exhaust installed, therefore I am keeping thee stock valve sizes.
I am reusing my stock cam (but 4° advanced instead of the original 4° retarded) with a 1.65 roller rockers, the max lift of the valve is 0.381".

I will show a little bit of progress on the head here. Maybe there are other people out there who are interested in upgrading the small log. There is a lot of data on the large log and aluminum heads, but not on the small log. I appreciate every kind of advice on how the make the head perform better!

And to measure the results, I put the mustang bone stock on the dyno when I got it. Load o matic distributor, standard 2" exhaust with manifold, holley 1940 carburetor was the starting point. After all the mods to the head and some upgrades (progressive ignition HEI distributor, Weber 32/36, Cold air intake from the wheel well with K&N air filter, 1.65 roller rockers, pacemaker long tube headers and 2.5" single exhaust) I will get it again on the dyno to see the tq/hp gains
 

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clochard68

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First thing I did was getting the aluminum adaptor for the 32/36 weber. I took some CFK plates to make an insulator with heat shield, and CNC machined them with the spacer to get a new inner shape. The opening has the same cross section surface as both venturis of the carburetor together (can't remember the exact number right now). Then I matched the opening of the log head to the new adaptor.
The adapter also got a fitting for the PCV as I need the other original manifold vacuum for the distributor and power break.
The minimum wall thickness on the intake casting is now around a little more than 1/8 of an inch, I will put JB Weld on the outside to stiffen it after all the machining is done.

I have a radius on the bottom of the cutout, but I guess I will make it bigger. Next step will be to remove the plugs on the sides of the log intake and smoothen the short radius on the intakes of the cylinders 1, 6, 2 and 5. I hope I will get to the 2 and 5 radius with my tools... What radius should I try to achieve? The bigger the better?
 

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clochard68

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And one more thing, what is the best way to get an old stripped exhaust manifold bolt off?
 

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wakjob

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This is great info...

I was wondering if it would be worth knocking out those freeze plugs in the ends of the small LOG and giving it a line hone?

I don't know what the wall thickness is, so I don't know how much "meat" can be be removed or if it's even worth it.
 

chad

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i just mig a nut on the head of those studs. I usually don't need any penetrating fluid as the heat of the weld must loosen. Then I 'crack' it a bit in each direction B4 slowly backing it out, sometimes w/a back turn now'n then like U would w/a tap...
 

chad

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#4? I'd say volume ofa plenum is more important than 'smoothness'. Not alota automotive theory here (mine's a pretty big volume too but all I got in it is sawdust, not much brain goo) but think of roughness ofa air filter as what I mean...
 

bubba22349

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Sure is nice that you have the 98 grade fuel to use with that fuel you could go up to little over 10.0 to 1 CR if your quench height was in the .030 to .050 range. That's an excellent job on opening up the log intakes carb opening for tge 2V to 1V carb adapter, plus opening up the 2V to 1V carb adapter to match it, and fitting it to the head with the heat shield that's going to work very well certainly much better then adapters that are just bolted onto a logs stock small hole. Looks like you could maybe blend it a little more but I don't know what you have left for a gasket sealing surface. If you happen to have the ability to machine the log intake and adapter for an O Ring groove you cold probally open up log hole and adapter plate even some more. You mentioned that you have an 1/8 inch radius at the bottom carb hole leading into the log that is very good if you are able to get a little more radius like a 1/4 or 3/8 inch that will help the flow turn into the log lenght some more.

With rebuilding and modding the log head there are proven procedures that can increase the log and port flow which increases the power output. Such as a minimum of a good 3 angle valve job or better stil a Serdi radius type valve job, along with back cutting of the intakes and even putting a small angle or radius on the top outer edge of the exhaust valve helps flow into the exhaust port too. On porting the biggest bang for the buck is in opening up the valve bowls this is often done quickly with a bowl hog / a cutter tga opens up from the valve seat side down into the bowl and then hand blending the rest of the valve bowl from the size of the valve seats inserts down into the port and narrowing the valve guides to increase port flow. And since we can't reach that much further up into the intakes ports from the valve bowl side into the top of the intake and exhaust port roofs and sides and shaping around the bowl floor. Also be carful to not go very far modding of the short turn radius side of the port it's easy to hurt the port flow there if not carful. Then working into the port as far as you can reach through the valve bowls side but what you were able to do opening the log intake manafold out some is going to also help the flow. Port finish on intakes shouldn't be a really polished finish, the exhaust ports can be highly polished though as well as the combustion chambers. Flow testing has shown the areas of the port that give you the best flow increase for your work are in raising of the port roof (or the top) and then some for both sides of the port there isn't much of any improvement working on the port floor or bottom so just clean them up and try to match all the port sizes using templates or gauges. Some beginning head porters get the terminology wrong on the port roof and port floor when starting to do their porting. One important thing to remember is that the port roof and port floor is as the head would be installed on the engine as it sits in the car, but when your working on the head doing the porting the head is off the engine and up side down. If the log head was still assembled you could CC each exhaust port separately to see what you have before you start then re CC them to see the improvement and also how close they all match. Not much you can do on the intake other than get a total log and intakes CC measurement. If your are planing to replace your valves then a bigger 1 3/4 inch intake valve can help the engine to breathe better. If you can find a set of the 144 Six Intake valves they are 1.467 this size works very good to increase flow on exhausts ports (even if your staying with the stock 1.649 intakes valves) or you can go even bigger with a 1.50 exhaust valve if you can't find the 144 valves which helps a little more. It's a good idea to add the center exhaust port divider which helps with matching the flow center ports to the other 4 exhaust ports and also cuts out some the heat that would be transferring up into the carb bowl, full porting of the exhaust would help the flow too. Hope that's of some help your doing a great job on your 1968 log head and you should see some good improvement from it all. Edited
 

bubba22349

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That's a common problem on these Ford Log Heads of braking those end bolts off its best to really soak them good with penetrating oil before even trying to remove the bolts. At least on yours the bolt broke were there's still plenty of the bolt still sticking up. Yes X2 on methods that are used for removing a broken exhaust manifold bolt or any other broken bolt for tgat matter, I think this will help you get it out with out damaging or breaking off that small ear / tab on the head which is real easy to do when trying to remove an old broken off bolt. A couple months ago was working on my wife's pickup a 2006 Lincoln Mark LT is the same as the Ford F150's just more bling. It has a 5.4 3 valve engine and because of how the spark plugs are fitted they are notorious for being hard to remove the spark plugs sometimes they will even brake off. I tried the technique that Greg "FTF" over in the big Ford Six forum told me about on soaking the plugs with penetrating oil then turn the plug out just a little like a 1/16 turn then turn it back in again spray some more penetrating oil. I have to tell you that his trick worked like a charm along with this "Free All" penetrate I got from my local NAPA dealer the night before, and that penetrate really cleaned the carbon off the plug ends quickly and look at the single plug see how that penetrate oil traveled all the down to the bottom of the electrode plus cleaned off all the carbon from the plug ends. The carbon build up is what locks those spark plugs into the the ads and close tale range machined electrod port of the aluminum heads on these 5.4 engines. Also check out the picture of the three plugs these were all put in together in #1, #2, and #3, and only have about 15,000 to 20,000 miles on them maybe less but one was loose like #4 these plugs are real pricey and are suppose to be changed at 75,000 miles. You might be able to get that Free All online or check around in your area for good penetrating oils that creaps or traveials. I then would start spraying that broken bolt on both ends severial times a day for a few days to a week or more before you try to turn on it. X2 Chads suggestion of welding a nut on it that will also help get more purchase on the old bolt as well as heating it up to break the rust loose but I would still soak it good for awhile first. Best of luck
 

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bmbm40

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That Freeall looks like good stuff/ Can you get a large pipe wrench on that bolt? I have done that over the years but be careful not to snap the bolt off flush cause then you have drill it out.
 

B RON CO

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Hi, I wouldn't completely discount the old small log head. But yes, there is a lot of room for improvement. I think you are on the right track.
Did you CC the combustion chambers?
I don't remember hearing the 68 cams are set up at 4* retarded, but that should be better for high RPM. What are you going to use for valve springs?
I don't know why you would not get a high performance cam and degree it per specs.
My 200, with a Comp Cam (the milder one) with their springs and it pulls great to 4500 RPM and then seems to be flatten, like your graph, so that is my red line. I have a modified late model head with a Holley 350 and one of Bill's distributors.
98 octane is race fuel only around here.
I thought the newer distributor and carb were used on the 68s.
Good luck
 

clochard68

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One more question regarding the guides before I adress all the useful information I already got from all of you, thanks for that already!
I posted this question already in a thread called pocket porting, but that was in the "Big Block" forum, I guess it suits this forum better...

The small log head on my 68 already had some work done to the pockets. My guides and valves are worn, I will replace them both.
I bought steel guides (with plain and spiral inner surface). When I let the machine shop install them they will protrude into the pocket again. Should I grind them down again afterwards? Is it better to leave them in original length even if the reach into the bowl/pocket? When using shorter guides, is it better to shorten them before installing?
Would you go with the spiral (they have a plan part on the bottom) guides or with the fully plain guides?

I will blend the pocket into the hardened seat rings. I want to get max flow, but also longevity of the assembly, that's why I'm not sure if its a good idea to shorten the guides (although my 3.3 won't be making big numbers, I know) or leave them as the are. What would you guys suggest?

And has anybody experience with grinding down the smog bumps? Can I grind them flat? They are not drilled through, just cast in...
 

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clochard68

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A line hone would be interesting, I didn't think about that. When I pull the plugs I will take some pictures and will try to measure the wall thickness if its possible.

As for the bolt, I guess I will try welding a nut to it. I soaked it over several days a few times with PB Blaster, that helped me loosen some other stuck bolts on the exhaust manifold but this one is a little meaner. Will try the weld method, that sounds good!

As I mentioned, I stay with the stock valves (because I already have the hardened seats installed), will backcut the intake valves 30 degree and unshroud the intake valvles some more, especially where the spark plug sits... I want to take quite a bit of the spark plug bump away and smoothen it, or would that be a bad idea?
On the port divider I am not sure, I read it can cause a lot of trouble and the advantages are not really proven. As for now I don't plan on installing one.

I CC#d the chambers, I got an average of 51cc. And I degreed the cam when I put the dual roller timing chain on. I measured the 0.050 lift open/close and got basically the identical numbers that are listed in the picture attached (with the 4° retard).
I advanced it with the timing chain to 4° advance for more torque adn throttle response. I didn't change the stock cam as I said to myself for the small log head I'm not sure if a bigger cam will have so much benefit. I would definitely do it if I could get my hands on the alumnium head!
And the thing is I live in a big city, so the 200ci will see a lot of traffic and stop and go driving, therefore I am happy if I get as much low end torque as I can. As for the highway, I have a 2.79 gears in the rear end and cruising even in stock form now is sufficient for me. Or would you suggest that even with the small log a cam upgrade (with tight overlap) would be beneficial?

In the picture that is the only picture I have of the old distributor, maybe it is not a load-o-matic? Anyways, it will be changed to a HEI with gaped spark plugs soon ;)
 

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B RON CO

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Hi, that looks like the emissions vacuum can with advance outside and retard inside. Not LOM. Many guys remove the inner hose and plug the hose, not the can, and run ported vacuum to the outer nipple.
Check the carb for a SCV or ported vacuum port. I would rather use the Ford distributor then a giant aftermarket HEI.
I would definitely check out some aftermarket cams before putting it all together.
I am not a head expert but I would smooth the valve guides even with the head material.
Good luck
 

bubba22349

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On the guides its kind of a catch 22 deal, shorter guides will give you more flow however shorter guides won't last quite as long either, full lenght guides give more valve support against side loads. I think the replacement guides may also be a little bit longer than stock guides were but I haven't measured them in a quite awhile so you might check that out. If you were wanting to go with the shortened the guides don't have them drive the guides down as far into the valve pocket any farther than stock the excess can be cut off at the valve spring seat easier than trying to shorten or shape them in the valve pocket. With the shaft rocker arm assemblely that the 200's and other Ford small six engines have as well your going with the Yella Terella 1.65 roller rockers there shouldn't be as much side loading to the valve guides to cause any extra wear. The compromise position would be to use the full lenght valve guides or even longer than stock and then tapering them in the valve pocket so as to gain as much flow as possible that way. As to the spiral or plain the sprial might allow a little more oil in to lube the guides that can possibly help the longer lasting idea. Are you going to use a PC type valve guide seals?

Yes by all means on grinding out the exhaust port bumps I will always grind them out on any of the A.I.R. Heads and on some engines this can make quite a differance in port flow. As far as grinding around the spark plug I don't bother that area at all this could affect your swirl I only would polish the existing shape along with the rest of the chamber. With the stock size valves I don't see you needing to much unshouding the valves either. If you do unshoud the valves don't use the head gasket opening its 3.820 way to big the stock bore on a 200 is 3.680 thus would create a ledge that would cause turbulence. So scribe the blocks bore size around the heads combustion chamber and see what you have and for sure don't go out past that scribe line so the chamber isn’t any bigger then the bore size around the valves you are unshording, prorbally better is to keep most of the chamber smaller than the bore size, plus the more you grind on the chambers your add to your CC’s and loosing some of your compression.

You Distribitor is a 1968 duel advance with a duel vacuum advance canister these are the best of the older point distributors plus yours has a Protronix Ignitor so its not a bad set up if the center shaft bushings are still in good shape they can be rebuilt and recurved too. Best of luck
 

clochard68

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Hi, that looks like the emissions vacuum can with advance outside and retard inside. Not LOM. Many guys remove the inner hose and plug the hose, not the can, and run ported vacuum to the outer nipple.
Check the carb for a SCV or ported vacuum port. I would rather use the Ford distributor then a giant aftermarket HEI.
I would definitely check out some aftermarket cams before putting it all together.
I am not a head expert but I would smooth the valve guides even with the head material.
Good luck
The aftermarket camshafts I have seen will add hp at the top of the powerband, with wider lope center, higher overlap and more duration as well as more lift.

I am keeping the stock torque converter and street drivability is my main goal... from what I read in the falcon handbook the stock cam is the best for low end torque and economie. With the 1.65 rockers I increased lift and opening speed at least a little. What cam specs would you suggest?

On the guides its kind of a catch 22 deal, shorter guides will give you more flow however shorter guides won't last quite as long either, full lenght guides give more valve support against side loads. I think the replacement guides may also be a little bit longer than stock guides were but I haven't measured them in a quite awhile so you might check that out. If you were wanting to go with the shortened the guides don't have them drive the guides down as far into the valve pocket any farther than stock the excess can be cut off at the valve spring seat easier than trying to shorten or shape them in the valve pocket. With the shaft rocker arm assemblely that the 200's and other Ford small six engines have as well your going with the Yella Terella 1.65 roller rockers there shouldn't be as much side loading to the valve guides to cause any extra wear. The compromise position would be to use the full lenght valve guides or even longer than stock and then tapering them in the valve pocket so as to gain as much flow as possible that way. As to the spiral or plain the sprial might allow a little more oil in to lube the guides that can possibly help the longer lasting idea. Are you going to use a PC type valve guide seals?

Yes by all means on grinding out the exhaust port bumps I will always grind them out on any of the A.I.R. Heads and on some engines this can make quite a differance in port flow. As far as grinding around the spark plug I don't bother that area at all this could affect your swirl I only would polish the existing shape along with the rest of the chamber. With the stock size valves I don't see you needing to much unshouding the valves either. If you do unshoud the valves don't use the head gasket opening its 3.820 way to big the stock bore on a 200 is 3.680 thus would create a ledge that would cause turbulence. So scribe the blocks bore size around the heads combustion chamber and see what you have and for sure don't go out past that scribe line so the chamber isn’t any bigger then the bore size around the valves you are unshording, prorbally better is to keep most of the chamber smaller than the bore size, plus the more you grind on the chambers your add to your CC’s and loosing some of your compression.

You Distribitor is a 1968 duel advance with a duel vacuum advance canister these are the best of the older point distributors plus yours has a Protronix Ignitor so its not a bad set up if the center shaft bushings are still in good shape they can be rebuilt and recurved too. Best of luck
I am not planning to go crazy with the shrouding, just a little around the intake. But maybe I just stick with polishing it.

The hardest part will be to blend the seats into the chamber without ruining the seats, there is quite a ridge there. I guess I will try it carefully with stones.

After all your input I decided to use the spiral guides and will shorten the new guides to the length of the current guides and install them flat to the bowl floor as the old ones. (And I'll recheck the clearence to the retainer at max lift)
What I forgot to mention is that I bought dual springs and therefore also positive valve stem seals. I don't know how much oil is going to geht to the spiral inside the guide, but I guess it won't hurt either.
 
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wakjob

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From what I understand, Clay Smith is going to re-design their most popular selling cam for the 200cid.
264/264 110... There's an issue with it of some kind.

There' a couple of recent threads were members gave some currently available cam shafts they like.
 

clochard68

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From what I understand, Clay Smith is going to re-design their most popular selling cam for the 200cid.
264/264 110... There's an issue with it of some kind.

There' a couple of recent threads were members gave some currently available cam shafts they like.
Hello,

I do understand that there is a variety of different aftermarket cams available (and I seriously considered getting one). I didn't really mean to ask for a suggestions for a new cam, I rather wanted to clarify why I'm not going with an aftermarket cam (i.e. torque and economie, and I change the rocker ratio). Just to clarify that, I don't want to be rude or anything...

Regards
 

wsa111

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Do not get the Clay Smith cams regardless. Go with an Isky 262 Super cam & advance it 2 degrees, or call Jerry at Schneider cams & he is very familiar with our inline sixes.
What brand 1.65 rocker arms are you using?
 

bubba22349

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The aftermarket camshafts I have seen will add hp at the top of the powerband, with wider lope center, higher overlap and more duration as well as more lift.

I am keeping the stock torque converter and street drivability is my main goal... from what I read in the falcon handbook the stock cam is the best for low end torque and economie. With the 1.65 rockers I increased lift and opening speed at least a little. What cam specs would you suggest?


I am not planning to go crazy with the shrouding, just a little around the intake. But maybe I just stick with polishing it.

The hardest part will be to blend the seats into the chamber without ruining the seats, there is quite a ridge there. I guess I will try it carefully with stones.

After all your input I decided to use the spiral guides and will shorten the new guides to the length of the current guides and install them flat to the bowl floor as the old ones. (And I'll recheck the clearence to the retainer at max lift)
What I forgot to mention is that I bought dual springs and therefore also positive valve stem seals. I don't know how much oil is going to geht to the spiral inside the guide, but I guess it won't hurt either.

Yes that was the reason I asked about the type valve seals your going to use. Great with those PC type valve seals they are going to reduce the amount of oil going down the guides compared to stock Ford umbrella seals and that's a good thing. So it might not mater as much which guide is used, in any case the engine vacuum is still going to pull some oil down the guides, I think you will be fine with the spiral guides, in the old days when I was starting out I often used to Knurl the loose stock valve guides to tighten them back up this process also allowed a bit more oil around the valve stems kind of like a spiral guide even more so, but not as much valve stem support as a new guide did, the knurling process was a very low cost fix and lasted for awhile. When your setting up your valve guides be sure to measure your installed valve spring heights and the valve guide height with the PC seal installed to check that you have a clearance margin of .060 or more at the bottom of the valve spring retainer to valve guide seal at full valve lift. You will also need to check that you have at least .060 or more clearance at full lift before coil bind / stack at full valve lift. Sounds like you got a really good plain going forward, will be looking forward to seeing from test results after all your hard work. Best of luck
 
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