Large log upgrades

Recently had the motor rebuilt and bored 30 over. Also happily gained possession of a large log head. What mods should I have done to the head for a street car? I have a weber 32/36 with a generic adapter so I plan on converting the head to accept the carb without the adapter. Also I read to have the head milled to keep compression. Anything else worth doing? I read about large valves but is there a specific size? New cam?

Thanks

Before you go any further get the Falcon Six Performance book. The co-author, David, posts on this site. You can get the book directly from him at http://www.falcon6handbook.com/

I would defiantly get this book. Also headers, Dizzy II, bigger cam will help.

I have headers and DUI, was looking for specific upgrades to the head itself. I'll order the handbook this evening.

There is a list of upgrades for the whole motor, from least to most expensive. They also go into porting and polishing the head and doing something about the compression ratio. There is more stuff in there than you can imagine, and the $20 or so you spend will more than pay for itself in wasted time saved.

Mill to get a C/r of 9-9.5, valve seals, polish the chambers.

I would port the valve pockets.
3-angle valve job.
You can go to 1.75/1.5 valves but that would require slight unshrouding around the valve.

Port divider if you feel so inclined. This head has the exhaust ported but I don't think I would go to that expense again.

I'm currently going through this exact same excersize myself. I'm going to go with an Autolite/Motorcraft 2100/2150 2bbl, 1.75" intake/1.50" exhaust, hardened seats, new valve guides, new springs, and doing a port polish job.

On the porting effort, I cleaned up the combustion chambers. I'll be doing a polish job on them shortly with the Dremel. When I was done with the rough cleanup, I cc'd the chambers and I'm sitting at 61 cc. I'm going to have the head milled 0.070" which should net me in the 9.3:1-9.5:1 range, if I did my figurin right.

I matched the exhaust ports to the gasket, leaving them just slightly proud on the head (still have stock exhaust manifold). Right now I'm polishing the ports then will start in on cleaning-up/polishing the exhaust pockets. On the intake side, I'm just going to roughly clean up the casting flash and shape the valve guide bosses. I'm not going to bother trying to do much of anything to the log as that seems like a significant amount of work for marginal improvement. If I can't reach it from the combustion chamber, it won't get touched.

I got a quote from a shop here in town for all the machine work. They came back with something like $600 to hot tank, magnaflux, install new guides, complete valve job and cut for oversize valves, mill off 1 bbl boss, and 0.070" milled.

The FalconSixPerformance manual helps think through a reasonable build schedule. Head and other work can start with measuring current 'CC.s of compression chambers of head used. Confidence in projected CR - static and dynamic depend on reasonable figures for the cam selection and machine work. Drivability upgrades for modern times, , cruise and show or real hot rod six money, planning the basic engine work can optimize your goal.

I got a quote from a shop here in town for all the machine work. They came back with something like $600 to hot tank, magnaflux, install new guides, complete valve job and cut for oversize valves, mill off 1 bbl boss, and 0.070" milled.

Click to expand...

sounds like a plan' , the .070 cut will raise the compression ratio to figure.

My '63 wagon 170/5200/T5 gets @ 25 MPG but the worked D7 head running close to 10:1 SCR (48cc CC's and metal shim gasket) uses 93 octane minimum... , the '61 runs race gas at the track with 274 cam / 500cfm+ 2Bbl / blueprinted HiPo 250 (bored to 258) ,will shift @ 5000 RPM.

have fun

v . .

.. machinist asked NOT to cut D6 250 head with OEM 62cc chambers at all for needed low compression project:

da66stang":3bpye33e said:

What mods should I have done to the head for a street car?
Thanks

Click to expand...

B4 offering anything I would state that it all depends on application. In all matters involving systems it's important to gather facts first. One modification to one part of the system effects all other parts of the system (some more, some less than others). What do you seek in final use? I am of limited income and automotive customising has taught me more about planning and final application than all the other systems I work with...

chad":1ynb6umf said:

da66stang":1ynb6umf said:

What mods should I have done to the head for a street car?
Thanks

Click to expand...

What do you seek in final use?

Click to expand...

Basically I am looking just to add a bit of pep to the car. I don't drive fast and this car will be used only for pleasure trips.

It's a 66 mustang and here is the current list of mods. Bored 30 over, Headers, Dual 2in exhaust with thrush mufflers, DUI, Weber 32/36 and a T5. The car is still currently being put back together and I haven't driven it with this setup yet.

I was trying to plan out the head build so I can have it finished over the winter and have installed this spring. I am in no real rush.

Howdy DA:

On the head, in my opinion, for your use, I'd stick with stock valves. What is the casting code on your late head? In addition to milling to attain desired CR, I'd recommend back cutting the stock intake valves along with the performance valve job. Polishing the chambers and pocket porting is also worth the time and effort on a street cruiser engine. With a stock cam, shim the valve springs .030".

On the cam upgrade any thing more than .400" lift and 260 duration is overkill. A double row timing set is worthwhile.

For what its worth.

Adios, David

Casting number is d5de-8090-ba.

Everyone woke up with the right question haha

powerband":ib0qs1vf said:

The FalconSixPerformance manual helps think through a reasonable build schedule. Head and other work can start with measuring current 'CC.s of compression chambers of head used. Confidence in projected CR - static and dynamic depend on reasonable figures for the cam selection and machine work. Drivability upgrades for modern times, , cruise and show or real hot rod six money, planning the basic engine work can optimize your goal.

I got a quote from a shop here in town for all the machine work. They came back with something like $600 to hot tank, magnaflux, install new guides, complete valve job and cut for oversize valves, mill off 1 bbl boss, and 0.070" milled.

Click to expand...

sounds like a plan' , the .070 cut will raise the compression ratio to figure.

My '63 wagon 170/5200/T5 gets @ 25 MPG but the worked D7 head running close to 10:1 SCR (48cc CC's and metal shim gasket) uses 93 octane minimum... , the '61 runs race gas at the track with 274 cam / 500cfm+ 2Bbl / blueprinted HiPo 250 (bored to 258) ,will shift @ 5000 RPM.

have fun



v . .

.. machinist asked NOT to cut D6 250 head with OEM 62cc chambers at all for needed low compression project:

Click to expand...

That looks like a 170 head. What size are the chambers now??

OP, outside of some radical log cutting project you're left with larger valves, 1.44-1.5/1.75, basic porting, 2 barrel mod... I'm also going thru this currently. Had a D7 head that I had dipped and it turned out to have a couple cracks at the siamese exhaust valve ports so I'm back on my C9 head. The C9 casting looks much better anyway. My advise to you is to look at the cam you have, if you're keeping it and go from there. Carefully measure and then calculate your DCR based on your cam. Then you will know how much to mill the head and exactly where you are when you bolt it back together. I'm going with 144 intakes for exhausts, no hardened seats and some porting. Erson 280 cam, 1000-4500 short gears and overdrive, 7.5-7.7 dcr and 9.5-9.7 SCR depending on how much chamber I lose in the clean up and what gasket I use.

Some picks of the cracked head Had 4 hrs in it when I noticed the cracks. Machinist hadn't gotten to magnafluxing and I took it anyway in a rush....

Howdy Back D and All:

With the D5xx casting first thing is to check the size of the intake valves. This casting era will likely have 1.69" intake and 1.38" exhaust valves and an intake tract volume of approximately 1,240 ccs. This casting is very similar to your '66 head with two exceptions. The chamber volume increased from 52 ccs to 62 ccs, and the intake tract, (volume from the log to the valves) increased by 140 ccs. Personally, I would not invest too much time and money in this casting. The D7xx casting offer larger intake valves @ 1.75", induction hardened seats and 1,345 ccs intake tract volume. The EOxx castings have 1,420 ccs intake tract volume.

If the D5xx casting was my only choice I'd could live with it, but I'd limit myself to getting the most out of what it is. By that I mean NOT going to the expense of larger 1.75" intake valves and 1.5" exhaust valves. I'd limit porting to pocket porting and cleaning up the combustion chambers. I would invest in a performance valve job of, at least three angles, and a back cut on the intake valves. The good news is you won't have to mill this head too much to achieve your goal CR.

More questions; What is your CR goal? what octane gas do you plan to run? Have you given any thought to what cam upgrade?

FYI- Econoline mentioned DCR and SCR. These are Dynamic Compression Ratio and Static Compression Ratio. The SCR is the one to start with. It is determined by comparing the complete cylinder and chamber volume to just the combustion area. This is what car manufactures advertise as 8:1 for the 1975 model year. The DCR takes into account the cam timing of valve openings. A longer duration cam drains off cylinder pressure more so than a stock cam. Higher cylinder pressure = more heat, higher vacuum and more torque.

It's likely that your head is spinning from too much information. Mine is. My advice at this point is to take your own advice.
"I was trying to plan out the head build so I can have it finished over the winter and have installed this spring. I am in no real rush."
Take the time to enjoy the trip. And keep you thoughts and questions coming.

ps- nice work Econoline.

Adios, David

for Econoline et al '

That looks like a 170 head. What size are the chambers now??.

Keen observation! , the filled valve area give it away?. I think the uncut DODE (Maverick170) head measured 58cc' chambers. .

.. the pics' is from confirming combustion chambers volumes' for suitable head for low CR (@ 8:1 SCR) 250 project. Found D6DE uncut 250 head measured @ 62cc chambers.


have fun

Econoline from your pictures it looks like it would only take a couple of exhaust seats and maybe some pinning to repair that head for use again! The original head on my 250 very low mileage 77 Maverick (is also a D7) but its in much worse condition.

It's hard to see in those two pictures, but the cracks extend above and below the seats into the cast. Probably could be fixed like you say but I'd rather just put my energy and $ into a better head. The casting quality on that D7 is really poor. My plan is to use the original C9 head( which has cleaned up real nice in the tank, just got it back), do some mild porting, use the intake valves from the D7 and some NOS 144 intakes for exhaust, install the original rbs carb and get her running. Then look for another head to work on for all the better mods, Si valves, 2 barrel ect.

That is the only problem with iron heads is the limit of any crack repair.
That's whats nice with an aluminum head is the ability to repair them.
Jackfish that's some nice exhaust port work.
Econoline your work in the bowl area is real nice.
On my head i had a local shop with a Serta enlarge the chamber around the intake valve.
Even with my 262 Isky camshaft performance is better that i expected.
I really need to get it to the track to see what the trap speed is so i can calculate the real HP.
On a chassis dyno with my C-4 trans it put out 139 rear wheel HP. That is close to a 289 with a 2bbl carb.