boring out the log manifold ?????????

B

BCOWANWHEELS

Well-known member
I have a 1970 large log head and I was wondering if anybody has run a boring bar through the log to both smooth it out inside and to increase the I.D. to further increase flow all going in with complete port and polish of the chambers.
bob
 
Not much there , it is not round, there is a large flat side where the exhaust manifold mounts . It can be cleaned up with a long burr . That is why I Like tri power , full size carb bore at 2 and 5 favoring 1 and 6 ,it takes out any demands of the log.
 
I pick up my 69 250 head tomorrow from the welder, we media blasted it had a section of the log between 2 and 3 and 4 and 5 taken out.and then welded up. Also had the port divider welded in. We fabricated a 2 inch square log welded on top of the existing 3 - 2 cylinder ports. I will be mounting a Holley 500 cfm 2 barrel E-85 carb on top, turbo charged strictly for drag racing. The goal is to equalize flow to each cylinder and increase intake volume. My new intake log is good for 26 pounds of boost although I plan to run a max. of 18. This was not cheap to do but reasonable. All the porting and polishing I am doing on the bench, Valve size is being increased to 1.84 on the intake and 1.5 on the exhaust. Looking for good results and some sweet horsepower.
 
It's probably hardly worth the effort.
Little things won't make themselves apparent at much less than WOT.
I have read here that the roughness of the log helps atomize the A/F mix but since you're boosting and building a race engine that might not matter at all.
 
"...I have a 1970 large log head..."
might be a misprint there as '77 plus - was a larger log,
(D7xx and on castings I believe).
 
chad, what are you saying I do not under stand . 69-70 is not a bad head .It has the largest runners of all of the heads and a larger log. Later heads have larger valves and smaller runners ,last heads have the larger valves smaller runners and the largest log that is called large HEX head. They all flow better than the pre 69 dog logs.
 
BCOWANWHEELS":c4219sqy said:
I have a 1970 large log head and I was wondering if anybody has run a boring bar through the log to both smooth it out inside and to increase the I.D. to further increase flow all going in with complete port and polish of the chambers.
bob
Click to expand...

:unsure: Haven't heard of that being done with a boring bar, but have heard of some of them being drilled out. If it's not too costly to set up then it might be worth a try. Good luck :nod:
 
I thought it was close to round inside. anyway I got my scott drake exhaust port divider today and its a real nice cast piece. the pictures all over the web don't do it justice. I ordered my steel 1/2" x 3" x 4" pieces cr 1018 to make my ford 94 carb flanges today and my center carb block off plate too. gonna get them cnc cut out before getting them furnace brazed on and manifold log machined to except them.
 
will the 1.84 / 1.5 valves fit in the the chambers. I was going 1.75 and 1.5 with hard valve seats. si has the 1.5,s but told me all they had was 1.84 int as c/IL VALVES WAS ALL DELIVERED AS 1.84 INT AND WAS CUT DONT TO CUST SPEC,S. ???????? AT C/IL PLACE.
 
BCOWANWHEELS":1wbzzo3n said:
will the 1.84 / 1.5 valves fit in the the chambers. I was going 1.75 and 1.5 with hard valve seats. si has the 1.5,s but told me all they had was 1.84 int as c/IL VALVES WAS ALL DELIVERED AS 1.84 INT AND WAS CUT DONT TO CUST SPEC,S. ???????? AT C/IL PLACE.
Click to expand...

:unsure: You probably are able to fit that big of intake if you want. :shock: I don't really think you will need the hard seats though, Ford heads of that era all ready had a type of hardened seats. Personally I never had trouble with the stock seats though I did have some trouble with the stock cast guides when they finally took all the lead out the fuel in Ca. Good luck :nod: Edited
 
I intended to remove the core plugs on my log head, when I performed the direct mount 2 barrel machine work. Do some clean up on the inside


After the machine work on the adapter for 2 barrel. I decided not to work on the interior of the log. Seemed like too much work at the time. LOL

Also thought about the 3 carb setup on another head. That came down to a cash decision , the lack of xtra cash
 
Yes the 1.84 will fit, 1.88 max. I do not need hardened seats as I will be running E-85. SI was very specific about the 1.84 valves , I just received them 2 weeks ago. All my modification to the log and welding is done, looks good, now to finish the porting and then polish. Lots of work, I have nearly 40 hours in the head so far, but it will be worth it. If I can figure it out I will put a pic of the head.
 
FWIW, my machine guy was originally going to do seats but changed his mind after he saw the head.
 
humm,
'77 - 82 = hex log
'83= octogon log
all others = 'small log'?
 
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