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Offline waldo786

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possible to mill heads?
« on: June 08, 2014, 02:15:58 PM »
I was wondering if it is possible to mill the 2.3L heads at all to up compression a bit say 9 to 9.5.  I know the cam belt can be tensioned, so milling off just a tad should be feasible, correct?

Offline tbucketjack

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Re: possible to mill heads?
« Reply #1 on: June 08, 2014, 03:55:46 PM »
I imagine its possible. It would depend how much, and possibly valve reliefs enlarged in the tops of the pistons.

Offline 72pair

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Re: possible to mill heads?
« Reply #2 on: June 08, 2014, 04:04:18 PM »
Sure. I've seen them milled all the way to the lower intake bolt holes. I think it would take probably a 0.030" mill to gain a point of compression. You really need an adjustable cam sprocket when milling the head to correct cam timing.
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Offline Wittsend

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Re: possible to mill heads?
« Reply #3 on: June 08, 2014, 06:04:49 PM »
Yes, it is possible. And, yes, the tensioner will take up the slack. But, that will not compensate for the timing difference caused by the belt having to rotate further (essentially to "give" the slack taken up on the other side).

 As 72 Pair mentioned you will need and adjustable can sprocket to compensate.  Sometimes there are offset keys available. But you need to buy the correct offset. And generally they aren't cheap. So, ideally the cam sprocket being adjustable is a better idea.  Besides if you are looking at increasing power with the head milling, you probably want to try adjusting the cam timing too (not just for factory spec correction).

I would ask around and see if the compression increase provides and value, or just causes a problem.

Offline waldo786

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Re: possible to mill heads?
« Reply #4 on: June 08, 2014, 09:58:44 PM »
Hmm...now you've raised another question for me.  I have a ranger roller cam I am going to install in the car, how would that affect the cam timing and doe sit mean I need an adjustable cam gear?  I've seen others say good things about the adjustable cam gear on here.  I found this one in a quick search http://www.speedwaymotors.com/23-Ford-Adjustable-Cam-Timing-Sprocket,6570.html.  If I need one for the different cam, I might as well get the heads milled and get a little more compression out of it.

Offline amc49

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Re: possible to mill heads?
« Reply #5 on: June 08, 2014, 10:14:54 PM »
Most likely closer to .060" to get a full point......... ..............

Offline 65ShelbyClone

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Re: possible to mill heads?
« Reply #6 on: June 08, 2014, 10:17:08 PM »
The Ranger roller doesn't need an adjustable sprocket.

Milling the head will retard the cam timing which moves the power curve higher in the rev range. Rule of thumb is 100-150rpm per degree which may be desirable with the Ranger rolling being a truck cam.

The amount of timing shift depends on the cam sprocket circumference and how much is milled off. I did a really dirty measurement of my cam sprocket (still behind a timing cover) at 4.5" diameter = 14.1" circ = 0.039" per degree. That means the cam timing retards by roughly 1 for every 0.039" taken off the head.
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Offline Wittsend

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Re: possible to mill heads?
« Reply #7 on: June 09, 2014, 12:19:16 PM »
Not to discount the importance of cam timing..., but has anyone ever pulled a timing cover on a typical OHV V-8?  The chain slack and gear wear has probably retarded the timing at least 5+ degrees.    And, so, what if you dial it in just right?  Where is the timing shortly there after?  And, going back to the loose chain. As the engine revs does the inertia in the chain take over and advance the cam.  Logically when you consider the momentum in the valve train (especially near valve float) the load on the chain actually decreases while its inertia increases.  Maybe we had variable valve timing and never knew it!  Although in theory it is working against an advantage preferring advance at low RPM and retard at high RPMs.

Years ago when I was into Datsun's they had a pin in the cam and three holes in the sprocket. I'd move the timing around and never noticed a difference one way or the other.  With a stock type cam it seems to matter little a degree - or two.  I know..., Pinto's have belts.  Just thinking, that's all.

Offline 74 PintoWagon

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Re: possible to mill heads?
« Reply #8 on: June 09, 2014, 07:25:17 PM »
Not sure about factory cams, but aftermarket cams have 5* built into them to compensate for chain stretch..
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Offline amc49

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Re: possible to mill heads?
« Reply #9 on: June 10, 2014, 12:23:58 AM »
I do not agree with inertia pulling the cam back advanced at all. Inertia does not overcome the valve frictional forces and why engines with variable cam timing have assist springs to pull the cam timing back from retard conditions as vs. no assist when retarding to begin with. If the inertia advances then the spring is unnecessary. The spring helps overcome the valve frictional forces. End effect is what you see with a motor mounted on a spintron or strobe unit timed to watch sprockets, the timing moves around both advance AND retard, it does not stay constant one way or the other. Why high output drag engines go to belt drives to dampen that out. If you pay attention to enough engines at rev and with wear, it becomes obvious the chains retard and stay that way even at full revs. You lose too much bottom end that shows back up when you replace chain. The old Boss 302 my friend and I had did it regular as clockwork, we put 3-4 chains in it. Also showed up on the Honda CBF bikes I drove, they laid down and died on bottom end when chain slacks and that chain as heavy as a car one, it showed pretty quick. 1/4 mile times slowed, and new chain they got faster even though with new chain you could short shift to better use the bottom end, with stretched chain you had to buzz it more to even get near the quicker times. The engines were actually cammed at around 100-105 LCs, when the chains stretch to 108 you were p-ssing in the wind, the engines dropped lots of power. Still seemed to rev fine up high but dead down lower and mid. The engines were peculiar because the 'new' trick 4 valve head didn't breathe at high rpm because valve package was too small. They would always rev to 10000 rpm but the midrange was what you shot for with cam timing, if retarded they still revved high easily but simply blew up while not making as much power. How most ended up in the yards with rods sticking out of side of motor, everybody though 'bike motor, high rpm' but no, they did NOT like it.

And, there is no standard at all that says aftermarket cams are ground with 5 degrees built into them. Some may but not all. The numbers are to be taken as the numbers and set up with retard in mind yourself. Doing otherwise would beg the question, 5 degrees in relation to WHAT?, the last thing someone dialing a cam exactly in needs. The numbers on cam cards are what you shoot for and build in any retard space yourself. There is no way they can control what sprocket you use and it could be off so better to just give straight up numbers to avoid customer confusion. In fact, I'll pose the question myself, or, 5 degrees in relation to WHAT? You begin to see the problem....... ........

Offline Wittsend

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Re: possible to mill heads?
« Reply #10 on: June 10, 2014, 10:48:51 PM »
Just for the record I was only posing the inertia driven "variable" timing as an untested possibility. I'd think one could pull the vacuum advance, and the mechanical springs. That way the ignition advance would basically "lock" at full advance in short order.  Then you could see with a timing light what the cam is doing in relationship to a loose chain at RPM's. If (being a big IF) the timing advanced at higher RPM there could be some credence to the concept.  Anyone have a well worn V-8 they are willing to put at risk?  :-)

The concept of the aftermarket advance might have come from the concept that the manufactures retarded cams to deal with emissions. Both might be urban legends.  But, like you said the cam should be set up as designed. Only ever did it once. It was kind of fun seeing how close the cam (PAW Automotive knock off of the Edelbrock) was to specs.  As I recall lift was up .005 and duration 2 degrees longer than stated. I had no complaints. With a +/- 2 degree crank sprocket I opted for +1 rather than -1 (anticipating chain stretch). Spent more time on 318 swirl port heads than I should have, but the car has strong mid-range.

Offline amc49

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Re: possible to mill heads?
« Reply #11 on: June 10, 2014, 11:50:53 PM »
Actually, if there is no rubber damping of the full advance limit hit then it scatters spark, the advance weights hit solid metal to metal, bounce off in slight retard and then do it again and again. No springs on weights would make it horrible, they dampen it out some. Spark scatter, just like when chain transfers chordal chain motion jerkiness (no plate type metal timing chain on earth transfers dead accurate timing, they speed up and slow down on every link) to the cam and the cam itself winds up and the unwinds to make spark go everywhere. Motorcycles which can spin much higher often are rubber damped at full advance. My Honda fours were. And roller cams are made with no relief in between lobes to stiffen them to stop windup/unwind. All that stuff drives you crazy when running say a high rpm V-8 at 9000+ rpm. Lotta guys go to crank trigger to get away from all the unwonted monkey motion going on there. Then you use adjustable electronic advance curve. Hooray for MSD........... ....

At least some OEMs for a while did retard cams to lower NOx, the easiest thing to do quick until they could engineer better solutions. I used to drop ignition timing back to TDC or slightly ATDC to pass NOx tailpipe testing on my old AMC Concord. Then bring timing back up as soon as passed. Car was dead like that but the emissions dropped doing so. That and using highest vacuum idle and then kill that by 100-200 rpm lean and worked great on idle HC as well. Car would actually run cleaner in emissions than my MPFI Tempo did. Surprised the tester doing it, he wanted to know what I did to it.

Get to close measuring like lifts on all lobes and you can get an idea of who makes crap cams, some of those numbers vary a bit, no way are all lobes the same. Good part will be pretty close. And yes you even find the cam cards do not totally agree with what you find degreeing them in, they make slight changes in parts batches sometimes.

Offline waldo786

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Re: possible to mill heads?
« Reply #12 on: June 11, 2014, 09:50:45 PM »
Interesting information so thank you!  Newbie question here - do you still need a tensioner if you are using an adjustable cam gear?

Offline 74 PintoWagon

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Re: possible to mill heads?
« Reply #13 on: June 11, 2014, 10:10:07 PM »
Yes, the tensioner keeps the belt tight..
Art
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Offline Wittsend

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Re: possible to mill heads?
« Reply #14 on: June 12, 2014, 12:10:45 AM »
As 74PW stated, Yes, you still need the tensioner.  The "adjustable" part about the cam sprocket is that it is loosened, then rotated a few degrees around the centerline of the camshaft and then re-tightened.  The cam and crank sprockets never move any distance closer or further away from each other.  But, because the belts/sprockets have teeth the rotary relationship can be altered causing the valves to open earlier or later than originally designed.

Offline 65ShelbyClone

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Re: possible to mill heads?
« Reply #15 on: June 12, 2014, 12:46:00 AM »
That means the cam timing retards by roughly 1 for every 0.039" taken off the head.

Correction, that's 1 of cam rotation, which is actually 2 of timing at the crank where all valvetrain and spark events are referenced.
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Offline amc49

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Re: possible to mill heads?
« Reply #16 on: June 12, 2014, 11:02:35 PM »
Another correction, Racer Walsh states that .040" milled off a 2.3 head gets around one full point bump-up in compression when running the heart shaped chamber. The .060" number I gave is for the 2.0 EAO motor.

Offline waldo786

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Re: possible to mill heads?
« Reply #17 on: June 15, 2014, 11:37:13 AM »
Awesome, thank you good information.  Still deciding on milling the heads, but I feel like it may not be a bad idea to have that adjustability. 

Offline jeremysdad

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Re: possible to mill heads?
« Reply #18 on: July 22, 2014, 03:48:02 AM »
Whoa!!! If you haven't noticed, a timing belt tensioner usually isn't automatic. There should be no slack, because there should be no slippage. It's not an alternator...y ou can't get an extra 30k miles out of a stretched timing belt by tensioning it harder...that throws everything off, and the motor will run funny. lol :)

If mill more than 10 thou, then yes adjustable cam gear. If you do both, then you'll have to either be good at instructions, or pay someone that is. Yet another reason my head is coming off...again. First is why not bigger cam? lol

Offline waldo786

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Re: possible to mill heads?
« Reply #19 on: July 24, 2014, 12:43:22 PM »
Well, I do plan on paying a shop to dial it all in.  I did get the adjustable cam gear and I have the ranger roller, so I do have a little bigger cam.  Or one of these from Crane.  Not sure how the first one would compare to the ranger cam http://www.cranecams.com/188-189.pdf

Offline 65ShelbyClone

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Re: possible to mill heads?
« Reply #20 on: July 24, 2014, 04:19:49 PM »
A Ranger roller profile is not an upgrade over a stock slider cam. It usually moves power slightly downward compared to a stock turbo cam. The Crane 199541 is akin to the "RV cams" of years past. The 501 and 511 grinds are more of what I would be looking at, but $440 is way too much for an off-the-shelf cam IMO.
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Offline waldo786

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Re: possible to mill heads?
« Reply #21 on: July 25, 2014, 12:14:52 PM »
I agree about the price tag - way too much, that's why I got the ranger roller.  Could also get a comp cams flat tappet, although I really wanted to go roller: http://www.compperformancegroupstores.com/store/merchant.mvc?Screen=PROD&Store_Code=CC&Product_Code=70-119-6&Category_Code=70-CAM  Again, more for low and mid range power, which is  where I will use it.  I just want it to run good and have a LITTLE pep to it. 

Offline 65ShelbyClone

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Re: possible to mill heads?
« Reply #22 on: July 25, 2014, 01:36:14 PM »
If you're not adverse to spending the money on a cam gear anyway, then I would get that first and play with the timing on the Ranger cam before buying a whole valve train setup. I say "whole" setup because lumpier cams often need better springs than stock, especially if the stock springs have some mileage on them.

Modifying cars is a slippery slope. One thing leads to another and another and another. ;)
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Offline waldo786

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Re: possible to mill heads?
« Reply #23 on: July 25, 2014, 11:31:45 PM »
You can say that again, I know how it goes!  I've already gotten new springs, valves, retainers and valve seals for the build, so I've already started.  I got an adjustable cam gear too - shout out to Esslinger racing (they were the only ones that seemed to have any of it in stock).  I have a ranger header, so now I'm considering a new 2" exhaust too, which will mean I'd need a new muffler and catalytic converter too.  Geesh, I gotta stop this!

Offline 74 PintoWagon

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Re: possible to mill heads?
« Reply #24 on: July 26, 2014, 07:56:36 AM »
It never ends.. ;D
Art
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