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#26 (permalink) | |
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Project 1450 supporter...
Join Date: Mar 2002
Location: Pleasant Valley, CT
Posts: 7,452
Real Name: Bob Legere
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#27 (permalink) |
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Senior Contributor
Join Date: Oct 2002
Location: Kent Lakes, NY
Posts: 1,969
Real Name: Jeff
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Bob,
When ever you get around to posting a suggested cam profile for what has been posted previously I would be very interested. Take a look at my last post. Thanks
__________________
Jeff '73 GT,5spd,Recaro,EDIS4 2.2 EFI by MegaSquirt, Ali Flywheel w/S10 Clutch, Electric Fan, Roller Rockers, Venolia Pistons, 6 Cyl Intake w/ Custom Injection, 15" Wheels,Lecarra,F&R Sway Bars,Custom Exhaust,1" Sport Spring,Koni Reds,Big Brakes,3 Core Ali Radiator,Hse of Colors Kandy Pagan Gold. 123 WHP @ 6800 RPM ![]() '64 VW Karmann Ghia '08 BMW M3 |
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#28 (permalink) | |
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Project 1450 supporter...
Join Date: Mar 2002
Location: Pleasant Valley, CT
Posts: 7,452
Real Name: Bob Legere
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#29 (permalink) |
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1970-GT
Join Date: Sep 2005
Location: Clearwater, Florida
Posts: 1,237
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I am also in the process of building a big valve 1.9 head like Bob recommends above. I will port as close to what his pictures show as I can. My porting skills are not as good as Bob's, so I cheated and used my milling machine to do the port openings! Clamped the head in my 6" vise and used a 1/2 dia. ball mill and went in about 3/16" deep to give me a straight and square opening. This is easy for me, just don't turn the handle the wrong way!
The rest will have to be done by hand, I'll just go slow. Got most of my parts together. Got a cam blank from OGTS today and will take it to Cam Techniques for final grinding, there shop is a 1/2 hour south of me, so I will check the place out. He seems like a nice guy, and has worked with Bob when they were up north. So he knows Opels and he is willing to make one custom cam!!!! I will have him grind the cam with 3-4 degrees of advance, so I don't have to modify the cam gear! I will get information and pictures at Cam Techniques, I have never seen a cam grinder before, should be educational. Will also ask about a roller cam. Thanks again Bob for taking the time to post all this information! Lyle |
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#30 (permalink) |
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former opel racer
Join Date: Nov 2002
Location: near some glaciers
Posts: 2,863
Real Name: Jeff "Oh-Oh" Denton
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Hey that's cheating.
Oh, speaking of which, does anybody know anything about acid porting, you know, to hide the tool marks you just milled into your port openings? I'm just curious, you know. Not that I would ever try acid. Crown Royal is about the hardest stuff I do, and not very often, unfortunately... But, what kind of acid? I once heard it is muriatic, is this correct? And how would a tinkerer apply it to an intake port passageway? Lyle, do these guys regrind a new profile into a used cam? I kind of need to get something started in this department, Bob has a special circle track recipe I want to try. Gotta go. I think I hear my mommy calling me.
__________________
No Opels were harmed in the filming of this movie. However two Mustangs, a Pinto, and a Capri were hospitalized. One Mustang was euthanized the next morning. |
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#31 (permalink) | |
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Project 1450 supporter...
Join Date: Mar 2002
Location: Pleasant Valley, CT
Posts: 7,452
Real Name: Bob Legere
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We didn't use the acid to hide tool marks, but rather to enlarge the runners on intake ports. A piece of 1/2" polypropylene plastic was bolted to the intake face of the head to seal it, and a silicone plug inserted into the valve guide. The head was tilted so the valve seat was level, and acid was poured into the intake runner until just below the valve seat. Then you wait..... In all, we let it sit overnight, drained it, refilled with 'fresh' acid, and then did that again two more times to get the results desired. Effectiveness apparently depends on the temp of the acid (we should have heated the head on a surface place in retrospect), and the acid concentration (I have no idea how strong his acid solution was.). So it was three days in this case, but you just fill it up and go home for the night, then drain and measure the ports in the morning. No waiting around really. IIRC, we removed almost 1/8" from the intake ports of a 'stock' class 305 Chevy head! But you didn't hear that from me..... |
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#32 (permalink) |
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former opel racer
Join Date: Nov 2002
Location: near some glaciers
Posts: 2,863
Real Name: Jeff "Oh-Oh" Denton
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Thanks Bob, that sounds interesting. I just did a google search for hydrochloric acid, found a very informative site that says it is also commonly called muriatic acid, gives one popular use as "metal pickling".
I think a beginner would want to go easy on this stuff, huh?
__________________
No Opels were harmed in the filming of this movie. However two Mustangs, a Pinto, and a Capri were hospitalized. One Mustang was euthanized the next morning. |
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#33 (permalink) |
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2200 Post Club
Join Date: Jan 2003
Location: Chapel Hill, TN
Posts: 2,267
Real Name: Harold Collins
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I believe muriatic acid is a weaker form of hydrochloric acid. Muriatic acid can probably be picked up at your local hardware store. It is commonly used to prepare concrete for painting or can be used to speed up the patina that copper takes on with age. As a lifeguard, many years ago, we used it to eat the concrete away from the agregate to make the pool deck less slick.
HTH, Harold |
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#34 (permalink) |
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No Access
Join Date: Nov 2003
Location: in transit
Posts: 3,873
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There's another product out there that does real well. caustic soda and usually comes in beads you mix with water. At 75% strength it will take all the edges off car keys in under 5 minutes. Not that while working around a 500 gallon tank of the stuff the keys to my silver GT fell in and had to be fished out in a hurry or I was walking home. Takes off chrome in about the same time. We used it as a chemical polish for stainless and titanium parts. On them it took about 1/2 an hour.
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#35 (permalink) |
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Project 1450 supporter...
Join Date: Mar 2002
Location: Pleasant Valley, CT
Posts: 7,452
Real Name: Bob Legere
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I just did a little quick research and muriatic acid is just diluted hydrochloric acid (30% hydrochloric/70% water). So you may want something stronger for cast iron, or perhaps just heat it up a bit.
Warning: use with adequate ventilation! |
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#36 (permalink) |
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No Access
Join Date: Nov 2003
Location: in transit
Posts: 3,873
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Outdoors maybe, after a period of time the fumes mess you up. 3 vats over from the caustic soda were the acid tanks. Now I remember why I quit that job. Another good one is electro static discharge. Wait that's anode and cathode with a big tank of water. I'd stay with the acids but keep some bicarb soda around.....and a garden hose.....and a fire extinguisher.
Just an FYI the inhaling of the fumes off these types of chemicals is mood altering and 90% of the workers near that room had side effects. Ok outdoors and a big fan. |
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#37 (permalink) |
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The Great Opel Search
Join Date: Aug 2004
Location: Casey, Illinois
Posts: 411
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do any of you know where i can get a "air powered die grinder". do they make cutting blades for these also?
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1998 Sunfire "The Great Opel Search Continues" © of Skyler Shelton "The dictionary is the only place where success comes before work" Mark Twain "Tobmstones Dont Talk Back" Smoke Tires, Not Drugs... http://sportcar.net |
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#38 (permalink) |
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Senior Contributor
Join Date: Oct 2005
Location: Mt. Clemens, Michigan
Posts: 888
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Watch the Heat
When decapusating semiconductors (computer chips), we use concentrated sulfuric, It can sit on the mold compound for quite a while with little effect at room temp. We set the parts on a hot plate to get them warmed up (too hot to touch) and then it eats away the mold compound in a few seconds.
What I am saying is, the added temp will make it potentially VERY fast, so do some testing and get a good rythem going at a controllable temperature.
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Steve "ever notice you are never done tinkering with the GT?" Never mind, I am WAAAY beyond tinkering now...[/SIGPIC] |
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#39 (permalink) |
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Old Opeler
Join Date: Jun 2003
Location: New Zealand
Posts: 5,686
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Battery Acid
The acid used in batteries (Sulphuric Acid) will do the job too and it is much less fumey than Hydrochloric Acid. Easier to obtain too - and we all have a pretty good respect for battery acid ... don't we?
__________________
GTJim Opel Owner since last Century! Copyright © 2000-2009 J D Henry All Rights Reserved |
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#40 (permalink) |
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No Access
Join Date: Nov 2003
Location: in transit
Posts: 3,873
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wannabe, have a look at harbor freight near you, give your wallet to somebody else before you go in. Air compressors, air tools, hoists, presses lathes, mills, tooling, all at dirt cheap prices.
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#41 (permalink) |
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1970-GT
Join Date: Sep 2005
Location: Clearwater, Florida
Posts: 1,237
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Back to porting!
I have my valves, they are Chevy 1.80/1.50 11/32" Pro-flow type, with under cut stem. The stem is under cut about 1-3/8" from the top of the valve head. My question is should I machine the cast/bronze valve guides to match this distance? Thanks Lyle |
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#42 (permalink) |
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Old Opeler
Join Date: Jun 2003
Location: New Zealand
Posts: 5,686
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Under Cuts
Lyle, It is quite important that the under cut on the valve stem sits outside the valve guide or carbon builds up on the stem (particularly on the exhaust valve) eventually doing away with the undercut for a portion of the stem. Contra-wise - in the old British motor-cycle days - we used to counter bore the guides themselves to allow a ring of carbon to build up in there so that - theroretically - it acted as a close tolerance seal on the valve stem.
No use cutting the stem back further towards the guide as you may just form a stress riser on the stem - better to leave it "factory" finished. Of course, if the undercut goes back into the guide it is probably worthwhile to cut back the guide while porting as the unsupported bit of stem will do nothing for valve stability in the guide and removal may just improve the flow though the ports!
__________________
GTJim Opel Owner since last Century! Copyright © 2000-2009 J D Henry All Rights Reserved |
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#43 (permalink) |
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1970-GT
Join Date: Sep 2005
Location: Clearwater, Florida
Posts: 1,237
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More useless info.
The stock Opel intake valve weighs 102g and has a head area of 1.945". The 1.80" Chevy pro-flow weighs 102g and area of 2.544". Same weight with a 30% increase in flow! The stock Opel exhaust valve weighs 95g and has a head area of 1.410". The Chevy 1.50" pro-flow weighs 89g, area of 1.767". Lighter and flows 25% better! Also with the under-cut stem they will flow better than stock! The stock spring retainer, valve keepers and oil shield weigh 43g thats heavy! Will check the weight of titanium ones next. Lyle |
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#44 (permalink) |
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1970-GT
Join Date: Sep 2005
Location: Clearwater, Florida
Posts: 1,237
![]() Provided Answers: 2
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The head is coming along good. Bronze guides and exhaust seats installed and valve seats roughed in!
I set it up in my mill, tipped the head to about 24 degrees, indicated everything square. Then bored and milled the combustion chamber and valve port area! Then I un-shrouded the intake and exhaust valves and milled the valve guides down to match the undercut valve stems. This will give me good straight lines and arcs to hand port to. It took me about 2-1/2 hours to setup and mill as shown, milling is easy for me and this saved me alot of time. I would like to mill the whole thing! But to many arcs and decreasing radii blending....... Guess I have to do it by hand. Lyle |
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#45 (permalink) |
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1970-GT
Join Date: Sep 2005
Location: Clearwater, Florida
Posts: 1,237
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Still alot of work to go, but it's roughed in.
How polished should the combustion chamber be? I will polish the Exhaust ports. The intake will be rough 36#. Also after final surfacing of the head gasket surface, what edge break should I do around the combustion area? (.005-.010 rad)? Lyle |
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#46 (permalink) |
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No Access
Join Date: Nov 2003
Location: in transit
Posts: 3,873
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Sorry but I have to say this. For every CC you just removed from the combustion area it has effectively dropped your compression. Now with any standard piston your down in the 6s. To develope any power now you'll need custom pistons that are usually 160 per hole. Deck the daylights out of it might help a bit but you have to be carefull of chain slop and cam retiming then.
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#47 (permalink) |
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former opel racer
Join Date: Nov 2002
Location: near some glaciers
Posts: 2,863
Real Name: Jeff "Oh-Oh" Denton
![]() Provided Answers: 4
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A piece of plexiglas sealed with grease around the edge of the chamber, with a hole to drop your fluid in and another to vent it. The head should be as level as possible, naturally.
Also, I would be curious what your head measures from the deck to the valve cover rail after you mill it. Both sides, in case it is angled hopefully. Just to have some numbers to compare, you know. Yes flow is important but so is compression ratio. I'm sure you know Bob's spec of making the piston top out .005" above the deck. There are tricks for taking up some extra chain slack and the timing part is simple.
__________________
No Opels were harmed in the filming of this movie. However two Mustangs, a Pinto, and a Capri were hospitalized. One Mustang was euthanized the next morning. Last edited by jeff denton; 01-14-2006 at 12:33 AM. |
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#48 (permalink) |
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1970-GT
Join Date: Sep 2005
Location: Clearwater, Florida
Posts: 1,237
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Dave,I have Chevy forged 3.75 flat top pistons.
Tried to remove smallest amount of material to Un-shroud the large valves for flow. Will mill the head about .020, and the cam ground with 3-4 degrees of advance. I calculated about 9.5 : 1, but won't know until I'm done. What is the volume of a stock combustion chamber about 53? Lyle |
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#49 (permalink) |
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former opel racer
Join Date: Nov 2002
Location: near some glaciers
Posts: 2,863
Real Name: Jeff "Oh-Oh" Denton
![]() Provided Answers: 4
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52.1 to 52.5 cc, according to R.B.
With flat top pistons, stock deck height (which I really don't even know what that is) the CR should come out just under 9.0 to 1. That thread of Neal's, T-6 Driver, about cutting the top of the piston to effect a slight "dome" was interesting, that is the sport's most common way of making compression. It's gotta be tricky machine work, I don't remember if we ever did really have a machinist's input there, but you'd be the guy to figure it out. So you're gonna want to be sure to get that .005" of piston sticking up for sure, with maximum angle cut on the head. Bob has a post about this somewhere, he also touches up the head bolt's seating surface to parallel it with the deck. Max breathing, max compression, now it's all about the camshaft. I'm sure the roller cam will come along eventually, but it is probably gonna be a while yet. It looks like everybody who has invested in it has been burned so far, it is painful to just follow along and try to understand what's going on there! One more thing, it occurs to me that when fitting a bigger intake valve, it might behoove you to have the valve's head stick out as much as possible, in other words cut the 45 degree seat as high as possible, no 30 degree top cut. This could gain you a bit of CR, does this sound feasible to anybody? Not that I'm following this so closely for any personal reasons, of course...
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No Opels were harmed in the filming of this movie. However two Mustangs, a Pinto, and a Capri were hospitalized. One Mustang was euthanized the next morning. Last edited by jeff denton; 01-14-2006 at 02:15 AM. |
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#50 (permalink) | |
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1970-GT
Join Date: Sep 2005
Location: Clearwater, Florida
Posts: 1,237
![]() Provided Answers: 2
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I calculated if I get my volume to about 53.5. plus gasket .25, then I should be around 9.1 to 9.2 about! Good for pump gas! The piston sticks up about .003 plus a few years of carbon build up! So Bob mills the deck at an angle, with the spark plug side lower I would guess. Thats a good idea!! How much angle can we get away with before the head bolts won't go in anymore? 2-3 degrees? Will have to find that post. Cam is a Bob recommended Cam Techniques grind. Intake .459 lift with 246 dur @ .050 Exhaust .435 lift with 242 dur @.050 Im not racing my Opel like you, but still want a quicker/drivable street ride. Lyle |
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