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#76 (permalink) | |
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Opeler
Join Date: Oct 2007
Location: Rüsselsheim/Deutschland
Posts: 14
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Here in Germany is the old Steinmetz ST 17 or the Mantzel M 17 H one of the best profile in cams, which you can get to use it on the street or in semi race! She has 320° duration 11,8mm lift complete and 5,5mm in top dead center and 104° valve overlap, but you must use a single port for every intake, at best with Weber carbs in 45 or 48mm and the other goodies aforesaid! I use also an old profile from Irmscher, the IRM10 with 312° 12,3mm 4,25mm 107° with a street ported 2,0 head with original valves in 42/37mm on a original 2,4 block, 45mm double webers and a 63,5mm exhaust system and the engine has 175 hp at 5800 rpm and 227 nm torque at 4800 rpm! There was a lot of power from 2000-6000 rpm and no hole in acceleration, but i use a ZF 5 gear transmission with close gear ratio, that helps a little bit in acceleration! In my next engine, i will also use the ST 17 cam, then i will tell about the power envelope... ![]() Best regards Ronny Last edited by tekenaar; 08-03-2009 at 10:34 AM. Reason: were; short; envolvement |
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#77 (permalink) |
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Opeler
Join Date: Aug 2008
Location: England, leyland
Posts: 77
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Right guys
Need a bit of help/advice for the cam for my 2.3 long stroke motor. At the moment got a Kent 244 290 deg duration @.004" Timing figures 42/68 78/32 Valve lift IN 0.447 EX 0.445 Cam lift 0.309 After reading some of the articles on here i've learn't that due to the piston speed slowing at top dead centre due to the long rods it could mess the breathing of the engine due to the exhaust opening at the wrong time. UIs this correct or not? Is this cam ok to use or should i up to a Kent 254 300 deg duration@.004" Timing figures 47/73 83/37 Valve lift IN 0.470 EX 0.468 Cam lift 0.324 Bearing in mind i'm in the uk and getting stuff here seems to be hard work when it comes to cams, D Bilas distributor is not interested and won't even ring back with quotes. Cat cams, Kent and piper seem to be my only choices at the moment unless i can get something shipped from the US cheap enough!!! Any advice would be great. Thanks in advance Chris |
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#78 (permalink) |
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Project 1450 supporter...
Join Date: Mar 2002
Location: Pleasant Valley, CT
Posts: 7,451
Real Name: Bob Legere
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I'd ring Cat Cams then.
Tell them you have a 2.2 head, it makes a difference for cam design. These heads like a lot more valve lift than the 2.0 BTW, and would actually favor some exhaust lift and duration as the intlets outflow the exhaust side appreciably, so you need to make up for than in cam design. I'm had a few big cams made for 2.2 heads that were in the realm of .550" of inlet lift and .570" of exhaust lift. Durations of 262° @ .050" (inlet) and 266°@ .050" (exhaust), with 106° lobe separation angle. You might want 104-105° for more torque off the turns.
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My Flickr photos. Jan. 3, 1984 - Jan. 3, 2009, that's 25 years of this damn Opelitis! C.R.L. 9/22/69 - 12/8/99, J.M.L. 3/3/43 - 6/15/04 |
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#79 (permalink) |
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Opeler
Join Date: Aug 2008
Location: England, leyland
Posts: 77
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Thanks Bob
Did forget to mention that the head i'm using is a 2.0 with 46/41 valves, done by the late Bill Blydenstein, but the 2.5 i'm also building has a full race ported 2.2 head done by Geoff Dodd who worked on the DTM cars in the 70's so i'll kep that in mind for that head (think that will be a 324 deg Rallycross spec cam from catcams) Not got a lot of experiance with the cam theory so all your help is really appreciated Chris |
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#80 (permalink) |
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Member
Join Date: Mar 2004
Location: Paris, France, EEC.
Posts: 942
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I actually find it difficult to make sharp prediction only based on a CIH building data,
there are so many variables involved including the way the head was ported, that a given cam could give surprisingly good (or bad...) result IMO. the way I do is always start with a known (relatively small) cam from my "cam library" & see how the engine works, this gives me a baseline from which I can move on. then I upgrade with a bigger cam & eventually play with the valve lash to see if a bigger/smaller cam is necessary or not, here Bob's roller rockers were very usefull because they allow for another step of intermediate upgrade just by their own. my method is slow & requires to have a set of reference cams in hand, but the good side of it is that you gain some knowledge about the optimal cam/head/cid combo for next CIH building. HTH, Hiro |
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#81 (permalink) |
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Opeler
Join Date: Aug 2008
Location: England, leyland
Posts: 77
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Thanks Hiro
Bearing what you have said in mind i might upgrade to a 254 Kent cam for the moment then (cheap option!!!!!). The 244 Kent cam was giving around 180 bhp with the same head and std pistons. Now that i will have a larger capacity/comp ratio i can probably justify moving up a cam. The 2.2 with the 244 fitted had loads of low down grunt and revved clean to 7000, so the new 2.3 with a lighter flywheel, better rod ratio should be pretty safe to go to 7500. Out of interest, at what revs have you guys run into problems with the rocker arms? The 2.5 will be built to rev to 8000-8500 so i didn't want to risk using the std rockers on that, but i've got to wait for Harri's set up to be completed and tested before that can continue. I've now got a contact for getting shot peening done and i'm sure that somewhere on here it was recommended to improve the strength of the std rockers. if they're done, what sort of rev limit would i have then? Thanks again Chris Last edited by tekenaar; 04-10-2009 at 11:28 AM. Reason: there - where? |
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#82 (permalink) | |
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Living in the past
Join Date: Oct 2005
Location: Chesapeake, Virginia
Posts: 1,372
Real Name: Lloyd
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Stock Rockers
Last edited by tekenaar; 04-10-2009 at 11:24 AM. Reason: pedel |
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#83 (permalink) | |
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Member
Join Date: Mar 2004
Location: Paris, France, EEC.
Posts: 942
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above this limit it much depends upon spring rate/cam lift/rocker wear. the funny thing is I've seen more broken rockers on overreved stock old CIH than on full race ones, might as well be that valve float is the key in this case? I think our German friends are now working on using very light valve trains & relatively soft springs, this should put less stress on the steel rockers for sure. Hiro Last edited by tekenaar; 04-10-2009 at 11:21 AM. Reason: uptill |
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#84 (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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Wasn't there going to be new rocker arm available soon? I wonder where they are with that. I'm not getting excited about building any Opel engine until something other than stock rockers are available.
However, I too can say I had no problems with stock rockers, .425 lift and stock springs at 7100 RPM pedal to the metal.
__________________
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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#85 (permalink) | |
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Project 1450 supporter...
Join Date: Mar 2002
Location: Pleasant Valley, CT
Posts: 7,451
Real Name: Bob Legere
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My thoughts anyway! Bob
__________________
My Flickr photos. Jan. 3, 1984 - Jan. 3, 2009, that's 25 years of this damn Opelitis! C.R.L. 9/22/69 - 12/8/99, J.M.L. 3/3/43 - 6/15/04 |
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1 out of 1 members found this post helpful. |
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#87 (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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We ran in the 7500rpm range more than I wanted to and only had trouble with rockers with one cam. The fulcrum balls would get a groove in them and shortly after that the rocker or the stud would snap. We switched to an Isky OR-99 and fixed the problem. I understand someone else wound up with the cam and had similar experiences. It was a little too much cam anyway. Just when it started pulling hard we were past the midway point on the straightaways and were still accelerating when the driver had to back out of it.
The rockers were shotpeened but not polished. Harold |
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#88 (permalink) | |
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Project 1450 supporter...
Join Date: Mar 2002
Location: Pleasant Valley, CT
Posts: 7,451
Real Name: Bob Legere
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On the aforementioned 8800 rpm engine, I did enlarge the rocker arm slots to cope with the high valve lifts and smaller base circle. .545" intake and .528" exhaust IIRC.
__________________
My Flickr photos. Jan. 3, 1984 - Jan. 3, 2009, that's 25 years of this damn Opelitis! C.R.L. 9/22/69 - 12/8/99, J.M.L. 3/3/43 - 6/15/04 |
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1 out of 1 members found this post helpful. |
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#89 (permalink) |
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Member
Join Date: Aug 2006
Location: Goderich, Ontario, Canada
Posts: 275
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Possible Valves/Pistons interference?
Another question Bob, if you do not mind:
Based on the information I have, standard 1.9 cam has 0.257" (6.52 mm) lift. I am building 2.0 street engine with Isky "Combination" cam which has 0.430" (10.92 mm) lift. That is already +4.40 mm of extra lift. In addition, my 2.0 cylinder head is angle milled approx. 2 mm on the spark plug side (we discussed that in one of threads few months ago). Should I be worried about possible interference between valves and pistons? |
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#90 (permalink) | |
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1000 Post Club
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#91 (permalink) |
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Member
Join Date: Aug 2006
Location: Goderich, Ontario, Canada
Posts: 275
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Need more facts. Let me explain: I understand that the "Combination" cam can be used on high compression (flat pistons) engine without deepening the valve pockets on the pistons. Yes, angle milling brought valves about 1-1.5 mm closer to the pistons.
How much should I increase the depth of the valve pockets? 2 mm? Any experience or suggestion here? |
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#93 (permalink) |
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Old Opeler
Join Date: Jun 2003
Location: New Zealand
Posts: 5,686
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Custom Engine Builds
When ever you depart from 'standard' known components and machining everything has to be carefully checked ... and re-checked.
Angle milling of the head not only moves the valves closer to the piston top during overlap it also changes the direction in which they open which could move the piston/valve closest approach position away from the existing valve notches. You simply have to go through the procedure for checking valve/piston clearance (or lack of it!). 'Guessing' what the clearance will be with custom engine builds (or hoping that someone has done exactly the same before) can become a recipe for disaster. The individual engine combination MUST be checked. For a proceedure see: http://www.opelgt.com/forums/179994-post8.html BTW: Your figure for the standard cam is lift at the lobe - not at the valve. At the valve it is closer to 0.370/0.390" lift so the .430" lift of the combination cam is not that much greater- it is the angle milling that is the wild card in the build.
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GTJim Opel Owner since last Century! Copyright © 2000-2009 J D Henry All Rights Reserved Last edited by GTJIM; 08-02-2009 at 11:46 PM. |
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#96 (permalink) |
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Old Opeler
Join Date: Jun 2003
Location: New Zealand
Posts: 5,686
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Used ...
A used gasket is best as you don't ruin a new one - and the old one is already compressed to the thickness it will be when the motor is eventually buttoned up.
Count on having the head on and off at least twice and probably a few times more - check the procedure I linked to. Also in the next post is mentioned using light springs on the valves - not the real valve spring so it makes it easier to turn the motor over and also push down on the valve to check for clearance. With light valves and knowing where in the revolution the closes point is you can use a dial gauge on the spring retainer or rocker above the valve tip to measure clearance directly (without play dough) for final checking.
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GTJim Opel Owner since last Century! Copyright © 2000-2009 J D Henry All Rights Reserved |
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#97 (permalink) | |
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1000 Post Club
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I used a new one without crushing the fire ring all they way down. Math is a little tricky but it works.
Last edited by tekenaar; 08-03-2009 at 10:21 AM. Reason: your no fun? |
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#99 (permalink) |
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Member
Join Date: Aug 2006
Location: Goderich, Ontario, Canada
Posts: 275
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A simple visual test (see pics) shows that the "zero point" (valves just touching pistons) should be with the valve pockets approx 1 mm deeper. With the neccessary 0.1" (2.5 mm) required tolerance this would mean that I will have to cut valve pockets another 3.5 mm (0.1378"). That would not leave much "meat" on the top of pistons. Any thoughts?
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#100 (permalink) |
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Project 1450 supporter...
Join Date: Mar 2002
Location: Pleasant Valley, CT
Posts: 7,451
Real Name: Bob Legere
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Usually the point of greatest interference is about 15-20° BTDC and 15-20° ATDC. As the intake valves are opening the pistons are going down the bore, as the exhaust valves are closing the pistons are coming up the bore. When both valves are open the same amount the piston is usually nowhere nearby.
So with any new combination I'm running, I always fit test springs and check the clearances at 10°-15°-20°-25° ATDC on the exhaust side and 25°-20°-15°-10° BTDC on the intake side, just to be sure. That said, I once did a bit of diagnosis on an engine when I had C & R...the customer had bought some flat-top pistons from me, and a cam (CR-149), and a big valve head (1.72"/1.50" valves). The engine had a slight noise at idle that increased with rpms and as the engine heated up. It ran fine, just made a little knocking noise. Turns out the pistons were installed backwards...the valve notches were on the wrong side! The noise was the intake valves *just* touching the piston tops. Left a slight ding mark, but did not bend any valves, nor damage the pistons. The head was milled .030" (.75 mm), and the cam had .425" lift and 212° @ .050". If the head had stock valves, they would not have hit at all! Regarding the piston top thickness. If they are OEM Mahle pistons, AE pistons, or KolbenSchmidt pistons, the piston tops are .500" thick! I've actually notched those brands of pistons .375" deep before with no issues. I can't comment on other brands of pistons however. I like to maintain a minimum of .080" (2 mm) intake side and .100" (2.5 mm) exhaust side clearance...the exhaust valves grow/expand more with heat so they need a bit more room. HTH, Bob
__________________
My Flickr photos. Jan. 3, 1984 - Jan. 3, 2009, that's 25 years of this damn Opelitis! C.R.L. 9/22/69 - 12/8/99, J.M.L. 3/3/43 - 6/15/04 |
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1 out of 1 members found this post helpful. |
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