Performance Cams

[Paul]

Jim and others.....

I dug up a few more off my favorites list.

http://users.adelphia.net/~tlwoodbury/main.html

http://www.headerdesign.com/extras/design.asp

http://www.opeltuners.com/

http://www.tgsi.com/tech.html

http://www.techlinecoatings.com/

http://www.automotiverebuilder.com/

http://www.popularhotrodding.com/eng...305em_bigbang/

http://www.bacomatic.org/~dw/index.htm

http://homepage.ntlworld.com/david.jackson17/#whatsnew

http://www.swaintech.com/index.html

http://63.105.19.158/automotive/

http://www.bgsoflex.com/auto.html

http://www.flowdyno.homeip.net:81/

http://www.tractorsport.com/messages/165.html

http://yarchive.net/car/index.html

http://www.theoldone.com/

http://www.performancetrends.com/


Enjoy reading!

Paul

PS Read them ALL. They are ALL good sites, don't cherry pick!

[swindler_57]

I never thought my little post would ever grow to be this big! Lots of information being swapped back and forth. I don't mean to be pushy or anything but Rallybob have you come up with those specs yet? I was just wondering since my posted thread turned into something else that really wasn't answering my most important question. Just wondering.

[RallyBob]

Well, after much searching, I realized that there's not much for performance-oriented hydraulic cams that are under .430" lift (so you can retain stock springs).

Cam Techniques has a profile I've used a lot which uses their H284 grind for the intake (.426" lift, 212 @ .050", 280 degree advertised), and their H278 for the exhaust (.417" lift, 204 @ .050", 270 degrees advertised). Recommend having it ground at 109 or 110 degree lobe separation....109 will give a touch better torque, at the expense of a bit more overlap (rougher idle). They have some newer profiles that I don't have a list of which may be more in line with the recommendation below.

Now, in keeping with my original recommendations, Bullet Racing Cams has some profiles that are more my liking. For the intake, H265/286 which is .429" lift with 216 @ .050" duration, 265 advertised. For the exhaust I like the H274/280 which is listed as .420" lift, 208 @ .050", and 280 advertised. I would shoot for 109 degree lobe separation here as well.

These are not 'radical' cams by any means, they're pretty tame, but still a lot better than stock. I've run cams with another 30-40 degrees of duration @ .050" in my daily drivers, so you can see there's still room to grow.

Bob

[Paul]

Bob,

I have another "why" question about cams. In the cam you just described, what is so different about these profiles? The variations appear to the untrained eye to be slight. Intake & Exht have .003 more lift and 4* more duration at .050. How much extra HP/torque/rpm range does this translate to?

Is there a typo in the intake duration of the Bullet Racing Cams, H265/286? Your description says there is less intake duration than exhaust duration. I presume the profile designation is duration for these cams, where as the profile number for the Cam Tech cam, is lift?

Do have any recommendation for timing changes for these cams you just listed for Swindler_57?

TIA
Paul

[RallyBob]

Paul, by the same token, the smaller of the cams I listed is 'only' a few degrees more than a stock Opel cam. However, it does add more power. I was just giving options....

I have not found any great amount of power from higher valve lift with Opels, not at least with an unmodified head. But the duration adds to both the power and torque curves, with the lobe separation and intake centerlines establishing 'when' the power band is strongest (relative to the duration) and 'how hard' it hits.

That is not a typo, the advertised duration numbers are as listed. This is why I do not hold advertised duration numbers in high regard...the @ .050" and the @ .200" duration numbers reveal the true character of the cam. The stock advertised duration of a solid lifter 1.9 cam is something like 310 degrees. But the @ .050" number is barely over 200 degrees. The roller cam in Samdog's sportwagon is listed as 284 degrees (much less than the stock Opel solid lifter cam). However the @ .050" number is 248 degrees!

Regarding the ignition timing, my usual recommendation of 35-36 degrees total timing holds true. Depending on the camshaft chosen, the baseline timing setting should be about 4-6 degrees. There's modest overlap involved so the cylinder pressures at idle should be strong.

Bob

[Paul]

Bob,

Are the profile numbers for the Bullett cams "H" for hydraulic, 1st number duration, and 2nd number lift of cam lobe?

Looking closer, the Intake profile of the Bullett cam has a steeper flank since it comes off the seat later but has more duration @.050. I guess this would translate into less overlap & higher cylinder pressures but with increased flow from more duration at mid to high valve lifts? I guess this would also translate into earlier Intake valve closing which would give improved power at low to mid RPMs. Or am I reading too much into this?

How noticable would the changes from 110* to 109* be on either of these two cams you've listed.

Sorry, been doin' too much extracurricular reading and just try to put the pieces together.

Paul

[swindler_57]

I would just like to thank everyone here for all of there help with information and everything. It's really nice to have people so willing to help each other out. Bob, I will look into that cam. I just emailed cam techniques to find some more information and maybe pricing too. I think I just might save some money to get that cam because it's exactly what I want. A little bit rough idle but more power. That's really all I'm looking for. Thanks!

[opeldean]

"Now, in keeping with my original recommendations, Bullet Racing Cams has some profiles that are more my liking. For the intake, H265/286 which is .429" lift with 216 @ .050" duration, 265 advertised. For the exhaust I like the H274/280 which is listed as .420" lift, 208 @ .050", and 280 advertised. I would shoot for 109 degree lobe separation here as well."


Rallybob: I think I want a solid cam. My mechanic wants to know about "valve
springs and cam ' before he sends it to the machine shop.

Can my opel solid cam be reground to these specs?

in review . my head going to the machine shop to fit the 42mm intake valves-
engine is a 20 over 1.9 -9-1 compression,sprint with 2 in exhaust,weber 32/36,petronix ignitor, heavily ported intake with jbweld diverter per your design
can you pick me out a cam i would enjoy? thanks

[RallyBob]

Originally Posted by opeldean Rallybob: I think I want a solid cam. My mechanic wants to know about "valve springs and cam ' before he sends it to the machine shop. Can my opel solid cam be reground to these specs? in review . my head going to the machine shop to fit the 42mm intake valves- engine is a 20 over 1.9 -9-1 compression,sprint with 2 in exhaust,weber 32/36,petronix ignitor, heavily ported intake with jbweld diverter per your design can you pick me out a cam i would enjoy? thanks

There are specific cam profiles for solid lifters and others for hydraulics. Now you could use a hydraulic profile with solid lifters, the opening and closing ramps are gentler for hydraulic lifters so they certainly won't hard the solid lifters. You could (and should) run a solid lifter-specific profile however if you want better performance. However, hydraulic lifters should not be used on solid profile cams, the faster opening and closing rates of the lobe will probably collapse the hydraulic lifters!

The nice part is there are a lot more choices for solid lifter cams.

The bad part is there are a lot more choices for solid lifter cams......
Now there are a lot more to choose from, making it all the more complicated.

Bob

[opeldean]

rally bob:
do you still use a split profile cam when you have already improved the intake flow with bigger valves(42mm) in the stock 1.9 head.

my mechanic was thinking the duration should be around 230 at .050'' with 110 lobe separation..he wants to know about springs. I dont know how to relay the
information in a more intelligent manner to you.but this 230 duration seems so much farther from what you have in your prior posts.
thank you very much.

1-is it possible that you could suggest a cam for me? I would like a solid lifter specific - profile for solid lifters.I plan to learn how to maintain and adjust this set up.

[RallyBob]

Originally Posted by opeldean rally bob: do you still use a split profile cam when you have already improved the intake flow with bigger valves(42mm) in the stock 1.9 head. my mechanic was thinking the duration should be around 230 at .050'' with 110 lobe separation..he wants to know about springs. I dont know how to relay the information in a more intelligent manner to you.but this 230 duration seems so much farther from what you have in your prior posts. thank you very much. 1-is it possible that you could suggest a cam for me? I would like a solid lifter specific - profile for solid lifters.I plan to learn how to maintain and adjust this set up.

On the first question, yes, I still use a split profile. The intake manifold, even when ported, is still a restriction.

If you run duration nearer the 230 degree mark, then you might want to up your compression. I realize you are running flat-top '9:1' pistons, but these in fact are closer to 8.4:1 compression. For that kind of duration, a true 9.5:1 is a better starting point. That could be achieved with head milling.

110 degree lobe separation is okay, and the idle will be better than a narrower angle. But if you are striving for more torque, try 108 degrees, with 3 to 4 degrees of advance.

Regarding springs: I don't know of a combination that works with stock Opel retainers and the stock exhaust rotators, unless you use 2.2 retainers and rotators, then there are more options for springs.

Bob

[opeldean]

NEW SUBJECT:
I THINK ADAM OPEL IS TRYING TO TELL ME SOMETHING.

four factors;

1- AIR
2-CARB

3-COMPRESSION

4- EXHAUST

MY CARB WILL BE A 32-36. i AM NOT A RACER. I WOULD LIKE THE CAR TO BE ITS BEST.


i AM GOING TO PUT IN AN ISKY COMBO CAM OR66- i CAN USE STOCK SPRINGS,RETAINERS ETC. tHIS WILL BE THE SIMPLEST FIX AND WILL BE
APPROPIATE FOR MY CAR. iF i GET INTO DECKING THE THE BLOCK,SPLIT PROFLIE CAM..THESE GAINS WILL NOT BE REALIZED AT THE RPM I WILL BE DRIVING ,ESPECIALLY WITH THE CARB I HAVE , MORE UPGRADES ,ETC ..ETC.
WOULD BE NEEDED TO SEE ANY BENEFIT.

LET ME KNOW IF THERE IS ANYTHING I NEED TO KNOW.

[opeldean]

I panicked out of cam confusion. My head is waiting for a spring solution,nothing has been ported yet.I guess i will call OGTS on the 2.2 springs...unless their is a GM option.
Update; my mechanic wants to know ?
1-What is the piston to deck clearance(T.D.C.)?

2-What is exact bore and stroke(my engine is a 20 over 1.9 -9/1(actual 8.4)?

Their plan is to raise my compression to 9.5 to 1 to make this engine something better by decking the block and milling the head.
3- Springs are still a question, their comments were " surely seats can be cut deeper and there are GM springs that will fit to avoid bind with a more aggressssive cam"." "this head looks so GM"
4- are there thinner or steel headgaskets availible?

5- What problem does the rotator on the exhaust spring pose? I got the feeling these can be eliminated.

- the plan is for the car to go " lump-lump at idle...then power at 3,000rpm'

ps: I think I have a weber 38degas for its future.

[nobody]

If you deck the head get ready to fix the cam to crank timing. You will need to find adjustable sprockets and someone who knows how to do it if you take that route. Rally Bob posted once of the effects and the numbers it produces.

[opeldean]

I just spoke to ogts, they don't seem to have the parts for my head to go to a more radical cam.

I guess my car is going to be a 'radical street' and I need help on this.

Ogts gave me an opionion that spring bind might not occur until .450 lift as each head is a litttle different.

he also said "rocker ratio varies from 1.46-1.53 with an average of 1.5.

[GTJIM]

Have been doing lots of reading and hands on checking with my cylinder head too.

1 & 4) The distance between the top of the piston and they cylinder head should be minimum .040" (1.0mm) and maximum .060" (1.5mm) With the standard, composite head gasket this is easy as they compress to almost exactly .040" (1.0mm) thick so this means that the piston top (or flat area on dishes or pop-ups) should be level with the top of the block or maximum .020" (0.50mm) "down-the-hole" This allows for the correct "quench" at TDC - just like most any other GM engine ........

This clearance needs to be obtained by using the correctly dimensioned components (or by cutting the tops of the pistons if they stick up too high).
"Hacking" lumps off the block or head faces does horrible things to the cam timing - as Nobody has forcefully pointed out to me, till I am a believer - as does using a gasket of a thickness different to the original. Because of the unique cam shaft position up in the head as the cam centre line drops towards the crank centre line the cam sprocket "walks" down along the drive side of the chain and thus the cam has to turn - upsetting the cam timing.
If you "do-the-numbers" even .010" (0.25mm) of "hacking" has a significant effect on cam timing. This change has to be rectified by altering the angular relationship of the cam wheel to the camshaft - either by using an offset bushing (hit-and-miss) or a vernier cam pulley (UK imports from Kent or Piper which are horribly expensive - GBP90 or more).

Consequently, for the novice Opel CIH engine builder, keeping the top of the block and the cylinder head face "unmolested" is the best course of action.

2) Standard bore and stroke for a 1.9 litre Opel CIH motor is:

93mm bore by 69.8mm stroke (3.661" bore by 2.748" stroke)

So your "20 over" is 3.68" bore or 93.5mm bore - same stroke.

3 & 5) "Other GM" springs can and have been used. The exhaust rotator can be dispensed with but the high milage life of the exhaust valve may be compromised with unleaded petrol - unless a hardened exhaust seat is fitted.

All "intake" springs can be used with extra intake spring retainers and a suitable spacer under them on the "exhaust" valve spring seat where the rotator was to give them all the same installed height which is around 1.650" (check this on an intake one to make sure I have got this correct).

With Opel valves (even the 2.0 litre bigger ones that can be sourced from OGTS) this "stock" intake spring set up will allow the use of cams with lifts up to 0.425" for sure and may be up to 0.450" with careful measuring and checking for spring bind and valve guide interference at full lift. The later 2.4 litre springs can be used in this "modified stock" set up too - they are Pioneer Inc. Automotive Products part number RV-925-4 They are the same for intake and exhaust.

With Chevy V8 valves the sky is the limit for springs using any of the many V8 types - including the old favourite the 400 CID Pontiac ones that I have seen mentioned and I understand were in the C & R Big Valve Kits of yore.

I'm still "digging" for information and welcome verification of the above - or even being told that I don't know what I am talking about ( by more experienced Opelers!).

[Travis]

GTJIM,

Just a few comments

RallyBob has often advocated having the piston .005" or so above the top of the block to improve quench

Any proper rebuild will require decking both the block and head, although minimally. However, I consider 'degreeing the cam' an essential part of any performance engine. Each engine configuration will require a different installed position of the camshaft. Therefore, just leaving the block and head unmolested will not get you where you need to be. When you buy the offset bushings they come as a set with different offsets. Using the right bushing will get you where you need to be.

For moderate to high RPM engines, selecting springs merely by the fact that they don't bind is a hit or miss proposition. Valve float and even harmonics of the system will need to be considered. Your cam supplier will be able to supply info on required spring rates and spring seat pressures based on your cam and intended usage. If not, find another cam supplier.

And remember, cams aren't rated on the 'bumpity' scale....

-Travis

[nobody]

I couple of things to keep in mind when you even start to mention decking anything to anybody is thier knowledge of the entire picture and thier abilities not to mention the money factor. Just as decking it and then leaving it alone looses power the use of the wrong bushing or degreed position can have a big impact on the motor and I do mean impact literally. Having been down both of these roads myself with varying degrees of success I am very stronly on the side of get your design right in the first place and never try to make up for it in other areas. Decking the block or head either is a design problem or a bad part and if you are in a pinch for whatever reason you have to use you own judgement on what you do. I'm not trying to argue or start a debate but merely offering my views on this subject and maybe keep somebody from getting in over thier head.

[Gary]

I changed the name of this thread from "I need RallyBob's help!" in order to help out with future searches.

[Paul]

OpelDean,

It has been posted by RBob that for every .025" milled from either the block or head, the cam timing, wrt the crank, will retard 2 degrees. Also, in his post concerning the best low budget mods, he says decking the block to bring the pistons flush to the deck (or maybe as much as .005" above deck) and milling the head .050" will bring the compression up to a true 9.5:1, using stock valve sizes and new exhaust seats.

To correct for cam timing, there are several ways to do this. Some are easier than others and less expensive.... 1) redrill the dowl hole in the cam gear at the appropriate location; 2) modify the cam gear to accept Chevy offset bushing; 3) purchase an adjustable cam gear from Kent or Piper; 4) make custom offset key to relocate the crank gear by the approproate amount. I'm sure there are other ways someone in the group knows about.

In my big valve head by Roger Wilson (okay moderately big Chevy 1.72/1.5), he used a spring by Isky. The part number is 905-D, and is listed in their catalog as for the Capri. He also used their retainer and lock. I'm sure if you called them, they would be able to specify the appropriate part numbers.

This spring and chevy valve combo had seat pressures of: 95-100# valve closed and 195-200# valve open. Well within the recommended seats pressures recommended by RBob for use with the stock Opel hydraulic lifters and stock rocker arms. I believe the combo will also allow valve lift greater than stock. How much exactly,? I'm sure a call to Isky will produce the answer.

Yes you can toss the rotators and use all Intake springs etc. The late model seat pressure specs were I=93/182 E=97/180 Open/closed.

I measured a used head gasket I have saved. It measures .031-.032" I keep the gasket so I can build up the motor and check for valve to piston clearance without destroying a good/new gasket!

GL

[GTJIM]

Thanks Travis, Your points are well taken. Paul, thanks for expanding the info.
Gary - a good change! I posted mainly because I think we tend to overload Bob from time to time and he may just get exhausted from repeating stuff. His vast Opel experience is one of our Communities major assets. Nobody also has many years of Opel experience that are just as valuable to us. As does Travis.

I have spent years building Flathead V8s; Studebaker 6s and V8s plus a Jaguar or two and some experience with SB Chevy, Isuzu and Holdens. The Opel CIH engine is one of the most interestingly different engines that I have come across. I can appreciate why "molesting" the block/head surface is somehing to be avoided if possible but acknowledge that sometimes; "Needs must - when the Devil drives" and now we have much of the info on what happens and why plus what to do to fix the problems "decking" causes.

Can't understand why normally sane people use rough idling cams on the street - The standard Opel hydraulic camshaft is much under-rated with peak power being delivered about 5,000 rpm. Much of my comment is tempered with this thought and I shall use a new 2.0 litre CIH camshaft as a starting point.

[opelrun21]

Originally Posted by RallyBob I will work up some cam specs for you in the next day or so then. I would run a single 2" exhaust pipe out back, and then split it after the axle if I were you, as running twin single pipes on an Opel will lose you power. It is quite drastic in fact. Bob

I'm trying not to go over my rear axles with my exhaust, and just put a muffler with a down angle right before them. Is it going to hurt me to do this? If not should Ileave it 2 1/2 or go down to 2? If it is going to hurt me what should I do and why?

You guys are the reason my opel still gets out on the road.

[RallyBob]

I'm trying not to go over my rear axles with my exhaust, and just put a muffler with a down angle right before them. Is it going to hurt me to do this?

You may get exhaust fumes coming into the car because of this. Carbon
monoxide can kill you, so you be the judge...

If not should Ileave it 2 1/2 or go down to 2? If it is going to hurt me what should I do and why?

You didn't give any info about your engine, but if it's stock or nearly stock, a full 2.5" exhaust will kill your power. Keep it 2", and only use 2.5" over the axle.

[opelrun21]

Right now it is stock and it is killing my power. I put a 38 DGES on it and I'm jetting it to what I have gotten from what I've heared you said. (Bob)
135 Main
170 air corrector
The rest was right on the carb when I bought it.I only put the header on because I had all that torn apart. So if I was going to drive it with the stock motor until I can build the 9:1 motor I should run 2 off the header and no matter what always go over the rear axles? Hoppfully when the other motor is built I can still holla at you guys for the knowledge I don't have.


-------------
it's a 73
yeah way before our time

[RallyBob]

Running a short exhaust (before axle) with that header will definitely favor high rpm power instead of torque.

On the DGAS, did you change the emulsion tubes? That's more important than the jet changes IMO.

Bob