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Opeler
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444 Posts
Discussion Starter #1
Looking to start a concise thread on building a street 2.4 head. There are many threads on porting so not looking to duplicate those threads. The goal is what should you be telling your local machine shop to do with these heads? I'll start with the below:

  • standard clean and magnaflux to check for issues
  • Upgrade to SBC stainless valves, sizes 1.94" and 1.60" for intake/exhaust
  • add oil plug from OGTS in back of head
  • replace cam bearings
  • install mid-level good street combo cam (OR-66 or GM-77 or something else?)
Questions:
  • What valve springs or set of double springs are recommended for a bigger cam?
  • What valve spring pounds of force should be targeted for closed and open positions of each valve?
  • What valve stem heights are acceptable on the 2.4 head?
  • any other build considerations?
P.S. If the above has been covered concisely in another thread I apologize.....could not find all the above.
 

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Super Moderator
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13,458 Posts
Looking to start a concise thread on building a street 2.4 head. There are many threads on porting so not looking to duplicate those threads. The goal is what should you be telling your local machine shop to do with these heads? I'll start with the below:

  • standard clean and magnaflux to check for issues
  • Upgrade to SBC stainless valves, sizes 1.94" and 1.60" for intake/exhaust
  • add oil plug from OGTS in back of head
  • replace cam bearings
  • install mid-level good street combo cam (OR-66 or GM-77 or something else?)
Questions:
  • What valve springs or set of double springs are recommended for a bigger cam?
  • What valve spring pounds of force should be targeted for closed and open positions of each valve?
  • What valve stem heights are acceptable on the 2.4 head?
  • any other build considerations?
P.S. If the above has been covered concisely in another thread I apologize.....could not find all the above.
That sized valve is good for a race prepped head, but not necessarily desirable for a street head. I’d use 1.88” intakes and stock sized exhaust (1.57 made from cut down Chevy valves) unless you are significantly porting the head and using an aggressive cam.

Springs depend on numerous factors. Weight of valvetrain parts, valve lift, aggressiveness of camshaft opening/closing ramps, and intended rpms.

If you are going with nitrous or forced induction that is another consideration.
 
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Opel Rallier since 1977
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1,618 Posts
Agreed... 1.88" valves were used on stock 360 (5.9L) heads.

I would start with the general cam selection....type, duration, and lift.... to start the process on the valve springs. Very generally, 90-110 lbs seat force to start with. Open force depends on the cam acceleration rate 'over the nose'
 

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Opeler
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444 Posts
Discussion Starter #4
Copy Bob. Some more clarification:

The engine will be 2.6L using 97 mm bore and 88 mm stroked 2.4 crank. Rods are H-beam VW Golf 136 mm rods, pistons will be KB1745HC with some dish work to get the correct compression ratio. EFI induction, 4 to 1 header with 2.5" exhaust. No nitrous or forced air. I had planned to do some mild porting and polished based on your recommendations in previous threads. Nothing close to what you've done though! Some basic blending, port matching with manifolds, etc.
 

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Opeler
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444 Posts
Discussion Starter #6
What EFI are you going to do Mike, custom or factory Motronic? Reason I ask is if going factory, the aggressive cam may be a problem with the system
Keith,
Will be using the Holley Sniper EFI 2300 which I'm currently using on my 1.9 engine. Great unit and super easy to use. Fully tunable and has a self learning mode as well. Intake manifold is highly modified 1.9 manifold which as had both flanges cut off and replaced with 2.4 head and Holley 2300 flanges. Underside of intake has the "RallyBob Tent" modification. Also port matched to head and ported as much as I can do to smooth out all transitions.
 

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I'll go ahead and add a question, since my head is at the machine shop.

Do hardened seats only need to be put for the exhaust valves.
 

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I'll go ahead and add a question, since my head is at the machine shop.

Do hardened seats only need to be put for the exhaust valves.
Yes
 

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Just Some Dude in Jersey
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14,288 Posts
Install screw in pipe plugs at all oil passageways that had freeze plug-type plugs.

What are your plans for your thermo housing/heater/bypass? PJ advocates drilling the head to connect the passageways. Are you going to use the new thermos housings that Charlie got? I'm using a 195* t-stat with a bypass hole in it.
 

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I'll go ahead and add a question, since my head is at the machine shop.

Do hardened seats only need to be put for the exhaust valves.
If your head is a genuine X24 from a C24NE or a P2E/P22E, it already has stainless steel inserts from the factory.
 

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Opeler
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444 Posts
Discussion Starter #11
Gordo, I've got the adapter plate for the housing but I don't like that...not so clean. I've also designed my own housing which has two coolant ports front and back as we as bosses for both stock Opel CTS and the larger EFI CTS. Will most likely drill the head to avoid an external coolant bypass hose. I like clean installs!

So still looking for spring heights or any other guidance for machine shop. Any recommendations on springs?
 

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13,458 Posts
So still looking for spring heights or any other guidance for machine shop. Any recommendations on springs?
That still depends on the cam specs!
 

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Opel Rallier since 1977
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1,618 Posts
That still depends on the cam specs!
Yup.... need to know the cam. How the engine/car will be used is a guide to the cam sizing, but knowing if it will be an old, slow lift-rate grind, or some sort of newer grind will help.

But, some things you will probably be doing regardless: machine the head for dual springs, machine down the intake seats a bit (IDK if you can safely take them down to the same level as the exhaust seats), and prep guide OD for what ever stem seals you think will be used.
 

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Opeler
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444 Posts
Discussion Starter #15
Cam choice was one of my original questions above but what is recommended by Charles is the GM-77 , post #103 here: Modern 2.5 -2.7L engine build thread and copied below:

Lobe Center 109 degree

Intake:
Dur - 276
Open 29 BTDC
Close 67 ATDC
Cam Lift .310
Valve Lift .465

Exhaust:
Dur - 276
Open 67 BTDC
Close 29 ATDC
Cam Lift .310
Valve Lift .465

Overlap 58 degree

Timing checked .007 Open after lifter rise

Timing @ .050

Intake:
Dur - 238
Open 10 BTDC
Close 48 ATDC

Exhaust:
Dur - 238
Open 48 BTDC
Close 10 ATDC

Goal again is a streetable combination that can run on available pump gas.
 

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Opel Rallier since 1977
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1,618 Posts
I'll express one item of concern over this cam as the specs are listed: The duration difference between what would be considered the 'advertised duration' (shown above measured at .007" lifter rise) and the .050" lifter duration is only 38 degrees. And, if we took the duration at .006" lifter rise, (which is a more common standard across the industry) then it would probalby come in around 40 degrees duration difference. That is abnormally small for a hydraulic cam. In fact, I am not aware of any hydraulic cam grind with such a short difference in advertised to .050" duration, from sources like Lunati or Howards, who make some modern quick-opening cams like the Lunati Voodoo grinds.Those typically have a 43-44 degree difference in the same durations, and that is about as fast as you will find in an off-the-shelf, hydraulic flat-tappet cam these days.

Now Isky has the knowledge to do cams well, but this is quite a departure from the standard Opel cam grinds. I profiled an OR-4H recently, and the duration difference for the same lift specs was 60 degrees....! The concerns are for collapsing the hydraulic lifters at high RPM's and for the springs, which are going to have to be quite a bit stiffer for this quick rate of rise.

Not saying to not use this but I would be aware of the implications. I like the quick-opening cams for street use as they can allow the dynamic compression ratio to stay up and that helps low RPM torque. But this particular cam grind is of concern to me. It may fall out to be OK in the details of the cam profile, but we just don't have that level of detail.
 

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Senior Contributor
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4,971 Posts
This is what is in my 2.2. You can definitely use the info on the valves, guides, and seals. Unfortunately Roger never gave me the spring info. The cam, at this point, is more aggressive than I would like. If you are looking for a smooth running street machine I would go for a torquer. You will still have plenty of zip with less noise.

The following was copied from my EFI 2.2 Motor Build Thread.
-‐‐--------------------------------------------------------------------
Chevy Valves - SI Valves Single Groove Competition Series Stainless Steel
Undercut 11/32 Stems
Intake 1.880 Dia. 4.910 long P/N 1259E
(originally in Chevy V6)
Exhaust 1.600 Dia. 4.928 long P/N 1202SG
(originally in Chevy SB 265->400 CID)
Guides are Manganese Bronze Pioneer P/N 813102
Seals are Crower P/N 86072T-1
Exhaust Seats are SI Valves 1.693" OD 1.438" ID 7/32" Deep
P/N VS-14316821SD
Intake Seats were not used
Spring seat shims and cups to replace rotators are custom made by Roger
Installed height is 95 when seated and 242 open (from Roger)
This leaves only .100" before spring bind when running about .015" lash
58 CC/Chamber
Exhaust flowed 101
Intake flowed 142 @ .550 Lift
Cam blank was purchased from Roger and ground by Cam Techniques
Intake profile #F315 (.490 lift, 243 @ .050 Duration)
Exhaust profile #F313 (.487 lift, 248 @ .050 Duration)
Lobe separation 108 Deg.
3 Deg. Advance ground in

Exhaust ports were matched to the gasket, I will try to take picture of the internal porting work, but I don't know how they will come out with everything assembled.

.020" was taken off head to clean it up
Springs are ISKY I am waiting for the P/N from Roger
Retainers I believe are Manley, also waiting for Roger
Locks are ? also waiting for Roger


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Jeff
 
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This is what is in my 2.2. You can definitely use the info on the valves, guides, and seals. Unfortunately Roger never gave me the spring info. The cam, at this point, is more aggressive than I would like. If you are looking for a smooth running street machine I would go for a torquer. You will still have plenty of zip with less noise.

The following was copied from my EFI 2.2 Motor Build Thread.
-‐‐--------------------------------------------------------------------
Chevy Valves - SI Valves Single Groove Competition Series Stainless Steel
Undercut 11/32 Stems
Intake 1.880 Dia. 4.910 long P/N 1259E
(originally in Chevy V6)
Exhaust 1.600 Dia. 4.928 long P/N 1202SG
(originally in Chevy SB 265->400 CID)
Guides are Manganese Bronze Pioneer P/N 813102
Seals are Crower P/N 86072T-1
Exhaust Seats are SI Valves 1.693" OD 1.438" ID 7/32" Deep
P/N VS-14316821SD
Intake Seats were not used
Spring seat shims and cups to replace rotators are custom made by Roger
Installed height is 95 when seated and 242 open (from Roger)
This leaves only .100" before spring bind when running about .015" lash
58 CC/Chamber
Exhaust flowed 101
Intake flowed 142 @ .550 Lift
Cam blank was purchased from Roger and ground by Cam Techniques
Intake profile #F315 (.490 lift, 243 @ .050 Duration)
Exhaust profile #F313 (.487 lift, 248 @ .050 Duration)
Lobe separation 108 Deg.
3 Deg. Advance ground in

Exhaust ports were matched to the gasket, I will try to take picture of the internal porting work, but I don't know how they will come out with everything assembled.

.020" was taken off head to clean it up
Springs are ISKY I am waiting for the P/N from Roger
Retainers I believe are Manley, also waiting for Roger
Locks are ? also waiting for Roger


Show Full Signature
Jeff
Wow, that is an aggressive cam!
 

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Opel Rallier since 1977
Joined
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1,618 Posts
This is what is in my 2.2. You can definitely use the info on the valves, guides, and seals. Unfortunately Roger never gave me the spring info. The cam, at this point, is more aggressive than I would like. If you are looking for a smooth running street machine I would go for a torquer. You will still have plenty of zip with less noise.

The following was copied from my EFI 2.2 Motor Build Thread.
-‐‐--------------------------------------------------------------------
Chevy Valves - SI Valves Single Groove Competition Series Stainless Steel
Undercut 11/32 Stems
Intake 1.880 Dia. 4.910 long P/N 1259E
(originally in Chevy V6)
Exhaust 1.600 Dia. 4.928 long P/N 1202SG
(originally in Chevy SB 265->400 CID)
Guides are Manganese Bronze Pioneer P/N 813102
Seals are Crower P/N 86072T-1
Exhaust Seats are SI Valves 1.693" OD 1.438" ID 7/32" Deep
P/N VS-14316821SD
Intake Seats were not used
Spring seat shims and cups to replace rotators are custom made by Roger
Installed height is 95 when seated and 242 open (from Roger)
This leaves only .100" before spring bind when running about .015" lash
58 CC/Chamber
Exhaust flowed 101
Intake flowed 142 @ .550 Lift
Cam blank was purchased from Roger and ground by Cam Techniques
Intake profile #F315 (.490 lift, 243 @ .050 Duration)
Exhaust profile #F313 (.487 lift, 248 @ .050 Duration)
Lobe separation 108 Deg.
3 Deg. Advance ground in

Exhaust ports were matched to the gasket, I will try to take picture of the internal porting work, but I don't know how they will come out with everything assembled.

.020" was taken off head to clean it up
Springs are ISKY I am waiting for the P/N from Roger
Retainers I believe are Manley, also waiting for Roger
Locks are ? also waiting for Roger


Show Full Signature
Jeff
Good write up Gold... many thanks. If you run across any info on the durations at low valve openings, I'd love to see it. Whose cam lobe profiles are those?
 
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