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2.2 OR 2.4 HEAD ? WHICH IS BEST ?


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Hi all. Advice please. 

 

So had my car on the rollers this weekend for a setup and map. After hours of tinkering we could only get 140hp. Now the car runs better than it ever has and I can't thanks Antonio and Steve @ A&M enough for the time and attention to detail they put into my car last Saturday great set of guys. However after spending so much on this engine and the mods it's had 140hp was quite the disappointment......

Engine specs 

2.4 block fully rebuilt with 96mm forged woosner pistons and rods, ground and balanced crank, new shells, new mains, 2.0 big valve head, brand new gs racing valves, up rated valve springs, ported, solid lifters, Kent op254 cam, vernior pully, jenvey 45 throttle bodies, irmscher inlet manifolds 300 injectors, stand alone management, 4 branch manifold into 2 inch back.

 

We can now only assume that the head is the restriction holding it back. So the question now is do I go to a 2.2 or 2.4 head ? I've heard mixed reviews and I'm not sure what to do for the best. Can anyone advice the pros and cons between the 2 heads and which I'd be better using on this lump ? 

Thanks 

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Hi Andy

I used to have a 2.4 CIH in my rally car with a 2.0 bvh by PMC and it made around 240bhp at the flywheel. It was running a PMC 320 degree 13mm lift cam and twin 48’s. Peak power was around 7,500 rpm, and it didn’t drop much to 8,600. There was also good power from 4,000 rpm. I was running circa 11.5:1 CR using super with octane booster/lead replacer

Personally I think the 2.0 head ported with the 46/41mm valves is better than the 2.4 head as the combustion chamber is smaller giving a higher compression ratio with the pistons with the lump on the crown

I’m surprised it’s not making nearer to 180/190, and wouldn’t have thought the head was restricting it by 40bhp.

There isn’t something else at fault is there? I once had a rally prepared 2.2 CIH that wouldn’t make much more than 150. Turned out the head builder (who shall remain nameless) fitted the wrong valve springs which we’re going coil bound and it wiped the lobes of a Schrick 326 cam while running in.

Would be interested to understand as I’m planning on building something similar but I only have 2.4 heads. I actually have a spare std 2.4 head if you want to try one. Would need refurbing though

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What valve size is the head you have fitted? You just say bvh and i've seen many variations of those over the years. I've run a bvh with 45/40 valves on a 2.0 bottom end with an op234cam and standard injection and made 150bhp, so 140 from what you have isn't right certainly. If the valves are smaller than 45/40 46/41 they would be a restriction certainly and loosing some power but i wouldn't expect that to be enough to give such a low figure.

Also as i say on FB cam timing is the thing i'd get right first. Its not that complicated to do and it can loose a load of power being just a few degrees out.

 

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Could it be the cam? Im not sure what the Kent op254 cam is like. Ran a 2.1 with big vale 2.0l head and that was about 150bhp. Think my cam was the 234 but that was a long time ago! Running the ENEM cam in the 2.4 and that just pulls right through the rev range, not sure on bhp on this one as never got back for the full power run due to the old covid! but feels about 180bhp ish.

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12 hours ago, Moonmonkey said:

Hi Andy

I used to have a 2.4 CIH in my rally car with a 2.0 bvh by PMC and it made around 240bhp at the flywheel. It was running a PMC 320 degree 13mm lift cam and twin 48’s. Peak power was around 7,500 rpm, and it didn’t drop much to 8,600. There was also good power from 4,000 rpm. I was running circa 11.5:1 CR using super with octane booster/lead replacer

Personally I think the 2.0 head ported with the 46/41mm valves is better than the 2.4 head as the combustion chamber is smaller giving a higher compression ratio with the pistons with the lump on the crown

I’m surprised it’s not making nearer to 180/190, and wouldn’t have thought the head was restricting it by 40bhp.

There isn’t something else at fault is there? I once had a rally prepared 2.2 CIH that wouldn’t make much more than 150. Turned out the head builder (who shall remain nameless) fitted the wrong valve springs which we’re going coil bound and it wiped the lobes of a Schrick 326 cam while running in.

Would be interested to understand as I’m planning on building something similar but I only have 2.4 heads. I actually have a spare std 2.4 head if you want to try one. Would need refurbing though

Thanks for the info . My valve are 37 and 45. No idea on compression ratio no idea how to work these things out, on compression test it was pumping 240 psi 👀 .... we checked the valve springs was not going coil bound static but I suppose that doesn't mean there are not when under load and running. How can this be assessed? 

It's doing my head in. Pun intended 🙈

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32 minutes ago, ANDY ABBOTT said:

Thanks for the info . My valve are 37 and 45. No idea on compression ratio no idea how to work these things out, on compression test it was pumping 240 psi 👀 .... we checked the valve springs was not going coil bound static but I suppose that doesn't mean there are not when under load and running. How can this be assessed? 

It's doing my head in. Pun intended 🙈

Exhaust valves look a bit small at 37, normally on a BVH I would go for 41mm. A C24NE head has 41mm standard (I think)

The C24NE Wossner pistons compression ratio are typically quoted as 12.0, I presume that is with a C24NE head which have a 54cc combustion chamber, depending which 2.0 head you have the combustion chamber can be as small as 49.8cc.
 

Compression Ratio = (swept volume + combustion chamber volume) divided by combustion chamber volume. 

I would say 240psi is very good cranking pressure so no cylinder leaking. CR and compression test are not the same thing as the pressure test can be influenced by camshafts. However I don’t think CR is the issue.

In terms of the valves springs going coil bound you can assess it by measuring the gap between coils at full lift with feeler gauges. You could also check that the cam lobes are not worn by using a dial gauge on the top of the valve cap and check the maximum valve lift/opening. A Kent OP254 has a max inlet valve lift/opening of 11.93mm and exhaust of 11.88mm. If the cam lobes have been worn you will see a lower opening value

I think Dave’s point to check cam timing is also a good idea. 103 degrees ATDC will give most power. I think standard is 110 ATDC

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Posted (edited)
4 hours ago, Moonmonkey said:

Exhaust valves look a bit small at 37, normally on a BVH I would go for 41mm. A C24NE head has 41mm standard (I think)

The C24NE Wossner pistons compression ratio are typically quoted as 12.0, I presume that is with a C24NE head which have a 54cc combustion chamber, depending which 2.0 head you have the combustion chamber can be as small as 49.8cc.
 

Compression Ratio = (swept volume + combustion chamber volume) divided by combustion chamber volume. 

I would say 240psi is very good cranking pressure so no cylinder leaking. CR and compression test are not the same thing as the pressure test can be influenced by camshafts. However I don’t think CR is the issue.

In terms of the valves springs going coil bound you can assess it by measuring the gap between coils at full lift with feeler gauges. You could also check that the cam lobes are not worn by using a dial gauge on the top of the valve cap and check the maximum valve lift/opening. A Kent OP254 has a max inlet valve lift/opening of 11.93mm and exhaust of 11.88mm. If the cam lobes have been worn you will see a lower opening value

I think Dave’s point to check cam timing is also a good idea. 103 degrees ATDC will give most power. I think standard is 110 ATDC

Thanks again. The cam is brand new and only covered a couple hundred miles. We did check the springs when we fitted the head and they was no coil bound. Mr rutts helped me rebuild the head  

Edited by ANDY ABBOTT
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I can't find what i wrote before about cam timing, but i'll give it a go explaining it again here.

Please note this is how i do it,i'm not saying this is how anyone else should do it, or that this is the only way/ or even the right way :ph34r:

First you need to know where TDC (top dead centre) of number 1 piston is. You can use the flywheel marker/ woodruff key position or whatever you like for this but it needs to be as accurate as you can possibly get it.

For me I find this while the head is off and a dial gauge is set up against the top of no1 piston. Slowly rotate crank watching dial gauge, its upward travel will seem to stop for several degrees of crank rotation. TDC is half way between it stopping and starting again (i put a little tipex dot at each end point and check it a couple of times to be sure). I then add a groove on the crank pulley lip in line with the big timing case marking. I use a small triangular file and drop a bit of tipex in (wiping off the 2 other dots from before)

Then i take the pulley off and lay it face down on a timing disc (the big plastic thing you get with kent cam kits thats basically a full 360deg protractor) Putting the new mark you just made on the 0 line go around clockwise to the timing for you cam (which is 103ATDC for the op254 according to kents site) and thats where you want to add another groove/tipex etc. Its clockwise with the pulley face down so when the pulley is back on the engine the mark will be 103deg of engine rotation after the tdc mark.

To make it a bit easier i draw a line from 0 to the centre of the disc and 103 to the centre. Put your tdc mark on the 0 line with the pulley face down and as central on the disc as you can and the 103 line shows where your new mark goes.

Then with the pulley back on the engine, head on and bolted down with cam fitted you setup the dial gauge on top of no1 cylinders inlet valve. Then watching the dial gauge again rotate the engine slowly until it tops out, there is a small dead spot like the piston topping out but its a lot less on the cam. But full lift is in the centre of those points again.

Now look at the crank pulley. If the long timing case mark lines up spot on to your new 103deg mark the cam timing is correct. If it doesn't you need to loosen the allen bolts in the vernier slightly (you'll need to make a short extension allen key to reach them and probably take the plastic bit out of the centre of the cam). Then you can move it slightly and retighten. Then rotate engine twice and check again.

If its better but not enough go a little more the same way. If its worse go the other way with the adjustment. I'm not going to try explain which way to go for what movement on the pulley as i normally get it wrong and then go back the other way even after these many years :huh:

Couple of additional notes:

You can add the 103deg mark to the pulley without taking it off the engine by holding the disc to the face of it. But for what little it takes to get the pully off i find it easier.

Don't use a hex bit in a holder on a socket to loosen the vernier bolts, if that drops out down the timing case you are taking the engine apart to get it back (don't ask how i know its a painful memory from long ago!)

If you hit the end of the slots in the vernier and still need to go further you will need to move the timing chain 1 tooth along.

Make sure if using a dial gauge that the mount thats holding it is as firm as it can be, any movement or shake will screw up your work

When you think you are right with a mark rotate the engine by hand a couple of full revolutions and see if it still looks right.

 

Right i think that makes sense (at least to me) but i'll come back later and read it again and see if it still does then......

 

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Posted (edited)
8 hours ago, mantasrme said:

I can't find what i wrote before about cam timing, but i'll give it a go explaining it again here.

Please note this is how i do it,i'm not saying this is how anyone else should do it, or that this is the only way/ or even the right way :ph34r:

First you need to know where TDC (top dead centre) of number 1 piston is. You can use the flywheel marker/ woodruff key position or whatever you like for this but it needs to be as accurate as you can possibly get it.

For me I find this while the head is off and a dial gauge is set up against the top of no1 piston. Slowly rotate crank watching dial gauge, its upward travel will seem to stop for several degrees of crank rotation. TDC is half way between it stopping and starting again (i put a little tipex dot at each end point and check it a couple of times to be sure). I then add a groove on the crank pulley lip in line with the big timing case marking. I use a small triangular file and drop a bit of tipex in (wiping off the 2 other dots from before)

Then i take the pulley off and lay it face down on a timing disc (the big plastic thing you get with kent cam kits thats basically a full 360deg protractor) Putting the new mark you just made on the 0 line go around clockwise to the timing for you cam (which is 103ATDC for the op254 according to kents site) and thats where you want to add another groove/tipex etc. Its clockwise with the pulley face down so when the pulley is back on the engine the mark will be 103deg of engine rotation after the tdc mark.

To make it a bit easier i draw a line from 0 to the centre of the disc and 103 to the centre. Put your tdc mark on the 0 line with the pulley face down and as central on the disc as you can and the 103 line shows where your new mark goes.

Then with the pulley back on the engine, head on and bolted down with cam fitted you setup the dial gauge on top of no1 cylinders inlet valve. Then watching the dial gauge again rotate the engine slowly until it tops out, there is a small dead spot like the piston topping out but its a lot less on the cam. But full lift is in the centre of those points again.

Now look at the crank pulley. If the long timing case mark lines up spot on to your new 103deg mark the cam timing is correct. If it doesn't you need to loosen the allen bolts in the vernier slightly (you'll need to make a short extension allen key to reach them and probably take the plastic bit out of the centre of the cam). Then you can move it slightly and retighten. Then rotate engine twice and check again.

If its better but not enough go a little more the same way. If its worse go the other way with the adjustment. I'm not going to try explain which way to go for what movement on the pulley as i normally get it wrong and then go back the other way even after these many years :huh:

Couple of additional notes:

You can add the 103deg mark to the pulley without taking it off the engine by holding the disc to the face of it. But for what little it takes to get the pully off i find it easier.

Don't use a hex bit in a holder on a socket to loosen the vernier bolts, if that drops out down the timing case you are taking the engine apart to get it back (don't ask how i know its a painful memory from long ago!)

If you hit the end of the slots in the vernier and still need to go further you will need to move the timing chain 1 tooth along.

Make sure if using a dial gauge that the mount thats holding it is as firm as it can be, any movement or shake will screw up your work

When you think you are right with a mark rotate the engine by hand a couple of full revolutions and see if it still looks right.

 

Right i think that makes sense (at least to me) but i'll come back later and read it again and see if it still does then......

 

Thanks David for the detailed info but this is way out of my league. I'll keep searching for someone to sort this for me 😀

Edited by ANDY ABBOTT
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Yup, good info there from David 👍

Obviously both myself and David have had the same thoughts about where your at currently and the cam timing been out. It’s not that hard when you see it done Andy if you was next to someone settings it up. The hardest part is actually finding the dwell on TDC and getting the crank timing wheel to accurate zero degrees. Rest is quite simple. Shame your so far away. But there are tons of guys who will be in your area that do this. Rally groups or even grass trackers will probably find someone who can do these in their sleep with the right dial gauge, angle disc etc.

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4 hours ago, Jessopia74 said:

Yup, good info there from David 👍

Obviously both myself and David have had the same thoughts about where your at currently and the cam timing been out. It’s not that hard when you see it done Andy if you was next to someone settings it up. The hardest part is actually finding the dwell on TDC and getting the crank timing wheel to accurate zero degrees. Rest is quite simple. Shame your so far away. But there are tons of guys who will be in your area that do this. Rally groups or even grass trackers will probably find someone who can do these in their sleep with the right dial gauge, angle disc etc.

Can this be done in situe? 

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10 hours ago, ANDY ABBOTT said:

Can this be done in situe? 

It’s a lot easier to do with the engine out, I’ve never done it with the engine in situ but i can’t see why it couldn’t be done. It’s just more awkward to set up and see the timing marks/protractor. The biggest issue is finding an accurate measure of TDC with the cylinder head on. You could work it out from the ignition timing marks, and some engines have a ball bearing and a pointer on the flywheel. You could strip off some ancillaries and take the radiator out to make it easier to work on.

I would be happy to come over and help you do it, I’m just getting over Covid but should be ok in a few days😊

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Posted (edited)
11 hours ago, ANDY ABBOTT said:

Can this be done in situe? 

Yes easier with engine out, but everything is of course. But remove the radiator and then it’s really easy too.  I lost count of how many times I was messing with mine, quite surprising swinging a couple of degree either how much it changes the engine characteristics. But obviously that’s the advantage of VVTI on the modern engines.

‘It’s as easy as rocker cover off, n01 plug out, for getting the true TDC,  Front crank pulley might need to be off to get the degree wheel on (depends what type), but I have always been able to mount over the pulleys, And access to the vernier adjustment bolts through the front cover plate on head. 

There is no engine stripping to do, so pretty simple mate. Only reason I say to remove radiator is for easier access to get in an setup the crank angle wheel and make up a zero marker with a welding rod ( https://www.demon-tweeks.com/piper-cams-camshaft-timing-disc-pipdisc )
 

there are some guides about that might confuse the way to set the cam with ATDC, so careful as those are setting up by valve lift at TDC and IMHO is more technical and easier to get wrong.
‘Full lift  @ Deg ATDC Looking for the Maximum number seen on the dials, so you don’t need to worry about moving and resetting the dial gauge between valves.

 

Sorry I have not been able to find a guide that would be suitable with pics that would potentially not add confusion, so the only written one is this. It explains what I am talking about the dwell at TDC and how to find the accurate point. It’s pretty good, so pointless me writing more about it, better to answer questions if you have any. Take a read mate with a cup of coffee.
https://www.kelfordcams.com/nz/technical-advice/the-sole-purpose-of-degreeing-your-cam/

 

Some pics showing the tools and wheel setup on a ford, principle of course, as with single cam you will only set full lift for inlet valve.

http://www.dubaipetrolheads.com/biggles/cams.html

 

 

 

7F73559D-3700-4FFB-AD5C-0237D3D907FF.jpeg

Edited by Jessopia74
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15 hours ago, ANDY ABBOTT said:

Can this be done in situe? 

I've always done it with the engine in the bay. But i have the head off to fit the new camshaft so its easy to get an accurate TDC marker. Finding tdc without the head off can be done its just harder to be accurate, and you really need to be accurate to get the cam timing spot on.

 

 

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ive probably missed it in all the info above but just in case !

yes the timing marker (pointer) in the bellhousing hole under the exhaust manifold reads against the ball in the flywheel to give std ignition timing .but the actual rivet that the pointer is fixed on with reads tdc. sorry if you already mentioned it .

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17 minutes ago, cam.in.head said:

ive probably missed it in all the info above but just in case !

yes the timing marker (pointer) in the bellhousing hole under the exhaust manifold reads against the ball in the flywheel to give std ignition timing .but the actual rivet that the pointer is fixed on with reads tdc. sorry if you already mentioned it .

Didn’t know the point about the rivet, I was thinking you could work back from ignition timing ball which is 5 degrees BTDC ( I think). The other option is to use a long reach  dial gauge onto the piston crown through the spark plug hole in the way David suggests with the head off. Just more awkward 

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58 minutes ago, cam.in.head said:

ive probably missed it in all the info above but just in case !

yes the timing marker (pointer) in the bellhousing hole under the exhaust manifold reads against the ball in the flywheel to give std ignition timing .but the actual rivet that the pointer is fixed on with reads tdc. sorry if you already mentioned it .

Not accurate enough, it needs doing with DTI on #1 piston for setting cam at DEGREEEs ATDC

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34 minutes ago, Moonmonkey said:

The other option is to use a long reach dial gauge onto the piston crown through the spark plug hole in the way David suggests with the head off. Just more awkward 

I've tried a rod down the plug hole so it moves with the piston but because of the low angle of entry it never really worked for me. Never tried a dial gauge down there, that could be ok as you can clamp the body firmly in place. The rod kept trying to fall out because more of it was outside the plug hole than in.

I've never compared the flywheel pointer/mark to a measured true tdc, will have to remember to do that next time i'm fitting a cam. Of course that assumes the flywheel hasn't been fitted out of rotational alignment by someone along its life while doing a clutch change and flywheel skim :blink:

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In my experience, the 2.4 head  is required for maximum power, with a 2.4 bottom end can make 340 bhp Turbo'd that is ( Richard Lamb's 90's white hatch). I will be happy with 300 bhp..the larger valves, higher inlet ports and large exhaust ports aid this performance. In your case, I would continue with what you have got, and carry out the above checks recommended by others. ie set the cam up/find your real TDC/timing... 

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On 06/07/2022 at 10:06, Jessopia74 said:

Sorry I have not been able to find a guide that would be suitable with pics that would potentially not add confusion, so the only written one is this. It explains what I am talking about the dwell at TDC and how to find the accurate point. It’s pretty good, so pointless me writing more about it, better to answer questions if you have any. Take a read mate with a cup of coffee.
https://www.kelfordcams.com/nz/technical-advice/the-sole-purpose-of-degreeing-your-cam/

Davids method made sense...that one on the Kelfords website is just a brain-bender...!

One thing I noticed on it tho, it says that if you're using hydraulic followers, you need to swap in solid lifters when timing in the cam...makes sense I think, but just never heard it mentioned before.

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58 minutes ago, moodoo said:

Davids method made sense...that one on the Kelfords website is just a brain-bender...!

One thing I noticed on it tho, it says that if you're using hydraulic followers, you need to swap in solid lifters when timing in the cam...makes sense I think, but just never heard it mentioned before.

yeah, it’s hard to find a guide that would not introduce more confusion unless you have done the task before. But fair play for some having a go to help others out. 
The Cam Andy has should be on solid followers anyway (if not then that’s an issue in itse, but yeah it’s worth a point that they should be swapped 👍

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17 hours ago, Jessopia74 said:

.....but yeah it’s worth a point that they should be swapped 👍

...good to know...does setting valve clearance with the solids come into it? I mean, if I had a Hydraulic cam, and swapped in solids to time it...what would I have to do regarding valve clearances?

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5 hours ago, moodoo said:

...good to know...does setting valve clearance with the solids come into it? I mean, if I had a Hydraulic cam, and swapped in solids to time it...what would I have to do regarding valve clearances?

If you use max lift ATDC method, then it’s immaterial tbh. The only reason you need to swap out the follower (just the 1!) is that hydraulic not been fixed can decompress a little not under your control when on full lift lobe segment  (top of the egg if you like). 
If setting by the lift@ TDC , then the clearance gap chooses will need to be taken into account , hence why I have tried to only reference the full lift ATDC method as it’s far less critical of ‘numbers’ as such, just what was the biggest seen on the dial gauge. As the needle (analogue) or digital will increase as full lift achieved and decreases either side of the highest point on the lobe ( there are special cams that have an extended duration of peak lift, with these it’s the first point that the cam hits the highest point you use).

 

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