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Old 07-26-2020, 10:22 PM   #1
fatcatbestcat
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Default B20 - Cam for an oddly specific build

Hello all,

I'm still in the middle of building up a B20 for my 144, and still going through all the performance parts I could throw on.

The engine in question in a B20D (I previously thought it was a 20B, but I discounted that by looking into the combustion chambers).
  • I'm swapping an early B20F head onto it (which I'm doing a fairly basic port job to and upgrading to 37mm valves)
  • I'm running a header instead of the stock combination manifold
  • I'm probably going to be running 45 DCOE carbs
  • I'm probably going to leave this engine with 8.7:1 compression (partially because you can find 87 octane anywhere, but I'm also thinking about doing a carb'd turbo in the future)
  • Probably going to be a mostly street-driven engine

I'm taking the stock cam out (it had been run flat), and I'm deciding what cam to replace it with. The previous owner included what was alleged to be a NOS 'D' cam and lifters, but I really don't know how to be sure - even if that's correct for this application.

If anyone has any suggestions, let me know. I'm thinking about doing an Iske or IPD cam.
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Old 07-26-2020, 11:08 PM   #2
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Run the D.
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how psi stock cna support?

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Old 07-27-2020, 12:45 AM   #3
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Run the D.
What he said. Apparently there are markings on the end of the cam which might help you identify it.

What did looking into the combustion chambers tell you?

You can decode your engine from this:

https://www.scandcar.com/motortypen-volvo/
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Old 07-27-2020, 10:39 AM   #4
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Originally Posted by c1800 View Post

What did looking into the combustion chambers tell you?


https://www.scandcar.com/motortypen-volvo/
Comparing the cylinder head pulled of my carb'd engine with the EFI one, the combustion chamber volumes look to be exactly the same. The valves are the same size too, oddly enough.

EDIT: I'm not totally sure how to read this, but the cam I pulled from the engine says 'K28' and 'S' on it.

The engine's currently in the car, and the block is too crusty for me to make any numbers out except the very obvious 'B20' on the right side.

Also dug the cam out, and there's a big 'D' stamped into the side of it. Seems conclusive enough to me. A friend gifted me an old set of Iske 'VL123' pushrods and I have some (allegedly compatible) SBC lifters from a previous project lying around. Is switching over from stock valvetrain components to those worthwhile?

Last edited by fatcatbestcat; 07-27-2020 at 11:18 AM.. Reason: got the cam out
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Old 07-27-2020, 11:17 AM   #5
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B20 combustion chambers are all the same. The late B20 carb heads also had 44mm intake valves, can be identified as they have P shape castings where the injection inlet would be. If they are not there and no injection inlet holes then it is originally a 42mm inlet head.

You can measure valve lift with a dial indicator to see if they are all in spec and what they should be.

Last edited by mitch1971; 07-27-2020 at 11:25 AM..
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Old 07-27-2020, 12:01 PM   #6
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Originally Posted by mitch1971 View Post
The late B20 carb heads also had 44mm intake valves, can be identified as they have P shape castings where the injection inlet would be. If they are not there and no injection inlet holes then it is originally a 42mm inlet head.

Here's the head that came off the engine. No injector holes, so definitely a carb head.


The one I'm going to port and throw on; looking at v-performance's guide, this looks like a '72-'73 F-head.
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Old 07-27-2020, 12:22 PM   #7
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That looks like an injection head, just plugged holes.
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Old 07-27-2020, 12:25 PM   #8
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Originally Posted by cwdodson88 View Post
That looks like an injection head, just plugged holes.
Oh. I didn't have to buy a separate head then.

Score, I guess? I have two injection heads now.
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Old 07-27-2020, 12:54 PM   #9
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Any opinions on an R-sport cam vs a D cam?
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Old 07-27-2020, 01:00 PM   #10
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Originally Posted by fatcatbestcat View Post
Any opinions on an R-sport cam vs a D cam?
If you mean D vs R cam, they are totally different animals. D is a stock cam. R is for racing, mainly rally and short track.
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Old 07-27-2020, 01:03 PM   #11
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Originally Posted by OttoB View Post
If you mean D vs R cam, they are totally different animals. D is a stock cam. R is for racing, mainly rally and short track.
Is it one of those where you have to set a really high idle?
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Old 07-27-2020, 01:10 PM   #12
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Originally Posted by fatcatbestcat View Post
Oh. I didn't have to buy a separate head then.

Score, I guess? I have two injection heads now.
Check the thickness of the heads. The F will be thicker than an E and if you want to keep the CR low then the F will be a better choice. The F casting will be more amenable to modification of the exhaust port because of additional material. Do a little research on port modifications on the B20 because opening up the exhaust port in the wrong places on the B20 will not give you the desired results.
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Old 07-27-2020, 01:16 PM   #13
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Originally Posted by 142 guy View Post
Check the thickness of the heads.
I don't have a set of calipers, but both heads seem to be about 3.5" thick from the gasket surface to the top of where the injector ports are supposed to be.

I'm almost undoubtedly measuring those wrong.
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Old 07-27-2020, 01:20 PM   #14
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Originally Posted by fatcatbestcat View Post

Also dug the cam out, and there's a big 'D' stamped into the side of it. Seems conclusive enough to me. A friend gifted me an old set of Iske 'VL123' pushrods and I have some (allegedly compatible) SBC lifters from a previous project lying around. Is switching over from stock valvetrain components to those worthwhile?
Not sure what you mean by 'side'. My recollection from 7 + years ago is that the D on the cam on my B20E was stamped into the back end of the shaft. However, that may only be for Volvo OEM replacements. I don't know what the aftermarket copies of the D cam have for markings.

If you want to drive the car in stop and go traffic, stay away from the R cam. Volvo replaced the D cam with the K cam I think in 1973. The K cam has the same advertised lift as the D cam; but, a nudge less duration with the result that it idles better. However, if your plan is to install dual DCOE 45 carbs then 'better idle' is clearly not high on your list of priorities.
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Old 07-27-2020, 01:25 PM   #15
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Originally Posted by 142 guy View Post
Not sure what you mean by 'side'. My recollection from 7 + years ago is that the D on the cam on my B20E was stamped into the back end of the shaft. However, that may only be for Volvo OEM replacements. I don't know what the aftermarket copies of the D cam have for markings.
Pretty sure mine is an aftermarket one. Did OEM ones say 'MADE IN USA' on the side?

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If you want to drive the car in stop and go traffic, stay away from the R cam.
Alright, so I'm guessing the idle (and probably also low-end torque) is going to suffer. I live in the city, so that's probably not ideal.

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However, if your plan is to install dual DCOE 45 carbs then 'better idle' is clearly not high on your list of priorities.
Nope.
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Old 07-27-2020, 01:25 PM   #16
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Originally Posted by fatcatbestcat View Post
I don't have a set of calipers, but both heads seem to be about 3.5" thick from the gasket surface to the top of where the injector ports are supposed to be.

I'm almost undoubtedly measuring those wrong.
I think A, B and F heads are all the same thickness, only difference the gasket.

If not using the D cam I'd go a modern cam from somewhere like Tinus Tuning or KG Trimning. I have a KG 10 cam in one engine with a E head and fitting a TT3 cam in my B20A engine. Postage to the US might kill the idea. It can get expensive as you need gaskets, followers etc and then may as well change the timing gear set while you are there and think about the clutch, lightened flywheel etc. Can be a can of worms if you get what I mean.

https://translate.google.com/transla...search&pto=aue

https://www.kgtrimning.org/tuning-special/b18b20b30/
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Old 07-27-2020, 01:36 PM   #17
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Originally Posted by fatcatbestcat View Post
I don't have a set of calipers, but both heads seem to be about 3.5" thick from the gasket surface to the top of where the injector ports are supposed to be.

I'm almost undoubtedly measuring those wrong.
The measurement points as defined in the service manual are from the cylinder contact face to the contact face for any of the head bolts. I don't know whether the head bolts are the same height as the injector mounting surface.

A stock B20 E head is 3.33 " thick. The F head is I think 3.43" thick so accuracy in measurement is important. The photo in post #2 is definitely an F head because the head casting is flat across the top of exhaust port #2 (compared to how it dips down above #3 in the casting). Both heads have the identical flat casting above exhaust port #2 indicating early F heads. Later F heads have flats across both ports #2 and #3. E heads and carb heads lack these flats.

If you are not going with a custom Cometic gasket, stay away from the Elring gasket for the fuel injected engines. They are all the thicker F head gasket and will make it all but impossible to establish a proper quench zone. Use the Volvo B head gasket which has a compressed height of 0.028"

Last edited by 142 guy; 07-27-2020 at 01:44 PM..
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Old 07-27-2020, 01:45 PM   #18
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Originally Posted by 142 guy View Post

Both heads have the identical flat casting above exhaust port #2 indicating early F heads. Later F heads have flats across both ports #2 and #3.
I suppose it's good that I have two, then. I can use one as a practice head, and probably keep the other since it has all the studs I need. It'll probably need to be cleaned, though.

Sounds like I'll just go with the D cam for now.
Thanks, everyone for the responses!

Last edited by fatcatbestcat; 07-27-2020 at 02:13 PM..
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Old 07-27-2020, 02:39 PM   #19
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Only the A and F heads are the same thickness.



The B head gasket doesn't have the bumps in the fire ring for the larger E/F combustion chamber so part of the fire ring is exposed. You can still get the thin E head gasket in a set from Volvo.

https://www.tascaparts.com/oem-parts...ket-kit-275553
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Old 07-27-2020, 06:00 PM   #20
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Originally Posted by hiperfauto View Post

The B head gasket doesn't have the bumps in the fire ring for the larger E/F combustion chamber so part of the fire ring is exposed. You can still get the thin E head gasket in a set from Volvo.

https://www.tascaparts.com/oem-parts...ket-kit-275553
I have seen that part number before and I remain confused! Every listing of the genuine Volvo 275553 gasket kit includes the correct thickness 0.8 mm head gasket; but, they list the gasket kit for application to both the B20B and B20E. In addition, all of the kits I have seen labeled both Volvo and Elring are based upon the Elring 0.8 mm head gasket with the Elring B20B part number. This plus internet 'wisdom' led me to believe that the actual E head gasket was now unobtanium.

Are some of these kits that are labeled as genuine Volvo just a package of Volvo parts and Elring parts put together by vendors?

https://www.ebay.com/itm/Genuine-Vol...sAAOSw3iRe0mYf
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Old 07-27-2020, 07:33 PM   #21
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That looks like the Volvo kit. It comes with a thin Elring head gasket and the rest of the parts are in Volvo bags. The head gasket thickness info in the pic I posted above is incorrect. B20B and B20E use the same gasket presumably because the late B20B head uses the FI casting. The early B20B uses a different gasket.

The Elring kits with the thin head gasket are NLA.

FYI, the Volvo kit doesn't come with the intake/exhaust gasket like the Elring kit did so be prepared to shell out more $$.
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