B20 rebuild
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    Thread: B20 rebuild

    1. #1
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      B20 rebuild

      I'm rebuilding a B20B engine basically from scratch and I'm looking to get some more HP out of it. What should I do to the block and what other equipment should I lob in there to ensure good 140ish horsepower without compromising low-end torque and reliability? I've just landed a new job so I've got the resources but not quite the time for it so it's going to be a slow project

      If possible, I'd like to retain the twin SU's I have now as they are in good working order
      Last edited by ozzymanhattan; 03-15-2015 at 07:48 AM.

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    3. #2
      Moderator Phil Singher's Avatar
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      The most important thing is improving flow through the head. You should have that work done by an experienced professional, although it doesn't have to be a Volvo specialist. It's easy to do more harm than good if you try it yourself.

      Do not fit larger valves -- that works against you.

      Shave the head so the chamber volume is 52cc and use the .8mm head gasket.

      Bore the block to 90mm, which is a large as makes sense with the B head.

      Deck the block so the new pistons come up even with the deck at TDC. They probably won't all be even, but you can remove metal from the crowns of the taller pistons so they all match the shortest piston/rod stack. It's best to do a test assembly before the final decking.

      A Volvo D cam will improve power with no noticeable loss of low-end torque. This will be compatible with your SUs, which should have KD needles fitted.

      Lightening the flywheel won't add any HP, but it will improve acceleration in the lower gears. Simply remove as much as possible from the clutch side outboard of the pressure plate without going quite all the way down to the ring gear. It only takes of 1.5 kilos or so, but it will make a difference.

      Have everything balanced. It won't add power, but it makes the engine much more pleasant.

    4. #3
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      Thank you for your answer!

      Is the overbore important? It's at it's stock bore and if I don't completely overbore it I can bore it when I've done a million miles on it and the cylinders are all scratched up

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    6. #4
      Moderator Phil Singher's Avatar
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      The overbore is not all that important for performance, but I assumed you were planning on new pistons, which would require some amount of boring. 90mm is not particularly large as far as the block goes, it's the bore that's the best match for the combustion chambers in the B head.

    7. #5
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      I got a good price for the new pistons and overbore so I'm having it done soon! For the head I'm still to find someone who knows what they're doing

    8. #6
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      I pulled apart a B18 while waiting to acquire all parts for the B20 rebuild and I came across an aftermarket camshaft with the following markings on it, front to back

      (1) (1) [inside spheres] (J) (5) K-235-C MADE IN UK LYD 5 S-733

      any idea where I could find more information about it? or should I just try to measure the lift and duration? It's in good shape

    9. #7
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      Meh, I ordered the D cam anyway now waiting for the parts!

    10. #8
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      What will the compression ratio be after planing the block and having 52cc combustion chambers?

    11. #9
      Moderator Phil Singher's Avatar
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      10.0:1

    12. #10
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      Quote Originally Posted by Phil Singher View Post
      10.0:1
      Alright, thanks!

    13. #11
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      It seems that the head will be ready weeks later than other engine parts. Will it be OK to run the new inside parts in with a slightly planed B20A head before the custom head is finished?

    14. #12
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      Quote Originally Posted by ozzymanhattan View Post
      It seems that the head will be ready weeks later than other engine parts. Will it be OK to run the new inside parts in with a slightly planed B20A head before the custom head is finished?
      And to continue on that, what is a sufficient run in for all new insides for maximum reliability? I was thinking of running one day on idle, changing oils and then running 500 miles very carefully and changing oils again, adjusting valve clearances when necessary

      For oil I was planning 10W30 mineral, unless the valvoline racing 20W50 is on sale, I've heard it has useful additives

    15. #13
      Moderator Phil Singher's Avatar
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      You must use a break-in additive meant for use with flat tappet cams. A good parts store will have it.

      You want the engine to start with as little cranking as possible. Take the covers off the SU float bowls and fill them halfway with gas (then put the covers back on, of course). Fill the oil filter halfway and then spin it on quickly. Make sure the ignition timing is close to right. The battery should be fully charged. Don't forget to hook up the engine ground strap.

      Start the engine and run it at 2000 RPM for at least 20 minutes. You can rev it higher than that briefly, but do NOT let it idle. Then turn it off, drain the oil and toss out the filter. Let it all cool down fully.

      Replace the oil and filter (if you have some break-in additive left, put that in, but it's not strictly necessary). Remove the rocker assembly and retorque the head. Put the rockers back on and readjust the valves. Start the engine and warm it up at a fast idle, then you can let it idle long enough to tune the SUs and check the timing. As soon as possible, drive the car -- you don't need to go find the redline just yet, but use plenty of throttle. You need pressure in the cylinders to seat the rings. If you don't do this early, they may never seat fully.

      Work progressively up to higher revs over the first 150 km or so. After that, you can drive it however you want.

      When you put the modified head on, you don't need to break anything in over again. You do need to do the retorque and readjust the valves.

    16. #14
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      Oh interesting! Glad I asked! Thank you very much!

      I got the break-in additive free with the cam, and both the cam and the lifter packaging are most insistent on using it

      10 degrees before TDC should be close enough shouldn't it?

    17. #15
      Moderator Phil Singher's Avatar
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      Yes, 10 BTDC is a good starting point.

    18. #16
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      Cheers

      I think I'm going with Gulf SAE 30 Classic oil for the break-in, it should have plenty of ZDDP and other poisons to minimize the risks involved

    19. #17
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      I had to have the cylinders overbored anyway, #3 was going elliptic so I ordered a new set of 0.030 over Mahle pistons hoping for delivery next week so I can get this going again

    20. #18
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      I should have the engine close to running soon, I have thursday and friday off this week

      Any idea which of the 123ignition advance curves would be best suited for the modifications?

    21. #19
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      Took quite a bit of cranking because the old pointy diz' didn't give a spark so I had to change to the new one but eventually it fired up and ran beautifully. I even drove about half a mile but I have to adjust the clutch to be able to go further

    22. #20
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      Great progress on this! I'm sure you haven't thrashed it yet, but how does it feel overall?

      My daughter and I are starting assembly of my over-bored B18 this weekend ourselves after getting the a B20 head rebuilt, crank balanced, and flywheel turned. Just have to order a few remaining bits from VPAutoparts and get her shoved into the 444.
      Tony

      2017 Jaguar F-Pace R-Sport
      1958 Volvo PV444 - B20/M40 swap
      Past Bricks: '95 855, '98 V70T5M, '04 V70R M, '10 XC60, '83 245 Turbo, '12 XC70 T6 P*

    23. #21
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      Going well I've driven it about 1500 miles already, most to work and back. Soon it's time to swap the modified head in, but new head bolts are still on their way

    24. #22
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      Engine is going strong after about 6k miles!

      However I'm wondering what might be the reason the engine practically cuts off at 5500 RPM when accelerating. I feel that, if I corrected this, there would be some more performance until at least 6500 rounds.

    25. #23
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      Did you ever put on the "performance" head? Results?

    26. #24
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      Quote Originally Posted by R32rennsport View Post
      Did you ever put on the "performance" head? Results?
      Yeah, and I inspected it myself after the work was done, a lot of material came out with really smooth results. I don't think I ever pushed it beyond 5.5K before I got it, power peak was at around 4500 and started falling after that so there was no use pushing the engine further.

    27. #25
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      Oh never mind, I seem to have fixed it by accident I changed the timing gear, alternator and engine oils and soldered some feeble connections properly and sanded the important grounds nice and shiny.

      Now it pulls angrily to just over 6500 after which it steadily loses grunt. I'm happy

    28. #26
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      Quote Originally Posted by Phil Singher View Post
      This will be compatible with your SUs, which should have KD needles fitted.
      Ashamed to say, I forgot all about the needles for the last 18 months give or take current carb needles have about 200k miles driven with them

      Do these look about right?

      http://www.ebay.com/itm/Volvo-P1800-...-/281443866597

    29. #27
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      I'm about to fire up my build for the first time this weekend.

      Do you have to worry about overheating if you let it run at 2K RPM for 20 minutes? I'm still using the smaller B16B radiator and am concerned about that aspect. I am going to put two fans blowing on the front of the car like they do on dyno days.
      Tony

      2017 Jaguar F-Pace R-Sport
      1958 Volvo PV444 - B20/M40 swap
      Past Bricks: '95 855, '98 V70T5M, '04 V70R M, '10 XC60, '83 245 Turbo, '12 XC70 T6 P*

    30. #28
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      No, the load on the engine is minimal and it won't have an issue assuming the coolant is flowing. A n extra fan won't hurt a bit either.
      2005 V50 T5 AWD 6MT w/Heico tune, Heico exhaust, Bell intercooler, IPD TCV, Viva Forge CBV, Elevate rear swaybar and torque mount, Snabb shift kit, etc.
      2016 XC60 T6 AWD
      1956 PV444 complete, running
      1956 PV444 very original, very rough

    31. #29
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      It's cooler out this weekend anyway, so I have less concern about this. The junkyard starter I bought died between my bench test and the engine install and had to order another one. Firing it today (hopefully)!!
      Tony

      2017 Jaguar F-Pace R-Sport
      1958 Volvo PV444 - B20/M40 swap
      Past Bricks: '95 855, '98 V70T5M, '04 V70R M, '10 XC60, '83 245 Turbo, '12 XC70 T6 P*

    32. #30
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      If I slap this engine in a PV 544, can the drivetrain handle the torque?

    33. #31
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      It all depends on what you're starting with. If you have a B16B in there now, it likely has an M4 transmission. The bellhousing for that trans won't bolt up to a B18 or B20. And I wouldn't put an M4 behind this engine.

      However, if you already have a B18 in there, should be an easy swap. Your components can definitely handle this engine, no problem.

      Sent from my SAMSUNG-SM-G891A using Tapatalk
      Tony

      2017 Jaguar F-Pace R-Sport
      1958 Volvo PV444 - B20/M40 swap
      Past Bricks: '95 855, '98 V70T5M, '04 V70R M, '10 XC60, '83 245 Turbo, '12 XC70 T6 P*

    34. #32
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      Yeah, a -64 with factory b18. I'm going to do a swap between my two cars so i have time to fix the rust that's worryingly grown in the 144. Thanks for your answer!

    35. #33
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      Then you are all set to drop one of these in! Lucky man, I had to find an M40 trans and the correct bell-housing along with several other key bits. Still, was a lot of fun.

      Sent from my SAMSUNG-SM-G891A using Tapatalk
      Tony

      2017 Jaguar F-Pace R-Sport
      1958 Volvo PV444 - B20/M40 swap
      Past Bricks: '95 855, '98 V70T5M, '04 V70R M, '10 XC60, '83 245 Turbo, '12 XC70 T6 P*

    36. #34
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      I'm in the process of a B20 built, too, and I was wondering what you guys do as far as rod bolts go? Do you just reuse the existing ones?The rod bolts that I supposedly have coming in a roundabout way through ARP (third party) haven't shown up yet, and I ordered them almost a year ago. You might imagine I'm getting tired of waiting, because I don't know if they'll ever actually show up at this point.

      To give a background of the engine being built, here's a brief summary:
      B20F with 6-bolt crank installed, carbureted with dual SU HS6's on the shorty intake with the IPD performance headers.
      I've had the head shaved to 10.5:1 compression and had it worked over to wring the betterest performance out of it that I can, bored the cylinders forty-over (with pistons to match, of course) and a street performance cam.

      I have no idea how many miles the engine I'm using had on it when it was pulled, but it wasn't blown or anything.

      I really just don't want to blow up my engine by reusing rod bolts. Should I wait, or just go for it?

    37. #35
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      If you don't know the history of the bolts, I might not use them. But they can definitely be tough to find. I got mine through VP Autoparts. They didn't have them in stock but it didn't take all that long to get them. I'm sure there are cross-referenced rod bolts for other engines that used the same ones (old Fords maybe?).

      Sounds like a nice build, btw!

      Sent from my SAMSUNG-SM-G891A using Tapatalk
      Tony

      2017 Jaguar F-Pace R-Sport
      1958 Volvo PV444 - B20/M40 swap
      Past Bricks: '95 855, '98 V70T5M, '04 V70R M, '10 XC60, '83 245 Turbo, '12 XC70 T6 P*

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