PBS Heads, teach me about them

Discussion in 'Rear-Engine Fiats' started by RocketMonkey101, Dec 3, 2018.

  1. RocketMonkey101

    RocketMonkey101 Daily Driver

    Location:
    Los Angeles
    Ok so after looking through the thread on the 1050 engine it seems like getting all the bits together to make it happen might be a pain in the butt. So with that in mind I'm thinking about just boring out the cylinders. Then I remembered tale about PBS heads. As I understand it they are still available from a new vendor. What's the deal with them? Are they streetable? Do I *need* a crazy cam to see an increase an power? Or is just that a crazy cam will help me make the most power out of one of those? My goal is to make enough power for daily driving. I was hoping to hit 70-75hp and keep things reliable.
     
  2. Frank L. Di Gioia

    Frank L. Di Gioia Daily Driver

    Location:
    las vegas, nevada
    I've had several PBS 8-port heads on several engines between 903+ to 1070cc. First (one of 26 of their early boat oriented heads) application was a 1 liter motor 74mm stroke x 65mm bore based on a 903 motor in a '67 Spider. It had a single DCOE Weber and ran very well. I seem to remember rather high compression (180psi) and an Alqualti cam. It acted about the same as a 903 but simply more power. Clark at PBS sent me a dual sidedraft manifold with two DCOE's with I think 28mm chokes and his jetting. It ran even better. Then I Got a 1050 A112 motor from Norb McNamara and went the full route. Slightly oversize pistons gave it about 1070cc with Greg Schmidt's carbon fiber pushrods, cam, alloy flywheel, 5-speed, and a few other perks it was put in an Abarth 750 GT. At somewhere around 1250lbs it was quick BUT if applied slowly from 1500 RPM it would pull top gear! It was NOT hard to live with. As to horsepower I talked to Clark and he had the following to say: On a tired (needing rings and a valve job) stock 1050cc A112 they got 90+hp on the dyno. With cam and other work he said 100+ hp was reasonable and still have a motor easy to live with in a LIGHT car. I bought one of their heads/carbs when Clark told me they were making a final production run. If you told him what you had they could jet it perfectly out of the box! I'm restoring a '67 HP SCCA Spider right now. I'm starting to get involved and would also be looking at an 8-port head and carbs if reasonable. Around 2006-8 PBS sold me the entire kit- head, manifold, and Webers for about $1650 if I remember correctly.
    I've always been rather value oriented with my car projects in that they had to have some balance between cost and return. I don't think I've ever actually "made money" but try to keep my losses in order. Best of luck and send me any info on your findings.
     
  3. myredracer

    myredracer Daily Driver

    How much do you want to spend? :)
     
  4. RocketMonkey101

    RocketMonkey101 Daily Driver

    Location:
    Los Angeles
    I'm hoping to keep the whole build under 5k. Right now my thoughts are thus: 67.2mm cylinders, full flow work for oil, an oil cooler, keep the stock cooling and add the PBS head... I don't know how reasonable that is or if I should hold off a little longer and keep saving my pennies.
     
  5. myredracer

    myredracer Daily Driver

    Well, I have a 1050cc motor built on a 903 block. Has A112 crank, rods, cylinder head, oil pump & performance cam and some various special parts. The main journals on the A112 are larger dia. and I had them ground down to 850 size. 67.2 mm for pistons is about as large as you want to go on the 903 blocks and requires offset boring of the cylinders and needs to be done by a machine shop that knows what they're doing. The cylinders need to be notched at the bottom and the cam needs to modified to clear the rods. The A112 oil pump has a built-in pressure relief valve and IIRC has a higher flow rate. I'd have to go look up the info. on everything that was done. I collected all the special parts over a period of 2-3 years or so and then sent everything to Paul V. (S/T) for the special machine work and assembly. I've got over $10K into the motor not including DCD carb and exhaust... :eek: It will put out up to 90HP.

    If you're going to be running much above stock HP, you will most likely be replacing the rubber-filled axle couplings every other week especially if you have a heavy foot... A CV joint setup can be done, but is more $$ and some special shop work is needed. I bought special hub carriers from S/T and 128 CV joints and axles. The hardest part is joining 850 axles to 128 axles. And with a lot more HP you may find you'll want to upgrade the suspension and maybe the braking. Again, more $$.

    Another option would be 65mm pistons with an A112 crank to get 982cc. Can't recall offhand what rods are needed for this.

    Personally I wouldn't run a PBS head for regular street use unless you have deep pockets to do everything that will be needed, not to mention maintenance time and expense. A bone stock A112 1050cc motor is rated at 70HP and IMO a very good option if you reverse the rotation. No more centrifugal oil filter! Not sure what these motors are going for these days and will be hard to find in the US. A few years back I think they were something like $5K for a decent used one.

    If you haven't read these sources, they have some excellent info.:
    Paul V.'s old S/T info. on building a high performance motor. http://www.fiat850.co.uk/download_store/documents/other/Scuderia_Topolino.pdf

    Mahlon Craft: http://users.ntplx.net/~kinukoyc/Pages/tech_pgs/engine_how_to.html

    The Guy Moerenhout forum in Belgium will have some useful info: http://www.abarth-gmr.be/new/

    Many of the parts you'd want can be found on ebay Italy and if you spend some time looking through what's available, you'll get a sense of what kind of money you'll be looking at to build a good high performance motor.

    I'm sure others will come along and make more comments.
     
    RocketMonkey101 likes this.
  6. Frank L. Di Gioia

    Frank L. Di Gioia Daily Driver

    Location:
    las vegas, nevada
    Jez guys I must have missed something while away from Fiats for a decade! I'm still stuck in 1990 prices and it's a shock to see what things are going for now. However, that said, I've noticed along the way that things rarely get cheaper as time goes by. There was the '57 Porsche Speedster, less motor, for $275, and there was always the sports car lot on Wikshire Blvd. Los Angeles that had 3 or 4 Cobra's at $3500 each with your choice of color! Honest, that's the world back then guys. My family has been running custom sports/racing shops since the 1920's and I just drug out some pics of customer cars. GASP I'd hate to price the Bugatti Atlantic now. Second car is a totally hand built alloy BMW 328 built in the shop by my Uncles for a client Image (38).jpg . I think I need to catch up on the value of the dollar today!
     
  7. Daniel Forest

    Daniel Forest True Classic

    Location:
    Montreal,Canada
    Frank,

    Don't upgrade to 2018 prices too fast...

    In the meantime I could offer you a huge 100$ for your car!
     
  8. Frank L. Di Gioia

    Frank L. Di Gioia Daily Driver

    Location:
    las vegas, nevada
    Located current production offering of 8-port head from Croatia for $3827 less carbs and linkage. Punch in PBS 8 port head and it pops up under "Ebay International." Normally on Ebay USA you have reasonable recourse if the product never gets shipped but I'm not sure this applies to other sites. Head includes valves and springs, studs/bolts, water outlet, valve cover with "ABARTH" cast in. SAME PACKAGE AVAILABLE FROM SCUDERIA TOPOLINO FOR $2730. I don't know if this includes VAT. If yes deduct a good 20+%. If it included carbs I'd be tempted.... Paul Vanderhayden also has the required pistons and a great reputation. If you really have DEEEEEEP pockets there's the Radiali (never could spell anything Italian) starting at about $5500 for the base package. As Gil stated; "How much do you want to spend?"
     
  9. Jeff Stich

    Jeff Stich True Classic

    Location:
    Norco, CA
    FYI: Paul sold his "Scuderia Topolino" business years ago, it's under different ownership now. Welcome to the 2010's. ;)
     
  10. bruakeman

    bruakeman True Classic

    Location:
    Ohio
    I'm not sure what my modified 124b engine (approx 1550c) puts out, but I'm still running stock 850 rubber axle couplings in my 850 convertible. Haven't blown one up yet, but I don't race or do hard off the line sprints. FWIW.
     
  11. myredracer

    myredracer Daily Driver

    What exactly did you do to that motor? I'm just building a 1608cc version based on a 1438 block, 1608 crank, 128 pistons and X1/9 rods. Have a Delta reground cam for it and will do a little porting & polishing of the head. The 1438 motor is brand new and the 128 pistons drop right into the 124 bores without having to rebore the block at all which is nice. Have a set of dual DCOEs and intake manifold for it too.

    I also have a 1585cc Euro 131 OHV motor that I was going to use but am going the stroker crank route. It needs the rotation reversed but have the cam & distributor needed to do it. For sale cheap if anyone is interested and includes new head and parts. Same exterior dimensions as a 124 OHV motor and a direct drop-in alternative.

    I used to have an extra crossmember and PBS bellhousing adapter and sold them a few years back. Still out there somewhere I guess and don't know if they ever got used by the buyers. Available from Berni Motori in Italy though as well as the reverse rotation gearset.

    The Abarth version of the 124 1197cc motor (enlarged to 1280cc) in the 1300/124s put out 88 HP. A 1438cc motor would be a good choice (and easier to find parts) and a 1600-ish motor would be even better of course. Not sure how much it would cost to round up all the needed stuff as of 2018?
     
  12. Frank L. Di Gioia

    Frank L. Di Gioia Daily Driver

    Location:
    las vegas, nevada
    First everything costs triple what I'm used to and now the people have fled the country! Jeff, do you do machine work at your shop? I've decided to put together a 1050 and when I get the parts I'll need a machine shop I can trust. Boring, piston installation, fix what I got wrong stuff.
     
  13. bruakeman

    bruakeman True Classic

    Location:
    Ohio
    Gil,
    It was about 20 years ago when I built my car, exact details are now a little fuzzy. I had a rusted 1300/124 that I robbed for all the parts to do my own version on my 73 850 convertible. PBS did the shortblock using a 1438 124b block, 1608 crank and I believe stock 124b connecting rods. The pistons were 128 but I don't recall if they were 80mm or slightly larger. I know the extra set I have are 81mm and I figured when and if and ever needed I could rebore and use them then. I know we modified the head, a SEAT head I got from Gregg Schmidt, so as my compression was manageable on pump gas. On a compression check I'm at 160psi. Stock 124b cam. I know they had to clearance the block/crank a bit to keep anything from hitting. I don't know if they ground the block, the crank or both. They did not reverse the orientation of the rods even though I was reversing the crank rotation using Abarth Timing gears. Not sure why not but said it didn't really matter. I'm using the single carb side draft intake using a Weber 32 DCOF2. I did port match the head a little, and made my own exhaust using a cast dual exhaust manifold with a double header pipe plumbed into a Supertrapp mufler. Engine runs great though I wouldn't use the Supertrapp again. Oh, PBS also modified my Abarth bellhousing to use a much more stout and readily available Type 4 VW starter.
    Also at the time I sent my reverse rotation Abarth water pump out for rebuild. Somehow it got "lost", more likely stolen. I ended up using a standard pump, seems to work ok. Hard to figure. That's the gest of it.
     

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