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Hi,
I've jsut finished a950 km TSD rally in the 1973 142 I bought a month ago (and spent lots of time on in the meantime!). All ran well, handling was great, the only problem was a hole in the radiator, which we patched up by crimping down the offending crosstube, and tossing in a jar of that offending goop that clogs everything up.
Anyway, the old engine is blowing some blue smoke on overrun (valves) and a bit on hard acceleration (rings, I guess) so a good excuse to get some more grunt.
From everything I've read on this site, 150hp ought to be a reasonable target without breaking the bank.
I want a strong, reliable engine, rev limit about 6k, with good torque rather than outright hp. A 'fast road' engine. So tell me what I need: my initial thoughts run to VV71 cam (or is there something better?), steel timing gear, clean up the head to E specs or better and match the ports, compression about 10:1 to run on the 95/96octain PULP we get in Australia. Everything balanced. Will the Stroms or SUs be sufficient, or will I need to go to Webers/Dellortos to feed enough fuel? I've already got the dual down pipe, feeding into a 2 1/4" just after the pipes come together, with a single muffler where the resonator use to be (across after the axle). Not too noisy, with a nice note.
What else should I do?
JohnH
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Hi guys
This thread has answered heaps of questions I had been asking myself (being a relatively new Volvo owner).
Like John, I am in Australia (where are you John ?) and have a 142S that I use for navigation rallies - mostly "Touring" events, but the odd forest rally as well.
The engine is a bit of a "hybrid" ..... its actually a B18 block which I SUSPECT - but dont know 100% - has been taken out to 2 litre & is running a B20 head. Fitted with HS6 SU's and has a set of 4-2-1 downpipes. No idea what cam - but I suspect "warmer" than standard, as it is completely useless below about 2800 - 3000 rpm but pulls reasonably well above that and will happily rev to 5500 without fuss. (Unfortunately I haven't yet been able to contact the guy that built it originally to find out some more details)
The engine is pretty tired (low compression) & needs a freshen up. What I want to do is get some usable hp (& more importantly torque) lower in the rev range - basically a more "street tractable" motor, but still with a bit of extra "punch". Not after a rocketship. And it needs to be cheap !
Is there any way I can tell for sure what head it is, without pulling it to bits first ? I havent been able to find a part number on it, but it does have "K6" cast into the upper surface of the head beside the valve cover, just above the No. 1 inlet port (if that helps).
Some initial ideas on suitable cams would be good too .....
Dave
(owner of "Hagar the Horrible", 1972 142S)
Melbourne, Australia
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To the best of my knowledge - here's how to identify the three types of B20 heads, B, E, and F.
0) Determining if it's a B18 head vs. B20 - I *think* all the B18 heads had the umbrella type oil seals that sit on the very top of the valve - on top of the spring retainer. While the B20 heads have the stem seals underneath the spring that slip onto the top of the valve seat. You may be able to se this by looking in the valve cover. Of course - It's entirely possible that either late model B18s have stem seals or early model B20's had umbrella seals.
1) The B20B head will not have injector ports - these are holes through the head into the intake port in the narrow band between the valve cover and the intake manifold. If there isn't an approx 3/8 inch hole with a small threaded hole (covered somehow if using carbs) then it's most likelt a B head. Or possibly some sort of later model and pretty rare marine head?
2) If it has injector ports then its either an E or an F head. To tell the difference between them look at the middle cylinder head bolt along the manifold side of the head. It sits on a little machined platform. If that platform is connected by a little mahined flat 'peninsula' to the nearby injector mount then it's an 'F' head. If it's platform is free standing (surrounded by lower unmachined metal) then it's an 'E' head. Although AFAIK there is nothing really different between the two other than the F head having more metal on the underside (and resulting larger combustion chambers). Shaving some metal off an F head turns it into an E head.
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posted by
someone claiming to be Rhys
on
Sun Apr 6 15:19 CST 2003 [ RELATED]
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I have built lots of these engines to stock and performance specs.
The D cam is not going to get you to 150 horsepower. The F is more radical than the R. I have used the R on the street, but it works best with Webers and is a bit fussy with SU's due to the intake manifold pressure waves upsetting the carb pistons. Minimum idle with SU's would be about 1300 - and 700 is no problem with Webers. As George says, forget the Strombergs, although my reason is that fewer needle choices are available for them than the SU's.
The IPD Street performance cam, or the Isky original of it would be my choice. For sure 10:1 CR. Steel gears are a must for high RPM use. Use a Volvo OE oil pump.
FI or B heads are fine - the extra diameter of the FI intake is somewhat compromised by being shrouded more in the chamber. It is a toss up.
Lighten the flywheel. You should use double valve springs, and if so, then tubular pushrods are advised. The IPD Chev solid lifters are lighter than the stockers, so use them too if you buy the kit.
Have a plateau hone put on the cylinder walls, and skim the block and the head to ensure absolute flatness to keep the head gasket in it.
With SU's and the Isky cam, figure maybe a good 130-135 horsepower. Add the R cam and Webers, and 160-170, but you'll need to go to 6500 to get it.
Your exhaust system is perfect already, but I would stick with the iron integrated manifold (the one without secondary throttle plates) if you use the SU's. You will be able to run a leaner needle in the low and mid range and have reasonable fuel mileage, and still have good flow at top end.
Fill it with Mobil 1 synthetic and thrash it. It won't break.
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From the numbers, the F appears to be more radical than the R, but it produces more torque at lower revs than the R and doesn't have as much peak power. It is in fact a milder cam than the R, even though it has more duration.
I have seen the D produce 160 bhp with D-jet injection and a stock bottom end. This is not conjecture. (Historical note: the D was the original racing cam for B18s long before the B20E came along.) This was at 11.4:1 CR. At 10:1 CR, subtract maybe 10%. Go to Webers and get it back.
The stated purpose is a 6000 rpm power peak, lots of torque, and not breaking the bank. Therefore, stick with the B head (already paid for). Get the D cam, which does not require double valve springs or steel gears or special pushrods. Peak power will be right around 6000, with lots of pull from 2500 up, and you can overrun to ~7000 without floating the valves.
The IPD lifters are significantly heavier than the Volvo lifters. I held both kinds in my hands yesterday, in fact.
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posted by
someone claiming to be Rhys
on
Mon Apr 7 16:00 CST 2003 [ RELATED]
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Hi Phil;
You're right - my mistake - the IPD lifters are heavier.
But I thought that John's goal was 150 horsepower? The D won't get there. The engine you describe is an early '70's B20E with a B head and SU's. Maybe 120 horse on a good day - a fine runner, but not a powerhouse. The Webers would "break the bank" and give maybe 20 hp with that head and cam.
I haven't used an F - haven't even seen one. But the R-Sport catalogue from 1980 ( I don't throw anything away....) states that the R cam has a better mid-range than the F. Also, the R-sport crate engine that produces 145 hp uses their special head, sidedraft Weber style carbs, the F cam, and 10.5 CR. To get to 165 they claim more CR, and an even more radical head. I have used their guidelines for years, and I don't think the factory is that far off the real numbers.
Maybe we are into apples and oranges.
Rhys
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Rhys,
I'm looking at the VCS kits myself (very similar if not identical to the R-sport) and the info is a bit confusing. The Stage I and II motors use the F cam, and they develop peak torque at lower rpm than the Stage III with the R cam. Yet I see the same statement about the R being more tractable at lower revs than the F.
What we don't know is how the heads are ported or how their chambers are shaped. And I actually have no idea what happens if you stick the F cam into a regular B20B, on second thought, so silly of me to throw that into the mix. I do know what happens with the R and SU carbs on a B20B -- very lopey idle, and the power hits all at once around 3000 rpm, which I don't think is what's intended here.
So let's take a few steps back and rephrase the question (if that's OK, John). Let's forget about a specific target figure for HP, because it's actually not a useful measure of performance other than sustained top speed. What's needed for acceleration is a motor that can rev quickly under load, and do so over a wide range of rpm -- the more area under the torque curve, the better, and the less inertia in the motor itself, the better. You're quite right about lightening the flywheel (the rest of the inertia reduction gets expensive).
The tighter the piston-head clearance, the higher CR you can run for a given octane, and the less ignition advance the motor will require. Tight squish = quick controlled burn = less advance = high CR without detonation = high torque values = more area under the curve = performance and economy.
I'm going to stick with the idea that blueprinting and balancing are well worth the expense for increasing efficiency and durability -- machining is a better deal than aftermarket parts. I'm also going with the idea that most attempts at enlarging/reshaping the ports make the intakes flow worse than stock, so steer clear of that unless you know someone who has done that to 20 B20 heads and has seen them improve performance and tractability.
--Phil S.
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Hi Phil and Rhys,
Thanks for the very informative info. Just to throw a few more thoughts... Somewhere in the parts bin I have 2 Dellorto DHLA 48s on a short (about 4"?) manifold. They are from an old race car that I bought and running big venturis (44mm, I think), but at least there is a base for feeding more fuel. I've also got a "race head" from yet another parts bin. I've never tried the head,but it looks like it is pretty smooth, 44mm valves and shaved guides. I was told it was a good head, but who knows until you try. I'll take it to the bloke who will rebuild the engine and get his view before getting excited about it.
So the conclusion seems to be (from all your great info, and please correct me if I'm wrong)... stick with a carefully modified B head unless the 'race' head looks brilliant, get the lot balanced and blueprinted, compression ratio between 10 and 11 (more from decking the block rather than planing the head), lighten the flywheel (how much is sensible?), steel timing gears, FI manifold and the 2 1/4" exhaust, regraph the distributor if necessary, new lifters with hollow pushrods (are these necessary?). The starting point should probably
be a D cam, but I've emailed KGTrimning and Unitek for their advice on cams - this seems to be the main outstanding in my view.
Thanks again for all the help.
JohnH
Whew!
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posted by
someone claiming to be Rhys
on
Tue Apr 8 07:50 CST 2003 [ RELATED]
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Agreed Phil. The D-cammed engine as you describe would be a smooth runner, and have the all round throttle response for everyday driving. Keeping the head stock would also tend to maintain velocity at low RPM/low throttle openings which is all to the good for torque. CR increase commensurate with the available fuel and its good to go.
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150 HP on a budget:
1) Dead stock parts on the bottom end, go no further over bore than you need to, if you need to at all.
2) Blue print and balance everything. Go to the wide end of the spec on the main and rod bearing clearances, try to keep the endplay to the minimum end of the spec. Have the rods checked and straightened, etc. Precision = HP.
3) Match the chamber diameters to the new bore.
4) Smooth the intake ports to a nice fine sandblast finish. Do not enlarge or reshape the intakes.
5) Open up the sharp radius of the exhaust ports and smooth those. They already flow better on the B head you have than on the E or F heads.
6) Quality three-angle valve grind.
7) Deck the block and/or use a .030" head gasket to bring piston-head clearance down to .035" or so.
8) Calculate (as opposed to guessing at) the compression ratio; shave head the small amount remaining to get you 10:1 or slighly higher.
9) Find or rebuild a distributor so it works correctly without slop. Be prepared to recurve the advance. A vacuum advance (NOT retard) distributor will get you better economy than a pure centrifugal unit, but not more peak torque or power.
Go for the D cam, or if you're willing to rev a bit higher for torque, the F cam. If you have some extra money in the budget, consider a modern Swedish cam.
All parts must be surgically clean before reassembly. The last step in cleaning is hot water, soap and a toothbrush, followed by a rinse and dry.
If you are now out of money, stick with the SUs and put them into perfect shape. Hunt down one of the earlier separate intake manifolds instead of using the iron intake/exhaust combo. Hacksaw the old intake off and reuse the exhaust portion and downtubes.
If you weren't out of money in the previous step, go for 45 Webers or Dellortos and once again reuse the exhaust portion of the original manifold. Properly tuned, these are good for 10-15% more torque than the SUs.
Fabricate 2-1/4" exhaust system with as few bends as possible (go under the rear axle, not loop over), and a straight-through muffler of some sort as far back as you can get it.
If you still haven't spent it all, go for a Swedish 4-2-1 header and a 2-1/2" exhaust.
Notice that except for the optional carbs and header, we haven't actually departed from using Volvo stuff at all... this will get you far, far more performance than spending money on parts that actually hurt performance instead of on top-notch machining and workmanship.
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Hi Phiul, in the grand scheme of things, the difference between a modern Swedish cam, and a D cam probably isn't much. Any suggestions which cam I should target?
JohnH
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John, there's a 272-degree 12mm lift cam available from Unitek (and probably KgT) that's a good step up from the D in performance, but is much smoother than the R at low revs.
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I'd use SUs rather than Strombergs because you can adjust them a lot
easier. VV71 is a good cam but might not get you to 150 hp.
I'd use the front muffler and run the pipe straight back rather
than across.
If you can get the "R" cam or something like that it will give you
more power (and less driveability).
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma
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