To what RPM can a stock B20 (144/BW35 shouldn't make a difference) safely be taken to? When mine hits at around 4K, it's throbbing pretty good. With the BW35 I'm probably only doing 60-65 mph at that RPM. The M41 will improve that, but just for my information, what do these things do, stock, before you need to worry about spinning a bearing or worse?

Hello linc,

You do'nt have to worry about the crank, I have seen forged cranks pulled to 9,300Rpm´s (hardened and balanced, but in all other aspects OEM).

But an advice would be to use the late B230 rods, (grind the journals to that size(and if you want, use the extra 5mm stroke that is possible with that)).

Those rods, correctly prepared, can certainly take the "heat".

Note: bearing spin is´nt a known Volvo problem as far as I know.

So what is the journal size of the B230 rods. I know the B20/21 and early B23 mains are 55mm, and from '88 or so, they changed to the larger 63mm main bearings. I dont have any info on the big end sizes, but you say the B230 has smaller big end journals? So one could (off-center?) grind a stock B20 crank to a smaller size and fit B230 conrods? Is that what you mean?
If so: are the B230 conrods shorter (center-to-center) to be able to use the stock B20 24mm whrist pin pistons? Or would you need special shorter compression pistons (which would then be 2.5mm shorter)? (or is the whrist pin size different to start with?)
I've been looking into stroking a B20, so I'm eager to find out. All info would be appreciated!

Cheer, Ben
--
P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

As I understand it:
BW35's had an "A" cam installed in front of 'em. The "A" cam in my manual trans car (don't ask) won't go past 4,000 rpm's in fourth gear.
It can get it up to 'bout 5,000 in third gear though.
Maybe that's just the B18 122/1800?
So...if it's an "A" cam, there is no dangerous redline. You can run foot-to-the-floor all day long:o)
Hope this helps.
Beast,
Shayne

I'd swear my PV came to me with an 'A' cam in the B18. Absolutely gutless above 4K, although it pulled like a champ from idle. When the cam gear went out I pulled the head and replaced the cam too, even though there was nothing wrong with it, I just hated it that much. With a 'D' cam in it the B18 felt SO much better.
--
I'm JohnMc, and I approved this message.

Gutless? Heh heh, I'd describe it as "maxed". Certainly has a whole lotta torque from the get-go.
The engine came to me that way from an automatic 140 and was most definately purpose (re)built, but the 140 was just too far gone for the guy to keep on.
It's supposed to have the 6-bolt, 2130 pistons but it just keeps running too well to tear down and find out for sure.

Shayne.

HI, I've got the same problem with my '72 142s B-20.
I hope to find the answer, if you find out let me know.
I actually have been meaning to do a tune up, timing soon, I've been putting it off 'cause the car starts right up and runs good up untill 4000. I know my rear end is making a lot of noise as is my M40, (no overdrive yet).
I hope to rebuild the rear end, drive shaft, and axle bearings/seals soon then it is on to an engine rebuild and OD maybe over the winter or next year. I want 6,000rpms and smooth running.
CU

After I put on the 'R' cam, the R-sport head, and the Webers I found my delight that my PV's B20 would pull hard up to 7k. This was on a bottom end that had a shade tree rebuild with an IPD 6-bolt big bore kit some 20-ish years and 80K miles ago. It was still pulling hard at 7K, but the balancing was a bit casual and it felt buzzy, and I never took it past there. After about 10 months of 7K zings (I flog the PV fairly hard) it came up lame with a spun rod bearing on #2. The teardown didn't provide any clues as to why it happened - it was full of Mobil 1, no blockages, no problems with the oil pump (other than being a little scratched from eating bits on the #2 bearing). All I can guess is that perhaps the bearing was a little loose, or perhaps the rod a little bent, or - who knows really. But I'll just let that sit out there as a cautionary tale about running past 6500 - any weaknesses in your engine will come to light when pushed hard.

Now that it has a brand new professionally built bottom end (this time with standard B21 FT pistons) and an Isky vv-81 cam (Kgtrimning was out of Kg-16's when I was ordering parts) it pulls like a beast up to 6500. I've gone to 7K a few times and it feels great, but I think I'll try to keep it under 6500 from now on.

I should dyno it some time. Now that it has a few miles on it it feels really strong. I'd be curious to see what it does. it's certainly not the result of some carefully crafted high dollar engine building project, more a collection of interesting performance parts found here and there for cheap.
--
I'm JohnMc, and I approved this message.

I think as long as your oil pressure is up, and you don't have abusive
valve springs (and nothing has already self-destructed down below) you
can run it about as fast as it will go. Spinning bearings is not a common
failure mode in red engines.
--
George Downs Bartlesville, Heart of the USA!

You can take it up to and past 6k if you wanted to, but you won't be making power and you'll be wearing down your motor fast. Your motor will run out of spunk somewhere around 5600-5800 probably. Something else is probably holding you up. Shouldn't be throbbing as far as I know, but I don't have any experiences with BW35s over 45 mph, so I don't know exactly HOW much power they sap. My car was happy running 80mph at 4300rpm for an hour at a time many times... FWIW.

And I've heard of people running up to 7k on their B20Es that are stock, definitely not the best for the engines, but they've done it on their DD engines.
--
Kyle - '68 142? - Oregon Volvo Tuners?

The GT tach on my 71 E has red stripes from 6-6.5k, then solid red from 6.5-7k. Bringing it up to 6k now and then shouldn't hurt it.

Have it balanced then you can run all the way up to 14,000 rpm!

Nothing like a good race engine!

14,000 rpm with a B20? I assume this is down the proverbial mine shaft in 1st gear, with all 4 spark plugs removed? ;-)

On a serious note, I regularly shift my B20E ITB race engine (essentially a blueprinted and balanced stock engine with a custom exhaust header) at 6500. The last guy that owned the car said he shifted at 7000, but I think that was a bit much. The engine seems perfectly happy to do 7k, but I only find it useful in those cases where a shift up to the next gear would be immediately followed by a downshift.
--
Gary Learned - '71 142E ITB / '73 1800ES / '02 S60 T5

7000 RPM is about the safe limit for the stock rods in stock condition. Some racers using special rods and forged pistons run them up past 8500.

Peak power on a B20E/F is designed to be at 6000 (largely a function of the D cam), so I can definitely see shifting at 6500 so the next gear still lands you in a meaty part of the power curve.

There is something wrong with an engine -- or associated systems -- that feels like it's struggling at 4000, although it seems to be a common complaint.

"There is something wrong with an engine -- or associated systems -- that feels like it's struggling at 4000, although it seems to be a common complaint."

Seems like there's been more than a few people mentioning that lately, hasn't there?

It's probably not mechanical (i.e. bottom end, cam, cylinder head) in nature, otherwise you'd have some other symptoms (uneven compression, uneven running at 4k WOT). It must be related to either the induction, the ignition, or the exhaust. Although you can't completely discount the occasional cam gear installed a tooth off scenario...

Induction: Are the carbs jetted properly, do they get enough fuel flow from the pump to keep up with the engine's consumption at WOT. In other words, are they going lean when pushed hard? Is there any sort of unusual obstruction in the intake - clogged air filters, stuck secondary butterfly valves (get rid of those!)? If they are SU's are the pistons free to move up and down? Are they in decent tune?

Ignition: Is the advance stuck? With a timing light, watch the timing at idle, then rev it up to 3 or 4K, does the timing advance 20+ degrees? Is it set properly at idle? Is the spark nice, fat, and blue, or weak, thready, and reddish? Are the plungs in decent shape and have at least reasonably close gapping (I've never noticed much of a difference in gaps). Is the points gap set properly (do this first, otherwise you'll have to redo the timing) - if too wide or to narrow the coil won't get proper dwell, and improper dwell seems to affect higher RPM running more than low. Are the lobes the points run on worn down - imght be impossible to get proper dwell if so. (PS - Fram what I understand - dwell refers to the percentage of time on and off the coil sees - the points alternately ground and unground the current flowing to the coil - it needs enough time grounded to properly energize and enough time ungrounded to properly discharge - too little of either and you don't get a good spark). Issues with the ignition are often sneaky and can pass themselves off as other things. I could have SWORN that the weakness and wavery feeling my PV used to have up past 5000 was carb related, but it went completely away when I put on a Crane ignition and a Mallory coil. Ignition systems are NOT graded on a pass-fail basis. They don't either provide an ignition or a miss - there are quantifiable differences in the ignition they provide.

Exhaust: Not much here in terms of holding a stock motor throttled back to 4K. Even before i got rid of the puny original single downpipe system on the PV (seriously had a 1 1/4 inch ID!) my B20 would pull past 4K. However, a partially blocked muffler can do it - they can rust and partically collapse internally sometimes (depending on the type of muffler). And if you have a single downpipe manifold and a truly puny exhaust system you will notice it up past 4500 - 5000 rpm or so. Unless you are building a 180+ beast a dual downpipe cast iron manifold is sufficient, IMO.
--
I'm JohnMc, and I approved this message.

Hey guys,
Don't forget the floating valves. Double valve springs are a must for over 6 grand rpms. I have been using them and a IPD street cam for 25 years, never had a problem related to frequent shifting at 6500 on this balanced and blueprinted street engine. Although beyond 6500 there is not much power to take advantage of. I have heard of pushrods losing a valve to the float effect.
Joel
--
Antique Swedish Steel (Never Rusty) Silver 71 142E

Joel,

I have to say that I disagree with the statement "Double valve springs are a must for over 6 grand...."

The B20E ITB engine that I run has bone stock valve springs, mainly because the rules allow nothing else. The springs currently installed are 6 or 8 weekends old, which is a whole truckload of 6500+ excursions; several thousand of them, to put a number on it. The engine does not have a valve float problem.

So... while I agree that *good* valve springs are a must for 6000 rpm plus, I just don't think *double* valve springs are.



--
Gary Learned - '71 142E ITB / '73 1800ES / '02 S60 T5