What did I do wrong assembling the big bore b20?

Well the truth came in today. I took the car to Ed Pinks here in LA to get some much needed help sorting out the DCOE's. It was a comedy of errors

I was running lean because the fuel pump wasn't giving it enough psi. I checked the fuel pressure with a gauge and read 3psi, but turns out that gauge was wrong. So I swapped the mechanical fuel pump for a new one. Same story. So I went to autozone and bought a cheap electric one. It worked, but is the most expensive fuel pump I've ever bought because the car sat on the dyno the whole time. Check out this sick fuel pump setup!



We finally got it running only to find out that the rear DCOE was completely clogged. Long story short, we fixed it, and got them running well enough to do a power run... and boy oh boy the power she has! a whole 69HP at the wheels! Jealous? Don't believe me? Here's the dynosheet to prove it!



So the question is, why would an engine that is a pretty tried and true formula for being well north of 100hp suddenly not be? Since I built it I'm going to assume I messed up.

Right now there are three major theories from the knowledgable heads in the room. I don't know my ass from my elbow on this stuff so I didn't weigh in.

Theory 1: The exhaust (glasspack) has somehow broken and is creating a restriction resulting in too much back pressure.

Theory 2: The machine shop didn't shave the head enough to create a compression ration suitable for the engine specs.

Theory 3: The camshaft was either degreed wrong, ground wrong, or I put the cam gear on a tooth off.

What say you experts on the matter?

That?s a lot of work for 100hp...

I will no longer install a cam without degree'ing it. No guesswork or questions.

If you're going to do it, do it right.....

This policy paid off handsomely recently on a motor that was assembled by a "volvo shop".
It went from lackluster performance and poor mileage to a tire burning monster.

An exhaust restriction can be tested for with a vacuum gauge. Or/and temporarily removing the O2 sensor (creating a leak).
And a bad muffler will usually rattle.

How does it sound and feel cranking out that mighty 69hp? Sputtering? Clean?

What RPM did that pull top out at? I'm guessing short of 5250 because the tq and HP lines never crossed.

You can degree out the cam without pulling anything other than the valve cover off, so I'd check that.

Is it a programmable ignition? Double check it with a dumb timing light to make sure it's doing what it's supposed to be.

I don't think there's any way a lack of shaving on the head would drop you 50 - 70 hp.

JohnMc said:

How does it sound and feel cranking out that mighty 69hp? Sputtering? Clean?

What RPM did that pull top out at? I'm guessing short of 5250 because the tq and HP lines never crossed.

You can degree out the cam without pulling anything other than the valve cover off, so I'd check that.

Is it a programmable ignition? Double check it with a dumb timing light to make sure it's doing what it's supposed to be.

I don't think there's any way a lack of shaving on the head would drop you 50 - 70 hp.

Click to expand...

From what I recall it was somewhere right around 5200.. I'm asking for a more exact number right now.

The plan is to degree the cam this weekend to either identify or eliminate it as a factor.

The ignition is a 123+ distributor so it's completely programable. We tried a few different permutations but the one listed in the original post is the one that performed, and drove the best.

oemoilleaks said:

Well the truth came in today. I took the car to Ed Pinks here in LA to get some much needed help sorting out the DCOE's. It was a comedy of errors

I was running lean because the fuel pump wasn't giving it enough psi. I checked the fuel pressure with a gauge and read 3psi, but turns out that gauge was wrong. So I swapped the mechanical fuel pump for a new one. Same story. So I went to autozone and bought a cheap electric one. It worked, but is the most expensive fuel pump I've ever bought because the car sat on the dyno the whole time. Check out this sick fuel pump setup!

We finally got it running only to find out that the rear DCOE was completely clogged. Long story short, we fixed it, and got them running well enough to do a power run... and boy oh boy the power she has! a whole 69HP at the wheels! Jealous? Don't believe me? Here's the dynosheet to prove it!

So the question is, why would an engine that is a pretty tried and true formula for being well north of 100hp suddenly not be? Since I built it I'm going to assume I messed up.

Right now there are three major theories from the knowledgable heads in the room. I don't know my ass from my elbow on this stuff so I didn't weigh in.

Theory 1: The exhaust (glasspack) has somehow broken and is creating a restriction resulting in too much back pressure.

Theory 2: The machine shop didn't shave the head enough to create a compression ration suitable for the engine specs.

Theory 3: The camshaft was either degreed wrong, ground wrong, or I put the cam gear on a tooth off.

What say you experts on the matter?

Here are the engine specs:

IPD Big Bore: 2130cc
Valves: Bigger on both ends , stainless, 38mm intake, 46mm Exhaust
Head ported and polished
DCOE 45s
Steel Timing Gears
ACM.SE Forged H-Beam rods
VV71 cam
HD oil pump
123ignition distributor
IPD 4-to-1 header
Crank honed
Rotating mass balanced
9.5:1 Compression Ratio

Timing Specs

0500 RPM - 5.0?
1000 RPM - 10.0?
1700 RPM - 18.0?
3000 RPM - 33.0?
4000 RPM - 36.0?
5500 RPM - 34.0?
8000 RPM - 29.0?​

Click to expand...

06-09-2008, 07:33 PM #14
andrewlcraft
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Join Date: May 2004
Location: Oregon
Default
Quote:
Originally Posted by John V, outside agitator View Post
At what point is the intake valve closing ABDC?
valve events @ .050
intake / exhaust
btdc . abdc . bbdc . atdc .
6____42____42__6


valve events @ .020
intake / exhaust
btdc . abdc . bbdc . atdc
26___62____62__26

Compare to a stock D cam:

valve events @ .050
intake / exhaust
btdc . abdc . bbdc . atdc .
0____42____42__0


valve events @ .020
intake / exhaust
btdc . abdc . bbdc . atdc
29___71____71__29

VV71 duration @.050: 228, "D" @ .020: 222

VV71 lift: .446, "D": .420

VV71 lobe center is 108, "D" is 111

So they're pretty damn close. The 108 lobe center and slightly more overlap moves your power band up & gives a lumpier idle. The VV71's got a decent increase in lift, duration's about a wash.

Click to expand...

Seems like an incredibly weak cam and bizarrely low compression..

OH and when making any power Webers want a real 5-6 PSI.

Isn't the VV71 what IPD sells as a 'street performance' cam? It really should be pulling pretty strongly at 5000 rpm - not dropping off like that.

How does it feel driving around? Does it feel pretty good at low RPM, and then fall on its face as the revs climb? I guess the answer is on that dyno graph - it just looks pretty weak across the board.

But still, does it drive like it has 69 hp? Or is it possible the dyno settings are doing something to the numbers? What gear was it in? OD accidentally engaged?

JohnV - if the fuel supply wasn't keeping up (not enough PSI for full fuel flow at WOT) wouldn't that show up on the O2 sensor - going lean and sputtering a bit?

Did it sound like it was running on all 4 cylinders? How about a compression test just to see what's going on?

And did you double-check the timing with a dumb timing light? On my PV's motor I don't really even use a timing light - there ar enough weird things going on with that motor (dished pistons, very smoothed out chambers, a Mallory distributor body w/no vac advance or retard) that it's probably not going to time to spec anyhow. I just test drive it and advance until I get a light smattering of pinging, then back it off a tiny bit.

I think the regulator on mine is set to 3.5 psi, but I've never checked that with a gauge, so who knows what it really is. I got some weird behavior from the DCOE's that I attributed to bowl overfilling when it was higher, and they certainly seem to starve on an extended WOT pull with less, so I just sort of arrived at that setting by trial and error.

I would start with some basic tests and procedures.

Check your valve clearances.
Check the compression
Check the leakdown

What sort of ignition coil are you using with the 123 distro setup?

I used to think ignition was graded on a pass/fail(miss) scale. But since then I've learned it is a sort of gray area. I've fixed various weak-feeling issues on my PV motor, not outright missing, by upgrading the spark. First off was the original firewall mounted coil used with the points and condenser. It put out thin wispy weak looking blue sparks, and the motor had a sort of wavering weakness to the high RPM range. I put on a big old square Mallory coil, got fatter red sparks that sounded mean, and then it pulled clean and hard up to the redline.

Now I work it even harder, and I had a Blaster 2 coil and an MSD box that sends significantly higher voltage to the coil - and does it multiple times per ignition event at lower RPM's. I would have thought that would all not mean much of anything other than perhaps powering through fouled plugs in some situations, but it really is noticeable. I can easily bypass the MSD box by putting the Crane output directly to the coil instead of it, and the car starts noticeably less eagerly, and has a noticeable loss of power and responsiveness at low-moderate RPM's.

JohnMc said:

Isn't the VV71 what IPD sells as a 'street performance' cam? It really should be pulling pretty strongly at 5000 rpm - not dropping off like that.

How does it feel driving around? Does it feel pretty good at low RPM, and then fall on its face as the revs climb? I guess the answer is on that dyno graph - it just looks pretty weak across the board.

But still, does it drive like it has 69 hp? Or is it possible the dyno settings are doing something to the numbers? What gear was it in? OD accidentally engaged?

JohnV - if the fuel supply wasn't keeping up (not enough PSI for full fuel flow at WOT) wouldn't that show up on the O2 sensor - going lean and sputtering a bit?

Did it sound like it was running on all 4 cylinders? How about a compression test just to see what's going on?

And did you double-check the timing with a dumb timing light?

I think the regulator on mine is set to 3.5 psi, but I've never checked that with a gauge, so who knows what it really is. I got some weird behavior from the DCOE's that I attributed to bowl overfilling when it was higher, and they certainly seem to starve on an extended WOT pull with less, so I just sort of arrived at that setting by trial and error.

Click to expand...

We did double check the timing with a dummy light and we were 14? advanced at 1000rpm which is about in line with the map we were using at the time.

Honestly it feels like 69hp. I had a Merkur that was off a tooth and it drove the exact same way. Nothing was obviously wrong, it just felt weak. Right now the 142 will rev up but it doesn't feel like those rev's are achieving anything, feeling the weakest at low RPM.

And as for fuel, I think the regulator was set to about 3.5psi as well because we were loosing fuel in the top end.

planetman said:

I would start with some basic tests and procedures.

Check your valve clearances.
Check the compression
Check the leakdown

Click to expand...

I can do two of those three at home, and I will. Like meatloaf said, 2 outta 3 ain't bad!

JohnMc said:

What sort of ignition coil are you using with the 123 distro setup?

Click to expand...

Bosch Blue coil. Which 123+ says is ok with their distributor, but it is an old coil... I'm just worried about getting a knock off one now if I try to buy a new one

Probably an insulting question, but where did you get your head ported, and was it flow-bench tested?

Not on volvo engines, but I've seen people lose as much as 30-50 horsepower from a bad port job.

poulrais said:

That?s a lot of work for 100hp...

Click to expand...

I cant recall who it was as this was years back, but they went all out with an engine rebuild and spent a lot of money on the head , intake carbs ect. When it was all said and done they did a hooptie +T on an older hooptie and it ran circles around the high dollard carbed car for like tree-fiddy and a weekends worth of time.

fatcatbestcat said:

Probably an insulting question, but where did you get your head ported, and was it flow-bench tested?

Not on volvo engines, but I've seen people lose as much as 30-50 horsepower from a bad port job.

Click to expand...

This is honestly a big worry. It was a machine shop called Engine Machine Services near LAX. I had been recommended them a number of times from various people who have cars that are worth more than my house. (not to say expensive is better, just that they have an extremely vested interest in not having their cars ruined by bad machine work).

I told them not to take too much out since it's been known to ruin b20 heads. But I couldn't provide them with any instructions on what to do other than a 3 angle grind, port and polish.

Jeh said:

I cant recall who it was as this was years back, but they went all out with an engine rebuild and spent a lot of money on the head , intake carbs ect. When it was all said and done they did a hooptie +T on an older hooptie and it ran circles around the high dollard carbed car for like tree-fiddy and a weekends worth of time.

Click to expand...

Cool.

I learned years ago that a glowing rep doesn't mean squat if the guy actually doing the work is clueless. Hopefully that's not your issue though.

I would seriously suspect cam timing, with numbers that low. Even mine on k-jet and a stock head, with a VV61 cam, 9:1, and 2130cc was 112whp.

I can't see a bad porting job-killing half the hp. It might not add much, or even cost a little, but not totally strangle things.

How about something silly - like the throttle linkage on the DCOE's not opening them all the way? I know it was a bit of a puzzle to sort out on mine - getting a nice progressive throttle tip-in, and a complete throttle opening.

And the loss of power all over the RPM curve doesn't point toward a blocked exhaust. I've had that a time or two in the past - feels fine and pretty good down low, but totally chokes up high. When bad enough - it won't even rev in neutral with the throttle wide open, but still pulls pretty hard down low.

A 1/4 mile drag calculator suggests mine has about 165 at the wheels, from a fairly similar setup. 2.1L B20, R-sport head (double valve springs, biiiig valves, big ports), DCOE 40's (a bit too small, but with 36mm chokes), 4:1 header (at the time - now has a 4:2:1 KGTrimning header), really zappy ignition, roller rockers.

Here would be my order of diag:
1. Pull valve cover and verify all 8 valves are opening
2. Check cam timing
3. Compression
4. Disconnect exhaust

This may sound weird, but the tq/hp curves show that you're having flow issues. Why? Well, weak flowing heads make great torque down low (with a corresponding limp cam) and poor hp (usually done up top). I'd wager something is awry with the cam timing, valve lash, or exhaust.

It's also lean from 3600 or so up.

Is this the cam?

http://www.iskycams.com/shop/index.php?main_page=product_info&products_id=936

If so, you need a lot more cam to make torque past 4000.
That duration number is "gross" duration. We need the numbers at .020 or .050" to really know the deal when you do find a gross 280-300 degree cam, hopefully in the .450-.490" lift range. (I don't know how much lift your springs and piston/head combo can stand)
Also agree on a possible restriction, but that is a very mild cam.

mikep said:

It's also lean from 3600 or so up.

Click to expand...

I wasn't quite sure what the values were on the O2 line.

If you have the carbs bolted solidly to a buzzy 4 cylinder, and the Volvo engine certainly is a bit buzzy - then I think the fuel bowls can get a bit frothy and the jets start pulling in air along with the gas. I've heard you can get issues with that by overzealously tightening down the soft mounts. Or by just bolting the carbs up directly to the manifold.