Valve not opening - Volvo Amazon B20

Something something "hiding in that long block"

In reply to buzzboy :

Now that there is a healthy mammajamma cam!  Would the SUs be okay with that or would it be time to step up to some DCOEs/similar?

I was told it wouldn't idle on SUs. At the time I was planning side draft/s.

Streetwiseguy said:

Pete. (l33t FS) said:

Is recession an issue on Volvos?

You betcha, but a 75 head has hard seats.

Right. So it'll run 87 octane unleaded just fine. 

Pete. (l33t FS) said:

In reply to buzzboy :

Now that there is a healthy mammajamma cam!  Would the SUs be okay with that or would it be time to step up to some DCOEs/similar?

Racers use much wilder cams than that and SU's are just fine. 
 In fact SU's with their variable Venturi's  work where fixed Venturi's like Webers won't.   2" SU's are stock on Jaguar XKE's that's 600 CFM on 250 cu in  The only reason Webers make 15 horsepower more than SU's is  the intake manifiold is curved on SU's and straight on Webers. 

In reply to frenchyd :

Right, but big cams tend to not like manifolds that share a carb, and the SU manifold I have seen only used two carbs for a four cylinder engine.

This is one place where engines that are multiples of three are okay with sharing carbs because of the timing of three equally spaced cylinders (like 123 and 456 on an inline six).  Fours usually don't, one cylinder starves the other one.

In reply to Pete. (l33t FS) :

 Take a typical V8 with a 4 barrel carb.  The path from the corner cylinders is longer than the path to the center cylinders.  The result is a wider/flatter  Torque curve. 
 It's the same way with a 4 cylinder and 2 carbs  or a six cylinder with three carbs.  
       I realize that for all out power, individual  throats are optimum.  But that tends to produce narrow torque peaks.  If you remember the Can Am Big Blocks used different stack lengths  to produce a wider, flatter Torque curve.  

The firing order attempts to balance it out, 1-3-4-2, so that two cylinders "sharing" a carb don't have sequential intake strokes.  Plus, the Volvo SU manifold has a balancing tube between the carbs.  

Regardless, I'm running the D grind cam, which is about the hottest "stock" cam Volvo used.  And I'm idling around 1500, because reasons.  

volvoclearinghouse said:

The firing order attempts to balance it out, 1-3-4-2, so that two cylinders "sharing" a carb don't have sequential intake strokes.  Plus, the Volvo SU manifold has a balancing tube between the carbs.  

 

The firing order is also 3421, so...

In reply to volvoclearinghouse :

Que?  A balanced inline four fires from the inside out, a 360 degree paired manifold would have 1 and 4 paired, 2 and 3 paired.

Edit for brain fart

Forget what I typed,apparently I was having a brain fart, too.