HS6 SU carb conversion advice please...

[v8250]

As per title, could you knowledgeable Amazonian Gurus suggest the right HS6 +inlet/exhaust manifold conversion to adopt. Will be rebuilding ignition and fuel system over the coming months and want to remove the existing single Zenith and replace with twin SU's. Want to let the old girl breath/perform a bit better, this is shopping list...

HS6's and manifold
Performance/free flow twin port exhaust manifold
Simons st/st exhaust
Set of K&N's
FACET blue/silver top fuel pump [blank off existing mechanical pump]
Rebuild distributor with some little tweaks

All recommendations welcome...

Thank you
Andrew

[Ron Kwas]

Andrew;

Changing to dual SUs with low restriction Filters will definitely allow the old girl to breathe well, along with factory Alu intake and 4-2-1 cast exhaust manifold, and decent Exhaust Sys.... however, the Cam should be at least a factory "C" grind! If this engine has less of a Cam (as suggested by single ZS carb, others can verify what standard Cam was with this setup), all engine external changes will be for naught, because the Valve lift and overlap will not allow best breathing!
So I recommend you Verify Cam...if necessary with a dial indicator gauge set to measure the lift at Rockers. You might need to also change Cam!

Good Hunting!

[Derek UK]

All of the mods you mention are bolt on without disturbing the engine too much. A 1962 B18 with downdraught Zenith would have an A cam as would the later single carb engines including the B20. The C cam is the standard one with the later twin carb engines. It is usual to jump past the C cam and fit either a D or K cam. These were fitted to injection engines but work well with twin carbs. Fit as a kit with new followers. Push rods are usually OK but check them visually and roll them on a sheet of glass to make sure none are bent.

[jamie]

Whilst it is fine to have the
FACET blue/silver top fuel pump [blank off existing mechanical pump]
It is not necessary as I found out doing what you are about to do on my B20. I did change the cam as well. I also had my distributor rebuilt to bring it back up to spec rather than buying a 123ignition, which only the price put me off. I have posted the results here
http://www.volvoforums.org.uk/showthread.php?t=267904

Good luck

Jamie

[v8250]

Originally Posted by jamie

Whilst it is fine to have the
FACET blue/silver top fuel pump [blank off existing mechanical pump]
It is not necessary as I found out doing what you are about to do on my B20. I did change the cam as well. I also had my distributor rebuilt to bring it back up to spec rather than buying a 123ignition, which only the price put me off. I have posted the results here
http://www.volvoforums.org.uk/showthread.php?t=267904

Good luck
Jamie

Thank you all for your replies + thanks Jamie, your engine project work is what I'm after. I'm new to B18/B20 engines but long in tooth with historic/classic engine redesign and rebuild. My choice for FACET changeover is simplicity + together with a non-crank driven fan will ensure minimal unnecessary load [read power sapping] on engine :. peak available power. Of course, primary issue with any non-viscous crank driven fan is that fan rotation/cooling is directly proportional to engine rotation :. engines are often running too cool which in itself is no good.

Have yet to pin down final spec', will post upgrade project as time work progresses. Plan is to procure necessary components between now and winter, then build and install this coming winter ready for next Spring. Re' SU needles, Burlen Fuels of Salisbury have data for all SU's supplied since Skinner Union started, so I'll buy a std, rich, rich+1 sets from them and play around myself...have been rebuilding SU's for over 20 years now. I like the results your rolling road sessions produced, it always amazes the power/efficiency gains available from older engine designs with just a few tweaks.

Rgds, Andrew