Thanks Arthur,Arthur wrote: ↑Sat May 14, 2022 2:55 amNice worksteve cowan wrote: ↑Fri May 13, 2022 5:56 pm To insight a bit of discussion I am curious on why peaks fell where they did and why it carries up top to 7000rpm.
The only headers I could use were my 1 3/4" 4 into 1 headers
Could not use the 13" extensions as they hit dyno frame.
So shelf header with 3" collector at 6" long with a curved extension to clear frame.
The 300-25 intake is to suit my Dart 180 shp heads so port match is far from perfect, testing carb spacers certainly changed my perspective on Google theory as well.
Would you elaborate on your spacer journey -
The spacer deal was a eye opener for me that's for sure and I understand every combination responds differently.
We initially ran engine up with my 830 annual but I removed 130" needle and seats for new 110" just so we would not get caught out with fuel pressure confusion.
1" aluminium spacer with 4 hole timber spacer,ran engine in to seal up first 15 pulls on engine were with 28 degrees of timing and engine made over 500ft/lbs with 28 degrees, putting timing later pushed and smoothed power curves to 522 ft/lbs @5300rpm and 568 hp at 6600 .
We pulled with 830 carb but after adding jet up to in the 90 range and still lean we went to 850 carb .started at 88 jets all round no power valves.
We kept adding fuel and power increases, went from a 28 bleed down to 25 HSAB power increased.
So we are at 94 jet all round 25 HSAB still 28 degrees timing and around 515 ft/lbs 550hp
At this stage we have 1" open and 1" taped 4 hole spacer.
So now timing going in 30 degrees pushes power higher,32 power higher in rpm range.34 degrees torque down but hp up slightly at higher rpm.
36 degrees power down but AFR not going silly.
32 degrees to peak torque at 5300rpm and then 34deg up to 7000rpm nice power curve ,engine sounds very nice.
I check and set lash to spec 20" - 22" per cam card,replace oil filter every thing looks good, still on BR30 oil.
Fit 2 " open spacer that I made that fits perfectly and it's down 15 plus hp and AFR go goofy.
The boys say try a 2" 4 hole spacer no taper,I say it don't fit very nicely, they say try it.
Best torque and hp at highest rpm and AFR not moved on both sides throughout the range,I am in shock and thought they we having a go at me some how,I have known these guys for 35 years so anything is possible.
Put 1 " open under 4 hole and lost 10 hp.
Tighter lash was up on the curve.
Vac pump worth 5hp max at 11" and lost at 17" down 10hp
Expensive synthetic race oil 5w-30 was down 5hp on 19th pull and broke even on 20th pull.
Russell made sure that water and oil temps were stable as best as possible on all 20 pulls.