Ok I was asked why I don't just go down to the station and fill it up the guy that drives his old 350 hp 327 vette says he does. I have 331" with 11.25 :1 pistons and 461 heads big valves I have always ran some sort of race fuel there use to be a turbo blue or cam 2 pump around not any more. Maybe shell has some higher oct gas they use to and I would mix I keep reading lots of Hamb'ers are running pump gas and high compression im no scientist. Here is the Isky cam I just installed its not a drag race grind instead Circle track but it might still work with the old Hilborn
I have almost the same engine combo , with a Schneider cam. I don’t have a whole lot of seat time in this car but I always mix something with the gas , either a few gallons of leaded VP or lately just the VP 32 oz. additive can . It always feels / sounds better with higher octane . Especially in summer . I’m assuming these other old cars are just cruising and not really pushing it. Does your 106 lobe separation bleed off some of the compression ? Also that’s a lot of lift for camel hump heads .
Just order a 5 Gallon can of Sunoco 110 Octane and mix a gallon in here and there. It helps.... less chance of detonation.
these heads came off my blown inj. alky the blower cam is 645. lift they are really worked over for double humps
that's what I have been using Sunoco 110 but im out at the moment we run that in our vintage road racers so every few mth's there is usually some around here in a can.
Could just mix in some Avgas if needed too. Just about any local airport will sell to you, pumped into a can. Won't let you pump into a vehicle directly, as no road taxes are levied and collected in avgas. Question I would have is: Do you truly have 11.25:1 compression?? Because if the rest of the combustion space clearances are not blueprinted out to their minimums you don't have anywhere near 11.25: 1..Block needs to be at correct deck height, minimum gasket thickness, gasket bore, cylinder heads cc'd and equalized to minimum published volume, etc. If this is the factory half moon shaped flat dome high compression 327 piston(the "L79 piston" )and minimum blueprinting wasn't done you are closer to 10.3:1 compression than you are to 11.25:1. Try a 75% pump gas/25% race or Avgas mix , run the math to determine actual mixed octane rating, and test it. If you don't get detonation, back off the race or Avgas percentage and test again. find what you can live with, and don't be surprised if on a non-blueprinted assembly you end up fine on pump 93 alone.
Static compression is only a reference. Dynamic compression ratio (DCR) dictates fuel usage. A practical max is 8.0 DCR for pump fuel if you have good quench. 7.7:1 DCR would leave you some safety margin. DCR is determined by intake valve closing (IVC). Calculate here: http://www.wallaceracing.com/dynamic-cr.php
no I never have done any of that on this engine, Yea I really never checked it out as its not blue printed, its nothing that wild just your basic lower end 350 hp 327 with good bolts on the rods clevite bearings iol pump cloyes had lots of trw stuff the the pistons are a raised flattop dome , the machine shop that was always used is no longer, but they were one of the best in the area and I used to take lots of 50-60's factory corvette engine to them for machine work for our mechanic always had a ton of that stuff to get done for D and A Corvette 100% resto's that's how I ended up with this little 327 (maybe the numbers did not match one of those car years) lol. I slapped the heads off my blower engine the 461's I use to run 462's 194- 150's and that large 305 comp hydraulic cam which sounded wicked that little set up was a great street - strip screamer with the 4 speed 7000 rpm
what do you guys think a .40 over 350 with the 461's and flat tops average on compression That what I ran on my blower engine with 32 percent over drive 32 top and 36 bottom cant remember the boost for the 2 pulleys I tried the Wallace racing estimater for the 327 set up but I don't know what degree the 547b cam intake closes after Bdc my blower cam for the .40 over 350 has 77 degrees Abdc its 645 lift ex and intake with 298 intake dur. 302. ex dur. I was using 600 for altitude
350 w/flat tops is about 9.6-9.8:1 unblueprinted and 10.2-10.4:1 blueprinted to minimums with 64cc heads.Thick head gaskets, reduced height "rebuilder" cast flat tops and undecked block could push it as low as 9.2:1. Differences in head gaskets, actual chamber volume vs published specs(lies) and actual piston compression height(piston pin to top of piston) account for the differences. Plus you've got to know if the chambers in your heads were opened up for the bigger valves and if the head was milled back down to compensate for this. 32 top and 36 bottom pulleys on blower makes 12.5% overdrive, no where near 32%. On a 350, with small bore case 6-71 it's 9lbs boost, if large bore case 6-71 it's 15 lbs For the 547-B cam - Using advertised duration of 288°, intake closing point is 70° ABDC if cam is ground straight up(106° lobe separation, 106° intake lobe centerline), if cam is ground 4° advanced (106° lobe separation and 102° intake lobe centerline) then intake close is 66° ABDC. If you need the .050" closing numbers, straight up is 55° ABDC, and 4° advanced is 51° ABDC
That's a big help thank you and I was guessing on that over drive ratio brain fade I guess I just looked it up 12.5 ratio what was I thinking sorry been 3 years since I have fooled with the blower set up. The 350 blower block was not oring'ed we used special head gaskets for blown engine I probably have a set around here with a part # again brain fade the 350 is at the machinist changing the crank as the front snout got messed up some how as the pulley fell off yes it was double keyed and I run a blower hub complete assembly was balanced but the end of the crank was not strait I got pissed about that I think some how it got dropped on its nose not by me thou it has ross blower flattop pistons and h beam rods yes its going back in the chevy with the 4 port but I would rather be on gas and not alky. the blower is the big casing 6-71 the new crank to me is nitrate cheverolet
With all this above ^^^^^ Only one Q....... Race, or Street? Just take some timing out. Kill a few degrees, and call it good. Track time= Run race gas, and bump it up a few degrees....... Creeping up on a tune is a science. Go slow, and start conservative.... If you swing for the fence, it might cost you $$$$$$$.
Answer: street strip a play toy something like in all the cool old movies and take it to the nostalgia events If I could come across a cool rail I could afford I would drop that blower motor in it - bucket list There is nothing like the sound at the end from a screaming Jimmy
When we used to run our dirt late model . The rep for VP recommended we run one gallon of oxygenated 93 octane to 5 gallons of his race gas. Around here in Tn. a lot of the Sunoco stations sell a 5 gallon jug of 100 to 105 octane for around $45.00 . I built a pretty hot 5.0 for my neighbor's Mustang and he runs 5 gallons of 93 to 1 gallon of the Sunoco and it does fine. It's a 10.5 to 1 motor, but it has aluminum heads which are a little less prone to detonation. the cam I used bleeds off a little compression also.
Well as I have said before this is the same 327 really 331 I have had forever when the blower motor was removed my son begged me to just put it back in the car so I could drive it on gasoline instead of alky the long block has not been touched the heads are off the other motor i removed we are able to drive on gas around this small town short trips. I got to fooling around with the compression gauge removed all the plugs and did not make that much of a difference wot or not Here is what the psi numbers showed cylinder 1,3,5,7 all 120 lbs cylinder 2 was 120 lbs 4 was 130 lbs 6 was 128 lbs 8 was 125 lbs if memory serves me right all the rings were chromoly this motor sat on a stand no heads for years it would get turned over or rotated every now and then I ran it pretty hard when I would race others 7000 to 7500 was the shift point held up pretty well for no more miles than I put on it not a oil burner at all. with the 11.25 to 1 pistons and 64cc heads 202. 160's valves set up for over 650. lift why would these psi numbers be where they are, is it the camshaft its the Isky 547b solid im not saying we should have hone and re ringed the cylinders and pistons but probably should have! We were planning on fooling around a bit with this hilborn stack injection a bit while the blower motor gets fixed, most likely its return back in the car, I love the 4 port hilborn with blower so throw out your thoughts o yea my valve lash at cold is .022 it calls for .016 I would guess the head gasket is just what ever the general is over the counter sbc fel-pro kind of like the right arm stronger than the left a bit lol.
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