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I have a 240z that I have drag raced for three years with a 75 modified 280 engine that ran flawlessly until a missed speed shift at over 8000 rpm left me with a wonderful two piece crankshaft(aarrgghhh).Anyway after amazingly making it home 40 miles, with believe it or not perfect oil pressure, I put my old 240z block back in the car but retained my .070 shaved, ported and polished N42 head.This combo has given me a compression ratio of approx 10.6 and runs with 36 degrees total ignition advance.THE new combo runs perfect and I have since drag raced the new combo with a best 1/8 mi time of 8.88 @ 79 mph(the old 280 block ran a best of 8.56 @ 81.2mph(( 1/4 mile time of 13.4 @101 mph)) but that was speed shifting at 8000 rpm which I obviously no longer recommend:: LIFT THEN SHIFT :: THE CRANK YOU SAVE MAY BE YOUR OWN::) I am now slower than I used to be,which is NOT GOOD. SSSOOOOO what I am now contemplating is an 82 280 block w flat top pistons and the aforementioned head which will yield an 11.8:1 ratio. Now I know everybody says dont go over 10:1 compression on a street engine but my 240z block runs great at 10.6 on 93 octane.I know the longer rods of the 240 make it less likely to detonate but i am thinking of putting a 282/292 duration cam(it has a 272/282 cam now)with the 280 block which I THINK MIGHT ALLOW me to get away with this high compression. I know Hot Rod magazine built an 11:1 chevy this year and it ran on 87 octane with longer than normal rods BUT THEY DID USE 87 OCTANE pump gas!!! NOW AT LAST MY QUESTION. I KNOW WHAT THE DATSUN HOT ROD BOOK SAYS, BUT I WANT TO KNOW HAS ANYONE OUT THERE IN Z LAND PERSONALLY TRIED THIS COMBO WITH DISASTEROUS RESULTS??? P.S. fuel system is modified SUs and electronic ignition off 78 datsun 810.
 

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> I have a 240z that I have drag raced for
> three years with a 75 modified 280 engine
> that ran flawlessly until a missed speed
> shift at over 8000 rpm left me with a
> wonderful two piece
> crankshaft(aarrgghhh).Anyway after amazingly
> making it home 40 miles, with believe it or
> not perfect oil pressure, I put my old 240z
> block back in the car but retained my .070
> shaved, ported and polished N42 head.This
> combo has given me a compression ratio of
> approx 10.6 and runs with 36 degrees total
> ignition advance.THE new combo runs perfect
> and I have since drag raced the new combo
> with a best 1/8 mi time of 8.88 @ 79 mph(the
> old 280 block ran a best of 8.56 @ 81.2mph((
> 1/4 mile time of 13.4 @101 mph)) but that
> was speed shifting at 8000 rpm which I
> obviously no longer recommend:: LIFT THEN
> SHIFT :: THE CRANK YOU SAVE MAY BE YOUR
> OWN::) I am now slower than I used to
> be,which is NOT GOOD. SSSOOOOO what I am now
> contemplating is an 82 280 block w flat top
> pistons and the aforementioned head which
> will yield an 11.8:1 ratio. Now I know
> everybody says dont go over 10:1 compression
> on a street engine but my 240z block runs
> great at 10.6 on 93 octane.I know the longer
> rods of the 240 make it less likely to
> detonate but i am thinking of putting a
> 282/292 duration cam(it has a 272/282 cam
> now)with the 280 block which I THINK MIGHT
> ALLOW me to get away with this high
> compression. I know Hot Rod magazine built
> an 11:1 chevy this year and it ran on 87
> octane with longer than normal rods BUT THEY
> DID USE 87 OCTANE pump gas!!! NOW AT LAST MY
> QUESTION. I KNOW WHAT THE DATSUN HOT ROD
> BOOK SAYS, BUT I WANT TO KNOW HAS ANYONE OUT
> THERE IN Z LAND PERSONALLY TRIED THIS COMBO
> WITH DISASTEROUS RESULTS??? P.S. fuel system
> is modified SUs and electronic ignition off
> 78 datsun 810.
I run an L28 with flattop pistons and decked block and milled E31 head so I have around 11.25-11.5:1 comp. ratio. I run regular 92 octane now, with the ignition slightly advanced. When breaking in my engine, I used 110 race gas, and slowly worked my way down to octane booster and finally to pump gas where I am now. I know it sounds weird, but over 3 years time, I now run 92 with no pinging. The engine seemed to get used to the lower octane if I spread it out over a long period of time. I also run bigger valves, porting, triple 44mm Mikunis, and my cam specs are .495 lift for 290 duration. Good luck!
 

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107,695 Posts
> I have a 240z that I have drag raced for
> three years with a 75 modified 280 engine
> that ran flawlessly until a missed speed
> shift at over 8000 rpm left me with a
> wonderful two piece
> crankshaft(aarrgghhh).Anyway after amazingly
> making it home 40 miles, with believe it or
> not perfect oil pressure, I put my old 240z
> block back in the car but retained my .070
> shaved, ported and polished N42 head.This
> combo has given me a compression ratio of
> approx 10.6 and runs with 36 degrees total
> ignition advance.THE new combo runs perfect
> and I have since drag raced the new combo
> with a best 1/8 mi time of 8.88 @ 79 mph(the
> old 280 block ran a best of 8.56 @ 81.2mph((
> 1/4 mile time of 13.4 @101 mph)) but that
> was speed shifting at 8000 rpm which I
> obviously no longer recommend:: LIFT THEN
> SHIFT :: THE CRANK YOU SAVE MAY BE YOUR
> OWN::) I am now slower than I used to
> be,which is NOT GOOD. SSSOOOOO what I am now
> contemplating is an 82 280 block w flat top
> pistons and the aforementioned head which
> will yield an 11.8:1 ratio. Now I know
> everybody says dont go over 10:1 compression
> on a street engine but my 240z block runs
> great at 10.6 on 93 octane.I know the longer
> rods of the 240 make it less likely to
> detonate but i am thinking of putting a
> 282/292 duration cam(it has a 272/282 cam
> now)with the 280 block which I THINK MIGHT
> ALLOW me to get away with this high
> compression. I know Hot Rod magazine built
> an 11:1 chevy this year and it ran on 87
> octane with longer than normal rods BUT THEY
> DID USE 87 OCTANE pump gas!!! NOW AT LAST MY
> QUESTION. I KNOW WHAT THE DATSUN HOT ROD
> BOOK SAYS, BUT I WANT TO KNOW HAS ANYONE OUT
> THERE IN Z LAND PERSONALLY TRIED THIS COMBO
> WITH DISASTEROUS RESULTS??? P.S. fuel system
> is modified SUs and electronic ignition off
> 78 datsun 810.
I run an L28 with flattop pistons and decked block and milled E31 head so I have around 11.25-11.5:1 comp. ratio. I run regular 92 octane now, with the ignition slightly advanced. When breaking in my engine, I used 110 race gas, and slowly worked my way down to octane booster and finally to pump gas where I am now. I know it sounds weird, but over 3 years time, I now run 92 with no pinging. The engine seemed to get used to the lower octane if I spread it out over a long period of time. I also run bigger valves, porting, triple 44mm Mikunis, 6 into one header, 2.25 exhaust and my cam specs are .495 lift for 290 duration. Good luck!
 

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> I run an L28 with flattop pistons and decked
> block and milled E31 head so I have around
> 11.25-11.5:1 comp. ratio. I run regular 92
> octane now, with the ignition slightly
> advanced. When breaking in my engine, I used
> 110 race gas, and slowly worked my way down
> to octane booster and finally to pump gas
> where I am now. I know it sounds weird, but
> over 3 years time, I now run 92 with no
> pinging. The engine seemed to get used to
> the lower octane if I spread it out over a
> long period of time. I also run bigger
> valves, porting, triple 44mm Mikunis, 6 into
> one header, 2.25 exhaust and my cam
> specs are .495 lift for 290 duration.
> Good luck!
i ran mine 3 yrs with nitrous,and high compression 11to1 kinda hard on motor,but speed costs money, how fast u wanna go? i got tired of breaking parts.i put a 350chevy in mine,it dont break **** anymore,+chevy parts are cheap.entire conversion using kit from johns cars in dallas cost 3000 dollars aprox .i have my expenses documented,an as it used to cost 2500 dollars per zx motor,at a rate of 1 every 3 months,i think it was a bargan to go chevy .they go REAL fast for minium bucks.think not, come down here an i will give you a ride that will scare **** out u Stan
 
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