Detune a Motor?

Posted By: 340SIX

Detune a Motor? - 12/16/11 12:21 AM

I have a 340 that was built to much and was wondering what could be done to to detune it for street use or at least more liveable street use.
Virgin 340 X block bore is 4.040 stock stoke forged crank
With the flat top forged pistons that are in it with the small cc heads came in at 12.3-1 compression.
Aluminium heads 202/165 valves
Hdy cam that has like 230 something @50 with .504/.515 lift but has 1.6 rockers so .538/.549 to make the compression more liveable with a smaller cam
Auto hemi type fairbanks 11" stall that RPM matches cam{rebuilt by turboaction}
Reverse manual valve body in the 727 with 430 gears but have other sets

Posted By: JohnRR

Re: Detune a Motor? - 12/16/11 12:27 AM

What's the cranking PSI ??? Looks like a nice pump gas engine to me if you built it right .

Posted By: rickraw

Re: Detune a Motor? - 12/16/11 12:47 AM

i'd run it the way it is. i'm street driving with more than that. by the way, lookin real good.

Posted By: Dean_Kuzluzski

Re: Detune a Motor? - 12/16/11 12:49 AM

What do you mean by "built too much"???

Is it a driveability issue??? Soft low-end throttle response?

What's been done to the mech. ignition curve??

What carb and carb tuning so far??

Typically many guys bolt on a carb and drop in the distributor, set total advance, and then the dissappointment begins when they want to street drive it.

Posted By: 340SIX

Re: Detune a Motor? - 12/16/11 01:31 AM

Quote:

What do you mean by "built too much"???

Is it a driveability issue??? Soft low-end throttle response?
No car runs fine and leaves well with the gears and stall so seems matched right but have not driven it much as it was shown plenty but want to drive it
What's been done to the mech. ignition curve??

What carb and carb tuning so far??

Typically many guys bolt on a carb and drop in the distributor, set total advance, and then the dissappointment begins when they want to street drive it.
Stock 100% 340 auto carbs from holley for 340 six pack out the box starts up and runs fine.

Thing is the gas cost as I was running 100% 110 with lead for one high compression and 2 no problems with storage getting lines and carbs messed up from bad gas
So wondering how low I can go with octane etc...
Dist was set so it starts up fine and runs well that's all I know at this point.
I know I have to do a few things to get the kinks out as they never were addressed
Small oil leak at pan conner,
One water pump bolt leaks antifreeze and needs sealant Intake I think is sucking oil in from galley and needs pulled and milled and reinstalled as it sat to high on the commando heads
I never fooled with it as I had to rebuild a whole home ND THEN OTHER THINGS CAME UP SO CAR SAT.
would like to address those issiues and drive it if gas is not a large cost

Posted By: HotRodDave

Re: Detune a Motor? - 12/16/11 01:43 AM

Got E-85 ?

If you can get it then run it. You can have your carbs re-worked for it or buy a single 4 set up for it or do what I do and just use it like pump gas with NO CHANGES. I have done it for years and never had any problems. It is much less picky than gasoline about the fuel curve, it does like more timing though for sure.

Posted By: Performance Only

Re: Detune a Motor? - 12/16/11 01:56 AM

there's at least three things you could change to de-tune it, but i'd want to know the cranking compression on it before i suggested anything.
it sounds like you want to run pump gas, right?

Posted By: 340SIX

Re: Detune a Motor? - 12/16/11 02:52 AM

Quote:

there's at least three things you could change to de-tune it, but i'd want to know the cranking compression on it before i suggested anything.
it sounds like you want to run pump gas, right?

yes or a weak as i can do mix and still have it be ok

Posted By: Performance Only

Re: Detune a Motor? - 12/16/11 05:01 AM

Quote:

Quote:

there's at least three things you could change to de-tune it, but i'd want to know the cranking compression on it before i suggested anything.
it sounds like you want to run pump gas, right?

yes or a weak as i can do mix and still have it be ok

let me ask again if you don't mind; what is your current cranking compression?

Posted By: 340SIX

Re: Detune a Motor? - 12/17/11 01:56 AM

Quote:

Quote:

Quote:

there's at least three things you could change to de-tune it, but i'd want to know the cranking compression on it before i suggested anything.
it sounds like you want to run pump gas, right?

yes or a weak as i can do mix and still have it be ok

let me ask again if you don't mind; what is your current cranking compression?

have not checked and tools are not here for doing that at my home right now.
Things are moving fast on my health issues, so looks like more test and meets with docs next week minor surgery. And Chemo soon after that so will just let the car sit more till that's over with.
Was thinking i had time to pull it down mill the intake fix a few things install full exhaust and use it some first.
Thanks for the responces

Posted By: hemi-itis

Re: Detune a Motor? - 12/17/11 03:47 AM

Good luck with your health isues

Posted By: domingo

Re: Detune a Motor? - 12/17/11 06:16 AM

Kevin, get some Cometic Head Gaskets and drop your compression to whichever ratio you want...

you can order cometics in any thickness you need and they are suoper reliable, you wont blow them!