Bracket Talk
degree as spec or best crankin compression

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November 03, 2024, 11:02 AM
wideopen231
degree as spec or best crankin compression
Question for those who do your own engine work.

When installing a cam in your engine. Do you just go with as spec'd or do you play with degreeing to get higher crankiung compression,provided you have piston to valve to do so?

New cam in this combo can moved all over the p-lace due to shorter rod,Hey new 1500 buck set for 750 and loose .45:1. Hard to pass up.

Cranking compression is well below what would like at spec, can move cam and get better. HGave checked cam 10* advance and up good amount aqnd still have piston to valve. Just seems a lot and tells me need another grind. Grind is on me not guy who did it. First did not spec open and closing points and was regrind which may have dictated part of it.




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November 03, 2024, 12:36 PM
Alaskaracer
My current build I installed the cam where Bullet wanted it. Haven't checked compression on it yet. Last one I installed straight up and ended up 4* advanced to get it to run right...it was a dog until I advanced it.


Mark Goulette
Owner/Driver of the Livin' The Dream Racing dragster
www.livinthedreamracing.com
"Speed kills but it's better than going slow!"
Authorized Amsoil Retailer
November 03, 2024, 06:11 PM
wideopen231
Well is advance makes go from dog to running good. this bytch should fly now. Moved cam few tims weant to 10* and backed it up to 8* advance, CC went from 195 to 240. If does not have any issue like detonation it should pickup some. Bad part is can not really say how it ran as spec'd.Only fe3 decent hits with it. They where about .15 off what think should have run.MAy have to make few hits before swapping engines.

This is small motor not new bigger one.Yea I know 540 far from big , but bigger than the 482 in car. Will not have as much room to move cam in that combo since 2.75 more squeez there. guess I will be checking piston to valve with few cam changes for future knowledge in case.




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November 05, 2024, 03:40 PM
329L
Cranking compression does not always mean it will run better up top.


Jeremiah Hall
November 05, 2024, 04:05 PM
wideopen231
Not much is always. Right now thinking goiung to make some runs if get chance between now a christmas. Fi car shows good amount more power than alls good, Never understodd why bracket guys wory about top enjd. 99% tracks are 1/8 and 7500 is max engine4 sees for good amount.

Since new combo is about ready or ready if decide to run with crank in car, Compression is 2.5 more and bore is .125 more. So amy or may not need to amnipulate cam.




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November 09, 2024, 07:11 AM
Bucky
I always considered the cam card a suggested starting point. I don’t know how piston to valve clearance is on your combo but was usually the limiting factor for me.
If you want to go down a rabbit hole add running lash loops to the test. Changing lash can change your cranking compression as well.


Foxtrot Juliet Bravo
November 10, 2024, 11:44 AM
Goob
quote:
Originally posted by wideopen231:
Not much is always. Right now thinking goiung to make some runs if get chance between now a christmas. Fi car shows good amount more power than alls good, Never understodd why bracket guys wory about top enjd. 99% tracks are 1/8 and 7500 is max engine4 sees for good amount.

Since new combo is about ready or ready if decide to run with crank in car, Compression is 2.5 more and bore is .125 more. So amy or may not need to amnipulate cam.


This bracket racer wannabee only cares about operating between 5500-6500 RPM's, the rest is just for getting in and out of the trailer, and to the starting line.


"Despite the high cost of living, it remains popular."
Dave Cook
N375
November 10, 2024, 02:09 PM
wideopen231
hell only care about stage leav emshift and anything extra b4 finish line. the rest is just ride around pits slowly so useless info there. Now if street junk I might care about lowend and part throttle crap. Heck with SLE only thing other than about 1500 rpm is just revving up to go.

I am open to suggestions as why anything else matter unless you run footbrake. I can see lowend importance there. Never said 5500 to 6500 that is just stagfe and leave numbers

This message has been edited. Last edited by: wideopen231,




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November 10, 2024, 02:14 PM
wideopen231
more of a stuck bracket racing than wanna be. Just a way to play with car and have something to work on. Far from the end all of things for me.

Not knocking bracket it is tough way of racing, just its not heads up like I really enjoy most. Main reason for so few runs I guess hard to get wound up for it. For me.




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