Stock Predator Valve Springs Question
- Thread starter DRC21
- Start date
Yep. The billet lifters probably have a fillet from the stem to the head that is hanging up. It's worse on the exhaust side. I was too put off to even investigate. My wife has been on my case for having spent too much time in the shop anyway!!
Does the .356 have a stock size base circle?
Does the .356 have a stock size base circle?
Nice picture, Al needs to add his "compression is the holy grail" caption to that
Lol... How much is too much? I honestly think compression can be too high in one of these. Compression can work against these engines when operating in broad rpm ranges. The motor has to work too hard to overcome the compression at lower rpm. But I've also read that alcohol's potential isn't realized until CR are 14:1 or higher.
alvin l nunley
Site Supporter
I think you will find that the rest of the world of automotive engineering will disagree with you.
From my experience, the only limiting factor on compression is the octane of the fuel.
"Alcohol's potential"? I'm wondering, you might want to change that to, "alcohols full potential".
From the desk of Al Nunley
Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory. (Al Nunley)
Hey what does he know, hes just a WELDER jk Brad. looks good. going to be doing one soon, all I weld these days is Aluminum. The OTC machines "mig" we have at work are finiky as hell. weld speed/ feed changes when room temp changes . they have people grinding out the seam welds on one part.. 0 porosity allowed.. good thing about these heads is they will fit in a lunchbox.. Government work approved.
Well I'm not really much of anything and I darn sure ain't the best welder or engine builder. But sure do love to do lots of things, including welding and engine building.
I'm still not gonna build a 20:1 go kart motor because it will run like crap. I know because someone very close to me did just that. Talk about a bogger. Too much compression to get around the track and work well in all rpm ranges. But Al, I will agree that more compression makes more power... To a point. All good man!!
I'm still not gonna build a 20:1 go kart motor because it will run like crap. I know because someone very close to me did just that. Talk about a bogger. Too much compression to get around the track and work well in all rpm ranges. But Al, I will agree that more compression makes more power... To a point. All good man!!
youngengines
Member
modifiedman
Member
I cut them on mine just to play it safe I also run the 356 cam
I use my spring pocket tool for Mods that I used on my flat heads.
the lifters do come very close either the stock or billet with this cam
as for 26 springs you should be fine with out cutting pockets
but if running dual you will have too.I also have taken the inner
spring out and runs just fine
I use my spring pocket tool for Mods that I used on my flat heads.
the lifters do come very close either the stock or billet with this cam
as for 26 springs you should be fine with out cutting pockets
but if running dual you will have too.I also have taken the inner
spring out and runs just fine
youngengines
Member
I agree on the too much compression on a single cylinder. ..now with more cylinders helping ...give me compression. ..
alvin l nunley
Site Supporter
very interesting. And why would multiple cylinders like more compression than single cylinders?
From the desk of Al Nunley
Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory. (Al Nunley)
youngengines
Member
My thoughts.. a single cylinder uses momentum to push the piston up on the compression stroke..a multiple cylinder would have another cylinder "helping " in the process...Now , that's my thoughts...
alvin l nunley
Site Supporter
then how do you explain the Rotax twin 250? Both cylinders fire at the same time. You know at one time F1 V8 engines had pairs of cylinders firing at the same time. The Harley Davidson twins don't fire 180° apart.
From the desk of Al Nunley
Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory. (Al Nunley)
youngengines
Member
I cant comment on those, I know nothing about them. I just have the idea in my head..may be wrong though. I haven't been able to make a noticeable power increase over 14 to 1 compression, but I may be doing something wrong.
alvin l nunley
Site Supporter
what octane fuel did you run with that 14–1 compression ratio? Did you try testing with a colder spark plug? Did you try a bigger jet? An EGT gauge might have told you something.
From the desk of Al Nunley
Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory. (Al Nunley)
flattop1
Dawg 89
180* degrees helps with smoothness of engine. Balance factors.
Yankee motor cycle was same way twin fireing together. In 1970 we had a 100cc Yamaha twin with the crank turned so as to fire both cylinders at the same time it was called twindled. course all 2 stroke stuff.
Now triumph bsa and Norton, run both pistons too the top together but fire 180* apart . That's not going to help any with moving the piston up against a higher compression. They also benefit from higher compression.
youngengines
Member
It was ran on M5 methanol. I didn't relly try a lot of different heat range plugs, I did try different timing. It made great power.
MO Predator Racer
Member
Found this old thread and I saw the modifications to that head, I have never seen anyone modify a head like that to get higher compression but it makes since.