i need help with my 416

[400exstunta]

ok so i have a 416 io just put it together... started it... im running 92 octane. 11:1 compression web cam stage 2 all the goodies port and polish.... bla bla bla...

im gettin a knock that pretty loud to me. i havent broken it in yet. so i check the valve clearance. its .004 on the intake and .006 on the exhaust. i added some octane booster and its still knocking. there is oil in the head... cam chain is tight, cam is seated. i take the spark plug out and it goes away.... any ideas?

well for 1 the valve cealance on the outake is suposed to be .005..and check for oil leaking out around where your head and cylinder are together..you might have blown a head gasket

[Dune Surfer]

Could be a head gasket or the piston installed backward. If it is a gasket feel around the head for air leaks and look for oil leaking. If it is the piston, buy a new head gasket and turn it around. good luck:)

[Dirt]

Is the Knock heard while running and/or not running when turning over? What piston are you running and what gaskets?

92 octane and 11:1 compression is begging for predetonation...:(

[YZROOSTINYA]

mine pings on pump when hot out under load

with a XR head gasket and 10.8 JE piston

[mikeboone]

Originally posted by nacsracer27
well for 1 the valve cealance on the outake is suposed to be .005..and check for oil leaking out around where your head and cylinder are together..you might have blown a head gasket

On the out take? :D Anyway--Web and Hotcams use different lash specs than stock cams. His #'s are correct and off by .001 wouldnt cause a knock..

I had to run 50/50 race gas with my old 10.8:1. Running 93 sounded like a bag of nails in the motor. If the cylinder has been decked you are a good bit over 11:1 also. I know you said b4 he replaced the connecting rod--do you have the box it came in to determine the correct one is installed?

[Chanman420q]

whats the lowest octane you can run with 11:1 because the highest pump gas around here is 94..........

[Ty's400]

I have also wondered what octane you should run with 11:1 compression. I thought I have heard of different places that say you can run pump gas. What exactly is the 50/50 mix too? Is it where you mix pump gas with some type of additive or race gas? thanks

[Dune Surfer]

50-50=1/2 110 race gas with 1/2 pump gas. I had to use that mix with my 10.8:1 and my 11 compression pistons

[YZROOSTINYA]

I run 4 gallons of 93 with 1 gallon of 108

you need about 95-96 and thats it.

Mine runs fine under 75-80 degrees on pump

[kargaaro]

Sparks Racing told me to run 110
I run 100 for riding but it does get hot when racing and will break down the oil. Change oil after every race!

[Glamis400ex]

110 octane sounds a little excessive on a 11.1:1 416 piston. I mix 2 gal. of 110 w/ 3 gal. of 91. Comes out to around 98 octane.

Glamis

[RytM1]

You sure its a detonation knock, or does it sound like a valve noise? When I put my 416 together, I had a distinct vavle noise, and a little problem starting. I thought I had the cam sprockets lined up, but after talking to Marcum's, he told me it sounded like the sprocket was off by a tooth or two. I went back in and messed with the cam sprocket again, and the knock was gone.

[F-16Guy]

Originally posted by mikeboone
I know you said b4 he replaced the connecting rod--do you have the box it came in to determine the correct one is installed?
Yeah, that's important! When I ordered my Carrillo, I was talking to the guy, and he said the XR400 and 400EX rods were not exactly the same. The slight difference in transmissions requires different clearances on the bottom of the rod.