Big Chiefs?

Thanks for the responses.... Here is a little more info.... T&D rockers with the long bolt in the exhaust, Big M block, Smith Bros pushrods, not sure on wall thickness but 1/2" on exh and 7/16 on inlet. Static comp a whisker over 11:1, 3.9 gear ratio with 'Glide, plan to keep it to 8500 max. Valve springs are 420+ on the seat. So I guess I have most things reasonably well covered. What timing are you guys running? Minimum and maximum...

Cheers Pete

 

bbc

I ran 30 total with a roots. I think 32 is about max.
Be prepared to dump half your timing on the hit...it will be violent.

 

Thanks BBC... I am prepared to pull timing at the hit, was thinking 28 max so I am in the ballpark so it looks like about 15 off the start line... I have a Spud Miller enhanced Supermag and his timing control so I should be able to make it work. Maybe not as controllable as an MSD controller but I think it will work OK...

Cheers Pete

 

bbc

if you have a good blower and fuel system it will be fast. Don't abuse it in the waterbox. Apparently,the chiefs get pissed when run without load.
I think the combo gets a bad rap for reliability..we'll find out next year. The weakest link in our program is the head castings. It went 4.0 @183@2660lbs on a shakedown run.

 

That's some quick times, what cam?

Cheers Pete

 

Bill Doucet of louisiana had the cam ground. He has a lot of big chief experience. Look him up on here.

 

Ok 450

OK 450 on the intake seat. But with all the terror posted about exaust stands pulling whats the lowest you can go on the out valve (since there isnt a blower on its back side)

 

450

I don't know how hard your going to spin this motor,however our first engine from Jim Oddy back in 99 had 250lbs.seat presure and after six passes shifting at 8100 the springs had started to break the lip off the spring cups! Jim said that was normal! don't worry about it. After repeated failures we went up on spring presure to 350lbs.seat and took the .120 wall push tubes out also because they were flexing terribly.Car picked up a tenth and stopped our valve train issues.The pulling out of the head rocker issues have gone away since we installed longer quality bolts. I might add that in 2000 we started building our own motors. overthehill.........