Big Chiefs?

Was wondering if any of you guys were running big chiefs. And wanted to know your results with them.Im thinking of getting a set for my winter update but had heard they had valve train issues. Any info would be greatly appreciated before i go spending all this $ to change things over. Thanks, Tony BTW There going on a blown 540 on alky - century block

 

I run the 18 degree Big Chiefs with jesel setup. Don't know of any issues nor have I had any. Ran these same heads on a 632 nitrous motor and currently 565 blown gas motor. I do hold the rev limit to 8600 rpm, but it's seen 9K. Just make sure you run a good quality (Smith Bros or Manton) heavy wall push rod and adequate spring pressure.

Blessings...........Ron Clevenger.

 

Get one piece rocker stands from jesel, they are fairly new or weld yours together with small bits of Cm steel. This helps stabilize the valvetrain. Yes to the heavy pushrods I run .120 wall 7/16. Also put in longer heli-coils and use extra long bolts to hold the stands on the head, I had some issues until I did this stuff but no problems since. Jody Stroud TD 9325

 

Valve train geometry is CRUCIAL on these motors. Take the time to get this right and these will make BIG power. Several years ago went 6.0's in TD legal trim. Probably would have seen the 5's if the car hadn't burned to the ground. That was a BAD day

 

what type of blocks are you guys using under the chief heads. Anyone using an iron bowtie & How much power can you put in it.

 

My buddy Dave Harris from NC ran 6.18 in the 1/4 and 3.99 in the 1/8 with a iron dart block with ray franks 24deg heads in a dragster. Blower was a two year old littlefield, and he runs without a computer. His car runs really well and repeats. Prob. makes about 2000 HP.

 

We run the Big Chiefs on a 540 ci Rodeck with a 14-71 HH. Once we got our valve train geometry dialed in (Jesel) the combo really made a lot of power, we ran a 5.788 et on the liquid 1/4 mile.

 

I was told Chiefs are 150hp gain on a 2000hp combo. We made the switch and had all the aforementioned valvetrain issues plus broken water castings.
I wouldn't spend the money unless you already have a top notch blower and fuel system.
I've seen several KB olds big chief engines for sale and they don't bring any money at all. You can steal an entire longblock if you don't mind used stuff.
After all the headaches,I am impressed with our Big Chief combo. K9 superman at 37% on a 540 makes well over 2000hp.We've seen 9200 rpm and the valvetrain seems happy. Bearings are another story..lol.
Mike

 

Are we talking about the Dart Big Chiefs 18° heads? If so could any one tell me what port volume they come in and does anyone make a cast blower manifold to suit the heads on a std. deck BBC?

 

I Know it's a little off the post but what are your thoughts on the Big Dukes by Brodix?

 

we ran 14 and 18 deg darts with no big hp difference. I think the runner volume is around 400cc stock. I know one of the Dukes is a virtual twin of the 18 deg dart but they are very expensive to get solid.

 

Mkr 588

Indy cyl head makes a spread port manifold for (pontiac 18* & 14*) in 9.8 &10.2 deck standard blower and set back and a couple for real tall deck.

 

heads

We ran 14 degree stuff. With indy intake. Custom port work. Made tons of power, Always had rocker arm problems. If I was to use them again, I wouls contact Sunnys, They seem to have better top end stuff. Just my thoughts Don

 

I built a 470 cube engine with 14 degree solid big chiefs and, because of the rules for the class, used a dart big m iron block. I experienced no valvetrain issues whatsoever (jesel), ran a 206d psi at 72%, car (altered) weighed 2320 lbs and used a powerglide trans, went 6.49 @ 223.9 mph, and left .2 of a second on the table at the start line due to a stumble (glitch in the fuel system). Engine did 60 passes with absolutely no problems before car was sold, checked rods and bearings at 25 passes, changed rods and bearings at 50 passes.
It is my belief that these are the best off the shelf big block heads available for this type of application, and valvetrain issues are almost always a result of a geometry problem.

 

I agree, if you already have conventional head motor(s), make sure your blower and fuel system are top notch. If your starting from scratch and can't afford the best blower, ok, compromise on the blower, but build a HP long block by using Big Chiefs. Later down the line, get a really good blower.

my 2 cents.

Overkill69, I'm assuming your k9 is an 8-71?

 

There are so many options in the "Big Chief" world in the way of intake volumes, different makers, big dukes, 18 degree profilers, etc. The flatter valve angles helps more in the naturally aspirated world. (12, 11 and 10 degree stuff.) True it is that the actual big chiefs are easier to get in a solid head, but comparing wet headed castings, the Big Dukes are every bit as good as the Dart, and Brodix is so much easier to deal with.
If you find the pre-curser to the big chiefs, which is the Pontiac 427 (18 degree) and the 386 (15 degree), you do not need to run the offset rocker arms, but get the big ports and flow of the big chief and comparable fast chambers. Lots of boat guys ran the 427's with superchargers. You must weld the stands together on the 427's and 386's if you plan on running over 9 grand.

 

We ran 18deg Dart water castings dry and torched/cracked every exhaust port at less than 30 psi boost soft tuneups. The matl was less than .100 thick to the waterjackets. I would be scared to death of any GM water casting unless it was filled with something to dissipate the heat. Good luck finding a manifold for the 427 castings.
We have always run near perfect valvetrain geometry, IMO the problem is enormous exhaust valve loading as compared to N/A or N20 applications. All of our failures were on the exhaust. Jesel stands are made of mild steel dog$hit and the exhausts bend like a horseshoe around the stand bolt once you timesert it and do all the other mods. We ran from 380psi to 425 on the seat pressure and saw no improvements.Some guys run custom tool steel stands on the exhaust. I welded our bent stuff together and had the cam reground to slow the ramp rates on the exhaust side. About 20 passes shifting at 8800 and it's working good.
SoDak We run a 14-71 helix.

 

Interesting stuff overkill69, we just ran our combo with the 427 heads ,350 @ seat & with some dyno work & testing , the first race meet pulled the Ex pedestal bolt clear out with the bent rocker pedestal. Early Jessel rockers made out or sh#t material.Having said that ,the heads were second hand with some blow ups on them already so now we are looking to update but my customer has found some one local with another second hand set as it will work out cheaper for him at the moment rather than buying a new set of Big Dukes which i reccomended. EEERRRR! Like I said cheaper for now but more in the long run.

 

I've built and run a few Big Chief/Duke engines. I have a customer that runs 1802 Dukes on a 540 with a screw that has been as quick as 3.94 @ 193+ in a 2800# car. T&D rockers with the 1.500 long exhaust bolts work fine for keeping the stands torqued on. The Dukes are tapped deep enough from Brodix, so no extra work needed. .500 exhaust and .437 intake pushrods with a .120 wall work the best for me. The 1802 has the largest intake runner size of the out the box heads and the 18* valve angle/ combustion chamber size are very forgiving for minor tuneup problems that sometimes occur. If you need to price a set, I'm a WD dealer for Brodix and Dart. Call me @ 337-543-2028

 

hmmmm
paul,
that did go real fast .\, mate....
you build me one???