Cracked 906

-
BadAss71

BadAss71

Let's Go Brandon
Joined
Jun 13, 2010
Messages
1,584
Reaction score
122
Location
Pueblo West
So I have been chasing a coolant leak for the past few months and finally located it. I thought it was coming from the header bolts initially. We decided to take the header off to further investigate the leak, which by the way the 2" tti headers are a real ***** to get out! Especially the drivers side, the one that needed to come out. After removing the header it was obvious we had an issue. We found a hairline crack just below the exhaust ports on cylinders 3 and 5. The crack is about 2 inches long and hard to even see but big enough that when you would rev the engine coolant would spray out of it. Is this a common problem with these heads or am I just a lucky guy? A lot of work has gone into these heads and to duplicate one would be costly and time consuming which neither one is good at this point. I need to get it welded up and I have a line in a guy who is great with cast iron welding so he will get a call tomorrow. Pinks all out is saturday and I will be there, come hell or high water! Here is a picture of the affected area.
 
Did you forget the pics?

I would say it's not that common for 906 heads to crack,but they are 40+ yr old castings..

Why bother saving them? Do you have a ton of money/porting in them?
 
Couple pics, its hard to see but its there!
 

Attachments

  • IMG00111-20101114-1047.jpg
    70.5 KB · Views: 375
  • IMG00110-20101114-1046.jpg
    51.5 KB · Views: 308
needsaresto said:
Did you forget the pics?

I would say it's not that common for 906 heads to crack,but they are 40+ yr old castings..

Why bother saving them? Do you have a ton of money/porting in them?
Click to expand...
Yes they have had many hours spent porting them, and everything is fresh. It looks like it would be a common area to crack just because both of the exhaust ports are so close together, I imagine the heat generated there is quite a lot.
 
needsaresto said:
At least it's an easy area to clean and weld.
Click to expand...
Thats what im thinking. The 440 runs like a raped ape the way it is, I dont want to have to make a change at this point. Just fix it and go. I will also be finishing up the nitrous install this week. Hope to see a 11.6 with the hundred shot. We shall see.
 
I lost a good 440 that way! The cracks USUALLY go all the way thru and mine filled the cylinder full of water. When it was started, the connecting rod folded (because water doesn't compress) and destroyed the entire rotating assembly, in the middle of a burnout!
Make sure, or build a new one!!!!!!!!!!!!!!!
GOOD LUCK.
 
sst3193 said:
I lost a good 440 that way! The cracks USUALLY go all the way thru and mine filled the cylinder full of water. When it was started, the connecting rod folded (because water doesn't compress) and destroyed the entire rotating assembly, in the middle of a burnout!
Make sure, or build a new one!!!!!!!!!!!!!!!
GOOD LUCK.
Click to expand...
That sucks! I'm really glad I took it apart now. I found a guy at a diesel repair shop that is well known I guess for fixing cast iron. So well known that it will be atleast two weeks before I get it back! Soooooo I just bought a pair of heads that have been rebuilt not too long ago according to the seller. They came off of a 73 motor home 440. They won't flow even close to what I have now but for short notice and $50 for the pair what the hell. The nitrous will probably make up a little bit for the lack of flow. I want to put a good pair of head gaskets and arp studs. Any recommendations for head gaskets running nitrous?
 
i just run a felpro gasket... with a 150 shot for 3-4 years with no problems
 
100 shot, maybe a 150 if needed. Trying to get the car to 11.5. Can't go any faster because I don't have a cage. I think I will just stick with the felpro blue gaskets like you said. I'm going to get a set of studs also. By the way I think your valve covers are bad *** lookin man!
 
BadAss71 said:
100 shot, maybe a 150 if needed. Trying to get the car to 11.5. Can't go any faster because I don't have a cage. I think I will just stick with the felpro blue gaskets like you said. I'm going to get a set of studs also. By the way I think your valve covers are bad *** lookin man!
Click to expand...


I think it was Car Craft that Nitroused a 440 for an article. The stock head bolts held onto a 350 shot for a bunch of dyno pulls. a 400 shot lifted the heads several times, but the bottom end remained unharmed.
 
BBBCUDA said:
I think it was Car Craft that Nitroused a 440 for an article. The stock head bolts held onto a 350 shot for a bunch of dyno pulls. a 400 shot lifted the heads several times, but the bottom end remained unharmed.
Click to expand...
WOW! Thats amazing! My measly 100 shot should be just fine.
 
Well I went and did it. I ordered a set of 440 source stealth heads today and had them shipped overnight. Should be here early afternoon and the re assembly begins! I will update how she performs here soon.
 
Just a little update, the heads showed up on time yesterday and for her up and running last night. I have to say I am very impressed with heads. They are a very nice product and required zero modifications to install them. Only adjustments made were to the damn headers, and the valve lash. While the headers were out they received a little beating, mostly around the steering box. Took the car out to test and tune today for the pinks all out tomorrow and was only able to get one pass all day! Too many guys breaking **** and killing track time for everyone else. So the new heads took 3 tenths of a second off the et and got me 5 mph faster. Everything the same as the last time it was out minus the heads. I didn't expect that really at all considering the heads I took off of it "looked" like they should flow really damn well. Never had them flow benched so can't way what they actually do flow. I did pick up a but more compression with the new stealth's over the previous heads. I was told roughly around a half a point. The other thing that amazes me is I have the timing backed off to 28 degrees total advance because I was planning on spraying the next pass. The plugs are also gaped at 25. I will update the thread after I make some nitrous runs tomorrow and let you guys know how she does.
 
stealth's are good heads.

and yeah...if you don't flow test your stuff ...you'll never know if you done good, or just wrecked something.

It looks like you had lowered the exhaust floor at the exit a bunch, is that right?
 
Then again,flow isnt all about peak #'s either. A head with more area under the curve is what you need.
 
Actually I didn't do the heads myself they were on the motor when I bought it. Today I got the car into the elevens with just a little but more timing. I am definitely impressed with the heads.
 
You must log in or register to reply here.
-

Back
Top