Cracked Intake runner

[Anonymous]

Have pretty much determined that my preignition/spark knock problem in my recently freshened 200 is the result of a lean condition being caused by the recurring small crack in the intake plenum/runner area just behind the carb. Have tried every possible timing combo I can think of and still experience preignition after engine has been running for a while. Have tried couple of different hi-heat epoxies to mend crack, but all seem to fail after short period. Was wondering if anyone has ever experienced a crack in this area of head and/or welded in this area of head/intake with any kind of success?

Thanks,

Phil

 

[addo]

I think most people just replace the head if it's cracked. You could try a recommended welding rod if you're game.

Is there any chance of coolant flow restrictions in the head? They seem to build up a lot of crud in there over the years, and many rebuilders don't pop the brass plugs out when servicing - so how can they be sure to have removed all accretions?

Regards, Adam.

 

[Anonymous]

After running around most of the day today, I have decided just to go ahead and buy a new bare casting and reinstall my new valves/hardware etc from my cracked head. Seems such a shame that ther'e's not much a guy can do but junk an otherwise good cylinder head because of a crack in that integrally cast-in place intake "manifold" Sure was hoping someone would have had same problem and knew of a good fix.

Thanks for replying, though,

Phil

 

[Stubby]

I have fixed a lot of cast iron heads with pins. Check with your local machine shops and see if any can pin cracks.

The pins I used were tapered cast iron pins and they worked great. If you need more info PM me and I will try to help.

 

[kirkallen143]

When I first acquired this fine 200, I too had a cracked ear off the head where the exhaust manifold bolts to in the front. First I tried to braze the stud and head together with a rod used in the HVAC field called, "UTECTIC", it held but not up to 18ft-lbs of torque (the rod is used for welding/brazing non-like metals together (hint-- like a crack in the plenum)). I did pre-heat the area with a torch before attempting to weld.
This time I tried the MIG welder using the gas-less fluxcore wire (0.035") on a medium setting and fired away. Suprisingly this worked, I concentraited the weld on the cast then pulling over the bead to the exhaust stud, melting them together. I then tapped with a hammer the area I had just welded (someone said to do this on the forum a long time ago) and it worked, no futher cracking of the cast, yet and it does hold the 18ft-lbs of torque applied to it.
The problem with cast nowdays is that you do not know what kind of materials it is made of, it is not pure like in the old days (especially since recycling metals started) and that's why it is hard to weld/fix.
In our favor of that, at least the heads are numerous and cheap to come by!

Kirk

 

[wallaka]

I had the same problem and mig welded a stud in the head...didn't even have to take the head off. It's worked fine so far.