65 327/350 heads HT

[Jimmy Roggenbuck]

I am about to do a top over haul due to findings on a compression/pressure test causing a back wash in to the coolant reserve and a vapor leak. A shop put it on a diagnostic machine and suspects a head on #7 cylinder. I am suspossed to have hydrolic lifters on the heads.
My question is if I find a cracked head can a machine shop repair it and does it need specific replacement parts?
If I do one side does the other side need to be pulled and checked/rebuilt?
Someone also mentioned putting in hardened seats due to no lead gas is this necessary and does the machine shop perfom this? If I need to order parts or find a special shop I can make some phone calls before I tear it apart. Any help or tips are greatly appreciated

[Duke W.]

Re: 65 327/350 heads HT

You should pull and refresh both heads. You'll likely want to rebuild the guides and at least replace the exhaust valves. The inlets are useable if they don't have more than half a thou stem wear IMO, assuming there is enough margin for a seat surface reface. (I think Clem might disagree with me on this.)

It's my understanding that some head cracks can be successfully welded, but success if a function of the welder and the location and severety of the crack.

I would recommend that you not got with "hardened seats" unless you plan on running the car very hard. In normal driving seat recession is not that much of an issue.

While the heads are off, measure the tops or the bores for taper to get an idea how much life you've got left on the case. Up to .003" wear at the top is probably acceptable. Above that, it's marginal. If any are worn .005" or more you should pull the block for a bore and rebuild.

Duke

[Duke W.]

Re: 65 327/350 heads HT

You should pull and refresh both heads. You'll likely want to rebuild the guides and at least replace the exhaust valves. The inlets are useable if they don't have more than half a thou stem wear IMO, assuming there is enough margin for a seat surface reface. (I think Clem might disagree with me on this.)

It's my understanding that some head cracks can be successfully welded, but success if a function of the welder and the location and severety of the crack.

I would recommend that you not got with "hardened seats" unless you plan on running the car very hard. In normal driving seat recession is not that much of an issue.

While the heads are off, measure the tops or the bores for taper to get an idea how much life you've got left on the case. Up to .003" wear at the top is probably acceptable. Above that, it's marginal. If any are worn .005" or more you should pull the block for a bore and rebuild.

Duke

[Joe L.]

Re: 65 327/350 heads HT

Jimmy-----

1) It's hard to say if your head could be repaired if cracked. It depends on the nature of the crack and it's location. In any event, it takes a skilled professional to repair a cylinder head and, often, the cost will exceed just finding another cylinder head of the proper casting number and casting date. For crack repair, I recommend American Cylinder Head Repair of Oakland, CA.

2) I would never recommend removing and servicing just 1 cylinder head. If one requires service, I'd remove both and rebuild both. At that time, the other cylinder head can be checked for cracks;

3) hardened exhaust valve seats offer some measure of ehaust valve seat recission protection for engines originally using leaded gas but now forced to use unleaded gas. However, for most engine operating conditions they are NOT really necessary. It's VERY unlikely that any excessive wear or damage to your cylinder head exhaust seats will result from the use of unleaded gas with your non-hardened exhaust seats. Plus, it's very risky installing hardened seats in 2.02/1.60 heads like yours. American Cylinder Head will confirm that if you ask them.

[Joe L.]

Re: 65 327/350 heads HT

Jimmy-----

1) It's hard to say if your head could be repaired if cracked. It depends on the nature of the crack and it's location. In any event, it takes a skilled professional to repair a cylinder head and, often, the cost will exceed just finding another cylinder head of the proper casting number and casting date. For crack repair, I recommend American Cylinder Head Repair of Oakland, CA.

2) I would never recommend removing and servicing just 1 cylinder head. If one requires service, I'd remove both and rebuild both. At that time, the other cylinder head can be checked for cracks;

3) hardened exhaust valve seats offer some measure of ehaust valve seat recission protection for engines originally using leaded gas but now forced to use unleaded gas. However, for most engine operating conditions they are NOT really necessary. It's VERY unlikely that any excessive wear or damage to your cylinder head exhaust seats will result from the use of unleaded gas with your non-hardened exhaust seats. Plus, it's very risky installing hardened seats in 2.02/1.60 heads like yours. American Cylinder Head will confirm that if you ask them.

[Pat Bush #35083]

Re: 65 327/350 heads HT

Jimmy:

You have excellent advice from both Duke and Joe. I regularly tell people NOT to install hardened seats in older heads. Under normal running conditions, I seriously doubt you will have issues. Joe is right.

If you choose to go that route, hardened seats can be installed in "fuelie" heads but it depends on the general condition of the head, how many valve jobs have been done and if intake seats were installed at any point. Not withstanding the fact that installing a seat removes material -- which is precious little on 202/160 heads. If you do have it done, make sure the machine shop has done this before and hope they have an "old man" who knows these heads well. There is little margin for error because the seats run so close together and the water jacket. I've done them before but "the old man" was always watching my set-up and depth settings to make sure I didn't screw up.....

Pat

[Pat Bush #35083]

Re: 65 327/350 heads HT

Jimmy:

You have excellent advice from both Duke and Joe. I regularly tell people NOT to install hardened seats in older heads. Under normal running conditions, I seriously doubt you will have issues. Joe is right.

If you choose to go that route, hardened seats can be installed in "fuelie" heads but it depends on the general condition of the head, how many valve jobs have been done and if intake seats were installed at any point. Not withstanding the fact that installing a seat removes material -- which is precious little on 202/160 heads. If you do have it done, make sure the machine shop has done this before and hope they have an "old man" who knows these heads well. There is little margin for error because the seats run so close together and the water jacket. I've done them before but "the old man" was always watching my set-up and depth settings to make sure I didn't screw up.....

Pat