Well...., picked up the heads today from the shop. Had em cleaned, manafluxed & pressure tested. Head#1 had 1 crack beside the exhaust valve next to the crossover. Head#2 had the same size crack in the exact same place, along with another small one on the opposite side of the runner. These cracks are in the valve cover area by the springs. Pressure tested the heads and they said they didn't bubble, but did foam alittle. Now, I questioned whether they think these may have been there all along, as in a weak casting, or if they believe it was do to overheating. They seem to agree that, since they are just foaming, that it is probably just a porous cast. He said they could use a nickle rod, and cut a trench into them and weld them up for about $175.00. Again, these did not bubble, but foamed. I bought the car in April of this year and only put about 100 miles on it before I decided to park it and start the resto. I didn't notice any milky oil on teardown and couldn't see any evidence of head gasket failure or coolant loss. But, I only drove the car for about a 100 miles. My question is, can these heads be saved and used on a stock rebuild 400? Or, am I just asking for trouble and should I look for another set of 69 castings? I was wanting to do a mild build with this 400 and keep it as original as possible (#'s matching drivetrain). But now, I'm thinking about just putting this back to stock and building up a 455 to play at the track. Any and all suggestions and advice will greatly be appreciated.:beer Thanks!
I'm definately no expert on engine building.... but I will say that I definately wouldn't skimp on something as important as heads. If you're going to do an engine rebuild.... you'll feel terrible if the heads are the cause of blowing up your brand new engine 30 days after you get it on the road. o No: I'd either have them fixed, or get new ones. When putting together a new engine... there's 500 things that can go wrong. Why add another one to the list right from the start? :TU: We can never afford to do things right... but somehow we can always afford to do them twice :gt:
Thanks for the reply Rick. I know to definately have a weld thrown in on the cracks. I guess I'm wanting to know if anybody out there has ran into this same thing and decided to weld the cracks and bolt and go? I've heard the early yrs (67-69) were prone to cracking in these areas. But like i mentioned, they do not bubble, they just foamed a little. Anybody else want to chime in on this that has been there, done that? Thanks!
Rick, Those cracks are real common in the 400/430 heads, both of mine needed to be repaired. My shop doesn't weld them though, they use a process called "stitching" basically drilling and installing threaded taper plugs that overlap each other. Keeps you from introducing a Heat Effected Zone crack later on. If you decide not to have them repaired and are going to go with different heads don't bother looking for other 400/430 heads, about 90% of them I've seen have these cracks.
same thing I had the same cracks found on my 69 400 heads two crack in each i drove the car for three years like that.Every time i took the valve covers off i found antifreeze puddled up on the head i thought it was coming up the head bolts but I had them check and were cracked so i junk them from a set of stage 2 heads.:TU:
These cracks are pretty common on 400-430 heads. I've seen them welded or simply epoxied with good results. Remember, the repaired spots don't need to hold back cylinder pressure, just cooling system pressure (14-16 lbs.)
Good point, Al. I've been concerning myself with cylinder pressure. If I epoxy these, should I try to trench the cracks, or just grind the area alittle to give the epoxy a good surface to adhere to? Also, should I just rebuild these to stock, or am I asking for trouble if I oversize the valves to Stage 1 specs along with a .030 overbore on the block? Thanks for all the replies. Keep em coming!!
Yup.. Had this deal a while back.. One 430 big port head was cracked slightly, between the valve spring pads.. Instead of welding, we peened the metal over with a shot peen, and then just for insurance, ceramic sealed the inside of the cylinder head water passages. Been that way for 3 years now... no problems at all. If you can do this depends on how bad they are leaking, but keep in mind they have prolly been like this for a very looong time. JW
Well Rick, I don't know how much the Stg.1 valves will help a .030" over 400 as common theory is the smaller 400 bore will shroud the valves enogh to negate any increase.I would have a nice bowl blend/3 angle valve job done with the money instead. As far as the cracking is concerned, I'd bet there are more than a few people running they're cars with these cracks who don't even know it....o No:
Re: Well Al, my apologies. I see where I misled you. I meant to say have the block bored to 430 specs. So, if I have the correct #'s, then that would mean I need to have the bore opened an additional .1475. With the 430 bore, I was led to believe that I could then put the oversize valves in to help in performance. Am I thinking correctly? I had a different shop look at the heads today, (speed shop), and he is pretty comfortable with the thought that these were just casting flaws. He doesn't see any reason to scrap these heads as long as they are used for the street. He said he wouldn't trust em to last under constant track use, so I told him to just do a nice bowl blend/3 angle valve job like you suggested. I've decided to build this back to near stock with changes to only the cam, intake and headers. Then, I will go looking for a 455 block to build to play at the track with. :laugh:
If this was already mentioned, I apologize for missing it. My machine shop sends out cracked heads and blocks to be repaired. The place that does the repairs grind out the cracked area and spray weld it (at least that what I think its called). From what I understand, they more or less heat the casting to a certain temp and spray powdered metal in to build it back up. The guy who runs the shop showed me a Chevy 400 that had the ear for the starter put back on. He also told me he sent a Model T block up to be welded. I mentioned a 70 casting head I had that had a crack between the two valves, and he said that that's a common fix. They just need to regrind the seats, and if the head has bronze valve guides they will need to be replaced. He also said that this is more reliable than stitching and none of the repairs have had any problems. I have also seen this process done on one of those silly car magazine TV shows. They toured a reman facility for various engines. They welded up a chevy head to give those bowtie lovers something to feel good about.
I had this problem, was told it's common on Buicks by my head porter and has a simple fix. Cadillac pellets, available from dealers, dropped into the radiator seal many water jacket leaks. It may not be a fix, but a patch that can eliminater both headache and expense of welding. I have read about these in several monthly publications that highly recommend this product. Dan
I used a set of 69 heads on my 455 - they had a crack just about like you described - we pinned those and they work fine.
Rixster said Can a 1969 Buick 400 engine be bored out that far. I would think hitting a water passaage well before that would be likely.
It is my understanding that the 400 and the 430 casting is the exact same casting, but they under bore it for the 400.
