VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 Those Heads Again

Hey from Down Under,
Time for an update on our repair attempts.
Yes, it was a slim chance and we have been unsuccessful so far.
The spray welding method using a special cast iron powder worked brilliantly on external cracks.( there were plenty of those exposed in the oddest places on the seven heads that we have abrasive blasted and dye tested). However inside the exhaust port the heat of combustion seems to have altered the metal composition and the weld would not take.
It may have been because we were struggling to get enough heat into the head, but even as we transferred it to the dry lime bath after welding, for slow cooling over a day or so, clinking noises could be heard that sounded like more cracking.
I'm have four more heads to collect and may eventually find a good one, but when I do, will have no faith in it at all. Cracking seems the norm, rather than the exception. I guess I was lucky to get the service I did from my original, but it was a low milage car.
Gentlemen, it looks like reproduction time is looming for us all if we want to keep Chev Fours on the road into the future. It seems that the only way to avoid the cracking problem is to not use the car, a rather repugnant thought indeed.
Where to from here? Any chance of a GM warranty claim? Suggestions welcome.
Cheers for now,
Geoff.

May be the club (someone) could find a suitable quantity, corresponding price and then organize a production of engine blocks and heads both for 4- and 6 cyl.? Luckily we have at least one company in Norway checking heads/blocks, repairing cracks, a.s.o. but the spare, useful ones in the garages around are coming down to zero soon.

Not driving is not the solution for me, on the contrary.

Strangely enough a company in Australia produced reproduction 1950s aluminium alloy cylinder heads to a pattern from an original. It would be relatively easy I believe to make a pattern for a cast iron 4-cylinder Chevy head, but which one do you go for? Say 1928 two-port for optimum power?

The probable reason why you had no luck with spray welding in the exhaust port was because the red hot exhaust gasses put additional carbon into the iron. I have found that is not worth trying to weld modern exhaust manifolds if they are cracked anywhere that the exhaust gasses touched. Broken ears weld OK on the same piece, so the problem isn't the metal as cast, but what has contaminated it in use. Spray welding isn't that strong anyway, it lacks tensile strength and penetration.

Herb

Interesting comments.
I have two Australian made heads from the 40-50's, each having different casting detail, perhaps indicating there were two suppliers, such was the demand.
However both are cracked in the exhaust port area also. So it seems even these did not overcome the problem.
They are iron castings and I have not heard of alloy jobs. Has anyone seen one?
I wonder how it would work. Alloy is easier to cast I believe, but many vehicles I know of with an alloy head on an iron block tend to suffer head gasket failure caused by differential expansion rates between the two metals. Given the low compression of the Chev Four this may not be a problem.
It would certainly not bother me to have an alloy head fitted to my car. Who cares, once painted it would not be obvious,and we know the iron ones are no good anyway.
One would like to stick to a single port design to keep interchangeability easy and also some originality, but the arrangement may be too hot for alloy also. The suggestion of a single port head design, but modified to have dual ports is an interesting one. It would aviod the cracking issues and also give those needed extra herbs.
Does anyone know the issues with producing a new casting. Die costs traditionally have been prohibitive ,but new methods have slashed these as I understand.
I know of one company in Melbourne that make all the replacement iron heads to fit very troublesome alloy ones fitted to some sort of GM powered military juggernaut, and send them world wide. Numbers of these one would expect to be low, perhaps indicating that small runs are possible, but then you know what military budgets are like.

Perhaps I might ask how many of you have had the cracking problem, and would you be interested in a replacement head even as a standby. I know you will eventually need it if you are going to keep using your Chev.
Keep the comments flowing chaps, and thanks for those so far.
Geoff.

An alloy head shouldn't warp if it is torqued properly and has proper gasket sealing. It will however produce more power than an iron head. I believe that the earlier FB 2-port head will also fit.

I have a 1914 Royal Mail Roadster and 5 cracked heads, all in the exhaust port area. You can't see the crack, you can't feel it, but when you pressure test the head, you can feel and hear the air escaping. I can't drive my car because I don't have a good cylinder head. Every one I have found are all cracked. I would certianly be interested in any method to repair them or seal the crack. I've been told that a 1928 head will fit. The rocker arms are different and it has 2 exhaust ports instead of one. has anybody used a 1928 head and do they have the same problems with cracking as the earlier heads.?

Paul-
The '28 head fits fine, and gives more horsepower, because it has larger valves and higher lift rocker arms. With a '28 carb and manifolds, you should get about 7 more horsepower. I have seen a couple "barn fresh" cars and trucks that had the two port head on earlier blocks, showing that the one port head was causing problems years ago. Not to say that the two port heads don't crack, but they are far, far, less likely to do so than the earlier ones. If you are more interested in driving than keeping the car original, it's the way to go!
Herb

Down Under Again,
I'm told by a Sydney chap whose family business specialised in Chev Four parts through to their death here as a useable car in the 60's, that '28 heads rarely cracked, and when they did it was usually between the two water ports in the centre of the head on the exposed under face when removed. This was easily fixed because it was so accessible and not affected by exhaust gases.
I've had my Chev for some 36 years, yet know little about it as far as repairs go, so I rely on all your collective genius. To be honest the damn thing has been absolutely bullet proof reliable til this head problem. The biggest repair I've ever had was to replace the original coil a couple of years ago.
Anyway it would appear that the single port head fits all back to the earliest model; is this correct? Are they in fact the same or just interchangeable? Models that early here are rare indeed, so I do not know them well.
Is the feeling that we just fit '28 heads (look very odd indeed with no side plates), or if affordable would we prefer a single port head, assuming that modern casting and metallurgy overcomes the cracking problem. Somehow I would prefer a single port, being a real characteristic of the earlier motors.
Given a choice what would you go for? All I'm doing at this stage is getting a feeling for what other owners think. Please submit a post here, however short.
As far as percentages go, three of us here in town with '25,'26 and '27 models have 22 heads between us (and not a brain to be seen) and every one is cracked in the port area. The '27 is the only one in service because it has a '28 head fitted!
Thanks again everyone.
Geoff.

I gather that the Olds T as also fitted to the late T Chevy, 1922-on 2-port FB-style Head will also fit...? And give more power? Must check.

The cracking in the single port heads will always be a problem,and very hard,if not impossible to repair,as the exhaust gasses over the years of use,burn out most of the iron from the casting,and deposit all sorts of chemical by-products from combustion.Even cast iron fusion welding,using oxy/acetylene and cast iron filler rods would probably not work,due to the heat required(this may cause more cracks to open up)and the combustion chemical by-products that are burnt into the cating,would in all probability,refuse to let the new metal "wet" and fuse to the old casting.
The 3 port Oldsmobile "Northway" engine head will fit,as it is nearly identical to the FB 3 port head,the only difference being the water outlet to the radiator.Either the Olds head or the FB head could be used(if you can find a good one),but I'm not sure if there would be any power gain.
The '28 2 port head would be a better option(especially if you just like to drive your car/truck)as the rocker arm ratio on all the early heads is 1:1,and 1 1/2:1 on the '28,giving you more valve lift.

I agree 100% with CJP'S 29. The 3 port Olds/FB Chevy head has the small 1½" valves and 1 to 1 rockers, and unless you put larger valves and increase the rocker ratio the better porting will not do much for you. They are hard to come by also because the speedster guys (like me) want them. They will fit with no alterations except for swapping pushrods, in some cases. Chevy, Olds, Scrips-Booth,and Oakland all used Notrhway engines, at one time or another. If the looks of the vertical ribs on the '28 head bother you, grind them off, or have a machine shop mill them off for you. I think that the '28 heads look much better on the early blocks if this is done. The tin covers over the pushrods on a '28 block and head do very little in regard to keeping the engine area clean in my experience.
Hope this helps- Herb Kephart

Actually, the FB and Olds T had Saginaw engines, not Northways. I hope that this file explains:

http://clubs.hemmings.com/clubsites/chevytalk/NORTHWAY.mht

David;
Thanks for the correction! At age 71 I'm still learning and enjoying it. I have a question for you. After reading the extensive study that Ken Kaufmann and you did on '24 to '28 casting numbers, I thought that, just for the heck of it, I would dig the one single port head out of my head pile, to see what the casting number is. This head is dirty but has no rust or pitting. After wire brushing I found, in the top center, some letters and numbers that looked like they had been heavily sanded down, as if to obliterate them. As best as I can tell they are- JAXON- then under that- HC7- and under that **7 (can't make out first two). The exhaust port flange is stamped in 1/8" characters A52 and upside down OV. Now we know that there aftermarket heads made- but if this is the same Jaxon that supplied rims and associated parts to GM, it puts them in the curious position of being a supplier and a competitor at the same time. Any info or comment on this?
Herb Kephart

I'm going to ask Ken but i appears to be a replacement spare part casting cast January 5th 1922 byJaxon Steel Product Division of Jackson, MI, part of the United Motors Corporation, then GM Inter-Company Accessory and Parts Manuafcturing Group. I have never heard of a Jaxon casting before! Very interesting.

David, aged 51. And the Northway-Saginaw thing has been causing confusion for 70 years or so now!

It appears this Jaxon head is actually a 1917 490 head that had the name Mason cast into it by the foundry. Mason Motor Co. by 1917 was a fully owned Chevrolet engine
company. **7 must be the head cast number #407. The H17 could either be the head cast date like 1-11-7 or January 11, 1917 or possibly the foundry mark - However the exhaust port serial # is that of the engine, and A52 is the serial # of a 1917 490 engine built about April 1917.
The #407 head was used on the later 1915 Model H's, all 1916-18 models except the D, 1919-21.
KenK

Is Jaxon Steel Product Division of Jackson the same company which made the nuts and clamps for the disc wheel rims? :confused:

I have read most of the book about the British Chevrolet Buses, David. Lovely lecture in the winter time. It warms!

Thanks Ken, and thanks Solan! Buy some more copies please everyone! Oh, and from what Ken has said in the past, "yes".

Thanks guys!!!
Herb Kephart

Has anyone actually put a 1928 head on the early Chevy 4 cylinder. I have a good 1928 head, exhaust manifold and rocker arms. The exhaust comes out the back of the manifold, rather than the center as on the single port manifolds. If I want to go directly to the exhaust pipe I am going to have to reroute the tubing for the oil pump/site gauge. It is directly in the way of a straigt shot from the exhaust manifold to the exhaust pipe. I suppose the other option would be to make some kind of loopy exhaust that follows the roughly the same path as the original exhaust from the manifold to the pipe underneath the car. Does anyone have any suggestions on the best way to make this work.

The ones that I have seen (and a long wheelbase truck that I bought) had the oil line relocated, and a '28 exhaust system.
Herb Kephart

Hey,
You guys get it easy. We have to wangle our way around the steering column, control rods etc. as well. On my '25 space is tight also because of the exposed oil pump.
My friends '27 worked OK but it was tricky getting the exhaust to align neatly without fouling the hand control linkages.
Perhaps it lends itself to a visit to the local exhaust centre and make up a two port extractor system, bent to fit the available spaces. Neat and simple.
Geoff.

Sorry Geoff, didn't realize you were down under. Why not use a RHD '28 exhaust manifold with the '28 head? I have read on this site that they have a center, horizontal outlet like ( but not perhaps the same size as) the '27 head. This would probably move the exhaust outboard enough to clear all the rods, steering etc. I'd like to get one of those exhaust manifolds for myself, if you end up with too many!

Herb Kephart

G'Day Herb,
Yes, I'm down under. Some say I should simply be under and that would save everyone hassles.
You are right in saying to use the standard RHD manifold, but without having the vehicles beside me to compare, there is a foul up somewhere because of the earlier shorter/narrower engine bay etc. however it is just a matter of cutting and shutting things to make them fit.
My suggestion of extractors may be absurd once seeing where it all has to fit, but I was just adding to the discussion. Getting things like that made these days is easy with the fancy pipe bending equipment that is around. I find the people usually quite interested to do something different, and it may be neater and easier than using the original bits.
I will keep you in mind when gathering bits, for a RHD manifold. I do not have any '28 stuff but doubtless will if that is the only anwer to my problem. I'm intrigued as to what you have in mind for it other than being an interesting discussion piece in a LHD world.

Two things
Putting the 28 head and manifolds on earlier models is a fairly common practice, however the second part of the manifold is too close to the bonnet (hood in US speak) and the it burns off the paint.
Herb I have a spare of each of the two piece 28 Australian exhaust manifolds, contact me direct if interested
Chris

All this is very interesting reading. To answer gmccorkelle's question about whether the real early heads are the same as 25-27 heads, they will fit but do look different with the back of the head being rounded from the top to the bottom, this head was fitted between 1915? and 1922. My 1915 Amesbury has a 407 head and the casting date is 1922 so it must have cracked and been replaced. I'm also fortunate enough to have 2 of the 3 port F series heads which I will use if the single port head becomes unservicable.
Just a short note for the Aussie's. When replacing the 28 two part exhaust manifold make sure you either check or preferably machine all the mounting surfaces as the twin port part will crack in the middle of the Y and the single bend section will break of one the mounting wings. Also it is recommended to use copper caskets if you can as the manifolds move a bit with heating and cooling and the after market gaskets can grab and cause the manifold to crack.
I've never seen a 28 cracked head in in 40 years of mucking around with 28 Chevs
Chris

I notice you say you have a couple 1928 RHD 2-piece exhaust manifolds. I am looking for the 'Y' section to buy so I can use it as the header piece for my speedster. I want to end up with a racer style outside exhaust system. Let me know if you will sell. Thanks.

hotroadster
I can help with one, it needs two broken studs removed otherwise ok. I'd have to get a shipping price to you. Reply by email if you want one
Chris

I have sent a couple of emails with no responce, have you received them? No longer interested?

I did get one email, which I replied to, but no more. I assume from your post that you don't need one now
Chris

Hi all you head hunters out there(LOL).I have had luck having heads welded at a local welding shop,but just heads with the small crack between the middle two cylinders on top.You have to V the crack out(eliminates extra carbon build up the exhaust gasses deposited),preheat the head,weld it with cast iron or nickel rod,and slow cool it.I am getting ready to prep a couple larger cracked heads( 1 all the way around the single exhaust port,and the other one crack around first head bolt hole, and see how successful they turn out.Will post results.Regards,tinsmith_ray