Topic: 1967 GTA 390 Oil Fill Cap

[travnemi]

I'm not sure if I have the correct air cleaner on it. But here's a picture of the air cleaner and breather cap that came with the car when I purchased it. I've been looking for the breather cap to have rechromed but I cant seem to find it. I hope the wife or kids didn't through it out (it did look a little rough).

Travis

[Bob Gaines]

I'm not sure if I have the correct air cleaner on it. But here's a picture of the air cleaner and breather cap that came with the car when I purchased it. I've been looking for the breather cap to have rechromed but I cant seem to find it. I hope the wife or kids didn't through it out (it did look a little rough).

Travis

I am not very familiar with a 67 390 GT thermactor set up other then what is in common with a Shelby. The breather cap in the picture is one I am familiar with but have never seen the twist on variety. I have only seen the push on variety which is small block. The twist on variety must be about as rare as the cookie cutter type that I am more familiar with. If the air cleaner base is correct for the application then It would stand to reason that the early style twist on cap with the fixed turned up elbow is the most likely candidate since the later ribbed style with the swivel elbow on top is more typical to 68 and later. You may have to settle with the easier (relatively speaking ) to find smallblock push on version and use the adapter that you posted earlier at least until you find the genuine twist on type. Just some thoughts.

[J_Speegle]

I'm not sure if I have the correct air cleaner on it. But here's a picture of the air cleaner and breather cap that came with the car when I purchased it. I've been looking for the breather cap to have rechromed but I cant seem to find it.

That is one of the versions used on 67 390 Mustang with Thermactors - the types and applications is a whole "nother discussion but as of right now think I have 4 different original styles/versions used on 67 390 Mustangs


Just my humble opinion at the moment is that the up turned nipple isn't right for the application - it produces an additional bend in the hose and requires slightly more hose to make a connection - one possible reason for Ford to use the straight nipple.  Since the air cleaner base is the same as the T-Bird and different from the taller Fairline base its interesting that Ford lists that the service replacement is the same piece. T-Bird's didn't come with the chrome dress up option so they didn't get chromed versions like the 67 Mustang and the GT Fairlanes did


Had forgotten about the "adapter you showed and could not recall if that was an aftermarket piece/fix or a factory one. Really can't recall if the 390's I had used a push on or twist so went back to the pictures and books from the period.



Here is what I found

Went through my pictures and I found these. I didn't include those where it was obvious that many things had been altered or that were using the 1970 - up style of breather caps. Because of this I still have a fair number of examples. Still some things on these cars that have been altered and replaced so no virgins. Normally I don't post pictures of restored cars but in this case I did for one example.

Cars shown in order from early to late. Please read the captions.

Just throwing this all on the wall to see what sticks - in a unbiased attempt to find a decent answer for the poster
You will see a number of different style of air cleaners with the front nipple - don't let this distract your focus


To remind everyone here is what the bare valve cover opening for the breather looks like



7R1059xxx pretty early car




7R141xxx - restored car




7R121xxx




7R151xxx - "restored" car




7R191xxx Not sure what to think of this one - plenty of stuff has been changed and messed with. Almost didn't include



7R212xxx - "restored car"



Somewhat from left field but still may relate
67 390 T-Bird with Therm. As mentioned the same air cleaner base so possibly same cap?


Last two (later cars) both messed with have the upturned nipple. Others have the straight

Now off to find reference to that adapter somewhere

[J_Speegle]

OK could not find the adapter (valve cover to breather cap) in the 67-8 MPC I have.

Turned to the assembly manuals and found it listed using the part number C5AE-6A873-A. So my assumption earlier that it was a twist on cap appears to be the result of not a perfect memory from 25 plus years ago. Last time I put oil in a 67 390

So I agree with the some of the others that your looking for a FoMoCo stamped chrome push-on closed cap with the nipple.

MPC and assembly manual do not match on what they suggest is the cap - not a surprise and with documented mistakes in one and the other being a list of replacement parts I'm uncertain that either is the perfect source

Just wanted to offer what I was able to discover - another puzzle - but we're getting closer with more documentation

[Bob Gaines]

OK could not find the adapter (valve cover to breather cap) in the 67-8 MPC I have.

Turned to the assembly manuals and found it listed using the part number C5AE-6A873-A. So my assumption earlier that it was a twist on cap appears to be the result of not a perfect memory from 25 plus years ago. Last time I put oil in a 67 390

So I agree with the some of the others that your looking for a FoMoCo stamped chrome push-on closed cap with the nipple.

MPC and assembly manual do not match on what they suggest is the cap - not a surprise and with documented mistakes in one and the other being a list of replacement parts I'm uncertain that either is the perfect source

Just wanted to offer what I was able to discover - another puzzle - but we're getting closer with more documentation

Jeff,I have always been under the impression that the push on adapter is a aftermarket gadget which may be reinforced by the fact you couldn't find it in the MPC.  The adapter and the push on cap my be a good alternative however as I suggested in my post.

[J_Speegle]

Jeff,I have always been under the impression that the push on adapter is a aftermarket gadget which may be reinforced by the fact you couldn't find it in the MPC. .........

Understand and that is the way I was leaning until I found it in the 67 Assembly Manual illustration (Thermactor system section pg 126 dated Feb 10), identified as an adapter for Cougar and Mustang 390 applications and with a Ford part number

[J_Speegle]

Found another (in my unlabeled pile of pictures)  on an unrestored but slightly played with 7R202xxx fastback I saw last year. Rare comp suspension car.

[Bob Gaines]

Found another (in my unlabeled pile of pictures)  on an unrestored but slightly played with 7R202xxx fastback I saw last year. Rare comp suspension car.

The bent style chrome monte carlo bar and the copper mecanicl oil pressure gauge line don't instill a lot of faith in the correctness of the oil filler cap  . I have only seen a twist type opening on BB valve covers . Was there ever a fill neck type valve cover on a BB?

[travnemi]

Thank you both for all the research. I tore my garage apart today looking for that cap to see if there was a part number on it. No luck! bummer!!!

Travis

[Bob Gaines]

Understand and that is the way I was leaning until I found it in the 67 Assembly Manual illustration (Thermactor system section pg 126 dated Feb 10), identified as an adapter for Cougar and Mustang 390 applications and with a Ford part number

I looked over that illustration and although the illustrated cap and air cleaner assembly bear little resemblance to a 390 GT air cleaner or any of the caps we have discussed the fact that there is a adapter which appears similar to the ones sold be Mustang vendors has changed my mind on it's existence. FYI breather caps typically do not have engineering numbers stamped on them.

[WT8095]

The text clipping is from Section 60.6 (352, 390) of the '75 MPC. It lists C5AZ-6A868-A for various big block applications. The -A is aso called out for a few small block applications elsewhere in the MPC.

The photos show an NOS -B for comparison. The only reference to this part number in the '75 MPC (that I could find) is for 240 sixes for 68/71. I haven't found a photo of an known original -A, but several Mustang vendors sell reproductions of the -A, and visually it looks close to the -B. The -B does not seem to have the same circumferential groove as the -A.

[67gtasanjose]

I will speak to the choir on MY understanding of the breather caps I have seen having lived in the Thermactor world of So.Calif. for +20 years, late-70's-up, working on countless of many makes and models of the era.

The Push-on OE FoMoCo breather cap with the attached steel hose elbow turned UPWARDS was found on 66-67 SMALL BLOCKS with thermactors. The turn-up was intended to clear the factory Air Conditioner bracket.

All Big Block Apps  that I saw , those which were running the thermactors for 67's (closed crankshaft systems) the OE FoMoCo breather caps were all the push-on's with the straight sideways steel hose attached. The turned up elbow was not needed on FE engines for clearing the bracket like it was needed on the small blocks.

FWIW, in reproduction, NOS or even the used world of parts, I have yet to see an OE or OE style FoMoCo CHROMED version of the push-on breather cap that has the turned up end, I have seen COUNTLESS of the OE or OE style CHROMED with the straight sideways steel nipple attached. Since(to my understanding), 390 Mustangs all came with the chrome dress up kit, then this is the only logically correct breather~ A CHROMED, straight-nipple push-on type.

NOW: 67Shelby??? ~ THAT IS ANOTHER CAN OF WORMS! I'll deffer to the Shelby experts for anything that would be on one of those.

[preaction]

The hose was adlibbed for lack of something to imitate, these are the pieces that came with my car4/28/67 dearborn

[Bob Gaines]

The hose was adlibbed for lack of something to imitate, these are the pieces that came with my car4/28/67 dearborn

interesting. A different style cap then has been shown in the previous discussion. That has to be a rare cap (push on and flat across the top with nipple).It looks more like the typical BB cap I am used to seeing although it is push on and has a closed emission nipple. I looked closer and saw that there was no trademark on the cap which leads me to believe that it is some kind of aftermarket cap.Ford caps typically had trademark on them.

[preaction]

Understand and that is the way I was leaning until I found it in the 67 Assembly Manual illustration (Thermactor system section pg 126 dated Feb 10), identified as an adapter for Cougar and Mustang 390 applications and with a Ford part number

That was the page I had highlighted as to the build of my 390.