428 cj exhaust manifold

[kazlaszlo 10]

i need help understanding the fitmet of exhaust manifolds.

I have the 428 CJ heads, the exhaust prts size; 1.84 x 1.28 , the manifold I bought from Dallas Mustang ports are 2.5 x 1.28.

An old dog needs to learn some new tricks?

The exhaust manifold port covers up the head ports if I do not use gasket.

With the gasket , being a third dimension, it creates a gap between the head port and the exhaust manifold port. This creates a leak.

Please someone help.

[SlimeGold 69 15]

If the gasket is the only thing causing you a problem (no bad port mis-match or pitted or damaged head flanges),try them without gaskets. Ford never used gaskets with exhaust manifolds anyway. If your head has a clean, strait flange area, the new manifold should seal up without any gaskets. Tube headers need gaskets 100% of the time however.

Edited January 7, 2010 by SlimeGold 69

[68stang289 26]

From the factory the 428CJ cars did not use a gasket. The aftermarket gaskets for 428 cars are complete garbage IMHO. I went through 3 or 4 different sets that didn't fit for crap before I went with no gasket. I have yet to start the car up so I don't know about leaking issues. I talked to a few guys over at the cobra jet forum who said they used the gasket maker stuff (I can't think of the name of it off hand but its available at any auto parts store) and that worked just fine.

 

The new manifolds as I understand it have been redesigned inside to create better flow. From what I've read they're now designed to flow almost as good as a shorty header would (within reason of course considering they are correct cast on the outside). I have repro's on my SCJ as well and while they aren't 100% correct, my car isn't 100% correct either and the motor is built so I needed all the help I could get without going back to headers (a huge pain on a 4 speed big block car).

[kazlaszlo 10]

Thank You, SlimeGold69 and 68stang289. You are both given me the right stuff. As you know, it is pretty tight to pull the 428 in and out tha 69. I will try the no gasket approach.The exhaust manifold ports completely cover the head ports. I just never noticed on any other engine so big of a difference in the port dimentions. ( head 1.84 in and the manifold 2.5 in )

Thanks again, I will let Y'll know how it goes.

[vettist 10]

just make sure both surfaces are strait and clean and a good temp safe silicone you would be fine

[kazlaszlo 10]

will do Thanks

[Fordrevhead 29]

Ultra Copper RTV

[Swags63 13]

Just a quick add on to the info you have already. I have a friend that is a restorer and he gave me a tip on exhaust manifold installation. I'm passing this on to you without trying it myself I installed Hooker headers on my car, so with that said here it is. He told me the easiest way he has found to get the manifolds on the car is to install the short block in the car bolt the manifolds to the heads then install them on the engine. I know the headers were a real pain so maybe this will help you out.

[kazlaszlo 10]

Thanks Guys.

I will put the engine back in the car this w/e.

Let You know how it goes.

The short block trick makes sense, easier to fit it in the car.( next time I have to pull it, I will do so )

[rajonmestra 10]

Well, I know I got this late but Mustangs got the GT version of the 390 FE engine, which had a different exhaust manifold bolt pattern in comparison with the regular 390's. On the other hand I have asked on the FE Forum though been hanging with those guys for over 10 yrs, some of the factory stock and resto guys will know if the manifolds physically bolt on i will send you the details.