Replacing 351m For 400
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Replacing 351m For 400
I am putting a 400 in my 78 f150 4wd to replace the 351m. A few questions. Is the clutch interchangable or do I need a new one? Am going to buy a new one either way though. Second, what is the best way to put a high flowing dual exhaust on this truck? I am leaning towards a pair of flowmasters. Should I install a crossover pipe & rum 2 separate lines? Also, what should the in/out diameter be on the mufflers. I am thinking 2 1/4".. Any other advice/input is welcome.
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I am going to use the stock manifolds. I assume the 2 1/4" is an outside diameter. Should I use 2 1/2" o.d. pipe with 2 1/4" flowmasters with a crossover? Anyone have a good place with a good price on Delta Flow 50 series in Stainless Steel?
Tuned
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I am confused as to why you want to use a cross-over on a 78 mode3l truck. The emissions laws don't let you put true duals on newer trucks (at least in Texas) but for these older models, there is no problem. What is your reasoning for wanting this setup?
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Tuned
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I am not obsessed with not using one. I was simply asking a question.
I didn't know what you meant by "cross-over" It sounded like you meant something similar to what the new trucks run. An exhaust shop told me that to be legal for newer vehicles, they had to run 2 pipes off the motor, into one pipe, through a CAT, back into 2 pipes and out the back of the truck. The term "cross-over" sounds similar to this setup.
An H-pipe is true duals anyway. Except they are tied together at one point, which, frankly, I don't think would work under my truck. The pipes have to come so far back past the tranny, that I don't think they would fit. But, since I have always had true duals, I never really looked into it.
But you answered my question, though. And I bet that Jeg's has better prices than Summit....but only by 2-3 bucks.
I didn't know what you meant by "cross-over" It sounded like you meant something similar to what the new trucks run. An exhaust shop told me that to be legal for newer vehicles, they had to run 2 pipes off the motor, into one pipe, through a CAT, back into 2 pipes and out the back of the truck. The term "cross-over" sounds similar to this setup.
An H-pipe is true duals anyway. Except they are tied together at one point, which, frankly, I don't think would work under my truck. The pipes have to come so far back past the tranny, that I don't think they would fit. But, since I have always had true duals, I never really looked into it.
But you answered my question, though. And I bet that Jeg's has better prices than Summit....but only by 2-3 bucks.
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Cargo Master
Joined: Dec 2004
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From: NE Texas
I'm not sure if everyone posting in this thread is aware of the EXACT chassis combination that Ace is dealing with. I also have a '78 F150 4WD with a 400. This particular chassis is a BEAR when it comes to fitting in a dual exhaust system. There is just no room to snake tubing past the transfer case.
The best I could do was to use cast manifolds and cross the left side over and run it down the right side along with the right side pipe and then go back across to the left for an exit at the back of the left fender. As far as the rear part you have lots of leeway, but the transfer case position will severely limit what you can do up front.
BTW, the clutch and flywheel will be an identical mounting, no worries there.
Good luck,
Doc
The best I could do was to use cast manifolds and cross the left side over and run it down the right side along with the right side pipe and then go back across to the left for an exit at the back of the left fender. As far as the rear part you have lots of leeway, but the transfer case position will severely limit what you can do up front.
BTW, the clutch and flywheel will be an identical mounting, no worries there.
Good luck,
Doc
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Thanks Doc. The reason I asked about the clutch is because I read that a 400 has a 12" flywheel & 351m has 11". I guess the flywheel/clutch combos are interchangable in either 351m or 400 as long as you stay with either 11" or 12" flywheel parts, right?
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After reading some other posts on exhausts, I came up with 2 ways that I would like to do my exhaust. 1. 2 1/2" pipe from stock manifolds into a 2 1/4" dual inlet/single 3" outlet Flowmaster 70 series or 2. the same as above with 2 2 1/4" single inlet/2 1/4" single outlet flowmaster. I beleive #1 eliminates the need for a crossover & only requires 1 muffler, therefore less expensive. I just want a good sound & good flow. Any suggestions? I am open to another method if someone has an idea. Thanks for all the input!
More Turbo
Joined: Feb 2003
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From: Alexandria, Ohio
I had 2 1/2 into 2 1/2 in/out glass packs, way loud, I was young. Next exhaust was the same with 2 1/4 in/out turbo's. Not sure of the brand. Sounded much better and attracted less attention. I did not do a crossover pipe though. The shop took a lot of time bending short pipes to fit them around everything underneath and keeping the pipes up between the frame then welding it all together. One of the factors is if it is lifted or not. Mine was a '79 F250.
Tuned
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It seems like a custom exhaust shop should be able to snake the pipes around to where they need to be, to do what you want to do. I don't know about how the headers would fit on a 4x4...I had a tight squeeze to get them to fit in my 2x4 and like I said earlier, I really don't think that I could fit an H-pipe under my truck due to the C6 and the 2 cross-members onder the truck.
I know a great exhaust shop that will do custom exhaust in Dallas, if you are interested, but I don't know where you are. This shop did my exhaust and they had to cut the headers themselves back a little to fit the collectors on there, because the ends were so close to the cross-member on the frame. Seems like the 4x4 has even less room than that, so getting it run through there is gonna be tricky, but should not be impossible for a good exhaust shop.
I know a great exhaust shop that will do custom exhaust in Dallas, if you are interested, but I don't know where you are. This shop did my exhaust and they had to cut the headers themselves back a little to fit the collectors on there, because the ends were so close to the cross-member on the frame. Seems like the 4x4 has even less room than that, so getting it run through there is gonna be tricky, but should not be impossible for a good exhaust shop.
Cargo Master
Joined: Dec 2004
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From: NE Texas
A long time ago after I built my 400, I took my '78 F150 4X4 to three muffler shops and none of them would do anything with it. They said they had tried on them before and that there is just no place to put the pipes through except crossing the left one over and running the mufflers down the right side.
The F250 I think is different, but the transfer case placement on the F150 is restrictive.
Yes, it SEEMS that you could snake them somewhere, but there were THREE muffler shops that said no. When my current system disintegrates, I may try to do something different since I now have a MIG welder, but I'm doubtful that I can do any better.
Good luck,
Doc
The F250 I think is different, but the transfer case placement on the F150 is restrictive.
Yes, it SEEMS that you could snake them somewhere, but there were THREE muffler shops that said no. When my current system disintegrates, I may try to do something different since I now have a MIG welder, but I'm doubtful that I can do any better.
Good luck,
Doc