>I have the chance to buy some pretty good 351c heads for my
>400M, if they will fit. I think i have read that the 351c
>heads bolt on.....
>Any tips or suggestions
>thanks Jeremy Martin
Well - they will fit if they are 2V (small port) heads. They would be pretty much the same as the original ones though the chamber size may vary by a cc or three. If you intend on adding headers and a 4v intake and carb, go to the expense of having the heads machined for the larger 4v valves. This is reportedly a good thing to have done. Even better - get ahold of some Australian heads and put the larger valves in them. They have the smaller quench chambers that will boost your compression ratio to about 10:1. The quench chambers will help you avoid detonation and it should run good on pump gas.
If they are 4v heads, you will need 4v exhaust manifolds or headers and you will need either intake adapter plates or a 4v aftermarket 400 intake which someone mentioned on here a while back. That intake is probably quite expensive if you can get one. The adapter plates are reportedly available but may require some machining to match. If you use headers you would have to use 351-4v headers but since the 400 block is raised in comparison to the 351C, you may encounter some clearance problems. Stock exhaust manifolds from a 351-4v should work better.
While you have the top of the engine off, it is probably worthwhile to put in a mild cam, a better intake/carb, and a straight up timing gear.
Only if you plan on spinning it over 3500 Rpm. would it be worth the time and money to do so.Actully what I would do is get a set of Aussie heads and have the bigger valves put in them, for street use you can't beat this set-up, I know I had it .
I currently have Hooker Headers, 1 5/8" to 3" collector on my stock 400. I have a set of 351c heads I am about to put on. Is there any way to get these headers to work?? I know I need an adaptor plate, but is there anything else I need to get thses heads to bolt up?
Jeremy, you keep saying you have 351C heads, but not whether they are the 2v's or the 4v's. If they are 2v's, they are virtually identical to the heads that came off your 400. If they are 4v's, not only will you have an intake port mismatch, but the large valves of the 4v heads having lazy flow under 3500-4000 RPM. (ie, low velocity, a torque killer). My suggestion would be to run a set of Australian heads. They are identical to the U.S. 2v Cleveland heads but have a smaller (58 to 60cc) chamber for better quench and higher compression (about 1 1/2 points). You'll have the best of both worlds when it comes to horsepower and torque. I have used them quite successfully. I still have a few used sets sitting around. If interested, let me know. - Don