Ok, we had a great discussion with 400 rods max rpm??? thread, time to start another. What type of heads to use for a 400 when turning 6000+ rpm. 4V Cleveland open or closed, Aussie, or 2V Cleveland. Right now I am using 2V Clevelands with 4V valves. Considering using closed 4V Clevelands. My best calculations have came up with 10.5:1 compression using closed 4V's. Most people that I have talked to that have built these engines don't suggest going any higher than 11:1 on these engines, due to being hard on the bottom end. I like the flow values of the 4V heads especially past 3000 rpm. I know of no headers made to match 4V's to our trucks, possible solution would be to get 4V flanges, then cut and weld them to 2V headers. There is also the problem of using an intake to match the 400 to the 4V's. Any ideas out there????

 

351C torker intake with weiand spacers hogged out to 4bbl size. Mill header flanges flat and weld on 4bbl flanges then smooth out the rough spots and bolt them up. The added thickness will help sealing.

 

I suggest staying with 2 bbl. based heads. Aussies or 2 bbl. Clevelands. Do a good job with porting them out, both intake and exhaust. 2 bbl. heads' exhaust ports flow at least the same if not better than 4 bbl. heads, and at lower lift. Port a Weiand or Edelbrock(400) intake to match the new port sizes. The 2 bbl valves will work to 6500, butt 400's love to breathe, so give it some 4 bbl. valves. Any competant machinist can do this.

 

That's why I created a Cleveland forum on Yahoo. We have quite a few members building 400 based engines. Some are using 351C 4V. Others are going with CHI 3V, Blue Thunder, and A3 Ford Nascar heads. Dan L ran some numbers through a Desktop Dyno program. Even if DD numbers are a bit optimistic, 600+ HP shouldn't be a problem with a 427/400 stroker.

There are no good intakes for the 400. The Edelbrock Performer should be advertised as a rev limiter rather than an intake manifold. Edelbrock specifically states NOT to port match their intakes. Here's why,

From
http://stangstable.com/manifold.htm

"TIP: Edelbrock Performer Manifold. The Performer was not strictly built as a performance intake for the 2v. It was developed for the 2v crowd that wanted a 4v and the performance of chunking an iron intake for aluminum.

NOTE: After just purchasing the Edelbrock Performer for my 351C 2V, there is a SPECIAL INSTRUCTIONS section that is nice to know: The port size of the Performer 351-2V and the Performer 351-4V manifold was thoroughly researched and was designed smaller than the head port for several reasons. Although appearing small in size, the legs of this manifold not only flow more than the port in the head, but they also increase the flow in the head. The design of this manifold allows us to use great runner speed which prevents fuel dropout and gives us better fuel and air suspension. This combination is excellent for throttle response, total performance, and provides very favorable emission qualities. As a final note, please do not attempt to match the manifold to the ports. This will not only hurt performance, but it will upset many of the fine features that took months of research and development."

For now, the best options are a spacer/adapter with a 351C intake or 351W intake with a few modifications.

What's your application? Are you looking for torque or HP?

 

OK, don't touch the ports. Try this instead. Relieve the plenum divider by lowering it 3/8 of an inch. The result? Increased HP and TQ from 4000-7000 rpm. And, if Wilson Manifolds says to do a mild cleanup and port job, just 1.5" up into the intake runner, I trust them. Sure, Edelbrock designed it for the street, but with help from companies like Wilson, they can make it into a healthy performer from Idle-7000.

 

Brian S,

Heres a link showing the problems with the 4V exhaust I mentioned. I will continue looking for floww numbers.



http://stangstable.com/FORD%20351%20...d%20Engine.htm

 

What are you going to use the engine for? Not for street I hope. Anywho if fuel octane isn't a problem the engine will like lots of compression and a large cam. You also need to solve the intake quandry. I agree the Performer limits rpms but it's about the only choice for the street in a heavy vehicle. a 1" 4 hole carb spacer helps.

 

The 400 I'm "playing" with right now is in a mudrace truck. I started out just doing a mild rebuild. Now I'm getting interested in just how hard I can push it and what combinations work best. I've got a mild cam with 270 degrees duration and like I posted above Cleveland 2V heads with the 4V valves installed. Since Neighborhood and cid 473 already have ran a 400 in their trucks, I was interested in combinations they had ran with success. Seems like the 400 is differant from any other engines I have messed with, it seems to be better suited for torque in a certain RPM range. Also, since their is very light aftermarket support for the 400, just looking at Cleveland combinations that would work.
The Cleveland 2V heads or Aussies do sound like they would work good on these engines, but I have ran across some post on other forums that have high regards for 4V heads. I'm also using an Offenhauser 360 degree intake and did come up with a Edelbrock Streetmaster 400. My best research is they both have a RPM range to 6000, so I'm figuring that either one will work well, since I don't wanna push it over that and blow the bottom end out. I've already got a decent collection of Cleveland stuff and aquired a set of Aussie heads after I already had motor toghther.
Thanks for the tip on the Cleveland forum Brian, I'm sure I'll go there to check it out.
Keep the ideas coming guys.......I'm listening!!!!!!

 

The last few weeks I've been working with a guy on the board who wasn't very happy with his 351C 2V dyno results. Based on the cam specs and several other engines using the same cam, it should've make power to 6000+rpm easy. It never got close.

It fell flat on it's face after 5200 and peaked at 330HP. I think the biggest restriction is in the Performer 2V intake. I've never seen a real dyno test where that intake made any decent power. If someone can direct me to one that did, I'd appreciate it.

I suggested a 1" open spacer might be helpful but for the long run, I really think a different intake will better. Edelbrock makes a couple good intakes for the 351W. The Performer RPM, and a new Air Gap Performer RPM. Both are designed for 1500-6500 rpm.

The cam Edelbrock recommends for these intakes happens to be within 2 degrees duration of the one he selected and the 351W dyno results were 400hp/412tq.

See 351W manifolds
http://www.edelbrock.com/automotive/man_ford_351w.html
&
400hp@6000
http://www.edelbrock.com/automotive/7181pp.html

What good is a Windsor intake when you have a 351C?

Why not do the same thing this guy did?
EFI 351C Ford Conversion
http://www.detomaso.nu/~thomast/efi/

The 351W intake on a 400 would be a similar swap if spacer plates were used.
-------------------------------------

The 351 4V exhaust port was nicknamed the Dogleg because of the odd shaped port needed to fit exhaust manifolds in a narrow engine compartment with shock towers. All the aftermarket heads I mentioned before modify the port for a much better transition. That one of the reasons I'm running A3 heads. The stock 4V exhaust isn't as bad as it looks. The old rules about having an exhaust port that flows 75-80% of the intake flow isn't used much anymore. Pro Stock engnes are closer to 60% now.

 

mudcobra
A piece of advice. The streetmaster is junk. You have to run a giant pump shot, and it doesnt feel like it pulls as hard as a performer. Also, we found when we removed the streetmaster that several runners had developed pin holes(and some quite larger holes) from what had been a perfect intake when installed. We found the casting to be porous. The performer pulls harder through the mid-range, and also, believe it or not, pulled to a higher rpm. Note that we are running a 1" open plenum spacer.

 

I have a Edelbrock performer manifold that had a small pinhole in the plenum that made for a nice vacuum leak. You should have seen all of the silicone gasket sealant that had been put on the carb surface chasing the leak. I fixed it with a rivet and JB weld. I may actually get it welded sometime.

If you look at a factory Ford cast iron 429/460 manifold you will notice a notch cut in the plenum divider below the carb secondaries only. The OEM manifold when running on a dyno outperformed both the Edlebrock and Weiand dual plane intakes it was tested against. Neither of those aftermarket manifolds had the notch.

If you go with a spacer make sure it is a 4 hole spacer to preserve the divided plenum on a dual plane manifold. You can carve out the holes to make it into a two-hole spacer. If you get an open spacer cut a notch in it and drop in a 1/8" minimum thick piece of 6061 T6 aluminum to act as a divider. The divider does not have to seal perfectly.

 

This is just a thought, It may sound stupid but on a 400 performer intake, if someone was to cut the notch in where the plenum and make it like the intake you described what could this do to your power or if any??....

 

Thats what Wilson Manifolds says, and it should increase throttle response.

 

OK. you are lowering the tourqe curve with a 2 or 4 hole spacer on a dual plane intake.
my qu is whats the change between a 4 hole and 2 hole? or better put, does one lower the TQ curve further or offer better throttle response?

 

I don't know about the throttle response at low rpm's but I think it would do wonders for it at high rpm.

Has anyone ever dyno'd a stock 351C or 351C performer against the 400 performer. Personally I think the 400 performer runs out of wind at about 4500-5000 rpm.