Hot Rod Forum banner
1 - 20 of 35 Posts

·
Registered
Joined
·
168 Posts
Discussion Starter · #1 ·
I've heard you can bolt 351C heads right up to the 351m-400m block with no modifications... What about the intake manifold? Would I switch to a 351C also? If not, what would be done to modify the 400m manifold?
 

·
Registered
Joined
·
721 Posts
The Ford 335 series of engines includes the: 351c / 351m / & 400. The 351c was the HiPo engine, the 400 the truck engine and the 351m (a low compression mix of parts) passinger car engine. The 351c has a low deck block and large main crank, the 400 block has a 1" taller deck and smaller mains. The 351m uses the 400 block with a relocated wrist pin location in the pistons to destroke it to 351cu in. The 400 and 351m used 351c 2v (2 barrel) heads. The 4v (4barrel) heads from the 351c will bolt on 351m & 400 engines with the longer 400 push rods. All 2v heads are open chamber and 4v heads come with open and closed chambers. 351m & 400 share a wider manifold due to the taller deck. 351c manifolds can be used with spacer plates. Soo.. to answer your question. Yes you can use 351c heads on a 400, but only the closed chamber would realy help. They would raise the CR about 1 point. But the larger ports will hurt low end. A better route would be to raise the CR to 9.5:1 with pistons, a mild hyd cam, headers/turbo mufflers and an Eldebrock performer manifild & 650cfm carb. Keeping the 2v heads will help low end power.
 

·
Registered
Joined
·
168 Posts
Discussion Starter · #6 ·
Thanks for the info, pony.

What about changing the valve size? What do I have stock, and what would you reccommend I put in? I've been told that changing out the cam, upping the cr to about 9.5:1 installing headers, muffler, and the such will give me around 350hp on paper... Is this so?
 

·
Registered
Joined
·
721 Posts
Your 2v heads have 2.05 intakes and 1.65 exhaust valves. As big as most HiPo Chevy heads and the ports are good sized also. Stock HP is in the 160-170 range so you asking to double your HP. A more realistic out put for the set up I mentioned would be around 260-275 HP and still run on 93 octane. For 350hp your looking at using 4v quench heads (getting harder to find and $$) around 10.5:1 CR, a more agressive cam profile, 351c 4v intake to match the 4v heads, intake spacer plates and the port matching to make all that work, bigger carb, better ignition, Ect, $$$. If your going to do all that you'd be way further ahead starting with a 351c 4v engine. Doing the mild build up on you 400 would wake it quite well and still be very street friendly and at the same time not break the Bank. :thumbup:
 

·
Registered
Joined
·
168 Posts
Discussion Starter · #8 ·
ok thanks pony, somebody on here had said thet 340-350 was what he came up with but maybe he didn't get the right numbers in there. I'm planning on getting all forged bottom end and putting in a 50-75hp shot of nitrous. You know, till I get a hi-po engine in there. (or till I find the perfect 500ci hearse) It's just gonna be a dailt-drive street machine so the high numbers aren't too important to me. :) Thanks again all.
 

·
Registered
Joined
·
168 Posts
Discussion Starter · #10 ·
Ok guys, I know we all hate these ford 400 questions... but here's one last one (actually, I'm not making any promises on that).

Does anyone know who still makes the oem 1971 400 flat top pistons? That's supposed to bring my CR up to 9.5:1... Thanks all.
 

·
I need a bucket of arc sparks
Joined
·
895 Posts
Another alternative would be to find some Australian 302 Cleveland heads. These heads have the 2 barrel ports but have the closed chambers for higher compression.
 

·
Registered
Joined
·
2,384 Posts
400 M

Pony, ya got the mains backward. The Cleveland had 2 3/4 inch mains and the M blocks all had 3 inch mains.

The 1971 400M had a compression ratio of 9:1, all others had from 8.4 and lower. If you want to get more than 9:1 compression, go with the 71 pistons and then have the heads machined about .020". .009" = 1 cc of combustion chamber on the open chamber Cleveland 2 bbl and M block heads.
As a note of interest, in 76-77, the 400M was offered with a 4bbl intake, but only in California, on passenger cars. A rare item to be sure, and would probably be better off going with an aftermarket if thats the way you are headed.
The M block was made in both 351 and 400 cubic inch. The 351 had a 4 inch bore and 3.5 stroke while the 400 was 4 by 4.
A hot tip for your oiling system. Both the Cleveland and M block (M for Midland Kansas where they were forged), had what is called an indiscriminate oiling system. The passages going from the mains to the cam bearings are way too big for the job.
When I raced Clevelands, I would get a hand ful of roll pins, 5-3/8ths inch about 2 inches long and 5- 3/16ths inch an inch long. I would drive the 2 inchers into the oil passages going to the cam bearings from the mains til they were about half way in, then drive the 3/16ths pins inside the 3/8ths inch, the drive them down into the block. You will also want to do this on the oil passage going to the lifter galley on the back of the block from #5 main. Do not put the pins in the oil passage from #1 main, as that would be damaging. What these pins do is restrict the oil flow some what, going to the cam bearings and keeps it down on the mains, where its really needed. Moroso and other sell restricter kits for this but when you consider the cost of their restricters, and that you have to tap threads into the passages to hold them etc etc etc, the roll pins are a lot cheaper and a lot easier and quicker to install and do the job just as well.

Besides the heads on the Cleveland and M block being interchangeable, so are the exhaust manifolds, cam shaft, valves, rocker arms, lifters, water pump, timing chain and gears, and distributor. Intake manifolds and reciprocating assembly will not interchange, nor do flywheels, bellhousings or engine mounts. The bell housings and engine mounts are interchangeable with the Lima block (429-460). I am not sure about whether flywheels will enterchange between the 351 M and the 400 M, as my parts interchange book doesnt go that far, the 351 M going into production in 75.

The 351 C had a deck height of 9.2 inches and the M blocks range from 10.292 - 10.302 deck height.
Your stock valves are 2.02 intake and 1.65 exhaust. The port size of the 2 bbl head is fantastic on both engines for flow charactoristics and its not necessary to run the 4 bbl heads or put in the larger 4 bbl valves, unless you are planning to run your engine all day long at over 7000 rpm.

The Open chamber heads can safely be milled up to .080". One other thing, if you are going to change the cam and run heavier valve springs, invest in one piece valves. The production valves are a two piece configuration and hi pressure valve springs tend to pull the heads off of the valves, and that equates for expensive engine repairs at minimum and a junked block at worst, the latter being more the case than the former.
Also, there is a freeze plug looking critter with a small hole in it just below your thermostat. Do NOT remove that from your engine. That separates the water coming from the water pump from the water returning to the radiator. IF you remove that plug you will kill your water circulation, winding up with a fried engine.
 

·
Registered
Joined
·
721 Posts
OPPS! :spank: Hey Max do you know if the 351m/400 blocks can be machined at the main webs to accept the 351c four bolt main caps? I realize that the whole assembly would have to be line bored after but it seems a 400 x 4 bolt block would be good start for a hipo Cleavland. Also have you ever used the Ford Racing direct bolt in roller rockers for the fulcrum type heads?:thumbup:
 

·
Registered
Joined
·
5 Posts
400 M

A 400 M is a 400CID motor the cleavland heads are the same as the Modified heads unless you come across a set of 4BBl heads. you can almost fit your fist in the intake side. The deck height is taller on the 400m so the intake will not fit. Ford never made a stock 4BBl intake for the modified engine , but you can get aftermarket ones. If you can come across a set of australian modified heads they had a smaller combustion chamber and are great for upping your compression. Have Fun
 

·
Premium Member
Joined
·
6,623 Posts
I've merged your thread D. Robbins, I think you wanted to post your reply here with this one.
 

·
Registered
Joined
·
2,384 Posts
400 M

For Pony, I presume that the mains could be drilled for a 4 bolt setup, however from what Ive seen of the M Block, there shouldnt be any need for that unless you are going to run a hi pressure setup like a blower and NOX combined. I do know of guys that have turned 400's in excess of 7000 RPM on a regular basis with no problems on the bottom end at all. To me it seems like a waste of money. The main caps dont go up into the block far enough to have sufficient room to cross drill them. One problem is that the Cleveland main caps arent as thick from top to bottom as the M blocks and the 1/4 inch difference in main diameter would require machining an 1/8th inch out of the cleveland main cap, severely weakening it.
If you are referring to the Crane type roller rockers that have a pedistol just like stock rocker arms, yes, I ran them on a Cleveland in a Late Model Sportsman and in an IMCA Modified. They work quite well. I never had any problems with them. Ive also used the type with the push rod guide that drops down into the groove that the factory pedistol would have gone into, this only requiring the use of a screw in stud to run conventional roller rockers. Either way works great. Ive never tried any of the Ford stuff for that.

Jimdog, there is what looks like a freeze plug located in the block, in a pocket just below the thermostat. There is a small port in it. You will need to have the thermostat out in order to see it. What that is, is the thermostat bypass for allowing the engine to warm up with out causing the pump to cavitate before the thermostat opens. IF you remove that plug, your water pump will just pump the water directly up to the thermostat without going through the block, causing you to seriously over heat.

In 1976 and 1977, only, and sold only in California, Ford did make a 4 bbl intake for the 400M block. It is moot as there are very few of them and were probably little more than a 2 bbl intake cast with a 4 bbl carb face on the plenums. Being it was for those restrictive California smog laws, I doubt they are much of a performance inhancer.

I have heard rumors that there were some M blocks cast with out the the freeze plug pocket inside the block for use as a thermostat bypass, however I have never seen that type, that there was just a small port or hole cast into the block instead.

Pony, more reflections on the direct bolt roller rockers. I just browsed through my 2001 issue of the Ford Motorsport catalogue, and found those. They are the same as the ones I used that were produced by Crane.
One postitive factor is that with all that area of contact and being clamped solid to the head, you will have a stiffer structure to hold the rocker arm so you wont have a flexing situation as you do with the studs alone.
An anecdote to this. I ran this setup with a 234/244 degree; 562/588 lift hydraulic cam. The heads I was running had been machined down .030", so I put .030" spacers under the pedistols, to compensate for the loss of head material. when I torqued the rocker arms down, the rocker arms had play in them. Come to find out that the cam I put in had a .060" smaller base circle diameter than the stock cam, meaning that the heal of the lobe or base was .030" closer to the center line of the cam shaft than with the stock cam. This smaller base circle, in effect off set the .030" that I had machined off the combustion face of the head, negating the need for the .030" spacer under the pedistol.
Little details like that can drive one batty. And for me that doesnt take much.
 

·
Registered
Joined
·
10 Posts
Oiling Problem

Hey, you may not now this but the 351M and400M had a oiling problem. The oiling system was designed to feed the camshaft bearing first and then the main bearing journals. The result is oil starved #4 and #5 main and rod bearings.

There is a fix for this problem. My book says to run a oil line from the front of the block where the sending unit screws in to the back of the block where there is an oil gallery plug. This mod channels a greater volume of oil to the back of the block to feed the #4 and #5 main bearings.
 
1 - 20 of 35 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top