First - it's the original engine for this - an almost completely original 1978 Bronco.



I picked up the one owner vehicle with the intent of making it a serious 4x4 rig. I owned a 1977 Bronco that was the same green and white, so I was partial to this one from the start. I was told the low oil pressure when warm was most likely that it needed new main bearings. I drove it home, and even drove it around a bit - nice and tight. I decided to tackle the main bearing issue before anything got worse and pulled the pan.

And then there was this...

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A cam bearing in the oil pan. I looked at and replaced all the main and rod bearings while I was in there and even checked the oil pump clearances. While rotating the crank around to change all the rod bearings, coolant started coming out of the No.8 cylinder - bummer!

So...

I've see a couple of really nice builds here of the 400 that are in the 325 to 350 HP range with gobs of torque and nothing too exotic going on. I've already done some mild port work on the D5AE heads - a little work on the exhaust throat being careful because of the water jacket around the whole valve, and taking out the bump in the roof of the port (thermactor pump?). I also did some bowl blending in the intake and exhaust.

So here is what I am thinking - Mill the heads .020" to make sure they are nice and flat. Add a Comp Cams XE256 or 255DEH complete cam kit. I think new valves would be worthwhile Ferrea probably, but 2V valves are quite a bit more expensive than 4V valves. Has anyone put 4V valves on a 400? How did it work out? I will probably add roller rockers of some sort on an adjustable valvetrain, some decent headers, and I already picked up a Performer 400, non-EGR manifold. I'm thinking I will get a Holley Truck Avenger carburetor because this is a 4x4 application.

I'm not sure I want to rebuild the bottom end beyond all new bearings, but if I do it will be ARP Wave-Loc rod bolts, polished rod beams, deburring of the crank and a .030" overbore, and balancing of the whole rotating assembly. It looks like hypereutectic pistons or straight cast is all that's available so I'll probably get the hypereutectic units.

Looking for a nice durable 4x4 engine in that 325 to 350 HP range - any pointers? The Bronco will someday be wearing 37" tall tires and 4.56 or 5.11 gearing locked front and rear.

 

Subscribed. Don't have anything to add because I've not done my 400 - yet.

However, you didn't say what the problem was for the coolant. What was the issue and how are you solving it? (I could guess you have a cracked head, but won't.)

 

Good question Gary!

I'm 90% sure the problem was a head gasket. When I removed the heads you could see where stop-leak was used and plugged up the leaking area. I'll get the heads into a shop in the next couple of days to get checked out.

It looks like coolant got into the oil and started to corrode the bearings, then when the engine was started the lubrication failed and it spun a cam bearing out. This Bronco has only 103,000 original miles, and was rarely driven in the last 5 years or so.

 

If it wasn't inside then it could be an exhaust bolt hole into the cooling system. I know because when I had one of my M's on the engine stand I rolled it over and coolant came out. Turns out someone had a problem with an exhaust bolt and drilled/helicoiled it. But, they drilled it too deep, right into the coolant passage. So, I treat it like my Mopar engines, which have wet exhaust manifold bolts, and treat them with sealant before installing them.

 

Simple performance upgrades. Pistons call tim meyer 9 to 1 comp. is a good place to start. Mild port work just clean up bumps and smooth out is a big deal. Usually work tops and sides and port match heads. If possible deck the block to make sure your head gskt issues aren't a uneven deck and machine heads for true machined surface. Check out www.gofastbronco.com great site specific to bronco's and more towards suspension related upgrades. 400 ford get compression up 9 to 1 and upgrade factory cam to something better 260duration to 268 duration. Ran a 268 comp cam back in the day, worked great with 9.5 compression. need to make sure springs are good or replace with new! don't go cheap on timing chain. Get a good chain. headers 1 5/8" tube for towing and good performance. hedman 89360 check out. run this on my 400 for towing. 1 3/4 tube is more for upper rpms but good for right application mud racer and bogger. nice intake edlebrock rpm and at least a 650cfm carb to 750 for serious performance. this will pretty much double your hrspwr or more with these upgrades. I have many photos of a upgraded 400 ford in my albums check out and talk later.

 

need to have machine shop look at closely. could be a cam bore issue. which cam bearing was destroyed?

 

If using arp wavelok rod bolts would reccomend using a bolt stretch on wave lok bolts. have used torque specs and have broken bolts. Standard ARP bolts are a upgrade and simple to torque up. waveloks need to be attention to details especially in the way the bolt fits to rod. have has some issues when using torque method over bolt stretch. forget the spec for stretch of overall length with this bolt. Use ARP lubricant with bolts for proper torque and stretch.

 

Thanks Wyoming4x4!

I might be able to score a pretty good deal on a set of Hooker headers with 1 3/4" primary tubes. Would it hurt my low end power over 1 5/8"?

I wouldn't have thought the Wave-loc rod bolts would really fit any differently than a standard ARP - just "waved" instead of knurled.

The heads are in the shop now. I asked the machinist about larger valves and he basically said - don't bother. Same with screw in studs - more money than it's worth. He suggested a Crane kit to install rollers if that's what I want. If money were no object I'd get studs just because that's the way it's "supposed to be". This whole Bronco project is supposed to be "on the cheap" - at least for now! The engine has no way of knowing if the roller rockers are on studs or bolt on. Ultimate strength goes to the stud but for horsepower on this engine it can't matter.

 

both will work 1 5/8" or 1 3/4" but the collector sizing will come into play with 1 3/4" and 2 3/4 collector or 2.5". But with your application would think 1 5/8" should do you well. I have a set on my orange truck in my albums and check out to see 1 5/8" tube outside frame application. guessing your engine will be in the 300/330 hrspwr range and low end 1 5/8" is the way to go.

 

With factory heads and parts. once you get in the .510 lift range need to look for coilspring binding. something to watch out for. but hyd cam your probably gonna be in the .450 to .490 lift. just working the ports and the valve openings/ turndowns and opening them up a little just helps things out. One thing to watch out is machine shop attitude. when you say 400 ford attitude says boat anchor. but if you say 400 chevy they say good to go and do upgrades. If your apply simple upgrades to 400 ford good things will happen whether its a ford or chevy or dodge. these simple porting upgrades work in all engines, basic engine upgrade for performance. Good luck and chat soon.

 

Dont listen to the guy about the rocker stud conversion.
fo a couple of hundred bucks you will have a better platform for a set of roller rockers than a the crane kit for probably similar coin although you will then have to install an aftermarket set of rockers. So if you are up for that on this rebuild, then fine.
Those conversions IMHO are for running engines that you dont want to crack open to machine the heads for a roller rocker upgrade.
depends on how much money you have really.

DO listen to him about the valves. Unless you are pulling big rpms much over 5500 all the time just dont bother.
The 302aussie head have 2V valves and dont give up much until you start wringing their neck and are better in the lower rpms for torque.

I was talking to an aussie intake manifold supplier/expert several years ago and he said the worst thing you could do to the 302CC heads was fit bigger (4V) valves-stuffs up the flow. Clevo heads are NOT like chevvies. If anything they suffer from ports too big and chevvies would love the port sizes the Clevo's have.
Clevo's if anything need some pulling back!!

 

Update.

I got the front of the engine disassembled this week. Here is a VERY loose timing chain! This is why you want a quality double roller chain. I'm thinking Crane makes a nice looking unit, as does Rollmaster. Crane is less expensive.




Here is the first cam bearing - you can see where there is some missing material on the lower edge. It looks like all the bearings are there, but the surface material (babbitt?) started coming loose. Coolant was doing very bad things inside this engine.



I did get the heads back this week from being surfaced. They cleaned up pretty well, guides are nice and tight and I can now continue on my port work.

 

I found a photograph of a sectioned 1975 and later 351M / 400 exhaust port and traced this out.


Grey - cast iron
Blue - water jacket
Red - valve
Green - where I removed material on my heads
Yellow line - where I could probably come around the sides of the valve (undecided on this)

The two circles in the throat represent the stock pinch point and where I opened it up. I think it will pay off even though there isn't a lot that can be done.

 

triple post

 

My pistons came in from TMeyer Inc. this week. Since these engines can be detonation prone, I broke the upper edge of the domed portion just below the red line.