Anyone have any experience on a 312 build where extra effort made for more performance as in more horsepower? Mummert has a lot of stuff like heads and cams and info on changing stroke for more cubic inches interested to know of someone's results or advice??
Thanks for any help....

 

What exactly is your goal and what are you starting with?

 

about 400 HP...with engine that looks period correct...using eventually a 5 spd trans, has top loader 4 spd currently with a 272 stock engine ...have a 312 std short block to build

 

If you will be buying parts from john, absolutely consult him on it.

I don't have a recipe for 400hp but there are things that you will need and things you can do to make it easier to get there. If you are familiar with any other engine, then the same things you would do to that will apply here. A pushrod 4 stroke engine is fundamentally no different from any other. Whatever you would do to another engine will have approximately the same result with a Y.

First things first, a 400hp 312 is not going to be a truck engine so if the desire is to use it as a truck, it's the wrong choice. If done well, it will probably handle light, occasional truck duty but it will lack the low end for typical truck use.

To achieve 400hp, ported large port, large valve factory heads or John's aluminum heads will be required. The total cost should be pretty similar so it may come down to what is available within the time frame because there is usually a wait list for the Mummert heads. The aluminum heads also have an added benefit of a modern combustion chamber, which should result in more power and efficiency, everything else equal. Another benefit of the aluminum heads is that they are designed to be able to take advantage of 1.7:1 rocker arms, whereas 1.6 is about the highest that can work on factory heads. These might not be a requirement, but will help if you have the extra money to spend.

You will also need a Mummert or Blue Thunder intake and you will need headers, all to compliment the heads. Headers will probably be the tricky part because to my knowledge, no one makes a header for trucks with primaries larger than 1 1/2" so this means that the headers will very likely have to be custom built.

Mummert heads and the blue thunder intake will look stock to most people, if painted but people who know what they are looking at will notice. An Edelbrock 2x4 might also work for a period look. I don't know if 3x2 would work because of the cfm limitations of the carburetors.

Going the stroker route is a good idea for several reasons. First is the obvious increases of displacement, which will make it easier to reach the goal but it also increases compression, which will be required for the best results. With enough displacement, flat top pistons might achieve the ratio desired but a dished piston can be required if displacement is large enough. WIth Mummert's stroker kit, which uses an offset ground crank, you will also have the benefit of smaller rod journals, which results in a slower bearing speed and reduced friction, freeing up some power. It also uses components which are lighter than stock and the pistons he provides use modern rings which are thinner than stock, providing further friction reduction and power increase.

When I put together my current 292 based 318, I used his most basic stroker kit and at that time, the cost was not much more than the things I needed, anyway - turning the crank, reconditioning rods, pistons, bearings, etc so it was a pretty easy decision. This kit was a drop in which means no clearancing is required. Larger strokes may require additional work to provide clearance for the rods.

The cam, I won't even try to guess on that. Call John, call Isky, etc. Tell them what you're doing and take what they suggest. Stay away from Comp. They grind Y cams incorrectly and there are others but I don't remember which at the moment.

It will probably need a minimum of a 750cfm carb. At this level of performance and expense, it's probably a no brainer to go with an MSD distributor but a stock 1957 or newer distributor can be made to work. They just aren't as user friendly when it comes to tuning and it's an old part. Even rebuilt, there are items that just aren't available and as a result are not likely to be quite right. And most importantly, take the time to tune it correctly. That can make the difference between hitting the mark and missing by a significant margin.

 

Thanks for the heads up on the things you outlined. I think we lucked up on a pretty decent block and crank which was all we were looking for. Knew we would need aluminum heads and updated internal parts. Checked the web site on Johns stuff and saw the cam they used on some of the engines they listed with HP and torque numbers. The truck has a decent running stock 272 engine in it that was some kind of Ford reman,,,it has a metal tag on the side of it saying so. Someone put a 4 barrel stock manifold and using a 600 chrome CFM Holly which provides too much gas fuel. It has ram horn manifolds for exhaust but will need bigger outlet. Do you know how much added to stroke can be gotten using the stock 312 crank? Hoping this crank will make ok as a 10/10 grind.

 

Using a 2.00" rod journal, and starting with a perfect, standard 312 crank, 3.62" is about the longest stroke that can be achieved.
Smaller Honda sized 1.888" rods have been used but finding a crank that will go that small is much more difficult. So in practical terms, more than 3.62" stroke requires a custom crankshaft and some people have done that.

 

I have a friend and he went with the supercharger route with a 292 and he is pretty happy with the performance when he wants it. Just an idea.

 

That's an idea hadn't thought about that....still trying to get everything checked to be sure everything is useable.

 

Supercharged is a very expensive endeavor. The only "bolt on" supercharged setups will be for rare F-codes and some of that stuff is ridiculously priced, for a guy who just wants a supercharger and is not concerned with it being original. Some items are reproduced and the VR-57 superchargers can be retrofitted with more modern (I think SN) internals. I'm acquainted with the guy who does the conversion and he may have one in stock and ready to go.

An Australian produces a 4-71 blower manifold, which would probably be an easier install, vs fabbing brackets and pulleys for any centrifugal blower besides the VR-57. That manifold is about $1000.

The most "budget friendly", if you want boost, will probably be a turbo. You can use the factory crossover manifolds as a means of mounting the turbo - have a Y pipe made, to replace the crossover. That's about the hardest part, possibly besides tuning, unless you also use fuel injection. This isn't he most ideal way to do it, but it has been done at least a few times.

 

Most likely stay with carb without blower. Trying to get decent HP but maintsin a close to stock appearance. Will hopefully add AC so don't want to compromise that.

 

AC with a blower is no compromise. It's just even more expense

 

Well, my block is bad main bearing saddle is cracked but crank is great. Question, what options do I have using 312 crank and 292 block? ? Have another block but it looks like its too far gone to use. Haven't got it apart yet everything seems pretty rusty. If 292 with 312 crank works for a combo then that might be the option??

 

312s do have that problem with cracked mains due to an incorrect torque spec in repair manuals. They also have problems with cam tunnel alignment.

Why do you say that the other block is too far gone?

You can turn the mains to fit a 292. Make sure to use a crank grinder with a stone thin enough to retain the rear crank slinger but I think the slinger does need to be cut to a smaller diameter to fit the 292 block and seal retainer. I have 292 cranks I can measure but no 312s.

The 292 is the better block to start with and is usually the best to start with for a really serious build. The most powerful Y-Blocks built to date have been 292 based - we're talking over 600hp naturally aspirated and almost 1000hp boosted. A big part of the reason is that they don't have the above mentioned 312 problems but also, 62-'64 blocks have the strongest main webs and the smaller main journal diameter has the same effect as smaller rod journal diameters, so everything else equal, a 292 based engine will produce more power than a 312 based engine.

 

Guess I need to see what's around....this other block is froze tight...I've gotten nothing to move...all main caps are off but #3 and I haven't got it to come up off the block. All the pistons are in it but stuck tight. Pan was off and water got to it.
probably need to regroup and go 292.....

 

Locked up doesn't mean bad. The 292 in my truck was locked when I got it. I didn't have time to wait for penetrating fluids to work so I ended up drilling and breaking out the pistons. It was standard bore and all but one cylinder was good. The bad one got a sleeve. That was probably 60k miles ago at this point.