Mild 400 build on a budget

[400Magnum]

With a steel shim (0.020) head gasket and 88cc for 452 heads, I get a compression ratio of about 9.4-1. Not a bad start, which is about the top of the range of compression that Crane recommends for this cam. This should be livable with premium pump gas, shouldn’t it?

If I get the 75cc Eddy heads later, using a multi layer gasket that’s 0.027” thick, compression goes to 10.5-1, which should still be very streetable, right?

Whatcha think?

 

[91r/t]

Yea on the aluminum heads, 10.5:1 should be no problem on premium fuel. You could also use a felpro standard head gasket which is offered in a .050 compressed thickness and that could get you lower compression as well as the standard .039". Depending on thickness, you can tweak it there also. You can also check the bore size on the gasket. All of this will equate to minor tweaks to dial in the compression in small margins.

 

[mgoblue9798]

I agree 100%...you're not going to make a lot of power with the pistons .100 down in the hole, but some closed chambered heads would sure help and should bring compression up about a point. He did say it was a budget build and was just trying to help in the easiest way.

Sure, more than one way to skin a cat. I have learned the hard way to plan ahead especially if you plan on keeping the car. He was talking about buying a set of $1000 plus aluminum heads. If there is a budget enough for that, spend it on the bottom end and upgrade later. Nothing says he cant get a set of 516's along with the pistons.

 

[mgoblue9798]

Ok, just for the sake of continuing the thought. Of all the pistons I’ve looked at, the KB 240 comes pretty close to my needs. The compression distance is better at 1.908, which puts me at about 0.057” below deck. That’s pretty good, certainly better than 0.152” with the stock pistons.

The piston weight is low, but I can get heavier pins for about the same amount of money that it’d cost me to get the crank balanced, that would bring me up to just about 8 grams less than the piston/pin assemblies I just took out. So, that should work out good for balance, right? Measuring the weights of what I just took out, there’s a max difference in weight from heaviest to lightest of nearly 23 grams, with an average difference of almost 8 grams. So if I could put together a set that is more closely matched and comes in just a little lighter, that should work out okay, shouldn’t it??

With a steel shim (0.020) head gasket and 88cc for 452 heads, I get a compression ratio of about 9.4-1. Not a bad start, which is about the top of the range of compression that Crane recommends for this cam. This should be livable with premium pump gas, shouldn’t it?

If I get the 75cc Eddy heads later, using a multi layer gasket that’s 0.027” thick, compression goes to 10.5-1, which should still be very streetable, right?

Whatcha think?

 

[mgoblue9798]

You didn't ask, but I will tell you what I would do. I would find a decent 383 and just swap it in. Keep the 400 for now and build it the way you want as budget allows, or sell it for $500 to someone that wants to build a stroker. Older 383 will have higher compression pistons and a forged crank. This is probably the cheapest way to get a decent performing efficient engine. Just a thought.

 

[91r/t]

You didn't ask, but I will tell you what I would do. I would find a decent 383 and just swap it in. Keep the 400 for now and build it the way you want as budget allows, or sell it for $500 to someone that wants to build a stroker. Older 383 will have higher compression pistons and a forged crank. This is probably the cheapest way to get a decent performing efficient engine. Just a thought.

I agree IF you could find a decent engine you knew something about. Scary grbbing an engine off of craigslist or somewhere and end up with more problems than ya had when you used the running engine you had. Orrrrrr.....you can make a hell of a stroker using a 440 crank in a 400 block I hear, but I can't think of the exact combo piston wise. I would lean towards using what you got, if it ran and has a good core you knew some stuff about. Motor for motor though, you are correct. The 383 has it for piston choice.

 

[mgoblue9798]

I agree IF you could find a decent engine you knew something about. Scary grbbing an engine off of craigslist or somewhere and end up with more problems than ya had when you used the running engine you had. Orrrrrr.....you can make a hell of a stroker using a 440 crank in a 400 block I hear, but I can't think of the exact combo piston wise. I would lean towards using what you got, if it ran and has a good core you knew some stuff about. Motor for motor though, you are correct. The 383 has it for piston choice.

https://detroit.craigslist.org/mcb/pts/d/mopar-383-motor-1967-model/6493280085.html
Even if it needs a rering and bearings it is a good price. If it is still factory is has the good closed chamber heads as well

 

[IQ52]

......................."Mild 400 build on a budget".....................

This is another thread about a dog chasing it's tail so far. Iron heads, aluminum heads, stock replacement pistons, custom forged pistons, hypereutectic pistons, heavy pins, strokers and B1 heads?.......Jeez.

Sorry about the potential loss of job. Therefore, just how big is the budget for this budget build? Are there any future plans for this same block? Where are you going with this? Until that is known we have a pack of dogs going in circles. Or do you want everybody to keep guessing until it fits your secret budget? Or sadly, maybe your nonexistent budget.

As stated, "This will be cruiser, go to the occasional local car show, drive to work on nice days, and once in a great while take it on along road trip." You don't need even 300 HP to accomplish that. Hey lets jack the compression up until must run on premium gas. There's an idea huh?

Are we just sitting around the round table, sipping beers and passing gas? 'Cause ya know, guys like to do that. But not everybody.

 

[91r/t]

......................."Mild 400 build on a budget".....................

This is another thread about a dog chasing it's tail so far. Iron heads, aluminum heads, stock replacement pistons, custom forged pistons, hypereutectic pistons, heavy pins, strokers and B1 heads?.......Jeez.

Sorry about the potential loss of job. Therefore, just how big is the budget for this budget build? Are there any future plans for this same block? Where are you going with this? Until that is known we have a pack of dogs going in circles. Or do you want everybody to keep guessing until it fits your secret budget? Or sadly, maybe your nonexistent budget.

As stated, "This will be cruiser, go to the occasional local car show, drive to work on nice days, and once in a great while take it on along road trip." You don't need even 300 HP to accomplish that. Hey lets jack the compression up until must run on premium gas. There's an idea huh?

Are we just sitting around the round table, sipping beers and passing gas? 'Cause ya know, guys like to do that. But not everybody.

Just tossing some ideas out that maybe the original poster wouldn't have thought of or known about. Never hurts to bullshit a bit and throw some ideas around. That's how some of the best combos are found. I'm always down for some diff ideas and thoughts.

 

[Garys1969RR]

I looked at the KB 240 piston, and I think that's the best choice for this motor and budget. The C/H is 1.908, and maximum compression distance for a B block is 1.935 ". So that puts the piston about .025 below deck. Then you can take .010 off the deck, and get .015 clearance. Then with 8 cc of valve relief, 79 cc heads, .020 steel shim head gasket, pistons .015 below deck, and a stock bore, you come out at 9.5 to 1 C/Ratio. Plus you get .035 quench with a closed chamber head, which helps the engine to have great throttle response, as well as being resistant to pinging. So there are about a thousand different combos for you to choose from. I suggest taping them all to wall, throw a dart, and choose the combo that the dart lands on. LOL. Just like my dog Homer, I sometimes like chasing my tail. Good luck!

 

[400Magnum]

You didn't ask, but I will tell you what I would do. I would find a decent 383 and just swap it in. Keep the 400 for now and build it the way you want as budget allows, or sell it for $500 to someone that wants to build a stroker. Older 383 will have higher compression pistons and a forged crank. This is probably the cheapest way to get a decent performing efficient engine. Just a thought.

I’ve actually considered doing that for a while, but the cost was going to work out about the same either way, assuming I can find a decent engine at a good price. Unfortunately I live in GM territory, so anything Mopar is beat to a pulp, or like buying gold if it’s decent. Of course, as you said, there are way better choices for 383 pistons than the 400, that’s the real advantage.

 

[oldbee]

......................."Mild 400 build on a budget".....................

This is another thread about a dog chasing it's tail so far. Iron heads, aluminum heads, stock replacement pistons, custom forged pistons, hypereutectic pistons, heavy pins, strokers and B1 heads?.......Jeez.

Sorry about the potential loss of job. Therefore, just how big is the budget for this budget build? Are there any future plans for this same block? Where are you going with this? Until that is known we have a pack of dogs going in circles. Or do you want everybody to keep guessing until it fits your secret budget? Or sadly, maybe your nonexistent budget.

As stated, "This will be cruiser, go to the occasional local car show, drive to work on nice days, and once in a great while take it on along road trip." You don't need even 300 HP to accomplish that. Hey lets jack the compression up until must run on premium gas. There's an idea huh?

Are we just sitting around the round table, sipping beers and passing gas? 'Cause ya know, guys like to do that. But not everybody.

Lol, haven’t done this stuff for 30+ yrs. What I want is 87 octane fuel in an engine that sounds like a top-fueler! and street mannered. It’s all a very fine line.

 

[400Magnum]

......................."Mild 400 build on a budget".....................

This is another thread about a dog chasing it's tail so far. Iron heads, aluminum heads, stock replacement pistons, custom forged pistons, hypereutectic pistons, heavy pins, strokers and B1 heads?.......Jeez.

Sorry about the potential loss of job. Therefore, just how big is the budget for this budget build? Are there any future plans for this same block? Where are you going with this? Until that is known we have a pack of dogs going in circles. Or do you want everybody to keep guessing until it fits your secret budget? Or sadly, maybe your nonexistent budget.

As stated, "This will be cruiser, go to the occasional local car show, drive to work on nice days, and once in a great while take it on along road trip." You don't need even 300 HP to accomplish that. Hey lets jack the compression up until must run on premium gas. There's an idea huh?

Are we just sitting around the round table, sipping beers and passing gas? 'Cause ya know, guys like to do that. But not everybody.

I think I’ve been clear enough about what I wanted from this engine, you even went so far as to state it above. That’s all I intend to do with this car, nothing else. Yes, I can do all of what my plans are with a slant six, I don’t need a monster motor, and I stated that as well in the beginning. What you call “dogs chasing their tail” I call an exchange of ideas and information. I was hoping to get that when I posted, and I did. I’m not an experienced engine builder, that’s why I’m asking questions. If that bothers you and you think I’m wasting your time as your last statement implies then you dont need to keep responding to it.

 

[IQ52]

I think I’ve been clear enough about what I wanted from this engine, you even went so far as to state it above. That’s all I intend to do with this car, nothing else. Yes, I can do all of what my plans are with a slant six, I don’t need a monster motor, and I stated that as well in the beginning. What you call “dogs chasing their tail” I call an exchange of ideas and information. I was hoping to get that when I posted, and I did. I’m not an experienced engine builder, that’s why I’m asking questions. If that bothers you and you think I’m wasting your time as your last statement implies then you dont need to keep responding to it.

How right you are. I'm too old and tired to fight all the stupid ideas that keep popping up. So, one last thing before I retire. I don't care if you use a cylinder head made of vanilla yogurt. If you run between 9.5 and 10.5 compression, as has been suggested, you won't be able to keep this engine from detonating with the camshaft you intend to run.

 

[400Magnum]

I’ll take some of your comment under advisement and ignore the rest.

 

[Garys1969RR]

I’ll take some of your comment under advisement and ignore the rest.

Good idea. Some of us have been doing this stuff for 40 plus years, have aches and pains, and don't feel as good as when we were 25. And we've been over the same things hundreds of times. So just take it all with a grain of salt, and absorb the wisdom that comes with years of experience. My new puppy is filled with the enthusiasm and energy of youth, likes to jump around and play with the old dog, but the old fella just lays there, growls and snaps at him once in awhile. He hurts and can't hardly move anymore. We're all just tryin to help each other. Some of us just have different ways of saying things. It's all good.

 

[91r/t]

How right you are. I'm too old and tired to fight all the stupid ideas that keep popping up. So, one last thing before I retire. I don't care if you use a cylinder head made of vanilla yogurt. If you run between 9.5 and 10.5 compression, as has been suggested, you won't be able to keep this engine from detonating with the camshaft you intend to run.

That is correct 400Magnum. That is a small cam to be playing with that amount of compression. I forgot about you saying you are using that smaller cam and not starting out with a new cam. Lost my train of thought when I was crunching deck height numbers and piston heights for the 400. IQ52 if you can find me a pair of heads made out of vanilla I will try and run those fuckers!

 

[400Magnum]

I can appreciate that. What I didn’t like was IQ52 criticizing others for offering up ideas, spitballing about what would be better than another thing. That’s the whole point of these forums, to work through a problem with others that have more knowledge and experience. He basically complained about wasting his time following the thread because of everyone’s stupid ideas, as he put it. Yet he spent a whole long post wasting time without providing anything useful. He was doing the very thing he was griping about. If he wants to contribute to the conversation with useful information, that’s great. If he doesn’t want to, no one isn’t forcing him to do this against his will. But he doesn’t need to be critical and demeaning to those who are only trying to help. Instead of just saying everyone has stupid ideas, he should be specific and point out what will and won’t work and why he thinks that. Just saying something is stupid isn’t productive or helpful.

 

[91r/t]

The problem with these budget builds is unless you commit to one thing you start toying with these ideas and once you upgrade one thing then you change another and then it gets to be where the whole fuckin budget is long gone! Trust me I did this with my Power Wagon. Was supposed to be a re-hone and ring a 318 and turned into a 360 with Indy heads and 375HP!!! It is ridiculous how fast it snowballs. In regard to the cam, I don't think you'd have an issue at 9.5:1 as the stock 383 HP cam was as follows in 68.

The 1968 ~ 383/330 HP and 383/300 HP 'Super Commando' Camshaft

Lift............. 431"/.443"
Duration.... 256*/260* Duration
Overlap..... 32* Overlap

The duration is quite a bit smaller on your cam, but with the newer cylinder head design, I feel it'll have less likely of a chance to detonate than an old open chambered Iron head if you go the aluminum route. Stock 383 in 1968 was 10.25:1 but was a bit overrated so maybe 9.75:1? Not too bad considering. Now that is if you get the piston out of the hole and get some quench on that combustion area. That'll definitely help as well.

 

[400Magnum]

Crane recommends anywhere from 8-9.5 for compression. I realize that the cam is rather small, and the higher the compression goes, the more likely I will have issues with detonation, which is why I initially thought using the aluminum heads with compression in the low 8’s would be a good combination. But as the thread continued, the thought was that I’d be better off increasing compression height to get closer to the deck to prevent detonation. So that’s why I started looking at previous parts that I’d considered, namely the kb240’s and heavier pins to get the weights matched to the ones I’d removed.
So, in your opinion, with iron heads and this cam, what do you think is a good compression ratio to shoot for?