What CC are the Iron heads you'd be using? Do you have the compression calculator and all the numbers(rod length, deck height etc...) set? I don't have the rod length, piston height, deck height chart on me at the moment.
Mild 400 build on a budget
- Thread starter 400Magnum
- Start date
BSB67
Well-Known Member
This.
If you're on a budget, leave the short block alone and put on a good set of cylinder heads with small chambers. Higher compression and better flow. It'll be the better bang for the $. You'll spent 2 times as much freshening up the shortblock and won't run as well with crap heads.
400Magnum
Well-Known Member
I’ve been figuring 88cc for the 452 heads, I’ve never measured them, but that seems to be about the accepted norm for them.
Yes, I’ve got a little spreadsheet setup where I can play with the numbers to get compression ratios to compare one setup to the next.
400Magnum
Well-Known Member
Yes, I am on a budget, but I had to remove the piston/conn rod assemblies to clean up the cylinders, so the short block is already apart. After removing the assemblies, I found that three of the pistons wouldn’t move freely on the pins. The pins had galled in the piston bores. I cleaned them and soaked them in oil and worked with them, but nothing helped. I didn’t like the thoughts of reinstalling them like that so I decided to get the pins pressed out. So, since I have to get pistons anyway, now is the time to decide what to look for. I had been considering just getting stock replacements, but most people are saying that I’ll be more satisfied with the performance of the engine and less likely to experience problems with knocking if I get compression height up to more closely match deck height. I’m trying to find pistons that will have better compression height and closely match the weight of the pistons I just removed so I don’t have to get the crank rebalanced. So far the best I can find is the KB 240’s, but they aren’t a perfect match.
66chargerpat
Well-Known Member
Just do it! Use the old pistons. GET SOME BETTER HEADS. You will burn some more oil. Use the cam your talking about! Don't over think this. be happy, save money! P
Yea there is really two routes to go. One you can shoot for a compression goal that will inevitably be wrong when you go to change heads down the road and go with that. I have been doing some stuing and am leaning towards what BSB67 said. Unless you grab the pistons you wanna run with later heads, you will be building kinda a combo motor with no true final definition. If you do grab some closed chambers and even deck them, you could bump the compression up quite a bit by doing that and running a thinner head gasket. If you are dead set on replacing pistons, then I say why the hell not buy the ones that will raise compression if you are buying them anyways. Try your compression calc using the closed chamber heads you would be using. I would stick around 9.5, that way you can get away with what you have, and in the future upgrade the cam and then get more from the same combo.
66chargerpat
Well-Known Member
Sorry, just read about the stiff pistons. That does changes thing. sorry, pat
400Magnum
Well-Known Member
No problem. Your advice is still sound.
Yea me too......if you are buying pistons then get something that will put you around 9.5:1 like I said.....it'll work with what you have and then later you can upgrade the heads to some nice aluminum heads and still keep the compression in the useful range. Edelbrock makes a nice aluminum head that is 88cc I believe in an open chamber just like the stockers and a couple in closed chambers (84cc & 75cc). That a cam and intake down the road and you'll have yourself a hell of a motor to play with.
400Magnum
Well-Known Member
You don’t think 9.5 with iron heads and this cam will be prone to detonation?
Ok do this.......What does 9.0 compression ratio get you with your combo now if you bump the heads down to 84cc later on? Work out your combo to put you at 9.0:1 now using the parts you have selected and 88cc heads with a .039 head gasket standard......Then bump the heads down to 84cc and see what happens.
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400Magnum
Well-Known Member
Hang on, my computer just locked up on me. I think it’s getting tired from calculating all these part combos tonight... ;)
Ok....basically trying to get you at 9.0:1 for now, and see what happens in the future if you go to a bigger cam, better heads, and intake package. At that point you'll wanna be around 10:1 so if you can do that with existing heads out there it'll be easier.
400Magnum
Well-Known Member
Ok, if I use the KB240 pistons, and the 0.039” gasket with 4.410” bore, and 88cc for the heads it works out to exactly 9.0-1. If I update the heads later to 75cc, using the same head gasket specs, it brings compression up to 10.1-1. Not too shabby...
400Magnum
Well-Known Member
Using 88cc heads with a 0.020” steel shim and 4.380” bore and stock flat top pistons, compression is at 7.4-1. Changing to 75cc heads bumps it up to 8.1-1, assuming I can use the same steel shim gasket. But I get conflicting information about that too.
1967coronet440
Well-Known Member
I read through this whole thread, wanted to reply to a lot of comments but didn’t. I’ll just say a couple things
1. IMO You can’t teally build a “budget motor” and expect it to last forever you said you don’t want to rebuild it in a few years... get your priorities straight and figure out what path you’re going to go down.
2. IQ52 is a talented builder, he does this for a living, and I would consider following any advice/guidelines he posts. If you think he’s criticizing (he probaly is) but it’s becaise he’s been answering questions like these for a long time.
3. If it was my motor and I didn’t want to be rebuilding it in a few years first thing I would be doing is taking it to the machine shop to be serviced/checked (bored/cam bearings etc... the works) it seems like what you’re after is longevity on a minimum wage budget, sorry but probaly wont happen.
Guy chimes in claiming he re gasketed a motor that sat for 30 years woth rusty cylinder walls and it ran for another 100k Miles in 3....2...1...
1. IMO You can’t teally build a “budget motor” and expect it to last forever you said you don’t want to rebuild it in a few years... get your priorities straight and figure out what path you’re going to go down.
2. IQ52 is a talented builder, he does this for a living, and I would consider following any advice/guidelines he posts. If you think he’s criticizing (he probaly is) but it’s becaise he’s been answering questions like these for a long time.
3. If it was my motor and I didn’t want to be rebuilding it in a few years first thing I would be doing is taking it to the machine shop to be serviced/checked (bored/cam bearings etc... the works) it seems like what you’re after is longevity on a minimum wage budget, sorry but probaly wont happen.
Guy chimes in claiming he re gasketed a motor that sat for 30 years woth rusty cylinder walls and it ran for another 100k Miles in 3....2...1...
In my honest opinion, there is not a motor alive other than a blower motor that will or should be considered a performance engine at 7.4-8.5:1
That second combo is what I was talking about. Gets you to a respectable number now, and when you can afford to do the top end power kit (heads, cam, and intake/carb) you have a motor with a stout performance output using the same bottom end you built now. Little tricks like that can save you some money now and a lot later.
I once had a 440 out of a motorhome that I regasketed and surfaced the heads and made 400hp on the dyno! Said no one ever!!!!! Sorry 67Coronet you made me hahahahahha!
1967coronet440
Well-Known Member
You know before I built my motor (keep in mind I’ve never built an engine) I planned on taking my old 440 putting some trickflow heads on it a comp roller cam and a new carb and It was going to be the baddest motor around... I quickly realized there’s a lot more to it then slapping a few new parts on, ended dumping around 12 grand into my stroker, but you know what now I know it’s built right (mainly because I didn’t build it lol)I once had a 440 out of a motorhome that I regasketed and surfaced the heads and made 400hp on the dyno! Said no one ever!!!!! Sorry 67Coronet you made me hahahahahha!
Yes the **** gets expensive. I had $4,750 in just parts in my 360 truck motor and I built it from scratch myself! Expensive to be a Mopar guy, but I wouldn't have it any other way!
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