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Stick with me here, there's a lot to tell!
I rebuilt a 400 for my 79 f350 back in 2007 back when I was 14. Being an excited kid, I messed a lot of stuff up, rushing through things. For example, I didn't tighten the oil pump bolts, so after about a week of driving I had oil pressure problems The truck had been parked since late 07.
Anyway, I FINALLY got around to tearing it back down and seeing what the total damage was. Looks like everything survived, no spun bearings, no damaged crank etc etc...
I also skipped out on going through the heads back in 2007. Upon teardown this time, I sent them to a machine shop and they are as bad as they can be. Guides, seats, valves, springs, and milling all need done, totaling $570 after labor.
Now to my dilemma!
I want to do this right this time around.. I want a good cam and a higher compression ratio. I should've got some flat tops when I rebuilt it, but I didn't know enough back then so I just got regular pistons (sealed power I believe) @ .040 over. I can't justify getting new pistons when I have 8 pistons with about 4,000 miles on them. My machine shop guy has a set of rebuilt 400 heads with high performance springs and .060 milled off them for $450. This would surely up my compression some, and I know that my block was milled at least .010. I know if I bought these I'd have to mill either the intake or the intake side of the heads and get correct pushrods for it.
What compression ratio could I expect if I do in fact have .010 milled from the block and go with these heads? Also, how much more would I have to mill to achieve a zero deck height? Will I have valve interference if I zero deck the block? I know that would condemn this block to being potentially not rebuildable in the future but I'm okay with that.
That's where I'm at with this project. If my heads only needed a valve job, I'd consider maybe getting pistons. But I feel $450 is a good price for those heads and it would lean me towards doing the "higher comp through milling" route since those heads already have .060 milled off. I realize that it's not the ideal way to raise compression but it's where I'm at!
Also, I am absolutely not interested in going the 460 route. The way I see it I have a Mallory distributor, Holley 4bbl, Hooker headers, Weiand intake, new motor mounts/clutch/radiator so to change platforms to say a 460 would be silly in my opinion.
I think all your prices sound pretty damn high to me. I will have $500 or less in all the machine work for my 400. Hell, last fall I paid $500 for a complete truck with a running 351m in it. I think i would slow down and start looking around for a different engine or something. Put an add on CL or one of those other sites looking for a 400 or 351m and start with better heads. Maybe look around for a different machine shop. I myself would not want to deal with the headaches involved in taking that much off the heads and block. I think the machining needed to get the intake to work and new pushrods and whatever else would end up costing more than getting different parts to accomplish what you want in a more traditional way.
Haha, at age 14 I hadn't even kissed a girl, let alone build a V8 !!
The first build sounds like a good learning experience.
Your second build could be a disaster !!
Option 1 :
Without knowing the deck clearance, piston dish volume (assuming dish), builder's head spring pressures, yes you'd have higher compression with the $450 heads, but the engine would no doubt run crap.
Option 2 :
Find out your current deck clearance and piston specs. (Measure them yourself while the heads are off. Both banks. Could well be different to OE specs, not just 0.10''.)
Find out what flat top, or slight dish, pistons are available to give +/- zero deck clearance if your current pistons sit too far down the bores.
Decide what type of cam you want. Driving Miss Daisy cam, mild bad *** cam, or a Forrest Gump cam.
Your heads will no doubt need new springs anyway to match the new cam.
Do your heads need hardened valve guides in order to run unleaded gas, or are they hardened already ?
With proper static and dynamic compressions determined, and a cam that fits in with the compressions, your engine will give years of trouble free, powerful and gas efficient driving.
(Ok, as efficient as a 400 will allow. LOL)
I'd go with option 2 personally !
If you have to sell your existing pistons at a huge loss, so be it. School fees !!
Don't trust a builder, buy a book like Haynes (gives full dimensions and torque settings), design and blueprint the engine yourself.
A machine shop can do block skimming etc, with you watching and checking !!
Milling that much off the block would be a waste of time and money when the pistons have that huge dish in them. Just bolting on a set of milled heads would not raise compression to what your looking for. Change pistons to flat top, mill block to zero deck and get the crank balanced.
4x4slik- I too just bough a running pickup (with a 460) in it for $550. They are definitely out there, less so in the rural parts of Montana where I'm at, but out there nonetheless. I get your point, but I don't see the value in getting into a totally new rebuild or taking a chance on a "running engine" to install. I have a fresh block/rods/crank, so Ill definitely stick with what I have. Another crappy part of rural life, there are 2 machine shops near me, both charge near the same amount for everything so I am stuck with that no matter what.
If I'm going to throw a running engine out of another rig into it, it will be an International DT360 out of a school bus Still, I see your point and appreciate the response!
FMJ- I too hadn't kissed a girl at 14 haha Wrenching was more important, or rather a clear second that was easier to obtain
Option 2 seems like the no brainer. I am in the process this evening of putting it back together enough to check deck clearance. Thats the obvious first step before any decision can be made. I also bought a Haynes manual when I went about rebuilding it the first time, so were good there.
I am sure I can get the head specs from the machinist on his .060 heads he has. He's a very honest old dude who hates Fords... Go figure.
The seats are very very worn on the heads. I believe they are hardened, but I didn't ask. This engine is a reman that was installed in about 85' so I would imagine they are hardened. Whoever rebuilt the heads back then was a real winner... All sorts of different types of "repairs" on the guides. Between the messed up guides, seats, and faces, you can literally see that the valves are sitting crooked in there respective ports!
So, Ill spec everything out, see what I have and go from there. I would still like to hear from anyone who has milled their way to a high comp (under 10:1) 400. I am definitely prepared to sell the pistons and do it the right way. Just thought Id see if the heads were a sensible option.
Not sure about a pricing problem from what I see. Depends on where you are. I did a 400 that cost me $2500 in machining and new parts. And that was more than 15 years ago!
Just did a 302 roller block and heads, and the same basic setup was more than $3200 including the heads being done. So for me at least, $400-$500 to have some heads re-worked sounds like a dream!
Sure, I rebuilt my first three engines for less than $500 bucks, but that was back in the "good old days" for me.
Sorry I can't help with the specifics of .060" off the heads. Sounds like a big number to me, but not sure if that's true or, if done, what it would net you.
You'll have a cascade effect of needing new pushrods and a machined intake by doing this, you will be a lot better off either getting the proper higher compression heads... or getting proper pistons.
On my 351C I am using (because I'm in Australia) the Aussie 302 Cleveland heads - 58cc closed chamber with 2.02" / 1.6" valves in 2V ports. Running my 351 at 10.7:1 with stock pistons and its a monster, haha.
I'd try figuring out the compression increase with just the head milling. How deep in the bore are your pistons now? If it's just .010" I wouldn't bother. If it's more, I'd want the motor disassembled for machining, and at that point it's a toss up between spending money on machining or new pistons. I found this
at this site: Head Milling 101: The Basics of Head Milling to Gain Compression - OnAllCylinders
According to this site : Milling Calculator It's a Pontiac site, but the math should be the same.
If your stock compression is 8.5 compression, taking .062 off the heads will give you 9.8 compression. I'd say run the heads, leave the short block alone. Milling an intake and custom push rods are part of rebuilding motors sometimes, it's not a huge expense or difficult.
4x4slik- I too just bough a running pickup (with a 460) in it for $550. They are definitely out there, less so in the rural parts of Montana where I'm at, but out there nonetheless. I get your point, but I don't see the value in getting into a totally new rebuild or taking a chance on a "running engine" to install. I have a fresh block/rods/crank, so Ill definitely stick with what I have. Another crappy part of rural life, there are 2 machine shops near me, both charge near the same amount for everything so I am stuck with that no matter what.
If I'm going to throw a running engine out of another rig into it, it will be an International DT360 out of a school bus Still, I see your point and appreciate the response!
Actually, I am using the 351m in my truck while I rebuild my 400. My point wasn't too use the engine, but have different heads to start with. Might even be able to just find a set of heads. Talk to you machinist or anybody about people who are into older Fords. Might be a 400 or 351m or a set of heads laying in someones garage you can pick up for next to nothing. I am just saying there are other avenues to look at.
Great responses everyone! Thank you!
So, I tried to figure out how far down my pistons are. I had to go buy a yard stick so it took me a few days
i checked cylinder 1 and 5 on the intake side and exhaust side of the deck directly across from each other on both pistons to verify that the reading across the deck was the same. Going from the highest edge on the piston to the deck surface i got 0.085 on both sides.. The only part # I can see on them is 1160 written in a casting circle on the inside of one of the skirts. That is a relevant Keith Black piston number on summit so I assume they are the Keith black .040 over pistons. Specs on summit read:
Angled valve relief, 2.944 diameter,
0.115 in. deep piston head.
Compression Distance (in):1.630
And yes, The heads make even bad cores haha. The only thing going for them is that they aren't cracked!
So FMJ, I realize that this is the not ideal way to go about doing this, but If I can raise my static comp to around 9.8, what are the downfalls in you estimation? Ill do some more reading on dynamic vs static and quench. I have a basic grasp on the importance of open vs closed chamber and quench characteristics but Ill read up on it.
03-22-2018, 03:12 AM
The truck had been parked since late 07.
Still, I see your point and appreciate the response!
