340 compression ratio

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ktcnn94 said:
I cked a few things last night after work. Looks like 75 cc’s on my heads (i had a hard time getting all the air bubbles out), I’m at 0 deck. I contacted silvolite via email and the pistons with the reliefs are 10cc’s with 1.824 compression height. The cylinders are .030 I just used the simple compression calculator on summits website. If I use a .028 headgasket looks like the best I can get is about 8.75. Unfortunately I pulled the valves from one of the heads and the guides are pretty worn. I know the wiggle test is not the way to check them but the wiggle test is all it takes to see these are worn out. So my delima is now to decide what to do. I can buy new heads but that’s a lot of coin for a working man. I’m gonna call our one and only machine shop and check for prices on guides and maybe milling the heads. I’d like to get the compression in the 9’s for the street.
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You need to put the hole in the top of the cylinder for the cover plate to help get the bubbles out, plus tilt the parts so the hole is the highest point so you can get as much air out as possible...

I know a great head guy in Detroit.... He can fix them up if you need his number, let me know... (he gives good head....LOL)
 
krazykuda said:
You need to put the hole in the top of the cylinder for the cover plate to help get the bubbles out, plus tilt the parts so the hole is the highest point so you can get as much air out as possible...

I know a great head guy in Detroit.... He can fix them up if you need his number, let me know... (he gives good head....LOL)
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Yessir I had the hole there and tilted the head around and actually was able to slide the plexiglass around without loosing my seal just couldn’t get the last little bit out. Thanks for the info on the Detroit guy but I’ll ck around here first lol. Thanks sir.
 
dibbons said:
So what is the CC size of each of the four valve reliefs in the top of the 1267 piston? I would guess between 1 and 2 cc each for a total of between 4 cc and 8 cc
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. That was from silvolite via email. I figured 2 each totaling 8 per but they said 10 total. Thanks.
 
It took me a bit to grasp the math, and I love math lol.
Big sheet of paper and a pencil. Lol
Swept volume(SV) is bore(4.07") X stroke (273-340 share same factory stroke) which is 3.31"
So 4.07 X 3.31 = 13.4717"
Swept volume is the distance the piston travels converted to volume.
 
Anybody using aftermarket heads other than edelbrock with success?
 
Just got off the phone with the machine shop. Probably 350-400 for a valve job, mill the heads and bronze guides installed. 2 weeks out.
 
ktcnn94 said:
Well you never know. It might change once I get them there.
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That price is pretty close. I'm assuming a 3 angle valve job, guides, hard seats and a surface so that sounds close.

When you start paying for other than "normal" valve jobs the cost goes up fast.
 
I know sometimes it takes me a while to get stuff done, full time job, been working late some and then winter time weather is terrible. Plus have wife and kids so I don’t want nor do I usually feel like spending all my time off in the garage. I also have my trans apart attempting my first overhaul. So even though I’m not down in the garage it’s hard not to think about this stuff. My heads have a casting number of 3769974 which from what I can find are mid 70’s 360 heads. So should I even bother spending money on these heads or should I be trying to find better ones. I know they’re all old so machine work will most likely be necessary on anything I buy so I’d have to consider cost of the heads along with machine shop costs.
 
Takes me a while too, don't sweat it. Garage is awfully cold this time of year lol
Pretty good price you were quoted from machine shop. Getting new/different heads i would think would cost you more??
If you invest a little labor in the heads yourself with some cleanup/port work and see if there's room for 2.02 valves?
 
Pic with casting #'s from book I have.

20180203_101830.jpg
 
Yeah it’s cold. I’ve got some decent heat but that concrete is hard to warm up if your not in there with the heater going for hours. Usually by the time I get home at night I don’t have much time to get it warmed up and accomplish anything. If the temps are in the teens, forget about it.
 
Yeah garage here isn't attached to house and have a 220v milk house heater. It takes a while to warm up. 8" of snow projected this weekend :BangHead::bs_flag:
 
4spdragtop said:
Pic with casting #'s from book I have.

View attachment 1715138007
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That’s similar to a list I seen. Look at the CC’s it’s listing for those heads. Unless I’m doing something terribly wrong that’s way off. I used a peice of plexiglass and syringe to measure, I done it more than once and came up with 75. I agree with buying another set adding to the overall cost of doing machine work but what I meant was, if they do the machine work for that price and I found a better choice in head for a reasonable price would I be better off? Would you put money in those heads if you had them I guess is what I’m saying. Thank you very much for your help and input.
 
4spdragtop said:
Yeah garage here isn't attached to house and have a 220v milk house heater. It takes a while to warm up. 8" of snow projected this weekend :BangHead::bs_flag:
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Mine isn’t attached either. It’s a concrete slab with a glorified carport metal building on it. I’ve put some insulation board in there and use a kerosene blow torch that’s pretty loud. About 6” of snow here and teen. I hate it.
 
ktcnn94 said:
Mine isn’t attached either. It’s a concrete slab with a glorified carport metal building on it. I’ve put some insulation board in there and use a kerosene blow torch that’s pretty loud. About 6” of snow here and teen. I hate it.
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But as I sit here and think, I’m thankful I have it. Lots of guys work in the yard or the driveway. At least it’s dry and can be warmed up.
 
Yep it could always be worse.
Next house will have at least one bay attached....and a hoist lol
ktcnn94 said:
But as I sit here and think, I’m thankful I have it. Lots of guys work in the yard or the driveway. At least it’s dry and can be warmed up.
Click to expand...
 
4spdragtop said:
Pic with casting #'s from book I have.

View attachment 1715138007
Click to expand...
I have the Direct Connection manual from the '80's, I believe those cc specs are minimum specs. From what I've found the stock combustion chambers are much larger than those you've listed. So they aren't saying that is the actual size of the chamber, it is the minimum size. If that makes sense. Had trouble getting my head around those specs because they don't make sense on a stock unmilled head.
 
ifishinbc said:
I have the Direct Connection manual from the '80's, I believe those cc specs are minimum specs. From what I've found the stock combustion chambers are much larger than those you've listed. So they aren't saying that is the actual size of the chamber, it is the minimum size. If that makes sense. Had trouble getting my head around those specs because they don't make sense on a stock unmilled head.
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I understand what your saying, yes that makes sense now that it’s put that way. Thanks.
 
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