The 360 build that has more turns than Willow Springs

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Oh yeah. The Charger is the only classic that I have driven there. This will be the 7th time in the car.

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There will be a group of us going in a caravan.
I’ve driven solo and been a little nervous about the risk of breakdowns but in all the years, I’ve only had the RH tailpipe hanger bracket break.
Last year a friend puked an alternator just as we exited the 405 in Van Nuys.
 
I wish I could go to Spring Fling this year.

We ought to keep in touch for next year. Driving in a group does alleviate some anxiety over roadside breakdowns. Last year aside from the alternator, another guy had a weird tire issue on the way home. We all waited with him while the tow truck was en route.
Rich is going in the Coronet but leaving on Thursday…

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We ought to keep in touch for next year. Driving in a group does alleviate some anxiety over roadside breakdowns. Last year aside from the alternator, another guy had a weird tire issue on the way home. We all waited with him while the tow truck was en route.
Rich is going in the Coronet but leaving on Thursday…

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I'm in! I should have the 518 OD in the orange car by then too. That'd make it more comfortable with the 3.91's
 
Two Fats Guys can be hard on tires...
And my alternator started failing around Magic Mountain... I just didn't see any point in stopping figured it would get me there & it did...
 
72cc chamber volume, Measured? Or from a spec sheet?
I will check these to be sure but I did CC another #308 head awhile back that did come in at 72 ccs. These heads have been gone though so they may be a tad smaller due to a light milling by the last owner.
 
All the rings are file fitted and on the pistons. Today I was busy with other things but I did get pistons # 1 and 2 in. The oil clearance on both was .002, right where I usually see them on other builds and right in the middle of the range.
I've never measured rod side clearance in the past but I figured I'd check on this engine. With the book I have, it shows a range of .006 to .014". I was able to get a .012 feeler gauge in and no bigger.

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I've seen Jim Laroy hisself say that .100" rod side clearance is nothing to be concerned about, so I'd say you're good. lol
 
I admit that I am not the most experienced engine builder but I’ve put a few together that stayed together. This is a hobby for me so I have the luxury of working at my own pace. This allows me to tinker a bit then do other things that need attention.
I did not have exact numbers as to where the pistons would be at TDC. More accurately, I didn’t look as close as I could have. I looked at the published compression height and saw that it was 1.675. I read the published deck height and with what others on this forum have reported, I expected to see the pistons .015 to .020 below deck at TDC.
They are not.

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Just at a glance you can see they are actually above deck.

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I measured .010 to .012 using a rather crude tool.

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Yeah, I had expected to use thicker than average head gaskets and it is a good thing I bought them. I have Edelbrock .051 ones here that will help. I was aiming for low to mid 9s in compression since this is an iron head build and I didn’t want to be stuck running 91 octane premium all the time. Now it looks like I’m closing in on 9.8 to 1. This is not ideal. I could run it and if it gets to the point of annoying me, I could pull the heads and install Cometics… or just order them now and avoid the aggravation.
Kewl. Positive deck height. What heads are going on this?
 
The side clearance in my 440/495 was a lot, partly because the aftermarket caters more to Chevy sizes of things and the rods of mine are narrower than a Mopar rod.

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Kewl. Positive deck height. What heads are going on this?

Iron # 308s that have been mildly ported by Hughes engines when the previous owner built the engine.

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Oddly, the guy had this engine around 9.5 to 1 with a moderate sized cam but with cast iron manifolds and a 727 with no increased stall rating and 3.55 gears.
I'm using headers and a 4.10 gear. I'm contemplating a switch later to a 727 with a factory high stall converter but will just swap the engine into the car with it's existing 904 for now.
 
Iron # 308s that have been mildly ported by Hughes engines when the previous owner built the engine.

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Oddly, the guy had this engine around 9.5 to 1 with a moderate sized cam but with cast iron manifolds and a 727 with no increased stall rating and 3.55 gears.
I'm using headers and a 4.10 gear. I'm contemplating a switch later to a 727 with a factory high stall converter but will just swap the engine into the car with it's existing 904 for now.
How deep are those chambers? Have you measured them? Measure the depth opposite the spark plug side.
 
I don't think the heads were milled much. I'll know when I cc the chambers.
Maybe before I take the road trip next week.
 
I don't think the heads were milled much. I'll know when I cc the chambers.
Maybe before I take the road trip next week.
What I'm getting at is quench distance. You won't know that unless you MEASURE the depth of the champers on the side opposite of the spark plugs.
 
Oh, okay.
I do not know the depth. All that I do know is that the #308 heads were rumored to be the best flowing 360 head before the 5.2/5.9 Magnum design came along.
 
Oh, okay.
I do not know the depth. All that I do know is that the #308 heads were rumored to be the best flowing 360 head before the 5.2/5.9 Magnum design came along.
If you measure that distance, then subtract "however much" the pistons protrude from the bores, than add in the compressed thickness of the head gaskets, you will get your quench distance. As long as those measurements are fairly even cylinder to cylinder you should have a pretty even quench distance from cylinder to cylinder. I'm goin the long way around the barn here.....bear with me. What I'm saying is, even at 9.8:1 or even a little higher, IF you can get some reasonable quench distance, there's no need for thicker head gaskets. I would also have those chambers polished like a mirror. That will do two things. First, it will remove any "bumps, irregularities, or imperfections that could lead to detonation and secondly, it will "big up" the chamber volume just a little and lower the compression a tad. I'd rather see you lower it that way, than with a big old thick Cometic head gasket. And I'd call anything under about .070" "reasonable quench". Much beyond that and the benefits just aren't there. They say about .035" is "optimal", but benefits of quench are had beyond that. If you can get some quench, and gat those chambers polished, you won't have trouble with detonation even at 10:1 and a little over, especially if you run a cam with some balls.
 
I'm goin the long way around the barn here...
I remember hearing that expression for the first time from my Grandfather around 60 years ago. I was a little kid, so I asked him what it meant. I can still see him throwing his head back and laughing. "Well, I'll tell ya" he said.
Thanks for making me remember that moment.
 
The heads only got a few thousands milled off to clean them up.

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This quench distance looks huge.

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Using my crude yet repeatable method…

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I got .068”. Subtract the .010 piston above deck and I am at .058. Add a .051 head gasket and I’m way out of the range for decent quench.
I cc’d a chamber and got the same 72 cc number as I got with another #308 head.
I admit that these numbers were not taken with NASA levels of precision but they aren’t likely to be off the mark by much.
The practice of using a thicker head gasket to reduce compression has fans and critics. I ran into several opinions on the matter 12-13 years ago when I was dealing with detonation in a big block. I was stubborn and didn’t want to pull the engine to put dished pistons in it so I went with .075 Cometic gaskets. It lowered the CR from 10.9 to 10.17 and it stopped knocking. It ran great and I noticed no ill effects.
I may be looking at the same scenario here. I’m not going to get any quench even with a stock .020 shim type steel head gasket. That would move the CR up to over 10.56 to 1.
No thanks.
 
There's no sense in being at the ragged edge of compression hoping the fuel you get is decent. Erring on the low side of CR won't cost must in terms of power but will buy you flexibility to run lower octane fuel and also help you sleep at night.
 
i don't think you need to worry about deck height mismatch, its not huge

mine stuck up 40 thou

i found a solution (mid gasket job after 8 years use...apologies for filth)

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I got .068”. Subtract the .010 piston above deck and I am at .058. Add a .051 head gasket and I’m way out of the range for decent quench
Just my opinion, I still think you’d be better off keeping the thinner head gasket you have, lower P/H clearance is still what you want even though you have open chambers.
A polished chamber is a good idea as Rusty suggests. I did this on some Eddy heads and got another 4-5cc of volume. On your heads you may get a couple of cc’s more being open chamber. That may get you to 9.5:1 SCR or so.
 
I have dealt with detonation before and it is very annoying. I do not want to do that again. I will likely use Cometic .075 or .086 gaskets to get back below 9.5 to 1.
We get 100 degree days here and are only about 400 feet above sea level. The best gasoline is rated at 91 octane and is “Up to 10% ethanol”.
 
We get 100 degree days here and are only about 400 feet above sea level. The best gasoline is rated at 91 octane and is “Up to 10% ethanol”.
I’m at about the same elevation as you are, gets red hot here as well. That sucks about the fuel you have, very limiting. There’s a few sharp edges around the exhaust valve in your chambers, if it were me I’d definitely smooth them off. Then again, I’d probably do the whole chamber! :)
Anything you can do to reduce the chance of detonation is worth it IMO. Especially with a road car & crappy fuel.

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Here is a weird one....
I decided to go back and cc the chambers again. I thought that I already did it but wanted to make sure. I used a syringe that only goes to 60 ccs so I run it to 60, fill the chamber then fill it with 20 ccs and fill it until it is full. Today I did that and the second fill showed 12 ccs left in the syringe. That means that I used 8 ccs of the 20 for a chamber volume of 68 ccs. I made a mistake last time and added the 12 to the 60 instead of the 8.

That means this:

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That is with a .050 head gasket. If I used a Cometic .075, I get this:

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A .086 gasket gets me here:

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I can live with the 9.48 to 1.
 
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The target was this:

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We all make mistakes and I am no different. I should have carefully measured the piston deck height with the other pistons before teardown.
The Speed Pro pistons have a compression height of 1.660 while the KB pistons are 1.675, .015 taller. It is ironic that the KB pistons I have sit out of the hole by approximately .012. Chances are, the block was zero decked to the old pistons and since I didn't check it, I am dealing with more compression than I want. If this were a drag race engine, I'd be happy as can be.
 
I'm a bit unsure of how to proceed with this next thing:
In many cases, you can defer to what the factory did and with that, you get OEM level of durability.
Then there are instances where the aftermarket addresses a weakness that can correct a flaw and make it even better.
In some books and elsewhere, it has been written that one needs to put plugs in the ends of the oil galleries that are at the front of the block. Some advise to drill those plugs and when installing the thrust plate, use a bolt with a hole in it on one of the upper bolts.
The thrust plate from this engine:

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The right side dead ends, the left makes a turn down. Why would I need a plug where the plate blocks off a passage? Why would I put a plug where the plate seems to direct oil to drip down to the pointer that aims oil to drop onto the crank sprocket as seen here?


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I'm tempted to skip those plugs and just put the thrust plate back in place like it was before.
 
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