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72 Nova, 65 Rambler, 37 Chevy
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341 Posts
Discussion Starter #1
Well as you may already know from my last post I blew my "new" 350 and I was looking for a inexpensive way out to get me running again. I have found a solution now:

Several days ago I bought a rusty 77 blazer with a 400 in it. The Odometer showed ~69000 miles on it which we were sure it has been turned over. But the interior was almost perfect and after removing the engine, everything was in great condition and worked. I pulled the heads and WOW - Barely ridge and you can still see the cross hatch hone pattern in the cylinders! It must have 69000 miles. It is also standard bore. never been rebuilt, 2 bolt main, and the 509 block to make things even sweeter. I have yet to look at the bearings, I hope it is sill all original. Ill post condition of those later.

But I/it may have a problem. We did a compression check before we pulled it and after it was out we did a leakdown test. Here are the results:

Cylinder -- Compression (PSI)
1. 140
2. 140
2. 130
4. 120
5. 115
6. 100
7. 140
8. 130

Leakage -- (%)
1. 40
2. 67
3. 74
4. 79
5. 89
6. 84
7. 42
8. 84

Now those two tests don't follow each others results...?...The cylinders with the most leakage has the highest compression and vice versa. Kinda lost hear but I think the point is that I got some serious? leakage. When we performed the leakdown, it sounded and felt like most of the air was getting past the rings.

So Im looking for suggestions of what I should do. Still on a budget here. Mainly my two options for a build are (for short block) since it is in so well condition, use it as it is. OR since it is in so well condition rebuild it (doesn't need to be bored) with new rings, bearings, etc. (Take it to machine shop and have it professionally honed, hot tank it, and new cam bearings and freeze plugs installed)(or I could clean it at home, reuse cam bearings, and use a honing stone at home, this would save a bunch of $$$) Then top it with vortec heads and use my 350 cam (224* .465 lift). I would just hope that the pistons can be reused, which im almost 100% sure they can be. And the crank and rods don't need to be ground or resized.
 

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10,722 Posts
If the engine has sat any amount of time the rings will leak due to the lack of lube. It`s also a 400, siamesed cylinders tend to suffer more from out of roundness since it doesn`t heat and cool evenly. However, I wish I could find a 400 and get that lucky, you came across something good.
 

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72 Nova, 65 Rambler, 37 Chevy
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341 Posts
Discussion Starter #3
Well it sat for about 3 days since it was last running to the point we tested leakdown. I pressure washed it after i pulled it...I duct taped off the carb flange and dizzy hole before, yet a large quantity of water found its way in somehow. (probably through valve covers) anyways would this effect the leakdown?

DoubleVision said:
It`s also a 400, siamesed cylinders tend to suffer more from out of roundness since it doesn`t heat and cool evenly
So would all 400s - even new - have this problem? Would I benefit from new rings and hone?

I want this engine to be able to hold ~450ftlbs/350HP and spin 5000-6000 everyday (thats high a high number but I think it will be doable with 224 .465 cam and vortec heads) and just planning for the future also. I think the stock cast dished pistons/5.565 rods/crank(i guess all 400 cranks are nodular?) will have no problem here too.

Just my delima is 69000 miles
1. leave it as it is?
or
2. since cylinders are in good condition new hone, rings and bearings. (would this help my TQ/HP/RPM capacity)?
 

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Warrant said:
I could clean it at home, reuse cam bearings, and use a honing stone at home, this would save a bunch of $$$) Then top it with vortec heads and use my 350 cam (224* .465 lift).
You're thinking about reusing the cam bearings with a different cam????????? :rolleyes:
 

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72 Nova, 65 Rambler, 37 Chevy
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341 Posts
Discussion Starter #5
Yes...?...whats wrong with that, I did it with my other 350 and had no problems...thats common...people do it all the time...switch out cams...
 

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10,722 Posts
Hone it, then scrub the bores good, and I mean really clean them, to test how clean they are, spray some WD40 on a Paper towel and wipe the bore down, if you see gray, it`s not clean. rering it, stab in a cam, and you`ll be quite surprised how much power it has over a 350. If you plan to use different heads make sure you have the steam holes drilled, other wise it`ll endlessly overheat.
 

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72 Nova, 65 Rambler, 37 Chevy
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341 Posts
Discussion Starter #7
K, Should I hone it using a that honing stone device were you can adjust size and tension (has like three arms with the stones) the kind you use with a drill? (I would have a friend who knows what he doing do this for me) OR take it to a shop?

Also, if I avoid a shop, how should I go about cleaning the whole block? Remove the oil gally plugs and get like a pipe cleaner in their? or not even go that far? just remove all internal rotating parts and power wash it, then spray it down with WD40 so it doesn't rust. Then do the hone job, clean again, install everything with new bearings, rings, oil pump, and gaskets. (I would keep same freeze plugs and cam bearings). How about that?

As for the main and rod bearings, should I buy standard size or .001 size since it is used and may be worn? (I guess I should do some miking here and plasti-guage? Whats a good way to check this? and what clearances is it ok to use without resizing and regrinding?)

Thanks so much
 

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72 Nova, 65 Rambler, 37 Chevy
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341 Posts
Discussion Starter #8
Well I looked at all the main bearings. Not such good news, I found that some junk has gone thruogh one of the mains and scarred up the crank, not to bad but bad enough to require a regrind. It looks almost on the verge of spinning, the bearing was severely deformed and wouldnt snap back into place in the cap. Im almost back in the same situation as before.

But I have another 400 and that crank is in great condition. So Im going to take it to the shop and have them polish it. Then get the block just honed. That will get me to where I want to be I think. Do the new bearings/rings/gaskets kit and install with the cleaned pistons and rods just how were removed.

Im still debating if I should remove the freeze plugs and have the shop do a full clean. I think I can just leave the plugs in and have them hone it and clean it the best I can and it will be fine? (its the inside that needs to be cleaned anyways...Dont care about the outside)

Also, Will I have any problems resuing main cap bolts, and Just leaving the pistons hung on rods and reusing the rod bolts?
 

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Race it, Don't rice it!
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7,734 Posts
Even if the shop does clean it, you need to clean it agian. That shop has been cleaning blocks all week with the same cleaner. Get the point. If you let the shop do all the work, and don't check it, your risking wasted money.

Use a ball hone not a striaght hone. You won't have to take as much out to get a even honing pattern. Use cheap(est) cast iron rings. Moly's are too hard for a oblong cylinder.


You wanna turn this thing to 6000 everyday, you need to do it right. Just reringing won't last to long. You have no idea how many revolutions those part's have. What if a rod bolt breaks at 6000? Ever see what happens to an engine? I'll email you some circle track engine pics. Your gonna be mad you didn't buy the right stuff in the beginning.

Just trying to help you keep rodding for a long time.
 

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I put up the tools against$300
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689 Posts
Your plans to take this engine to 6k rpm everyday kinda knocks doing things the cheap way out. Although small, you said that there was a ring ridge at the tops of the cylinders. But you also said that the hatch marks were still visible. Are they visible all the way around the cylinder from top to bottom? Mic the cam bearings and then decide on replacing, they often will last through several rebuilds and its very easy to get one in out of round or out of alignment when replacing them. I think you can get by with reusing the main bolts but they are the only ones I would feel comfortable reusing. Rod & head bolts gotta be fresh. Another thing that kinda raises an eybrow is not getting the main bores aligned. 6000rpm + 2 bolt main = a lot of flex in the bottom end. Pull the plugs out even if your cleaning the block yourself. Their inexpensive and it sure makes it a lot easier to get to all the crud. Where did the material in the crank bearing come from? What caused this engine to fail? Unless something got dropped in the valve cover, something broke. Flashing maybe, but I'd look very closely. You also said that one of the main bearings looked nearly spun. If you see any bluing or heat discolorations you must make sure your mains are straight. Reconditiong the rods is a must on any rebuild that I spend any money on. Good place for failure, especially on a 400
 
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