340 Rebuild "Musts"

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440fury

440fury

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Picked up a standard bore '71 340 last weekend, and curious as to what you guys think is "absolutely necessary" on a build, and what is more along the lines of a "nice to have". I picked up "How to Hot Rod Small-Block Mopar Engines" but this book isn't exactly what I thought it would be - lots of talk about race engines, not a lot of talk about street engines. For this 340, I'm shooting for 400 HP and to bearable on the street.

Known about this engine: Standard Bore, Rod journals .010 under, Main Journals are standard, forged 4-speed crank, stock rods. The bearings look like some debris got in the engine. Not "Holy Sh*t" bad, but they definitely have some stuff in them.

Things I'm curious about:
Sonic Testing (Book calls it a "must"), Align Boring, Decking, Stock Vs. Aftermarket Rods, Aftermarket Rod Bolts, Replacing Bushings on rods.
 
For a 400hp 340 build I would use stock crank and rods. Have rods resized and run good bolts. Extra mile on rods would be flash ground and shot peened. Have deck surface cleaned up and squared. My big block took .005 to clean up. I would run a forged budget piston and aim for 9.2-9.6:1 compression with iron head. Slightly aggressive solid lifter cam in the 240@ .050 range. Eddy performer rpm intake. Set of j or x heads with mild bowl work and decent valve job. A 750 Holley carb. Set of 1 3/4" headers into a 2.5" duel exhaust setup. Things like wind age tray are free hp. A good balance job is a must! Get timing at about 18-22* initial, 33-36 total and all in by 2000rpm and your gonna have s fun setup. I'd also run stock mechanical rocker arms. This setup leaves room for improvements down the road but still loads of fun.
 
Thank you for the responses! I read over my original post and what I'm trying to ask definitley could have been clearer - I'm looking for recommendations on what to have done at the machine shop in particular. Along the lines of if align boring, sonic testing, stress relieving, decking etc are needed on a street build.I really appreciate the help!
 
440fury said:
Thank you for the responses! I read over my original post and what I'm trying to ask definitley could have been clearer - I'm looking for recommendations on what to have done at the machine shop in particular. Along the lines of if align boring, sonic testing, stress relieving, decking etc are needed on a street build.I really appreciate the help!
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Leave nothing out.
It should be decked, and the piston should come out of the block .040-.050 depending on head gasket, heads you are using and final compression ratio.
You MUST set the clearances and the mains MUST be line honed.
If you are having the crank ground, have them grind it to the minimum to -.0005 so you can make the hole in the mains and rods as small as possible.
If you are runnnind solid lifter, BUSH the passenger side oil gallery and plug off the driver side lifter feed.
Make all the main oil feeds 9/32 to 5/16.
Do not restrict the oil to the rockers.
Use full groove main bearings and if the shop won't use them, get a different shop. Getting some oil to the rods all the time is better than getting it there late.
Order a custom cam.
If using other than completely stock valve train, use the B3 racing engines geometry correction kit. Look up his web site to see how far off most people run their geometry.
 
Here's a simple list:

Sonic checking - Must if you are boring it out. An excellent way to waste thousands of dollars is to bore it out without checking and end up with a cracked block. Yes a .020 is almost never going to hurt it. But better safe than sorry.
Align boring - Always a must. You want things to "line up" don't you? Align boring is a basic of "blueprinting" a block. It will line up center lines to the bore. Makes sure everything runs well and within spec.
Decking - This is up there with Align bore. Decking along with align bore will make the engine "square". Meaning everything will be equal to everything else. Bores will be lined up to cam/crank center lines. The deck line will be square to the crank line, which is also very important. Or else you end up with an engine where a piston in cylinder 7 might be .004 out of the hole and on cylinder 1 it's .004 in the hole. Not good.
Bushings - Just replace them. They are cheap. And fresh ones offer good insurance against anything else that might go wrong. A lot better to wear a new bushing/bearing then it is to throw a rod.
Aftermarket rod bolts - Once again, just cheap insurance. Rod bolts stretch. I wouldn't re-use them.

Any of these should really be done on ANY rebuild. Yes it costs money. But how often do you want to rebuild the thing? And as I keep saying with engine building. The devil is in the details. A properly balanced and bluprinted engine, with a strong hone, good decking and excellent rings. Can be worth an EASY 50hp over a thrown together engine without attention to the detail.

Only thing I don't think is ABSOLUTELY needed. Is new rods. If it is a 71. It should have forged rods. As long as they spec out. Give them a shot peen and polish. Then throw some ARP studs in them and back in the engine they go.

Now if you want an idea of 400 horse. My setup was rated (probably under rated) at 380 horse with the 340 manifolds. Now I have headers and a much better exhaust on it. I figure it's about 420 horse.

340 block, with all the work I mentioned above. As well as checking oil galleys, clearences, etc etc. Basically a full balance/blue printing. These details make a difference.
Stock forged crank/rods
.040 overbore
Keith Black 243 hypereutectic pistons
J heads, 1.88 intake valve opened to 2.02. Stock 1.60 exhaust valve. Excellent valve job (3 angle with back cut if I remember, Ill have to check the build notes). And while they did the valve job they also did light cleanup work on the turn, port and bowl.
Comp XE274H with comps recommended kit (lifters, springs, locks, timing gears/chain, etc) comp pushrods
RPM Air gap
HV oil pump
Stock 340 A body pan
Rebuilt/recurved stock style electronic distributor
Rev-n-ator ignition box

Right now. I have a garbage 12 year old 670 street avenger on there. It's some cheap chinese crap. The metal is flaking bad and can't be fixed. I also think I have some distributor problems. I am going to switch over to the distributor recommended by rev-n-ator. I am also changing over to FItech 600hp power adder setup. First I'll just run the fuel side of it. Let it learn, get a tune, see how it does. Eventually I will use it to run timing and nitrous as well. I've heard A LOT of great things about the FItech setup. Mike at MRL has used them on his last few builds and says the thing runs excellent and is worth a few hp over the usual carbed setups.

But as is right now. With 245's out back. A 4.10 gear set. A 2400 B&M off the shelf torque convertor (which I'm replacing with a custom built PTC unit as well). The thing will ROAST the tires at will. Anything over 1/4 throttle in 1st/2nd will light them up on completely dry pavement. If I mat it in drive. It will burn the tires all the way into 3rd easy. I can be cruising at 50k in second and if I push that throttle it'll light them up in the middle of the road. So it's definitely making good steam.
 
Yellow Rose and Lustle covered it.

-Have it balanced.
-Degree in your cam or its a waste of time to even build a motor.
-Match components appropriate for your build and application. (cam, intake converter, gears, carb, etc

My opinion, ditch the stock rods and run Scat I beams. For the money by the time to resize, deburr, shot peen and buy good rod bolts you've surpassed the cost of them. This is assuming your not doing the work and having a shop do it.
 
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bush the oil gallery for a street engine?....lol
positive deck height of .040 to .050 for street engine...maybe .018...
 
70aarcuda said:
bush the oil gallery for a street engine?....lol
positive deck height of .040 to .050 for street engine...maybe .018...
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With solid lifters, yes. I've done it since the mid 1980's. No need to have oil leak at the lifters.

.018 won't even get you 9.5:1 if using .039 or thicker head gaskets. The blueprint max is .054 positive, but that was with a .020 shim gasket IIRC.

They have to be positive with OEM heads. Most guys don't actually calculate CR and have way less than they think.
 
I expressed my opinion....that is all....

Cost of bushing lifter gallery????
 
yellow rose said:
Leave nothing out.
It should be decked, and the piston should come out of the block .040-.050 depending on head gasket, heads you are using and final compression ratio. Dude its a 400hp street engine
You MUST set the clearances and the mains MUST be line honed. If main housing is within spec and straight--doesn't need a line hone
If you are having the crank ground, have them grind it to the minimum to -.0005 so you can make the hole in the mains and rods as small as possible. Why does it need maximum bearing crush? again 400 HP street engine
If you are runnnind solid lifter, BUSH the passenger side oil gallery and plug off the driver side lifter feed. Not necessary
Make all the main oil feeds 9/32 to 5/16. Might not hurt although I've never gone over 9/32"
Do not restrict the oil to the rockers. Never have
Use full groove main bearings and if the shop won't use them, get a different shop. Getting some oil to the rods all the time is better than getting it there late. Sure why not?
Order a custom cam. Literally hundreds of catalog cams to get to 400 HP-Go custom if it floats your boat.
If using other than completely stock valve train, use the B3 racing engines geometry correction kit. Look up his web site to see how far off most people run their geometry. Won't hurt but not necessary with the sub .500" lift cam needed for 400 HP[/QUOTE]

J.Rob
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Since I can't quote like you do I'll just add this.

Never seen a square block yet. Don't matter what the HP is.

How do you set the clearance if you don't hit the mains. I've not seen many blocks that don't need a line hone.

You have to grind the crank and set clearances any way. Why not get max crush? Or you can grind it to the high side and Dick with bearings and open up the bores.

The cost of bushing the lifter bores is so small (I do it for $125.00 plus the tube) that it's STUPID not to do it. The oil timing on chryslers is jacked up, so why not help it out?

I've gone to 5/16 lots of times. Depends on the application but we are picking the fly poop out of the pepper over .028. Really?

Where I get cams they are the SAME price as most off the shelf cams. A custom cam will idle better, make more power and be better overall. We haven't learned this yet? Not everything needs to come from summit or jegs.

I don't run under .525 lift unless I absolutely have to, like stock rockers. And, if you ain't running stock rockers, you SHOULD be correcting geometry.

Sounds simple to me.
 
yellow rose said:
Since I can't quote like you do I'll just add this.

Never seen a square block yet. Don't matter what the HP is.

How do you set the clearance if you don't hit the mains. I've not seen many blocks that don't need a line hone.

You have to grind the crank and set clearances any way. Why not get max crush? Or you can grind it to the high side and Dick with bearings and open up the bores.

The cost of bushing the lifter bores is so small (I do it for $125.00 plus the tube) that it's STUPID not to do it. The oil timing on chryslers is jacked up, so why not help it out?

I've gone to 5/16 lots of times. Depends on the application but we are picking the fly poop out of the pepper over .028. Really?

Where I get cams they are the SAME price as most off the shelf cams. A custom cam will idle better, make more power and be better overall. We haven't learned this yet? Not everything needs to come from summit or jegs.

I don't run under .525 lift unless I absolutely have to, like stock rockers. And, if you ain't running stock rockers, you SHOULD be correcting geometry.

Sounds simple to me.
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This is pretty advanced advice to be giving a guy that is posting on a forum asking how to build his first performance engine. The factory got by with far less invested into these engines. Telling this guy to order a custom cam is not great advise. He is looking for a recipe for success.
 
younggun2.0 said:
This is pretty advanced advice to be giving a guy that is posting on a forum asking how to build his first performance engine. The factory got by with far less invested into these engines. Telling this guy to order a custom cam is not great advise. He is looking for a recipe for success.
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Ok. Call summit. It's like it's 1986 all over again.
 
Bore n hone , try for 4.060/.020 over, torque plate if available, if not don't sweat it.
Rods resized and either have the bolts stretch tested or better yet buy new ones, don't have to be arp, pioneer makes some cheaper builder bolts.
if the crank main/rods journals polish up, great, if not... just have the Mains ground .010 under and rods .020 under, since you say they are grooved and .010/std. Balance job a must, and try some hasting moly rings or perfect circle...kb243 pistons are great. If you can afford a square decking of block...go for it, if not...at lease have it cut .003 on each side.
Heads need a good 3 angle, guides, hard seats if regrinding stock valves to re use. When you pick a cam, the springs you need will follow.
Timing chain can be optional billet aluminum or you can simply run a 45 dollar chain and use bushings to dial the cam in...I'd buy a billet set.
 
yellow rose said:
Since I can't quote like you do I'll just add this. It's really easy-click the POST REPLY button.

Never seen a square block yet. Don't matter what the HP is. I took issue with the +.040-.050" piston above deck advice--terrible.

How do you set the clearance if you don't hit the mains. I've not seen many blocks that don't need a line hone. I've seen very few that NEEDED it. In fact I rub elbows with a BIG name engine builder and he stated once that if a factory block NEEDS a line hone it was probably junk--You know what? He's right--and I aint gonna tell you why.

You have to grind the crank and set clearances any way. Why not get max crush? Or you can grind it to the high side and Dick with bearings and open up the bores. You obviously don't know why or when bearing crush is important--A 400 HP street engine is not an example.

The cost of bushing the lifter bores is so small (I do it for $125.00 plus the tube) that it's STUPID not to do it. The oil timing on chryslers is jacked up, so why not help it out? I have plenty of these engines running around and have never tubed the lifter galley yet. I have done the cross over mod which is a waste of time IMO. None have had issue yet.

I've gone to 5/16 lots of times. Depends on the application but we are picking the fly poop out of the pepper over .028. Really? You're not looking at area increase--Pi r squared comes to mind here.

Where I get cams they are the SAME price as most off the shelf cams. A custom cam will idle better, make more power and be better overall. We haven't learned this yet? Have learned this LONG ago--its just NOT NECESSARY in this case. Not everything needs to come from summit or jegs.

I don't run under .525 lift unless I absolutely have to, like stock rockers. And, if you ain't running stock rockers, you SHOULD be correcting geometry. It is mind blowingly easy to make 400HP in this case with .450-.480" I also LOVE stock rockers--light, rigid, cheap and reliable when used correctly.

Sounds simple to me. It is , YOU'RE making it complicated[/QUOTE]

J.Rob
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I have an engine on the stand.

Piston is .045 OUT OF THE HOLE and it's still on 10.6:1 CR.

I bushed it myself.

Solid lifter cam with .540 lift.

Mains lined hone to set clearance.

Oil holes at 9/32

You're right, the oil crossover mod is junk. Lifter bore bushing is basic ****.

Custom cam $165.00 he could have gotten a summit cam for less but who cares? Better yet, he could have gotten a comp on a 110 LSA and run with the herd.

About 2 years ago I scrapped about 120 stock rockers. All were useable. I scrapped those Junkers. Had I known, I'd have sent them to you. I don't use junk like that. Next time I see some, I'll grab them and send them your way. Wish I had known.

And still, it's not complicated.
 
yellow rose said:
I have an engine on the stand.

Piston is .045 OUT OF THE HOLE and it's still on 10.6:1 CR.

I bushed it myself.

Solid lifter cam with .540 lift.

Mains lined hone to set clearance.

Oil holes at 9/32

You're right, the oil crossover mod is junk. Lifter bore bushing is basic ****.

Custom cam $165.00 he could have gotten a summit cam for less but who cares? Better yet, he could have gotten a comp on a 110 LSA and run with the herd.

About 2 years ago I scrapped about 120 stock rockers. All were useable. I scrapped those Junkers. Had I known, I'd have sent them to you. I don't use junk like that. Next time I see some, I'll grab them and send them your way. Wish I had known.

And still, it's not complicated.
Click to expand...

I hope your goal is more than 400HP
 
I'm with RAMM on most of his points although I use a 5/16 drill bit for the main feeds because that's what I could get quickly at the time years ago.
I own a good, certified sonic tester. I get paid to test others blocks, including some shops'. I would not sonic test a stad bore block going +.030 unless it was for a longer-than-stock stroke. It is not a necessity. There are times I do consider it but a 400hp 340 ain't one.
I do always line hone. That's so the CNC can have a confirmed straight centerline to index off of.
I always square deck - height TBD depending on the pistons and combinations but I can set deck height where I want that way, and know it's right for all of bores.
A good performance valve job on the factory heads will supprot the power level. I'd run a solid lifter because it will make the number and add some lower end grunt over a hydraulic. But that adds valvetrain cost due to the need for adjustability. If not, a hydraulic with the stamped steelies can certaintly make that power level. I've made 480 going off mph and weight using them and a hydraulic shelf grind cam.

I have no idea why redirecting oil or full grooved mains or "tight crush" would be needed here.
 
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