Good evening!

I found a moderately cheap 4-bolt '87+ block on craigslist ($250).

My block is still good, it's just a two bolt. The four bolt block would be cheaper than buying splayed caps and having the work done, but is a stock four-bolt strong enough?

The goals are:
Mostly Street.
400-450hp NA range (>350rwhp goal).
I'll spin it up to 6500 rpm max at the track.
Compression in the low 10s/high 9s (still researching the rotating assembly)
Nitrous 150-200 shot (as an option, not a crutch).

I plan on an all-forged rotating assembly, unless someone doesn't think a forged crank is necessary.

 

Two bolt block is fine for what you want to do. Four bolt is over rated for what they are.

$250 is a lot for a bare block. Especially a regular 350. Usually you can find them under 100.

 

Okay great, thanks!

 

I think that's a decent price for a 4 bolt main 87+ block.

My .02 cents is that if you're going to go through the money and time to have all the good internals, etc etc why not drop 250 more and have a better block to put it all in?

 

I use two bolt blocks up to 500 HP. My personal motor is two bolt. 470HP at the crank.

 

I would find a good machine shop to convert to splayed caps and align bore the block back to specification. 4 bolt mains are not overated, especially the splayed caps. They help prevent the cap from walking around and allowing your main bearings to spin.

 

I'm with Fast here...splay a two bolt, 450 + 200 is asking a lot from a factory 2 bolt block....assuming you already have a 2 bolt block now, put the cost of a 4 bolt factory block towards getting yours splayed and new caps.

 

The splayed caps that mildon offer are much stronger than factory 4-bolt main caps. Steel vs ductile iron. 650 from ANY factory block is alot of HP.

 

I was actually pricing out the mildons the other day. Alright, I'm sold. Splayed caps on my current 2 bolt.

Thanks!

 

I guess I should have said factory 4 bolt blocks are overrated. A properly converted 2 bolt block is better than that. Start adding splayed caps in and it's not apples:apples anymore.

I still stand by the price comment though. They made hundreds of thousands of them...not too difficult to find.

But....by the time you add up machine work; tank, bore, hone, deck, caps, align bore. You're into aftermarket block price range.

 

They didn't make that many 4 bolt main 87+ one piece rear main seal, roller cam blocks. I strongly agree though that machining a 2 bolt factory block for 4 bolt splayed caps is head and shoulders above a factory four bolt block. That's an old trick to build a stronger crankcase and save the cost of an aftermarket block. I'm running 420hp on a two bolt one piece, roller cam block and hit 7,000rpm regularly. No problem so far after 35,000 miles.

Of course now with the Dart SHP blocks going for about $1,700, the entry level aftermarket block isn't that steep anymore. My next build, a 406, will start with a Dart block. The cost is nominal when considering the added strength and durability of the high nickel casting. I mean, it's a few more months of saving pennies, not even 75 cases of beer. The factory blocks are engineered to be cost effective and meet the needs of the intended stock application. The Dart blocks are engineered for high horsepower street and race applications. That pretty much says it.

 

Almost every 87+ roller cam 350 I have come across is 4-bolt main. Maybe I just have good luck. The late model F-car LT1 I was given was a factory 4-bolt as well.

The practical limit for a 2-bolt main 350 block is about 450 HP and 6,500 rpm.

 

The 93-97 F-bodies got 2 bolt main blocks. The Corvettes got 4 bolt mains.

 

That myth has been debunked many times. Some Caprices and Special service cars (Cadillac Limos and Armored Fleetwood) also got 4-bolt main blocks. I have seen factory Vettes with 2-bolt mains.

Not the one I got out of a 95 Z28. 4-bolt main and still had the partial VIN matching the car. My 97 1500 Express was supposed to be a 2-bolt too, but it was 4- boltand had the block machined for a mechanical pump and had a factory block off plate on the block.

 

Or this
http://www.summitracing.com/int/part...0-30/overview/

Already clearanced for a 383.
1 piece rear main seal
4 bolt block
Roller block


Machine work ain't cheap.

By the time you a shop to splay, hone and bore it, you'll be better off buying this.

 

Actually I disagree. At 650 hp and the stress of nitrous, I would want the splayed caps for extra strength.

 

For your power levels I think a studded 2 bolt main block is fine. I have been using a 1971 350 2 bolt block for the last 10 years in my camaro.

1st build went best of 11.40@118, 1.60's 60' times. Shifting at 6400 rpm. Was using hyper pistons in that engine and after 6 years of daily driving street use and weekend track use I broke a ring land on a piston.

Rebuilt the same block with more compression, head and cam. No track time yet (life got in the way) but alot of street miles and playing on it. Shifting at 6800-7000 rpm Should be a 10 second car.

No prob with the block/2 bolt main.

I'm using ARP main studs, windage screen, rear main oil baffle, 7 qt pan, scat crank and rods, now wisco pistons, brodix IK200 heads, ARP head bolts, 249/252@.050" solid cam with .570/.579" lift. Th-400, 3500 stall 9.5" converter, ford 9" 3.89 gear with locker, 275/60-15 nitto 555R tires.

 

I don't see nitrous in your setup...Big difference!

 

OEM SBC blocks were simply not engineered to handle 650 HP.

Despite what jimbob and joebob say, it's a bad idea long term.,

even with along fill, short fill splayed caps.


An aftermarket block and forged rotating assembly is the best choice for long term durability in a performance application.

Even an entry level DART SHP is a much better starting point, and is not a lot of money compared to a do over.

Plus it is brand new.. not a questionable core with stripped out treads and messed up bores that you can't tell by looking at but will show up when the block is refreshed which is too late when you realize that sweet deal is junk.

 

Street use and track time are not the same.
let me guess you broke the ring land at the track?!

 

I agree Stock blocks even ones that pass a sonic test with splayed center caps front billet cap and a strap on the rear main cap I only rate a 600 horse.



Even studs don't make a 2 bolt block any stronger its still a grey cast cap with better hardware, Over the years I have collected a 5 gallon bucket of broken 2 bolt caps and ones that look like they have been welded on because of cap movement and ever some broke 4 bolt caps.



Good link to look over
http://www.ls1tech.com/forums/advanc...ever-seen.html

To the OP That one piece rear seal block will accept a older 2 piece rear seal crank with the Proper seal adaptor. Before you spend any money I would have it sonic tested to make sure you have a good piece to start with and don't go by core shift. Up grade the main caps fasteners to ARP hardware line hone, deck bore and plate for the best results.

That Summit block is not decked, has not bee plate honed, No telling where the decks are.

This block is probably a better block as you can deck it, Line hone if installing better hardware, Bore and plate hone and stroker clearance if needed. http://www.summitracing.com/parts/nal-10105123

Machined one for a 383 boat build last week turned out to be a very nice piece for the money.

Good luck which ever way you go.

 

No, no nitrous yet but I do plan on a NX 50-300 HP plate setup once I get back to where I have the money to go to track more. Buying a house and moving kinda got in the way of the toys/hobby lol

Now if you want to talk power adders. We built a junkyard twin turbo system for my dad's 327 in his '82 firebird. Twin T3's, 8-10 psi boost, studded 2 bolt block.
Lasted 3 years before it let go and that was due to detonation that beat up a piston and cracked the cyl wall. Still didn't have a prob with the main caps/bolts or lack of the extra 2 bolts per cap.

 

That is very true. That's why I wanted to chime in as I feel mine is a good combo of both street and track use. I avg. about 6K miles per year on it (would be a higher amount but car sit for about a year with a broke rear end as I was saving up for the 9") and rough guess of about 75 passes per year.

So 9 driveable years, roughly 54,000 miles and 675 track passes.

Nope the ring land broke leaving wal mart. I'm sure I damaged/cracked it long before but when it did give way was when I was pulling out of a wal mart parking lot. I jumped on the throttle some as I was pulling out into road. Car made a bucking motioned, with a little knocking/rattling, then big puff of smoke out the exhaust and engine died.

I didn't try to re start, just coasted onto the shoulder and called a buddy to bring his car trailer. Got it back home and took apart. #4 cyl, left side of piston was missing top ring land and a part of the very top of piston next to valve relief.

Damaged the valve, head chamber marked up some, and of course the piston. No real damage to cyl. wall.

I kinda knew that was gonna happen in the long run anyway, running hyper pistons and 218 psi cylinder pressure/ cranking pressure

 

218psi cranking compression? With that cam, even with 10.34:1 CR, that sounds a little high. Have you verified that with a gauge?

Myself, I try to build any motor to last over time. Therefore, maybe I go further than I need to ensure longevity. For me, it's just too scary to run excessive power levels from an engine build. I want to know that the foundation can support the load placed on it. It used to be the cheapest option to the questionable factory blocks was the Chevy Bowtie block that back then went for $2,500. Now with the Dart SHP going for way under 2K, it's an easy way to go to get real peace of mind. I have seen the SHP blocks offered with billet caps too, though I can just as easily have my machinist set one up that way.

Machine work isn't cheap but it's alot cheaper than most people think and worth so much more than it costs. As far as "ready to build" packaged blocks go, I want to know who machined a block. Just as important, I want to know that all the parts going in have been clearanced together for perfect fit. Or, perfect within .0001" anyway.

EDIT: I do absolutely agree that studs are the way to build any high revving motor. ARP head and main studs for sure.

 

Hard to compare apples to apples when you talking a 3.250 stroke and caps that have more meat do to the smaller housing bore.

 

You are correct.

The 218 psi was on this block but an earlier build. The new build has the 249/252@.050", 106 lsa cam and it's cranking pressure is 198 psi

The 218 psi combo was with a 218/230@.050" cam, 62cc heads, 5cc flat top 4 vr pistons, fel pro 1094 gaskets. IIRC the compression was around 10.64:1

 

Unsure why you quoted me here, the original question was answered properly .
Sure, an after market block is always a better alternative, but not always needed...the OP is building a 450 HP NA engine that will see some Nitrous...he's not building a 650 HP NA engine then adding on.

His motor will last plenty...can't imagine someone building a 450 HP motor, and turning it into a DD, and we're not talking about the last 20 years of technology, we're talking about a 3rd gen here.

A factory block will manage 450 HP for longer than you need, the splayed caps (if done correctly) and properly built, will probably save the OP a grand over an after market block.

I often wonder why every one has to have "the best" to have fun?

So his build only last 75K (underestimating) instead of 150K...probably take him 15 years to get it better the next time.

 

198 psi with that duration and 106 lsa is incredible. Not having the cam card in front of me, I can only guess the intake closing to be around 70 to 80 degrees ABDC. I would generally expect to see more like 150-160 psi with that lobe in the 10.5 range and excellent ring seal. My 355 cranks at 140 with less lobe(240@.050) at 10.2, with 112 lsa. It also runs low tension rings with vacuum pump and is due for an overhaul soon.

I plan on a 406 for my next build to provide more overall torque for the street but hearing once more about a 10 second 355 makes me think about just going a little further with my 355. Better internals this time and a higher flowing intake. I would only do it with 4 bolt splayed caps. I'm seeing my machinist on Monday. Think we'll crunch some numbers.

 

If overall street torque is what your after then your 406 build would be a better option. My 355 is a high RPM engine. I'm running a 3500 stall and 3.89 gears, shift at 6800-7000 rpm.

Street manners sucks on this one really. 4-6" HG vac at idle, power brakes don't work. I swapped to manual brakes. Get's 7 mpg on pump 93

 

I'm used to high rev motors. We used to put togther little 355s and 358s for the circle track that would wind to the moon. That's always been my preference. I like a 500HP small cube motor. The limiting factor in this build was my long time idea to build a high test TPI. Ever since it came out, I wanted to see what I could do with it. The TPI, unless you cut it up to shorten runner length and increase flow, does not favor high revs. Still, I feel like I did pretty well. I built a basically stock cube(+5) full runner TPI that makes good power to 6,000 and walks all over most of the LS motors on the road today. As you know, it's all in the heads, cam, and getting as much squeeze at the piston tops as I felt I could get away with. I went with the ZZX cam (240/240 at .050, .560/.560 112 lsa) and Trick flow twisted wedge heads, ported to 195cc.

I do wish I would have convinced my machinist to cut the decks down just a little more. Archie(Somers) is like the SBC god. He was worried about CR getting too high for pump gas. We ended up with .010 deck height and running .039 Felpro permatorque gaskets I have .049 quench. CR is right at 10.2:1 Would have liked to be closer to .040 quench and pushed CR to 10.4. I think I could push it just a little harder with the quench at .040. I'll try it on the next one.

It's been 15 years since I built this motor and I'm ready for more power. Been ready for a while. No limits on the next one. I may start out with the TPI just for a minute to see how it runs but I plan on a custom EFI intake based on the Edelbrock 7110 tunnel ram. I'm curious to see how much I can squeeze out of these twisted wedge heads.

I never cared much for strokers and feel like high rev power is just as useful at getting the job done as low end grunt. It's just a matter of gearing, stall speed, and getting the motor into its power band. For a long time, after building this 355, I though about a 377, which is also a high rev motor with just a little more potential than the 355 due to the larger bore. I finally decided though just to go for the added cubes of the 406. I can still make the power, up to about 7,000, and maintain a little more torque down low. I'll use lightweight components in the rotating assembly to offset the added weight of longer stroke. I know that piston velocity becomes an issue at high revs as stroke increases, but 7,000 isn't too high for a 3.75 stroke. I still have second thoughts too. I'll sit down and talk it over with Archie and make the final decision when I'm ready to move on it.

 

Cool deal sounds like you have a killer setup there. I never really played with the TPI myself. Seems like too much effort put in for the limited results but it looks like you worked through that.

I'm with you, I love the high rev'ing small blocks. I cut my teeth on short stroke engines like the 283, 302, 327 but for street use that added torque of a little longer stroke sure makes daily drives better. Like you said you got to gear and stall them to match the engine's power band. It sucks on a street or street/strip car with an engine making great #'s in the 4500-7500 rpm range and having to run deep gears to keep you in said range.

The 350 is a good example of low end and top end power though. I think a long rod 377 de-stroker would be the best of both worlds though.

With my car I guess you could say I pulled a doctor jekyll and mister hide. The goal at start of build was a mild high 12 sec/low 13 sec daily driver. Changed things around a bit, ended up with a very high compression, milded cam/head engine that pulled much better times than I could have hoped for. Great driver, got 16 mpg with a 3 speed auto, etc. Cracked the one piston and the "might as well" effect took over. Went from the mild mannered car to the almost can't drive it on the street, 7 mpg pass everything on the roads but the gas stations. I got the power out of it that I wanted but not the driveability.

 

Lol. I know exactly what you mean. Like Tim Allen said. "Just needs more power". I started this TPI build looking for just a little boost in power, maybe 325HP or so, and ended up with what I have. Once I started looking at head choices, it just spiraled from there. The limiting factor was that I stayed with TPI. I think that with these heads and cam, this motor could run alot faster with a better intake choice. I just had to try the TPI build to see what it would do. Definitely have more torque with this setup but I really do want more top end horsepower. I already said goodbye to fuel efficiency. I could probably do better if I drove it differently. The way I have the trans set up, I have to run the revs up between shifts. That doesn't help.

The 377 allows the use of 6.125 rods. I like to try to stuff as much rod into the equation as possible to help keep TDC piston velocity down at the higher revs. I don't know what I'll do yet. I've been thinking about the 406 for the last 6 months now, giving into the old adage "no replacement for displacement". Before that, ever since I finished the 355, I've wanted to build a 377. Everyone building stroker motors made me just want to build a destroked screamer even more. At least the 400 was designed as a 400 and isn't just another stroker. I always do things my own way, regardless of what is popular. We'll see what I decide on when the time comes.

 

Picking up a long block with 40k a 69 block with some smogger heads from jegs for 50 bucks Friday