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350 2 bolt block question


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hey peeeeeps, im going to start the rebuild process on one of my blocks and i was wondering which if either the 72 350 2 bolt or the 77 350 2 bolt is a better choice. i noticed that the casting and machining on the 77 looked much better. if casting numbers are needed to figure this out ill get them. -pete

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Pete,

 

I dont have the casting book handy so I cant say if there is any real difference... If all you have is the short block it probabaly doesnt matter which you use because you will need to put new heads on it anyway...

If you have both year long blocks then go with the 72.... 77 wasnt a good year for decent HP at all..

 

Myron

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Guest butlersZ

Use the "010" block, there should be a "010" just below and to the left of where you insert the cam, this "010" tells you it's 10% nickel content which makes for a stronger block, plus it's older which means it's a "seasoned " block, chances are it's had more start-ups or heat cycles which will make the engine more resistant to cracks and withstand a little more HP.

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alright ill look for that, neither one is too easy to move right now because its surrounded by other crap, but i got a caliper and checked the bores. the 77 is 4.000 exactly at the top (cant check down any further for taper) and the other the 72 is 4.005 so it was just honed once. the pistons in the 72 measured 3.990 which means piston to wall clearance was .007 all the way around isnt that way too much ? this (the 72) is the recon rebuild i had in my car that only lasted about 1500 miles. before it started puking oil out

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If the 77 has no ring ridge, the main caps are tight (and in order), and none of the main bearings has spun... run it.

A real live no machining needed stock bore block... nice.

 

I think some of the 010 markings (like on the block you have, perhaps) are just the last 3 of the casting number, and not an indication of 1% added nickel.

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the 77 had sat for a while (didnt know when i bought it ) and theres sand in one of the bores and rust in another so it will need machining. :( i did come up with a design for my dash tho which is good news :) after two days getting practically nowhere with the dash design. i just woke up at 5 am with it fully layed out in my head. almost everything already figured out. so i had to get up to draw it out before i lost the details forever. it was like boom my eyes are open dash design done. i guess in spite of stabbing it with q-tips all the time my brain decided to help me out this time :D

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3970010....302.....69....4...Z-28 Camaro

 

haha dude that'd be sweet

 

It can also be:

 

3970010....327.....69....2...Trucks and industrial

3970010....350...69-80...2 or 4

 

other 350:

 

14010207...350...80-85...2 or 4

 

 

The 302, 327, and 350 all have a 4" bore

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A 69 DZ block is small journal, should be easily distinguished from a 350 lg Jrnl. The DZ will have DZ stamped in the front boss, passenger side along with some of the vin #'s, ie. DZxxxxxxxx. 350 two bolts with studs are good to 400HP reliably.

 

could be a 327 large journal, which is the same as a 350 large journal except they came with a steel crank in the pick up trucks.

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The bitterness of poor quality lingers long after the sweetness of a low price!

 

I've been building race engines, trans and automotive rear ends for 27 years, sprint, late model, imca, blown alky, big blocks, small blocks, ford's, pontiac's, oldsmobiles, diesel's, etc, etc. back when aftermarket was a pipe dream and stock pieces were all we had and a turbo diesel was big time by Banks.

 

My recommendations for budget, go to a quality performance machine shop first, if the floor is so clean you can sit down and eat, then your in the right place, if not, well keep looking. Turn the cast crank on the high side, any quality machine shop will know what that means. Go with Hyper's, bushed rods aren't going to make it faster, just easier to change pistons so don't waste your money, go stock HP "x" rods, or whatever you have, resized on the small end of tolerance (maximum crush) with ARP fasteners, balance the rotating assembly. Check the block align hone on the mains, fix if necessary, debur block, don't get carried away polishing anything. Ask and watch if the machine shop heats the rods till they discolor to install press fit pins, if they do then the rods are now junk and again, you are in the wrong machine shop. Heat rods till they smoke, not discolor and be quick about fitting the pin. Make sure the pistons move freely after getting them back or you will have pin problems for sure. Bore the block with deck plates if you can afford it, finish hone with 500 grit, don't budge on that or your rings will be worn out before you get started, put some nice heads, camel humps, 882's, vortec's, dart's, world's, AFR, Edelbrock whatever you can afford, and add a mild hydraulic flat tappet, install high pressure spring in stock pump to get it up to 45-50lbs hot. Cheap double roller chains and the stock chain with steel gears is a toss up, both suck. When getting the heads done, ask what the guide clearance is or will be, don't want it too tight or too loose, again make sure they do a three angle valve job, check it for runout, and vacuum test after assembly. Go with new springs and hardedned keepers. And that is about as low buck as it gets and you won't be sorry.

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most of that is similar or identical to what ive read so far in david vizards books. the reason why i want to go inexpensive is because its my first build. to me inexpensive is 1500 complete for a healthy motor with mostly new parts. ive already sourced two very good machine shops. a good friend of mine just started working at the closest one and everything you mentioned is stuff he has told me to make sure i do and only until i started researching heavily did i actually understand what he meant he also just finished assembling his first motor a 351 just last month. i like bushed rods because most of the porsche motors ive dissasembled in the past had them and its alot easier. the extra cost for this conveniance doesnt bother me one bit.

 

also, i thought 882s werent a good head?

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882's are the highest flowing stock low compression (76cc) head chevrolet made. I think HotRod did a series on these back in the 80's, I probably have it somewhere in my magazine archives. In 1980 I had a 1973 Chevy Long bed half ton P/U with a 350, 882's ported, Crower solid cam with 248@.050 and .510 lift, Speed Pro 12.5:1's, stock rods and crank, netting about 10.6 SCR. At 4500lbs race weight, it went 13.55@100mph.

 

Camel heads are better, Vortec's are better yet, aftermarket is better yet and AFR's are top of the heap. Still, you can get 400HP out of 882's it just takes more cam to do the same job, that is why your best investment is in heads. Personally, I like strong bottom ends and great heads, but back then I couldn't afford anything and now it isn't a problem.

 

Stick to the budget and plan, and it'll work fine. Don't do like I did... When I was 13 I built my first sbc, I put silicone all over the head gaskets so they'd seal, still ran, put 80K on it before selling it used to a buddy. He and some friends laughed their ass off when they pulled the heads to check for ring wear before they used it and saw silicone everywhere. Oh well, live and learn my friend.

 

David

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no way, so i actually got lucky with something car related finally :) the heads i have have less than 2000 miles on them what do u think about just putting some new valve seals in them ? and does hot tanking ruin valve guides ? im only 22 im not working so that i can concentrate on my car (gotta love my parents for putting up with that) my father doesnt know anything about cars, everything so far is self taught except for workin a lathe and a mill. i bent a valve in my motor when i had it running being and idiot and doing a burnout. overreved the crap out of it. hehehe and i pulled the head replaced and lapped the valve properly set the valve lash this time (way too tight on that one because i had to replace a rocker and didnt know what i was doing) after i put it together it ran great except for the plugs getting oil fouled and the motor eating up a bunch of oil when i put synthetic in it (another mistake i guess) one last question, do you put rtv or something on your head bolts to keep coolant from leaking past the threads or no ?

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