Build My 350

Discussion in 'Small Block Tech' started by Seven6Regal, Jul 17, 2018.

  1. Seven6Regal

    Seven6Regal Well-Known Member

    It's time to rebuild my 350 to get my power, speed and burn rubber. The 76 350 is low in compression, and I have an opportunity to purchase a 71 350 2bl. I plan to rebuild it with better pistons, cam and minor head work.

    I'm wondering if I can achieve 300+ hp with the 76 or the 71. The article below is a very good write up on reaching my goal. My overall goal for the car is to autocross the car and highway driving for trips around the country.

    It's not turning the 255/55R18 hard enough to hear a screech on dry pavement. Handling is excellent with new bushings just about everywhere.

    Before I dump un-budgeted thousands of dollars in the engine, how can I achieve my goal on a dime? Either way, I'm going to rebuild the current 76 350 if I do not purchase the other.


    Great article: https://www.hotrod.com/articles/gs350-buick-455s-little-brother-deserves-due/
     
  2. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    #1 don’t spend much to buy the 71 engine... sure the heads are better but that’s all really.

    #2 head porting and oversized valves and even better if you can wait for the alum heads.

    #3 use good rods and pistons, TA sells molnar rods. Auto tech sells custom pistons for low cost.

    #4 have the block checked by the machine shop before any parts are ordered

    #5 it’s all in the combo, of you want streetability look into a Scotty brown custom cam, shoot for 10:1 static comprsssion

    No matter what you do if you do not do extensive head porting or alum heads then the Hp will not be there... and if you slump out on the rods and pistons then may as well just use a TA 212 cam and keep it a low rpm engine
     
    Seven6Regal and 300sbb_overkill like this.
  3. 70skylark350

    70skylark350 Well-Known Member

    I purchased a low mileage 72 350 to rebuild for $200.00.
    custom pistons are going to set you back between $800.00 and $1,200.00
    the machine work is going to be $3,000.00 to $4,000.00 at a good shop.
    This is where I am at anyway. I figure I'm going to have between $5,000.00-$6,000.00 in my 350.

    Just something to think about, looking back I think I may have just gone with a big block had I realized the cost to try and get any performance out of the little brother........ I know, I know, I can hear about 10 board members saying "we tried to tell you that ass hole" haha.
     
    Seven6Regal likes this.
  4. alec296

    alec296 i need another buick

    Getting around 300 isn’t too hard.. But it seems you want low end torque. You need to get a 3.08/3.23 rear end gear for Torque multiplication. If you get the 71 engine ,the 71 heads with light bowl porting and competition valve job , higher compression Pistons, a cam more for lowerend torque (Scott Brown or crower level 2 or 3) new valve springs and a 2200 small block rated torque converter should do well . The 71 block can benefit from oil modifications. The 76 the factory already improved. Using a 76 oil pickup tube will improve oiling on the 71. A Quadrajet Power built carb. Distributer recurve kit dialed in per power timing thread on this site.
    You can use the 340p piston (9.2 compression)or the flat top s1734 from silvolite (9.65) for budget build but both sit lower in cylinder . Custom forged Pistons are the better choice but much more expensive. But for a 300 hp engine, you will be ok as long as rpm isn’t to high. Look more at making torque.
     
    Seven6Regal likes this.
  5. 300-320 HP is affordable and easily doable, but boring. 320-350 is doable, but involves some head work. 350HP + is more expensive and involves custom cam and head work/ porting. However, prepping your short block for the potential of higher horsepower is essentially the same cost when talking about a rebuild. So I cannot stress enough. DO NOT USE STOCK RODS AND CAST PISTONS. You will just be setting yourself up for limited power potential. An extra $1000 spent on rotating assembly could mean the ability to make much more power down the road
     
    Last edited: Jul 18, 2018
  6. Seven6Regal

    Seven6Regal Well-Known Member

    Thanks for the information. I have to pore over it more to piece together the best combination. $2000 is where I intend to max out on the engine purchase and rebuild without skimping on quality. I know heads would kill that budget with no room for break-in oil. Hahaha! Turning the tires, fun runs at the auto cross and tripping is about the extent of my desires with the car. Over the winter is when I'll have the engine done until then I'm going to enjoy the summer in it and start my other project...at least mock up the engine install...1981 Malibu LS2 swap.

    The car is fun to drive now, I just want a little more out of it. Hopefully, the '71 will give me a good starting point with the '76 pick up. I'll work with my local machine shops to get started once I get the car stored away for the winter.

    Thanks again for the help!
     
  7. MrSony

    MrSony Well-Known Member

    my 7.8:1 plain jane .030 comp 268 with a good valve job, all iron, did great burnouts and sounded good. Spent about 3k. bet it was very near 300hp and 400ftlbs, maybe 260-270hp and 340-360ftlbs, at least according to desktop dyno. did awesome burnouts. Bump compression upto 9.5-10:1, use a crower level 3 (4* retarded ive heard makes this cam perform better that installed straight up) and headers. to be honest 500 bucks aint worth 30ish hp unless you have the cash for the headers or can find em cheap.
     
  8. 36racin

    36racin Platinum Level Contributor

    Currently in rebuild status with my 350. I'm at 4k. No way you can do it for 2K unless you own a machine shop and can do all the work. Parts alone will put you in the 2k range. Unless you use cheap parts. There is a(supposedly) rebuilt 350 short block in the Houston Face Book Market place ads.
     
  9. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    That's for a car with better gearing than a 2.41:1 rear gear ratio, like at least a 3.73:1 for more upper RPM power because the bigger gear takes care of the low end.

    With your gearing you should of installed it at least straight up or better yet advanced it 4* for better low end.
     
    MrSony likes this.
  10. Seven6Regal

    Seven6Regal Well-Known Member

    The 76 could benefit from 71 heads or, 76 pistons would hurt the swap?
     
  11. alec296

    alec296 i need another buick

    You can use the 71 heads on a 76 block. But can’t use 76 heads on a 71 block. Coolant port change. It will not change compression any and you won’t see much gain just by using the 71 heads on a 76 engine. So no, There won’t be any benefit by just bolting 71 heads on the 76. They are a better base to modify /port/big valves. Pistons in the 76 sit .030 lower in cylinder then the 71. The 76, has about 7.7 compression. The 71 has about 8.2 compression. That’s in the piston.
     
  12. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Actually he can get the AutoTec customizable piston, wristpin and ring kit for right around $699. You're right on your full on custom pistons, PLUS the wristpins and rings are sold separately!

    Block machining should be around $1,000 plus or minus a few hundred depending on your local machine shop pricing. Balancing without any heavy metal is around $200. So machining costs should only be around $1,000 to $2,000 at the most for the full monty of block machining and balancing. Assembly is around $500 to $1,000 that can be a substantial savings to buy better parts if you do your own assembly if that's something you think you can tackle?(not that hard to do, after you do your first one you'll think, that wasn't so bad and then think, yeah I wouldn't mind getting paid $1,000 to do this!:cool:)

    Anyway, with only a $2,000 budget you barely have the funds for the machining so might as well try to get a good used set of factory high compression pistons that are still on the rods and do a ball hone garage refresh/re-build. You can have the machine shop clean, magna flux(check for cracks), cam bearings and freeze plugs, polish crank and maybe mill deck to take off some of the excess deck height? And then have them do a basic valve job to the heads, hopefully they won't need any parts or you may run out of $ before you buy gaskets.

    With that limited of a budget, probably have the heads done first so you know what kind of $ you have left to work with. If the heads need extra work or parts a basic $200 valve job can go to $600 or more fast if the valves need to be replaced, guides need to be replaced and if the heads need seat work because they're hammered. If the seats are shot odds are the valves are too, might as well upgrade to the bigger valves at this point...............$$$

    So after the heads are done and you know how much you have left in your budget, you can go from there. Figure around $200 for a quality complete engine gasket set and you'll know how much you'll have left for block machining minus what the used pistons cost.(it goes quick!)

    Don't forget parts like cam, lifters, timing set and possibly pushrods if you had the deck and or the heads milled and rocker parts that may need to be replaced. To reach your 300 HP goal a custom cam would be a good investment, only about $20 more than an off the shelf cam so this won't break the bank.

    Now 300 HP at the crank won't be so hard to do BUT if you are wanting 300 HP @ the wheels, that's a different story that will take more $$ and or work to reach. :eek: 300 HP @ the wheels would be around 350 to 375 @ the crank! If you double your budget you'll make it easier on yourself to reach your goals and end up with a much better engine. Just take an extra year to spread out the costs. 12 months / 2,000 = just under $167 a month to put away for a better build.

    The earlier heads won't make a difference bolted to the 76 block. Factory unported head flow is roughly the same for both year heads and so is the chamber size so you won't even get a compression bump without having them milled. The '71 heads supposedly have more flow potential if they are ported, that's it.

    So yeah, the '76 low compression pistons are what makes the '76 sbb 350 a turd.
     
    UPSTAGED1970 and Seven6Regal like this.
  13. alec296

    alec296 i need another buick

    If the 71 ran good, and your budget is 2 g, get a gasket kit, drill out oil pickup passage, get a new 76 pickup.(it’s like 14 bucks at autozone). Get the crower cam , lifters and valve springs. And a timing set with advance key ways. Advance cam 4 degrees when installing. Degree cam if possible.Get a TA performance backgrooved front cam bearing. Spend the money on on getting heads done with bigger valves. Bowl porting. Competition valve job. Get flow about 235-245. And shave heads .060. Get TA performance.050 shorter pushrods. That would net close to 9 to 1 on the 71 pistons. Probably net about 250 hp/325 torque with right tune. Meaning a distributer recurve kit, and a Quadrajet Power rebuilt carb or Everyday Performance built carb. That would probably be most of the money but go over and get a 25-2700 small block rated torque converter. Then save up for a rear gear , 3.23 or 3.42 would go well. Matt Dennison has basically proved this combo in his 68 skylark running almost 14 flat without headers.
     
  14. Seven6Regal

    Seven6Regal Well-Known Member

    My list:

    eBay Rebuild kit includes pistons, timing chain, rings, bearings and gaskets $400 https://www.ebay.com/itm/1968-1981-...8-16V-PREMIUM-ENGINE-REBUILD-KIT/142227939281
    71 350 - $250
    Boring $20 per cylinder ($160)
    Block cleaning: $50
    Cam: TBD
    Carb: $332
    Home assembly: Time

    The car has Hooker Super Comp headers and full dual exhaust w/o cat. I have a Poston S divider with 1 inch spacer to install on new engine. This link has the type of build I would like to have but the budget says otherwise. https://www.hotrod.com/articles/gs350-buick-455s-little-brother-deserves-due/
     
  15. alec296

    alec296 i need another buick

    you can do better then that build with less.
    Focus on head flow/ porting/ big valve. Notice Mike Phillips did the heads for them. Am&p machine. Heads flowing about 235-240. Big 1.94 valve. Mikes 350 build is ussually about 350-360 hp with performance intake and headers.People on here have made 320 flywheel hp with stock intake and exhaust manifolds. So that hot rod build is not impressive. And with 38 degrees of advance timing, something’s not right
     
  16. MrSony

    MrSony Well-Known Member

    That's what I did. Straight up, to air on the safe side. no money or time at the time to degree. Runs good now. Lots o grunt. In my SP engine that is. My '76 7.8:1 had a 268 comp, straight up.
     
  17. Mart

    Mart '71 350 GS, almost stock

    Holy crap batman.....what a post...:D:D:D
     
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  18. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Hilarious, I have Batman on right now when I read your post!:D:D:rolleyes::D
     

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