'71 Skylark

Discussion in 'Members Rides' started by Skippy597, Apr 12, 2017.

  1. 300sbb_overkill

    300sbb_overkill Well-Known Member

    He is talking about hitting his goals with a sbb and being streetable, where is the challenge in making power with a big block? That is where you were going isn't it?



    Derek
     
  2. hugger

    hugger Well-Known Member

    Nah he was wanting to boost it I thought, no need for all that stuff for 500hp with 8lbs blowing thru it

    I'm getting a Skyhawk given to me and I fully intend to do a max effort NA 350 in it. I for the life of me can't understand how no one has ran 10's yet with a 350 in a 3200lb chassis. Im curious as to what one will/can do myself

    After driving a customer 72GS350 the other day after doing the rear main and feeling how strong the little car ran I'm intrigued again
     
    Last edited: May 16, 2017
    Dano likes this.
  3. 300sbb_overkill

    300sbb_overkill Well-Known Member

    If you want to boost then boost. I would do the upgrade and spend the extra $400 out of the gate with the pistons though if I were gonna do it that way just in case after I got use to the 6 psi power level I could crank er up more! Speed is addicting, and knowing that will enable you to build a solid foundation that would act well with upgrades if you so choose to. With a boosted engine you could always upgrade to the aluminum heads in a few years as well if your wife is still letting you play with the car?

    Plus with the upgraded pistons you can run the higher compression ratio that would be better out of the hole without boost, until you can afford to get the turbo kit, or a super charger like the one in this thread;

    http://www.v8buick.com/index.php?threads/the-dyno-numbers-are-in.200499/

    But with 370 cubes with 11:1 compression with a nice roller cam that matches the flow characteristics of the new heads you should be able to make your goals with no problem and perhaps even beyond with porting. And if in you wanted to run even faster there is always the assistance of a 150 HP shot of nitrous if you choose the AutoTec pistons, or a multi-stage 500 shot if in you upgrade to the custom 2618 alloy pistons!

    I built a sbc 383 for a friend that he regularly spins to 7,000 RPM at the Silver Lake Sand Dunes, its has around 580 HP with a solid roller cam and unported Dart 220 aluminum heads and 11:1 compression with a high rise aluminum intake and 1 3/4" tube headers. So with a sbb 370 built similar to that one should yield similar results that would be slightly lower because of the 13 less cubes as long as the air flow is there in and out. He does drive it on the street as well too.

    If you want to try to duplicate the above mentioned build but as a sbb 370, I believe the unported Dart heads flow peak at around .600" lift with a max CFM of 260 or 270 IIRC. Nothing spectacular there, sbb 350 factory head flow has been ported to more than that amount before. If the new heads are any good when they come out, they should flow at least that much out of the box but I'm hoping for more.

    Make sure you upgrade the suspension and brakes when you install more power, and be ready for parts like transmissions and rear ends to break with the addition of more power. The guy with the above mentioned sbc engine broke 3 Ford factory 31 spine 9" rear ends, 3 powerglide transmissions, and 3 "built" TH350 transmissions so factor in upgrading things behind the engine!!

    Many different streets to get you to your destination, you just need to choose the path you want to take and I would be happy to help whichever way you choose. GL


    Derek
     
  4. 300sbb_overkill

    300sbb_overkill Well-Known Member

    I see, yeah with boost it would be easy to make his goals even with less than 8 psi, the thread I posted a link to is a sbb 370 stroker that makes 422 low compression HP N/A and 630 HP with 6 psi of super charger boost!! That was with a Scott brown flat tappet custom cam! So yeah, if he went that way he could make his goals without the expensive fun parts like roller cams and aluminum heads.

    I like the fun parts but I like to post that link to show they aren't needed so much with boost.


    Derek
     
  5. Skippy597

    Skippy597 Well-Known Member

    Ok so I am gonna take your advice and go for the 2618 pistons and essentially overbuild the engine with the plan to eventually run at least low boost. I'll build then engine and run it NA til funds will allow me to do a turbo kit. I still plan on going roller for the cam and having Scott grind it for boosted use, as I am huge fan of roller setups and really enjoy the fun stuff like that.

    Where can I get a set of 2618 pistons for the Buick, I'm assuming they are customs but who do you recommend. Also what compression ratio do you think I should shoot for?

    As far as heads, I have never ported anything myself but I am willing to try as I enjoy learning new things and then have my machinist install larger valves and assembly. With that being said do you have any input as to how well the TA iron heads flow? Are they ported or just stock cast with bigger valves?

    So I'm probably still a year off before I start building my "dream engine" but since it's all I can thing about I really want to have it well thought out before I even start. Plus this way I can weigh out the pros and cons of different schools of thought on how to build it.

    Yeah the rest of the car is my biggest fear about making big power. I've got a pretty good idea of what I want to do to my suspension but as far as transmission and axle, that is where my fear lies since I don't have an endless budget. I think I am gonna go with a th400, and I was thinking about trying out the jegs th400 with BOP bolt pattern. Because even if or when I break it it's not too much invested. For the rear end for now I am planning a posi, 3.43s and 30spline shafts and doing the work myself. Obviously I would love a gear star trans and a Moser 12 but at least for the near future I do not see that happening.

    Really appreciate all the help Derek, you've been awesome!
     
  6. Skippy597

    Skippy597 Well-Known Member

    Hey so I just did a compression test to see if it would be worth it to shove a cam in for the time being and here are the results
    1) 120 lbs
    2) 120 lbs
    3) 120 lbs
    4) 115 lbs
    5) 125 lbs
    6) 127.5 lbs
    7) 120 lbs
    8) 120 lbs

    So I wouldn't say its great but at least its consistent o_O
    I also squirted some stabil down the cylinders to see if compression would jump to tell if its the rings and I only gained about 5 lbs per cylinder so I would say the rings are worn but fine.
     
  7. 300sbb_overkill

    300sbb_overkill Well-Known Member

    Scott brown can help you with pistons as well as with a cam. We got Andy's pistons from Scott Brown, we asked for the least expensive from the custom piston choices he has and we ended up with a set of Ross pistons that are awesome! We got the thick walled wristpins for extreme use that fits the rods that are actually still lighter than the stock wristpins!

    Just ask Scott to find the least expensive custom pistons he can get from the piston manufacturers that he deals with, they are all pretty dam good at what they do. They might not be Ross pistons when you order because of how these places change their prices to compete over time. Probably the fall or winter I would guess pricing would be more competitive?(not sure, but with a year to make this happen maybe you can find out?)

    Here is a thread with basic 101 porting in it that I don't want to write again, lol;

    http://www.v8buick.com/index.php?threads/heavy-build-up-on-valves-what-does-it-mean.320385/

    If you want to be a bit more aggressive then instead of removing 1/16"(.0625") per side on the ports, remove .080" per side of the port, you'll understand when you read that thread. In that thread, Andy has some great pictures of how you want the ports sculpted like as well.

    You would probably be better off using the $$ you were going to spend on the bigger valves to put aside to save for a set of the TA aluminum white whale heads, just get a valve job with yours. After your machine shop disassembles your heads and cleans them and they check them for cracks, tell them you want them back after that so you can port them. So much easier to deal with the heads when your hands aren't getting dirty ever time you touch them and that you're not doing all that work to cracked heads. Wear a dust mask as well when you're doing the porting or you'll be blowing black dust out of you nose for months!(ask me how I know)

    As far as the TA heads I'm not sure but if I remember correctly they used to sell the 350 heads in IIRC 3 different levels that are different levels of port work. You would have to call TA for flow numbers, I don't remember them advertising those.

    I never tried one of the Jegs transmissions, its either going to work or its not. If you break it, you'll have a TH400 that you can have performance built. There is also A-body 12 bolt rear ends that come up for sale once and a while that have all kinds of upgrade parts for them. If you do get one to build up, don't have the C-clip eliminators installed on it, have the ford 9" ends installed on it because the CCEs a lot of the time end up leaking. You'll understand what this stuff is when you start doing your research on rear end upgrading if you don't know already.

    I don't recall the spline count my friend with the sbc 383 got for his Ford 9", something like 40, Moser axles and a Strange center section and he said the axles are as big a round as a 12 oz beer can! I don't think he'll break those, but we'll probably never know because his wife threatened him so the way they broke, he probably won't try again? After breaking all the parts he did, he hasn't broken the '72 Buick Skylark convertible with a sbb 350 2 bbl the drive shaft came from that is cut and welded that he is still using! And that thing was pretty darn rusty, we thought that would be the weak point, go figure!

    You're going to have a strong runner when you're done. One thing to keep in mind though is the cast crank, although stronger than other brands cast cranks, we don't know its limits. That being said and you can make 630 HP with 6 psi and if you think you would be happy with that power level, then keep the A/T pistons in mind, you can upgrade the wristpins in those if you choose to. Something that slipped my mind. Its such a short crank with huge mains is what makes it so strong though that not to many people have found the limit of it so the 2618 pistons with 20 psi of turbo boost because turbo boost pressurizes both sides makes it a gentler form of boost so you may still be good? Dealer choice here.

    Try to get a '73 or newer crank, those will internal balance much easier than the earlier cranks because the newer rods are heavier so there was less weight drilled out of the throws and the 1-2 rod journal is partially drilled as well to lighten the balance. Perhaps look into surface heat treating the crank as well, should only cost around $150 or so depending what's available in your area? I hope this helped. GL


    Derek
     
  8. 300sbb_overkill

    300sbb_overkill Well-Known Member

    Those numbers look fine for a low compression engine, is it a 2bbl engine from the factory?

    Only rising 5 lbs with oil in it would be typical for even a low mileage engine, there is always just that little bit that makes it past the rings on most factory engines. That's why they have the PCV valves on the engines, to suck out that extra pressure so your gaskets don't get blown out.

    Looks like you could throw a like Crower L2 cam or a Scott brown custom in it and have some fun for a while the way it is. Try to find a core to rebuild and drive the car with the engine that's in it while you pile up your parts. Look for like a '74 or newer engine with the cap screw rods, people look for those for sale here a lot so you might be able to sell them. The bad part is that the later heads don't have as much potential as the earlier heads when they're ported but they don't crack as easy. Don't spend to much for a core so if the block ends up cracked, hopefully the crank will still be good to use is what you really wanted anyway.


    Derek
     
  9. Skippy597

    Skippy597 Well-Known Member

    Wow that's a lot of great info! Ok so I will try to find a later 70's 350 to build up and I will probably just use my heads of my current engine after I Port them and have them rebuilt with a valve job. And if you think that they can live with 6 psi I think I might just stay with the auto-tecs along with heavier duty wrist pins but if it's a close call I'd much rather error on the side of caution and get the 2618 pistons even if it takes longer to build the engine.

    I would be completely in love with it if I made 630 hp on boost and around 430 N/A and after reading Bobb's build I see no reason why it wouldn't, which has gotten me very excited to say the least.

    That's exactly my thought on the trans, either it will work live and I'll be super happy or I'll kill it and will just rebuild it better. But at only around $1000 that's a risk I am willing to take because the cost of finding a TH400 and rebuilding it I'm gonna be up there anyways.

    That's good to hear about the driveshaft because I really hate breaking those! The rear axle in my mind is gonna be my weak point. I'm going to keep an eye out for an A body 12 bolt to build instead but if no dice then I'll just have to see what the 10 bolt can do (probably not much I've broken a couple before).

    Glad to hear about the compression because I was hoping for at least 130 but like I stated I am happy they are all consistent. And yes this is a factory 2 barrel car.

    So for now I'm gonna throw a factory 4 barrel intake on it (already got one from a member on here), quadrajet from quadrajet power, Crower level 2 cam and some headers which I have a lead on. I think that will make for a decently fun car for the time being. Also since I'm gonna be driving it I'm gonna do the bearings and since I'm in there I might shove a 3.08 gear set in it or if I can find a complete A body 10 bolt with similar gears, because the 2.56s leave some performance to be desired.

    Thanks,
    Ryan
     
    Last edited: May 17, 2017
  10. Skippy597

    Skippy597 Well-Known Member

    I was also planning on following Doc's cheap tricks and cutting out the dividers on the manifold from front to back to make it a more conventional dual plane like all the other ones I have. Does anybody have any good feedback from doing this? Something along the lines of "yeah man I did it and it made like another 20hp" would be inspiring or do you think it's a waste of time?
     
  11. 300sbb_overkill

    300sbb_overkill Well-Known Member

    The sbb 350 platform responds really well to increasing cylinder pressure, no matter how its stuffed in it like high compression, boost or even nitrous.

    The doc mod is a good one, it helps un-restrict the incoming air, the better the combo the more helpful the mod would be.

    Here's what you can do, when you score the '74 or newer sbb 350, take the heads off and lap the valves, install a set of Stage 1 springs and have them milled .060" to get your compression up. Take the heads off that you're going to port and install the later model heads. In the unported versions, there isn't much difference in flow for the older heads and the newer heads until you start porting them so they'll be fine for a little fun until the real engine is in for a lot of fun.

    If you want to do a little bit of porting practice, you can do a little unshrouding and possibly some bowl blending and if you're don't mind spending the time do it all that is posted in the thread I linked for you. Get used to using the inside calipers, you can use those to make all of the bowls very close to the same size as well. That's why they use CNC machines to do port work, because the machine will make them all the same and that's why I recommend using the inside calipers, plus they're really cheap for all the things they can be used for. If you do the practice porting, make sure you lap the valves last you'll see why when you start porting.

    To recover some $$, you can sell that engine, let people hear it run while it is still in the car and you'll get more $$ for something you can prove that runs. Even better is to take them for a ride to they can feel how good it runs. Should be able to get between $1,000 to as much as possibly up to $2,000 depending on how clean the engine is and the right buyer. For a core, around $250 plus or minus a couple hundred.


    Derek
     
    Last edited: May 18, 2017
  12. Skippy597

    Skippy597 Well-Known Member

    Hey Derek, you mentioned the 74-later being easier to internally balance. But aren't all Buick 350s externally balanced? I'd much rather have it internally balanced but if so what harmonic balancer do I run as they all list for external balance? Also what about the flexplate? Or can I just run one for an internally balanced sbc?
     
  13. 300sbb_overkill

    300sbb_overkill Well-Known Member

    For the amount of power you want to make you need an SFI balancer. Which means the factory one that was engineered for an engine that was built to not see more than 6,000 RPM(more likely to not see 5,000 RPM:rolleyes:) an aftermarket balancer is a good idea if for anything, safety's sake. You don't want to blow up a 50 year old balancer at the track! Not to mention if its still external balanced when it blows up @ 7,000 RPM, now you're @ 7,000 RPM and your engine is out of balance because your balancer just blew up, a good way to break even more stuff!

    There are ZERO sbc parts that will just bolt in a sbb engine so you can put that thought right out of your head now and forever. Some parts can be altered to make work, but none that I know of that would bolt on.

    And yes, all sbb 350s are externally balanced. BUT when you lighten up the rotating assembly as much as you will using the nascar take out rods and light weight custom pistons with the later crank you have the opportunity to upgrade to an internal balance without having to add any heavy metal to make it balance(according to Sean on a standard stroke). The cap screw rods are around 1o0 grams heavier than the earlier nut and bolt rods and around 130 to 150 grams(each!) heavier than the take out rods! Even the extreme duty wristpins are lighter than the factory pins, not to mention how much lighter the custom pistons will be than the factory ones.

    Which balancer would you use, would be aftermarket one made for the Buick 3.8L v6 because they have the same size crank snout, among other similarities.(TA will have what you need, don't be afraid to discuss what you're building) I believe you'll be able to use a neutral balance an SFI flex plate from a v6 as well, but ask TA to make sure. If not you should be able to grind off the welded on weight on the flex plate.

    Derek
     

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