350/383 stroker conversion

[goingballistic]

Hi ladies and gents, new to the board and am looknig for some help and guidance. (No snide comments please, not THAT kind of guidance!) ha ha


Anywho.....I am toying with the idea of moving up to a stroker. I have a major rear seal oil leak and I'm gonna have to pull the motor to fix it. So with that, I'm figuring that if I'm going to pull it I may as well go all out. Now the fun questions.

I'm going to store the original motor and buy an old 350 short block from a junk yard. I see that there are stroker kits ALL over the internet varying in price from OK to "sign over your first new born". What I'm looking for is who/what is the best way to do this. I am not real keen on crate motors, I'm going to do this myself ( done it before, not stroker) so I need some input about this.

I'm looking for as much info as possible in relation to what, where, who, cost etc. AND as much written information as I can get my hands on to READ, READ READ so it goes right the first time.

I also need info on rear end changes, tranny upgrades, u joints, differentials etc. I want the car to "look" stock but not "act" stock, the only mod I may make other than the motor and drivetrain is the hood.

Any help would be appreciated.

 

[Macgyver]

Here ya go! Read up...

http://www.chevyhiperformance.com/techarticles/0304_zoops/index.html

Chevy hiPerformance rocks!

heres another
>>>http://www.hotrod.com/techarticles/79478/

The one from Hotrod mag uses the Powerhouse stroker kit that looks pretty good. Its also a decent price and you can finds them in google. I think someone mentioned it once here once thats more knowledgeable than myself. I think I have more in my favorites for you to read that Ill post when I get home.

 

[gedmeyer]

I had my L-81 block changed to a stroker this past winter. I think it cost about 2500 bucks when I paid someone to do it. You will have to have the block notched b/c there are some clearance issues with the rods.

-Tim

 

[Robin7TFour]

Tim, i like your site! what do you estimate the h/p and torque figures for the stroker?

Robin

 

[gedmeyer]

Thanks robin. I am not exactly sure on power figures yet. My enigne builder says he wouldn't doubt my engine being in the high 300's for both. Since I'm using a stock top end (intake, carb, heads) and a stock exhaust, I don't think I'll be at that full potential quite yet. I did not put in a crazy cam either, so my power should be low to mid range.

Actually, I haven't even driven her farther then around the block. I just started it the other night. I put the hood on 20 minutes ago and tomorrow morning I'm brining her over to the shop for the alignment...then cruise time!

 

[gedmeyer]

hey goingballistic, I forgot to mention that there is a certain "cool" factor when you get to tell someone that you don't have any old 350. First, you get to tell them you stroked it (...wait for their brow to raise...) then you have to proceed to explain what a stroker is.

Whether you have it built, or do it youself, the 383 is definitely cool to have.

 

[AKRAY4PLAY]

what are your power goals and budget for the project?? what type of street manners are important to you????? here is my project after installing a 406 small block. fun but expensive to drive! Brian
http://www.c3sharktank.com/sound/burnout.mov

 

[goingballistic]

Gents, thanks for the info, I'll peruse your sites and continue gathering info.

To answer some of the questions posed: The budget has no limit until the wife cracks down and realizes how much I'm spending!!! I'm figuring about 3-4K for the motor. I'd like to see it pushing 400+ HP when finished but again I want it (the car) to look stock..............I love to see those kids eyes next to me with those rice burners at the light when a "stock" vette JUMPS off the line, expressions are priceless !!!

I know I'll need to change the drive train and differential to match the output, kind of why I'm looking for info in that regard, kind of lost there, I'm afraid I'll literally rip the rear end of the tranny out...............yikes!!

I'm aware of the notching issue, hence the desire to buy an "old" 350 block ( I want the stock motor left in tact, matching numbers) in case I decide to sell it..........not likely unless I come across a 454 4 speed for a resonable price....again, unlikely. Thanks.

 

[goingballistic]

There are a couple of stroker upgrade kits on Ebay for around $600, anyone know if these kits are good or questionable??

 

[bobherr46]

Just finished putting a 406 in my 79 L82 4 speed car this winter. Did all the work my self. Had a ball. Old gearheads never get the grease off their hands. Why go 383 when you can go 406 (or more)? 1 cubic inch equals 1 horsepower and the extra cost for the 406 is very small. Seriously, first decide how much work you want to do yourself. If you want to build the motor your self, you got a lot of learning to do but it is very rewarding. If you are not wanting to build up the motor your self, I think one of the many crate engines available on ebay is your best value. I bought an Eagle brand rotating assembly and was impressed with it. All of the crank journals miked right as spec'ed. The shop that did my block machine work said the Eagle assy's always check out "on the money". - Bob

 

[bobherr46]

Back again. Check out the post under C3 parts for sale. Guy is trying to put together a deal on Eagle brand stroker kits. May save yourself some bucks. - Bob

 

[goingballistic]

OK gents got more info about this. I talked to a master engine designer as Delphi yesterday about this 383 conversion. the scoop:

Leave the original rods(5.7"), use new rod bolts ARP, DON"T use 400 rods.
Light weight pistons from SRP, ROSS or Linata, flat top aluminum, stay away from Hyper-Eutectic, they shatter from pre det or slight contact.
Zero Deck, gasket is the clearance.
AFR 195 heads ( 50 HP increase) $1200 per head........ouch!
Hydraulic cam, he's looking into the lobe for me, don't want it too loppy 10:1 compression.

He also mentioned that GM is releasing a Vortec head for about $400 per head, any one familiar with these? 35-45 HP increase??

He also asked about running open loop, apparently the 81 shark was the first production model to run closed loop so the computer and related hardware is coming out so I can run open loop. Any one got any tips on this aspect of the car???

I'll keep filling you in on what's happening so if anyone else is looking to do this, it'll be here.

P.S. 406 blocks are hard to come by, 350 blocks are a dime a dozen, hence the 350. I'm crating the original matched motor and rebuilding another......that way I can still drive this summer

 

[Jack]

For several years now, GM has been equipping most OE engines (including chevy V8) with OE hypereutectic pistons. Both material & design has proved-out well. Speed-Pro, Keith Black etc have sold zillions of em for hotrods/strokers with no problem. However, Nitrous/forced induction probably should use forged.

And the iron Vortec heads appeared on chevy small blocks several years ago ... also available separately for several years ... one complete Fe vortec head priced under $400. For about 2-3 years GM has made available a "fast burn" aluminum Vortec head ... one complete fast burn Al head priced about $600 each. Edelbrock offers a similar Al head (E-Tec) for similar money.

Either Vortec or Fast Burn or Edelbrock E-Tec require a "Vortec" style intake manifold.

Original 5.7" rods are ok for 383, but longer rods are preferred by many. When used in 383, OE 5.7 rods will require machining because otherwise they come too close to cam or hit cam ... this rod machining called "cam clearancing." Many aftermarket rods' design provides ample clearance with no additional machine work.

My 388 has speed-pro hyper, cam clearanced GM "pink" 5.7 rods ... no problem. If I were to do this again, I'd probably use aftermarket rods ... probably 6".

This not an absolute formula, simply a guideline: First get a book that covers stroking motors, then decide what your budget is, then determine condition of your block's decks and how much (if any) NEEDS to be removed to make decks smooth & straight, then what you want motor to do (including target compression ratio), then choose heads and cam, then choose piston and gaskets ALONG WITH how much extra (if any) you may want removed from decks ... all along focusing on target compression ratio.

Depending on purpose and other components, it could turn out the dished pistons are a better choice than flat tops.
JACK:gap

 

[goingballistic]

Hey Jack, thanks for the info.............the more the merrier.

I just read an article that said Chevy got it right when they designed the 350 5.7 rod and stock stroke in that it is less than 18 degree angle when the rod/piston is 90 BTDC. Apparently this was a problem in larger blocks say 400+ where the angle exceeded 19 degrees at 90 BTDC, caused excessive ring wear and cylinder scarring. I think I'm going to stick to the 5.7 rod and machine as needed, the stroke will change with the rotating assy but the angle stays roughly the same...below 18 degrees.
The budget went out the window, I'm figuring about 3-5K now as I'm very interested in the AFR195 heads, if not these the Vortec fast burn aluminum heads are about half the price. I'm looking at about a 10:1 compression ratio.
What I'm having the hardest time with is the cam, I'm struggling with the duration I need so the car is not overly "lopy" and doesn't affect vacuum too much.

the Edelbrock intake has already been recommended, thanks.
I'm not knocking the hypers, I just wasn't aware that they were so fragile, so I'm going with forged. More money but I think worth it.

Keep it coming guys this is a great informational thread.............any one else?

 

[bobherr46]

Aerohead Racing Components of indianapolis has fully prepped 400 2 bolt main blocks for $799(vs $599 for 350 4bolt). Be careful on intake manifolds. all of them will not fit under Corvette hoods. Also ,whatever block you end up using,be sure it has all of the correct bolt holes drilled and tapped in it before you assemble it. The 400 block I got did not have the holes on the front to mount the power steering pump bracket nor did it have the hole on the side to screw the clutch shaft ball in. It is no big deal to drill and tap these holes. you just want do it before you get the motor built and try to put it in the car. Last, if you go 400 buy the 6 inch rods to keep the geometry correct. Suggest you order"how to build high performance chevy on a budget by David Vizard. Tons of good info. Order from Amazon.com. Best money you will spend. - Bob

 

[bobherr46]

Some days I just can't shut up. Jack has it right. You gotta select the head before the pistons cause you gotta know the combustion chamber size to be able to calculate the compression ratio. I purchased a used set of Edlebrock heads with 70cc chambers so I ended up with dished pistons in my 406 to keep the CR at 9.7. Most of the stuff I read recommends max. CR at 10.2 for aluminum heads and 9.2 for iron. They guy I bought my parts from recommended I stay below 10.0 so I followed his advice. Hence the 9.7 with Al heads. talked enough for now. - Bob

 

[GerryLP]

Ballistic,

I think that it was a sound decision to keep the L81 stored and trick another 350 engine in the ways you have mentioned. Kudos!

Since it seems that you're not messing around... , then consider going with a 3.72 or higher in the rear end, and install a 2004r or 700R4 4-Speed Auto transmission. Save the TH350C as well.

For reliability, consider a Holley Commander throttle-body injection (TBI) system. Its closed-loop of course, but very modern (by leaps and bounds over the L81 computer). The computer can be programmed to handle your engine specifications. I guess the limit would be if you have State EPA limitations in NY.

 

[mmitzan]

383 Stroker

I'm doing the same thing building a stroker. For what it's worth if you are doing everything yourself there are great deals to be had on ebay. I'm using speed pro hypereutectic with a teflon coated skirt $179 for 5.7" rods $229 for 6" rods. (I'm using the 6" rods.) There are varying opinions on everything from piston type to rod length all the research I've done has led me to 6" rods but is is my personal choice. Eagle forged rods $249. 5140 forged crank $299. Check out this link and make you own decision (http://www.ecranks.com/) Pro topline aluminum heads 64cc-Powerhouse $899 (http://www.enginekits.com) Scorpion 1.6 roller rockers $169 crower hi-lift roller cam $250 (www.crower.com) FYI the block i'm using is an 89 4 bolt with a stock roller cam. Edelbrock RPM Air Gap intake manifold $125 Aluminum radiator $169 flex-a-lite dual electric fans the list goes on all the above prices with the exception of the heads and camshaft ( zz4 roller cams that are brand new take-offs can also be had for $135) are regularly to be found on ebay. The machine work to have my block prepped and the rotating assembly installed $500-$750. I am using desktop dyno I have no idea how accurate it is although I have heard good things about it. The above combination with a 770CFM carb or TPI with large runners pops up in excess of 450 HP and 450 ft/lbs. of torque it actually maxes out at 509 HP and 526 ft/lbs but I am having trouble with that. I would be ecstatic with 425 425. Hope this info helps. I have researched this project for over two years before I started to spend any money and have confidence in all my decisions good luck with your project P.S. I plan at attending Carlisle this year and I'd love to meet other CACer's
Mike Red '76

 

[Jack]

Tons of 383 info here ... courtesy of grumpyvette:

http://www.corvetteactioncenter.com/forums/showthread.php?t=46176

 

[goingballistic]

Quick update:

I picked up the block (74 Nova) on Sunday. Put it on the stand on Monday afternoon, my oldest son's friend came over to help and asked if I was going the use the carb, I said "no if you take it off you can have it"...........four hours later the block was completely disassembled and waiting for me to start cleaning.....( the old man is not as dumb as they think I am ) . Ordered a custom grind Extreme cam from Comp, timing chain (true roller 3100) and 812-16 lifters.
Had a line on a 400 crank and balancer for a very reasonable price and then found that the grind cost for the crank was in excess of $200. Just ordered a SCAT crank with clevitte bearings as an assembly for $240.
Next step install the rotating assembly and check all clearances, grind what I need off and then prep the block for the machine shop for decking to zero.

My boys are having a field day with this and can't wait to get this thing moving ( they are 20 and 16 both drive...........they won't be driving this).

My wife on the other hand is having a cow.:cry ..$$$$ out the window == parts in my car.......the saga continues.
:eyerole