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73-87 Chevy _ GMC Trucks => Performance => Topic started by: 305chevy c-10 on April 17, 2011, 08:45:42 PM
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i have a 2 bolt main (#638) block 350.with the following specs ...
vortec heads
750 dbl pumper holley
268 cam (roller)
.030 block
hei distr(procomp)
1.5 roller rockers 3/8 stud
electric fuel pump 130gpm
2500 stall on 350 trans auto
2.73 gear but will upgrade to 3.42
stock crank and rods 5.7
dished pistions
now my question is is this gonna make too much power for a 2 bolt main....i seen an upgrade kit to convert a 2blt to a 4 blt main .....just wondering what u guys think..........i hate to get this thing built and let it have it one .....and bottom end cant handle it ....i was told 2 bolts are no good ....
.now my question
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You'll be just fine since this doesn't sound like it's going to be anything radical. In fact it sounds like you are building a gas pig. Have you really thought out your whole powertrain combo?
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well tell me where im going wrong .........some things are already purchased someare not ...dont have fuel pump stall, or gears in yet
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Well I've actually had better luck with two bolt blocks over 4 bolts blocks. If you are building a small block that you plan on punishing, splayed caps are recommended. As far as where you went wrong, I'm not suggesting you did anything "wrong" but How about some more details about your ride, What is it, what are you trying to accomplish, why dished pistons, what made you pick that converter?, what size tires are you running?
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ok its a 85 c-10 chevy shrt bed 2wd .stock no body mods ....tire size will be 31-32 .i was told that dished work well with vortec s and it would not make my compression to high ..............want to run well on 87 oct ..........well on the converter i was told that with the cam i got i needed a bigger than stock conv.i kinda guessed on that info .......2500......yes i will punish it some time not racing just ......showing out a little ...i know the carb is big but the guytold me he can tune it to work on my app
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My 2cents; and some will say that's about all it's worth.
86 the dish pistons and run some flat tops. Just watch the quench and you can still run 87 octane fuel. While you're doing that, since you wanna show off a bit, go ahead and get some forged piston and ss valves so you can squeeze it a bit too.
Call the cam manufacturer, tell them about your set-up, and see what stall converter they recommend with that cam, carb, gears, tire size, etc...
Loose the double pumper carb and get a vacuum secondary 650 or so. It won't require nearly as much tuning, and will be a much more street friendly carb.
Unless you need it to fix other issues, or just want electric, you don't need a 130gph pump. A stock pump will feed that engine just fine.
Get a re-curve kit and adjustable vacuum advance for that dist. Timing tape too if your timing light doesn't have the advance feature. Set up the timing right and it'll make a world of difference over that pro comp dist out of the box.
Make sure the valve springs match the cam too.
the 2bolt block will work just fine for that build. If you want a little added strength, you could always stud the mains. Many a builder has told me a studded 2 bolt block is stronger than a bolted 4bolt factory block. Mine is a 4bolt, but it just happened that way. I certainly didn't seek it out. A 2 bolt would have been just as good for me.
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-Flat tops will give you a 9.7ish to 1 compression ratio on a 64cc head. (87 octane will work)
-Heavier valve springs will also be needed with that cam.
-A large carb will decrease your vacuum. (650 will work good and keep your vacuum up). Althought he 750 can be made to work just not as well.
-A stock fuel pump is good for your set up and will be much more dependable than the electric.
-2 bolt main is fine.
Just my opinion...
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nice advice ..........but my cam and pistion s are already brought .....the vavle springs are tested 115 on seat and 310 @ .550 lift ....i have stainless vavles in the heads ....as for the fuel pump ....this is a roller block .....the rebuild kit i ordered came with a roller cam that does not have a pump lobe on it .....that y im running electric maybe 95-115gpm .......the carb i got off ebay ...will go with a 600 or 650 and try to get rid of the 750
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I would still consider upgrading the pistons if your budget allows, it's easy power and would make a noticable difference.
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4 bolts are weak, for a street motor that will rarely see constant about 2bolts are plenty strong. Altogether my buddies broke more 4bolts than 2 bolts. I never ran a 4 bolt. If you are going to drag race, get the 2bolt machined for splayed caps.
your cam is barely over stock and doesn't need that much stall and that carb is to big for the motor, it needs no more than 600cfm unless you plan to overrev it past 5000rpms.
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well im looking into a summit 600 carb and i will have the specs on the cam tom ...when the kit comes in ...im hoping for atleast 350-375 hp/400tq ...i need to look at the old cam to cross reference the part # to see how much bigger is this cam
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How much abuse can a splayed 2 bolt handle? Say 10k rpm?
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The weakness in the blocks webbing and caps aren't necessarily prone to destruction based on RPM. 10,000 rpm out of a small block isn't realistic or practical but it depends on how it is abused. If you're building a budget 400 HP small block and have a good seasoned block you're safe.
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got cam kit in my cam specs are 215 @ .050 ....268 advertised dur ...489 lift ...dont really know what kind or idle this will have though.
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sounds like you'll be in the 300-350 gross horsepower range. WELL within the safe 2 bolt range. i always hear that 2 bolt factory blocks are safe to 500 or so. unless you are planning on HUGE (300+) NOS you'll be fine.
and for what its worth my 2 bolt 400 ran 11s at 111-113 all day and never had an issue.
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2 bolt is fine for that build.Im assuming a stock converter could have been used on this build also but the 2500 will be nice to have the motor flash into its meat.I run a 750 on a 355 but a whole different build.As for cam i dont think it will have a noticable idle but its possible.My .02 on whole build off your dish pistons and throw some flat tops in.It will be fine on pump gas.I know allot of circle track racers runnin 2 bolts twistin em 7500-8000rpms so i really think youll be fine with this cam.That cam is prob good for a 5200rpm shift.hope this helps and good luck.
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just left machine shop .guy talked me into clearancing for 383 ...........eagle steel crank ordered ..he told me to stud the main caps instead of bolts and i should be fine for 383 .....what do you guys think ......also ......for this ex balanced crank dont my flex plate and balancer have to be ex balanced also ...................same set up as before but got 600cfm holley and gonna be 383 not 355
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anyone rebuilding a 350 and not converting it to a 383 needs to see a shrink. OK that may be a little harsh, everyone has their reasons. But with such slight mods and a maximum advantage, a 383 is a terrific modification for more torque. They call these things stump pullers for a reason.
But, in addition to a 400 cid crank, you will need a 400 cid flex plate and balancer.
www.delbridge.net/install
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drop the 2400/2500 stahl
2000 is plenty for that small of cam.
with your gear tire setup you will be runin ~2400rpm @65.. cruising at stahl speed is very inefcient.. and create alot of heat in the tranny as well.
def raise the comrpession to min 9:1 close to 10 the better
BTW im running a 2 bolt 383 setup for 7000 havent had a problem, no sign of main caps walkin either... bottem end is in need of a rebuild been runing it for ~8 years now. lots of blow-by at idle and WOT..
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i cant seem to find a flexplate that for 1pc RMS .they all say 2pc and internal bal .......buy the way i have read that u can blow the motor with flat top pistons on vortec heads .....that y i used dished ..............also are u using a m55hv oil pump or standard ...i have a 7qt pan ......i was told that a hv pump would suck a standard pan dry ........
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HV oil pumps can suck oil pan dry IF you spin it fast enough IE drag racing time frame.you can do this with stock volume as well... i run HV pump in in all three engine i have dd for extened period of time.. 305, 383 and 468.. i go easy on the engine till warmed up... theres a high risk when could due to oil its thicker when cold and cant drain back fast enough..
flex for a 1 peice sbc heres a part number...pick one 168 or 153, internal or external inlcuding sfi spec... http://www.summitracing.com/search/Part-Type/Flexplates/Engine-Type/V8/Make/CHEVROLET/Engine-Size/5-7L-350/Rear-Main-Seal-Style/1-piece/?Ns=Price|Asc
blowing a engine with flat tops? only if way is the had serious interverance issue with valvetrian.. there was assemblee issue or the person doenst know what he was talking about..
im rungin flat tops in my 383(piston never come above the deck) and domed in my 468
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i would think that if you have a larger capacity oil pan, sucking it dry shouldnt be as much of a problem as a stock capacity.
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i cant seem to find a flexplate
If you are running a 2 piece RMS use a standard (weighted) 400 flexplate. The later one piece RMS engines are also weighted but are a different bolt pattern. If that's what you need then look for one for a TBI truck, 87-??, or if you are local to ND I have one in my garage that I will probably never use off an 88 TBI 350.
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i would think that if you have a larger capacity oil pan, sucking it dry shouldnt be as much of a problem as a stock capacity.
It mainly is detrimin by how fast the oil drain back down... oil temp weight and cleanlyness of the engine determin this.
Oil cools the valvetrian and r/a as well as lubercation. I run hv pumps cuase I rarely spin past 3k and I have ample amount of coolin on the valvetrain. And usually have a load on it
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when getting block clearanced for 383 ...do i need to have my balancer and flex plate to get it balanced or this can be done at home .or is a machine required ...i dont want to haul the block up there for the clearancing ..then have bring it back later when i get the flexplate & balancer .........also i read that stock rods are just as good to use on mild builds ....i was told the are forged not cast ..........clearancing ,press on new pistons,new cam bearings and re-hot tank it is 179.00 .......u think thats reasonable
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wow ........the machine shops eating my wallet .............275(port match intake for eq vortec heads ).179 (press on new pistons ,clearance block for 3.75 crank,rehot tank ).250 (balance rotating assem).185(machine the block +030,freeze plugs,cam bearings,hottank ).........wow my 305 is looking real good right about now... lol
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That feeling will pass as soon as you turn the key on that engine. It will all be worth it then.
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That feeling will pass as soon as you turn the key on that engine. It will all be worth it then.
Agreed!
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..275(port match intake for eq vortec heads )
Have you done this already? ::) It is a mistake at this point for a couple reasons. One is cost...that is WAY too much money (we are talking US dollars, correct?) for what anyone should/would do for a "driver pickup truck". Two, until the heads are on the finished, decked block with the correct head & intake gaskets...the top/bottom relationship can't be known, forward/backwards from head to head can't be known. Sure they can play around making the intake port opening match some opening in a gasket, but until you know how deep the intake sits in the "V" & where front to back placement is, no port matching should be done since they most likely won't line up once the engine is assembled...half of the time the gasket needs cut (either the bolt holes slotted or a side trimmed in the port) to end up with a correct relationship. I'll say it again: Port matching for the most part is way over rated. You'll never see or feel the difference of a 1/16" or ever an 1/8" out of line parts on an average street engine, so if you can't do it yourself or have it done correctly for a a reasonable fee (1-2 hrs.) Don't bother. My Two Cents...not that you asked for them ;) Lorne
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yeah its done already .he had the block and intake gaskets .....that was also fo putting in new retainers,vavle seats ,and guide plates with screw in studs
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are all these charges reasonable.....$179 (press on new pistons ,clearance block for 3.75 crank,rehot tank ).$250 (balance rotating assem)......what is a reasonable charge to install 2 bolt main studs
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Oh Ok, That sounds MUCH better for the money...That's a whole different story than "port match intake" ;)
I guess I mis understood you...with the part about not wanting to haul the block back & forth, I thought you had the block & he had the intake, Sorry.
Why did you need new valve seats?
are all these charges reasonable.....$179 (press on new pistons ,clearance block for 3.75 crank,rehot tank ).$250 (balance rotating assem)......what is a reasonable charge to install 2 bolt main studs
Those seem a bit high to me, if that is what they are doing & nothing else. The $250, is that just the weighing, grinding, ect. This is not to make it internally balanced is it? Who is assembling the engine? Them or you? The $185 for the bore, cam bearings & hot tank sounds pretty good to me. Lorne
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the eq(vortec style) heads were bare .after he matched them to intake he put them togather ..i had my own springs and valves,guide plates,and studs he supplied the retainers , locks and valve seats....that price for balancing is for external balancing of crank,rods,balancer and flex plate .....clearancing the block, and the balancing i have not got done yet ....bcause i got to order balancer and flexplate from summit ..........as for putting it togather ..they(NAPA) told me they would put it togather and tune it ,let me hear it run for $450-500.
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the eq(vortec style) heads were bare .after he matched them to intake he put them togather ..i had my own springs and valves,guide plates,and studs he supplied the retainers , locks and valve seats.
Do you mean seats or seals?
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yeah i mean seals ,but he also grind the seats so the spring would sit correctly and not bind ( u know on a single spring it has like a flat spring looking peice inside it )on seat when compressed