350 SBC Build Help
i'm looking for some advice and help,
my son and i are going to build a 1971 Chevy 1/2Ton p/u, it has the original 350 in it with the three on the tree, this is going to be a strong budget build / weekend driver/no real hwy runs, prob might give it hell once :D . I would like to end up with a 10.1 CR motor, nice cam, roller rockers, edelbrock RPM Performer intake, Qjet, MSD ign, headers, 350 turbo tranny, torq converter around 2400 to 2700RPM and 373s in the rear, (the truck is in N Carolina and i'm in Nebraska, i won't have a dime in the truck or transport to Nebraska, grandpa gave this to my son, and we are in the car transport business) butt it's not here yet to get # off block ect. or see what the inside of the motor looks like.
i can buy a set of SBC 76cc heads with stainless valves 2.02 160 they were off a 383 stroker for about 3000mi, and the guy traded them for a set of aftermarket heads, i can get them for $250.00 then i was looking at the speedpro hypereutectic pistons they are $240 a set that gets me into the 10.3.1 CR Range, (Speed-Pro Hypereutectic Piston # on jegs 844-H617CP30 http://www.jegs.com/cgi-bin/ncommerc...94&prmenbr=361 this piston CR is not figuring head gasket & piston in hole for the quench.
right or wrong i would like the 10. to 10.5.1 CR range. i plan to just recondition my rods and do what ever work needs done to the block & crank, (i'm looking for budget priced pistons,cam, roller rockers, intake and torq converter, even a used intake & headers and roller rockers if i can find em is ok ) is there good pistons for less money ? what cam would you pick for this setup ?
ok what CC heads would you guys run on a 10.1 CR 350cid motor ? you like the 76CC heads ? is $250 a good price ? what setup would you oldschool guys recommend for what i'm building ?
i would like to hear everyone opinion on this build from carb to pan, where i some places to buy my parts reasonable (or cheap, not so cheap thay are junk)......
all help invited
i would go to racers outlet at ebay motors.i got my crank from jegs for 195.00.eagle cast steel good to 500 h.p.and they have know shipping charges.atracers outlet i got new eagle rods good to 500 h.p. for 179.00.i got the speed-pro hyper. pistons of your choice for your build 179.00.if you get it all at one time kevin will treat you right on the shipping charges.i think i paid 700.00 for my 406 rotating assembly.get the new much better heads just out from gm for not much more than you are going to give your buddy and you can't beat the power from these heads for the price.and i'm not a vortec person.you will do much better to buy all this stuff new for not much more than you were going to spend and not have to deal with some of the machine work.you should not have to grind the rods for cam clearance cause they grind the throws on these new cranks for piston and cam clearance before you get them so you don't have to but check the clearance anyway.trust me you will make out much better this way.compare racers outlet prices to jegs and you'll be amazed.i was.i live up the freeway 1 mile from jegs main store and like them alot,but you can't beat the prices at racers outlet.also i have 3/4 ton van and got an 11" pro street converter from coan engineering with 2800-3200 stall and it works great.you may want to check them out.
Not to jack your thread, but where do you live in Nebraska. I'm 30 min west of Norfolk.
im in Elwood Ne, 15mi south of I80 at the Lexington Ne. exit. i worked for a company that had a main office in Holdrege Ne. and a office in norfolk too, i've spent my share of time in Norfork Ne. (i was in norfolk Ne this last march my wife bowled state there) been to the wine & wings in pierce too.
Go Big Red
Hard to get that much cr out of a 350 with 76cc heads. The head gasket adds 8cc and the piston in the hole adds about 4cc. Do the math.
You will need 64 cc on a 350 to make that cr.
76cc heads will do a good job with a 383 or 400.
You should set the cr to the cam that you want to use. First determine which cam you want then make the correct compression ratio (not the other way around).
A 10:1 engine needs a pretty big cam to run pump gas. Between 230 to 240 degree of duration at 0.050.
9.5:1 cr with a cam in the 220-226 range with a 383 rotating assembly and the 76cc heads would be a good combo for your truck
i bought claimer hypereutectic pistons 10.1 compression for $189.00 cdn
think 10.25:1 CR is to much ? or will it be that high cause, if 454C10 is right The head gasket adds 8cc and the piston in the hole adds about 4cc = 12cc + 76cc = 88cc heads. or is the 10.25:1 piston have the extra 12cc figured in ?
Northern Auto Parts said,
Yes, we can substitute pistons on these kits to roughly achieve a
compression ratio of 10.25:1. In order to accomplish this, you would
need a piston with a .275 dome (H617CP). The upgrade on the street
performance kit would be $106.40 for a total of $566.39.
However, there is one note of caution in using this configuration. Compression ratios in excess of 9.5:1 are NOT recommended for use on pump fuel unless you are running aluminum heads. The extra 5 horsepower you may achieve may not worth be the trade off of $5 per gallon race fuel. If you have any more questions, feel free to call us at
i was looking at this kit, Chevy 350 (to 1985) STREET PERFORMANCE -
HP350KHW Hypereutectic Pistons with Scat Crank.
1497 Hypereutectic pistons... can substitutions be made on pistons ?
pistons i need are .30 over, and i'm wanting around 10.1.1 to 10.5.1 CR
Hypereutectic Pistons with 76cc heads, a i haven't picked a cam yet, .......
No, 10.25:1 is not too much if the cam your use is over 240 degrees duration at 0.050". However, it would be too much if you plan on using a smaller cam. And I think you should use a smaller cam if this is going into a truck with 3.73 gears. Like I wrote earlier, a cam between 220 and 226 duration at 0.050 would be about right.
That "9.5:1 cr using iron heads with pump gas " is a VERY general guideline and depends greatly on the valve events (cam). A super simplified guideline for the novice engine builder.
I have a 11.0:1 350 sbc engine with iron heads that runs great on pump gas without the need of any timing retard because the cam is large enough to bleed off cylinder pressure (late intake valve closing point).
On the other hand, I have a 9.0:1 cr 454 that will detonate if I turn the timing past 40 degrees even with 93 octane. The reason is because the engine makes a lot of cylinder pressure from a short duration camshaft.
Both engine produce about 180 psi on the compression gage. Don't confuse cylinder pressure with compression ratio.
So, you should figure out the dynamic compression ratio, which uses the static compression ratio and the valve timing events. Buy a how to modify a sbc book and you can read it for yourself.
FYI, when buying pistons, the cc of the head should be listed along with the compression ratio of the piston.
I'd go with a milder stall converter if you want any decent mpg, or swap in a manual, I'd go with typical 3.55s for a good balance of performance and affordability.
gas isn't cheep anymore. If it were, I'd say run 4.56s for all I care.
what cam , lifters , timing chain , gaskets , oil , pump , would you guys pick 4 my setup ? motors not apart yet, so woud wait & see or just put new rods & crank in ?
all replys are welcome ?
You can do this cheap without any problems.
A summit racing cam and lifters for 100.00
Get a summit racing double roller timing chain
Get the oil pump and gaskets from autozone (melling pump and felpro gaskets)
Have the rest done at the machine shop. (resize the rods, press on the pistons, clean the block, install the freeze plugs and cam bearings, turn crank, bore the block, freshen up the heads)
Get the bearings from the machine shop (M77's)
Could have the machine shop ****emble the engine also for 200.00.
Make sure the springs on the heads can handle the cam profile.
Get a high volume fuel pump.
A little bowl smoothing under the valves at the head/valve seat inferface will make another 20 hp!
No need to balance the engine.
I don't think a q-jet is a good choice for the performer rpm intake. The performer rpm is set up for a square bore carb (holley) not a spread bore carb (q-jet). A holley 750 w/vac secondary (3310) would make a nice combo with the performer rpm intake. The regular performer (not rpm) intake will mount to a q-jet.
i have a fresh set of 76cc heads that come off a 383 that had 3000 mi on them, is a 10.25:1 CR SBC Motor with 76cc Heads with stainless 202 160 valves a good choice ? Heads cost $250 think thats a deal ?
(if im right it will end up less than the 10.25:1 CR when you figure the piston in the hole & head gasket)
does anyone have any sbc heads that are runable or don't need a much, or won't cost a bunch at the machine shop they want to sell ???
Heres a Link You Pick what you think is right 4 my build,
what cam , lifters , timing chain , gaskets , oil , pump , would you pick 4 my setup ? motors not apart yet, so woud wait & see or just put new rods & crank in ? there not big bucks. scroll down to pick ...........
what do you think of my cam choice ?
Comp 1800-5800 RPM # 12-211-2 270/270 adv duration .470/.470 lift Valve Springs must be changed,Not Computer Compatible + $76.55
Are the 76cc Heads the Best Choice for a 10.1 CR motor ?
engine asembly isn't a issue,
Yes, that is a pretty good cam. However, if you are on a budget you should get a summit cam and lifters for 79.95. sum-k1104 or sum-k1105. Comp lifters are another 86.00.
It is a good idea to run more cam duration on the exhaust valve due to typically low flow ratios (intake/exhaust) on stock exhaust ports, plus heavy cars with small engines like more exhaust duration. (good for a truck with a 350)
The heads sound like a good deal but they still need to be freshened up even through they have low miles. A valve job is really cheap if the heads are in good shape (less than 100.00). Plus I would add 1.5" OD springs with new retainers which will require machining. If the heads have 2.02/1.72 valves, the springs may already be 1.50". I would also install screw in studs. When spring pressure get higher, the studs will pull out if they are the press in type.
Here is how to figure compression ratio:
355cid (+0.030 over 350) is 44.375 cid for each cylinder. (355 cid/8)
44.375 cid is 727cc's (1 cid = 16.387cc's)
CR = biggest volume/smallest volume
biggest volume is: (volume with piston at bottom of stroke)
cylinder = 727 cc
head = 76 cc
gasket = 8 cc
piston recessed in block 0.020" tyipical for sbc = 4 cc
piston recess (+) or dome (-) = flats top about +1cc because of valve relief
smallest volume is: (volume with piston at top of stroke)
head = 76cc
gasket = 8cc
piston recess in block = 4cc
piston recess or dome =?
so a 350 with flat tops, 76cc heads, standard felpro gasket, and the piston in the cylinder 0.020" at top of stroke will have a cr of:
(727 + 76 + 8 + 4 + 1) / (76 + 8 + 4 + 1) = 816/89 = 9.17:1
So, to get 10.0:1 you would need more cylinder volume or smaller cc heads or a dome in the piston.
a 64cc head would give you:
(727 + 64 + 8 + 4 + 1) / (64 + 8 + 4 + 1) = 804/77 = 10.4:1
a 383 cid stroker kit with 76cc head would have:
(784 + 76 + 8 + 4 + 1) / (76 + 8 + 4 + 1) = 873/89 = 9.8:1
a 350 with 8cc dome pistons and 76cc heads would have:
(727 + 76 + 8 + 4 -8) / (76 + 8 + 4 -8) = 807/80 = 10.1:1
A 350 with a zero deck height block (block deck cut so the piston is flush with block), flat top pistons and 76cc heads would have:
(727 + 76 + 8 + 1) / (76 + 8 + 1) = 812/85 = 9.6:1
A 350 bored 0.060 with a zero deck height, flat top pistons and 76cc heads would have:
(737 + 76 + 8 + 1) / (76 + 8 + 1) = 822/85 = 9.7:1
It is always better to use flat top pistons because flame travel is quickest across a flat surface. Domes and dishes slow down flame travel and require more ignition timing advance to complete the burn.
A zero deck block, +0.060" bore, 76cc heads with flat tops might be a good way to go. 9.7:1 will work well with a moderate street/strip cam (220 to 230 degree duration).
1st thanks for taking the time to spell all that out for me. i Hate to ask more dumb questions, butt other wise i won't know. was you figures with this piston ?
http://www.northernautoparts.com/Pro...tModelId=10718 piston part # H617CP30 ? 10.26:1 CR not counting piston in the hole or the head gasket.
I went to that site and the piston spec doesn't spell out the dome volume. It specs out the dome height which is not a lot of help because the height is not uniform. However, it does give cr when used with a wide range of cc heads and bore amounts. I would assume the cr given does include the standard 0.040" head gasket and piston recesses. So, that 30 over piston will give you 10.25:1 cr with a 76cc head, but that may be a little high for the cam you want to use. Can you find a piston with a little less cr using 76cc heads? 9.5 to 9.8 would be about perfect.
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