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sbc engine build

5K views 90 replies 10 participants last post by  gearheadslife 
#1 ·
building a 350 its a four bolt main block 30 over (355) gm crank and rods flat top 4 eye relief hyper pistons cam is a 480/480 lift centerline 106/114 adv duration 287/287 heads are unported sports man 2 64 cc. the intake i have is a weiend team g,and dyna tech long tubes. gonna be running a t350 with 3200 stall 9in ford with 355 gears in a 72 nova my question is block is built cam installed the rest of the parts are stuff i already have for the engine will this combo work its for a street /strip car do not plan on driving it alot just to the strip and maybe on weekends any advice will help. im guessing should be around 10.1 comp also this is my first sbc build
 
#2 ·
First thing I would have you ck is the compression hgt on those pistons to be sure have the correct 1.56" hgt.Some of the cheaper flat top pistons can have 1.548,or,even 1.540.The shorter pistons referred to as "rebuilders pistons",will have the piston as much as .045 from the top of the deck on an undecked block vs .025.This excessive distance will rob you of power & detonation resistance.Measure how far down the bore they are before installing heads. You need to know this ACTUAL measurement from piston crown to deck to know your actual compression ratio & to choose the proper headgasket to setup your quench/squish distance as well.
 
#4 ·
Getting the actual compression ratio correct for the cam being used is very important.You didn't list the @ .050 duration,but,i'm assuming somewhere in the 230 range.With the correct piston & deck hgt/gasket,a .030 over 350 will give you just over 10:1 with 64cc heads.You will need that with your cam choice.If you have excessive piston to deck clearance,you could be as low 9.2:1 which would be too low to perform very well with that much cam.This all needs to be measured & sorted out before assembly.Guessing @ deck hgt,CR, will only lead to trouble for you.Measure everything BEFORE assembly so that your not 2nd guessing when things go wrong.
 
#6 ·
Just had a similar short block built up, using 64cc chambers also, and the flat top pistons with 4 reliefs. My cam is a Crower Hot Street Beast advertised duration 278/284, with .462/.470" lift, and 112 LSA. The engine builder came up with 10.25 c.r. on mine when they calculated the whole assembly. I can't run regular unleaded, but does work on mid grade.
 
#8 ·
Thanks for all the replies. Sorry the block had been zero decked pistons are speed pro's and the can duration @.50 is 231/231. I'm also have a 650 Holley double pumper with mec seconds. I was also wondering if the stall I choose is to high. The engine should perform from mid to high 3k 7k that's why I bought the 3200 stall
 
#10 ·
that camshaft will peak well before 7k
Yep, she's gonna be pretty much done at 6K. So will the heads. Strongly suggest high-rise, dual-plane intake such as Weiand 8150 or Edelbrock 7101 or Professional Products Typhoon 52021 or out of production Weiand 8016 or out of production Holley 300-36 to make more power than the single plane. If the motor is done at 6K, there is no reason to use an intake manifold that will pull to 7K+. You'll just be giving up power under 6K with it.
 
#13 ·
Thanks been working on this project for a couple of years now getting closer to having it running and driving. Another thing I was wondering is I have to drop the heads of to be cleaned up at the machine shop would I benifit by having them milled down to 63 CC to raise comp or is this not necessary
 
#16 ·
Thanks I have read that the spots man heads are a decent head but need some porting on the exhaust side is this something I should do. I have a pretty good exhaust set up for the car dynatech long tubes with 3 in collectors 3in x pipe and flow masters dumping under the car
 
#18 ·
No not me I was talking about having them done or would this just be a waste do they realty need port work or do they flow good enough . I'm not building an all out race car just a car that will see some 1/8 mile passes at my local track for fun and drive on nice days. Mainly a nice toy
 
#20 ·
I never saw a set of heads that couln't benefit from an expert porter grinding on them. What you have to do is balance the cost of porting with the cost of buying another set of heads that will outflow even your ported heads and how the cost works out. Lately, I like Pro-Filer 195's on a 350 or 383.
SBC 23 Degree Cylinder Heads
Under $1100 complete, ready to bolt on.
 
#22 ·
dan0311 perhaps MS tom is correct.If you are not building a rocket then use the heads as cast. The darts we had flowed less than 220 cfm on the intake side and the exhaust was 70% only. Test your head flow if you plan at anytime to rev to 7k like you first posted.
with 220 cfm on tap you will make power past 5,000 rpm.
for serious power to 7,000 rpm you will need around 275 cfm on the intake side and ideally 75% exhaust side( a little over 200 cfm exhaust side)

Correct tom?
 
#23 ·
Yep. The cam he has will quit pulling by by 6 grand. Massaging the heads will be a waste of time and effort.

The OP could spend months on cherrying out the perfect build. I think he will be more than happy to stick his engine together, stick it in his car, and beat on it like it stole his girlfriend.

Once he learns how to tune his engine, set up his suspension, burns up a tranny or two, he will probably be ready to sink some time, effort, and money into a fire-breather.
 
#24 ·
dan0311
just so you know,we ported our castings(twice) the heads will flow over 270 cfm. we ran 11s flat at 121-122 in a 67 Camaro. Similar to what you have. The car was all steel and weighed very close to 3000 pounds(about 3200 with driver and fuel)
Hope this all helps? When you decide to really match the parts exactly,Richard is the best guy here...
 
#25 ·
thanks for all the advice i think im just gonna have the heads cleaned up with new seals and spring matched for my cam and bolt it all together. just needed some advice before i did so. i got the heads realy cheap from a friend and aquired the intake also thats why i was wanting to use them if i could that way i can spend money on stuff i still need and get her going. your right i do plan on one day building a bad 383 for my nova but for now the 350,because was too hard to pass up. ill try to post some pics of my build soon. thanks again
 
#29 ·
dont know where i got the 3k to 7k for the cam its rated at 3k to 6200 rpm and i have some 1.5 steel roller tip rockers and standard length 5/16 dia by 7.800 length push rods these sound right for the build
Pushrod length will need to be verified for proper valvetrain geometry during actual final assembly & parts used. 7.8" may work fine.They may not.Anytime you change parts in the valvetrain,aftermarket heads,the length needs to be verified to obtain the proper geometry.
 
#28 ·
.
. Do you know the intake port CC's on the Sportsman II heads? Are they iron or aluminum? I suspect your engine will pull well into the 6,000's... maybe right up to 7,000... but don't know if you have the valve springs/retainers to handle that...

. Team G intake should work great...

. If your engine is truly at -0- deck, hope you used about a .035" - .040" thick head gasket...
.
 
#33 · (Edited)
Cool thanks for the link and as soon as I get a chance I'm gonna measure how far down the pistons are just to be sure I didn't have the block built I bought it from a friend at work who had it he said he wasn't sure how much it was decked. I talked to him last night he couldn't remember he has had it for a few years before I bought it. He went with a 400 SBC and never used the 350
 
#34 ·
I also have receipts for the cam and pistons used in the build the comp height of the piston comp is 1.56. According to the formula I used on a stock deck 350 and a rod length of 5.7 and stroke of 3.48 I got .025 down in the hole . But I will measure the depth at tdc to determine what it is for sure before I buy head gaskets. is around 40 quench what I'm shooting for
 
#36 ·
I also have receipts for the cam and pistons used in the build the comp height of the piston comp is 1.56. According to the formula I used on a stock deck 350 and a rod length of 5.7 and stroke of 3.48 I got .025 down in the hole . But I will measure the depth at tdc to determine what it is for sure before I buy head gaskets. is around 40 quench what I'm shooting for
.035 to .045 will work.
 
#37 · (Edited)
.
. Some brands of pistons have lower compression heights than they claim...

011150 World Products Sportsman II 200cc Iron Head Flow Data

Valve Job: Multi-angle intake and radiused exhaust

Valve Lift--.300 --.400 --.500 --.600 --.700 --.800
2.020 ------- 191 -- 231 -- 246 -- 256 -- 253 -- 254
1.600 ------- 123 -- 142 -- 156 -- 172 -- 183 -- 191


http://www.theengineshop.com/produc...rolet-iron-heads/sportsman-ii-iron-heads.html

Rocker Arms: 1.5 ratio (use of 1.6 ratio will require elongation of pushrod holes)
.
 
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