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fresh sbc 350 build 400 hp poss?

15K views 28 replies 9 participants last post by  jasont/a83 
#1 · (Edited)
:welcome:

hi im jason i just built a 350 for my lil bro for as grad pres
was wondering if my combo is a good setup here is what i have
1984 trans am aprox weigh 3200 lb with driver
7004r with 3:42 gears

cam ... comp cams extreme energy 12-213 3 h292 244 dur lsa 110

1973 010 hi nickle block 4 bolt main

416 heads fully ported polished "stock valves" intake runner size 2 1/8 X 1.50
200cfm est valve size is 1.85 1.5
bowl blended valves un shrouded removed all the flashing in the exhaust ports
heads are 58cc with a .015 head gasket hit 220 psi in all 8 thinking that's 12:1
pistonsare flat tops are h345np hypers with chrome molly rings

rods are powder metal rods like 1 up from stock like an lt1 rod no name on them

total piston and rod weight are 920g

crank is steel out of a 283 49 lb

the stall in the trans is a 2800 from what i was told from a trans shop cause
the car was a 305 hard to believe that

intake is a edlbrock dual plane rpm air gap performer with a bg speed demon 660 cfm carb

pertronics ditro with accel coil acdelco 45ts

so hopin to hit low 12s :evil:
 
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#2 ·
jasont/a83 said:
:welcome:

hi im jason i just built a 350 for my lil bro for as grad pres
was wondering if my combo is a good setup here is what i have
1984 trans am aprox weigh 3200 lb with driver
7004r with 3:42 gears

cam ... comp cams extreme energy 12-213 3 h292 244 dur lsa 110

1973 010 hi nickle block 4 bolt main

416 heads fully ported polished "stock valves" intake runner size 2 1/8 X 1.50
200cfm est valve size is 1.85 1.5
bowl blended valves un shrouded removed all the flashing in the exhaust ports
heads are 58cc with a .015 head gasket hit 220 psi in all 8 thinking that's 12:1
pistonsare flat tops are h345np hypers with chrome molly rings

rods are powder metal rods like 1 up from stock like an lt1 rod no name on them

total piston and rod weight are 920g

crank is steel out of a 283 49 lb

the stall in the trans is a 2800 from what i was told from a trans shop cause
the car was a 305 hard to believe that

intake is a edlbrock dual plane rpm air gap performer with a bg speed demon 660 cfm carb

pertronics ditro with accel coil acdelco 45ts

so hopin to hit low 12s :evil:
jason, I don't know what to say.
First you tell us you built a 350. Then you tell us you used a 283 crank. With a stock 4.000" bore in the block, that would make a 302 (that's if you could still find spacer bearings). Bored 0.030" would make it a 306. Then you tell us that you used 350 pistons (H345NP's that have a 1.540" compression height). A 283 crank with 5.7 rod and 1.540 piston would make a stack of 8.740", a little more than a 1/4 inch from what it should be to make a real motor. Now, you could have used a 6.000" rod with a 2.000" big end, but that would put the stack at 9.040", or about 0.015" popped out of the deck at TDC with a nominal block deck height of 9.025". You could still do that with a 0.015" gasket until you started the motor. You'd have zero piston to head clearance and all 8 pistons would crash against the bottoms of the heads and the whole shebang would go downhill from there. About the best you could ever get for static compression ratio with flat-tops in a 302 with 58cc heads is 9.78:1, so now you're telling us that you recorded 220 psi with a 12-213-3 cam that closes the intake valve at 74 degrees ABDC?????????

I was your age once.
 
#3 · (Edited)
type o sorry was a 350 crank and yes the cranking pressure was 220
and i did have my engine decked at 0 so when the piston sat in there it was flush with the top of the deck no down the hole bull**** 3.48 x5.7
was the rod and stroke .. as i mentioned the duration at .50 is 244 av is 292
seat to seat

i did all the work i pressed in the pistons in to the rods boy that was fun for doing it the first time have to be quick with that piston pin keep that thing cold the rod nice and hot not glowing never done it before. and i wasn't going to pay some one to heat something up and do the same thing i read up on it and did it only ruined one piston it expanded cause i got the pin stuck in there and over heated the piston and it expanded to 4.030 at the bodom top was still 4.000

btw the engine runs as of yesterday 7:41 pm 03/15/09
found a leak in the front seal .. but it ran real good mini starter has a hard time turning it over think its the starter it self
dose any one know how to get one defective one returned i called and emaild a week ago and they arnt there or something powermaster 9600 starter... ?


ill post a youtube link of the engine running i have a before one ... its really sad
http://www.youtube.com/watch?v=3g-mNPQldX4
thats a before ... i found what that noise was u can hear it when i rev ... every rod barring and main was spun the crank had a 1/8 in groove in it .. pic here

http://viewmorepics.myspace.com/ind...dID=13053888&albumID=2432049&imageID=51739184
and this one too


http://viewmorepics.myspace.com/ind...dID=13053888&albumID=2432049&imageID=51739173
 
#5 ·
DoubleVision said:
This a drag car or street car or both?
Was the 700R4 beefed?
Does the car have T tops?
Is the rear the 7.5?
yes both mostly street
700r4 is stock running an extra cooler
yes has t tops

i dont think the piston is going to kiss the head considering the compression distance and ring position i copyd a circle track setup i wish i could of used 1.94 too but dident have the money for it. will be getting a set of dart pro 1 heads this summer

i will be welding in a full roll cage and tying it in to the sub frame connectors

i haven't set time yet
 
#6 ·
piston to head interference has little to do witht he height of the top ring land. If you're truely at zero deck running a .015" gasket you will be buying pistons, rods, and bearings long before you get those heads... Long before you actaully get the car to the first gas station. No one is crazy enough to run that tight of quench on a SBC.
 
#7 ·
That much cam with smogger 305 heads? IMHO, you'd be better off waiting until you have a decent set of heads before even running it.

And, you need to rethink your 0.015" piston to head clearance. :nono:

Just use a good quality composite head gasket in the 0.040" neighborhood and you'll be spot-on, quench-wise. It's a no brainer, guy!
 
#8 ·
engine is working good set the time at 32 deg till i change plugs to r42ts
temps are good sits at 200 on the highway 160 at a stop think my radiator is too small for the engine its a single core i will be upgrading that..
i do like the tight quench must not be at 0 like i thought it was i did have it milled but that's when my dad had it and the machine shop went out of bis
should be like 9.24 i only had them surface it to make sure it was flat
i remember it wasn't much tho when i put the pistons in the piston sat flat with the deck tho ... ?
 
#9 ·
jasont/a83...with chrome molly rings [/QUOTE said:
Chrome rings or moly (plasma or filled) but not both. :)

There are steel rings but steel rings have to be coated so they will not scuff. That's where the chrome, moly or gas nitriding comes in.

One last comment on your head gaskets- IMHO, you should re torque the heads after you've heat cycled the engine a few times. Steel shim head gaskets are fairly unforgiving in this regard.
 
#16 · (Edited)
I've not had the opportunity to use one of the engine dyno software programs, so don't know if any of them could give an estimate w/those heads and their unflowed port work.

400 HP might be a bit of a stretch for those small intake valves matched up to a cam that makes its power upstairs.

Once the engine's broken in maybe the OP could run it through the 1/4 mile and post the results. That would allow a fairly close estimate of the HP- even just the top speed and weight of the vehicle would be enough.

the stall in the trans is a 2800 from what i was told from a trans shop cause the car was a 305 hard to believe that
If it's a stock converter, I'm w/you- no way.

Hard to say how this car will 60 foot. The heads might crutch-up the bottom end some, but it could use more gear and a loose converter.
 
#18 ·
jasont/a83 said:
ive noticed ...


well there's a new problem...
engine will not rev past 3000
backfires and thu carb and exhaust secondarys will not open

thinking carb is too small its a 650 demon with 74s for mains plugs have a brownish tint to them
Was the valve to piston clearance ever checked? It may have bent the valves, considering the tight piston to head clearance and the cam's overlap.

Or if the valves were floated (unlikely if it hasn't revved past 5K rpm).

I doubt the carb being a 650 has anything to do w/it- I ran a 455 Pontiac/'81 Camaro with a 4777 Holley. Ran 12.7 w/3.23:1 gears...

Plugs shouldn't be white or black; somewhere in between. Yours sound OK, for what you can tell by the description.
 
#20 · (Edited)
i think i have a fuel problum the carb seems like i run out of gas im running a stock fuel pump thats about 4 psi .. demon i think needs 8-12 right ... cause it revs up then backfires thru carb then wants to die i put bigger jets in and it got worse like i wont see 2500 rpm it just backfires ...? and the plugs are a little dark now so i went from 66 to 74 cause the engine started heating up on the highway and that took care of that the cam timing and ing are dead on valves arnt leaking or bent so im going to try a new pump the fuel pump is stock 305 ? im going to get an electric one ...
 
#21 ·
jasont/a83 said:
i think i have a fuel problum the carb seems like i run out of gas im running a stock fuel pump thats about 4 psi .. demon i think needs 8-12 right ...
About 5 psi is the max for that type of carb. 4 psi is enough, providing the volume is adequate.

The engine running hot isn't too likely to be solely because of the jetting- more likely is timing too retarded.

I'd get close to what came in the carb, maybe one or two sizes larger to start with and tune it from there.
 
#22 ·
i had the same heads on a 385 (stupid i know) and stock they could only flow about 200 cfm @ 0.500 that is garbage worked over you may be getting 205-210cfm @ 0.500 that's still gargbage, that was the only thing killing the motor about 340hp, but with a different set of heads its more like 420hp (for my 385) same cam and everything, get rid of those heads and i would do like everyone says and go to the .039 gasket your quench is way too low, optimal is arounf .037-.041 and like stated before when you put that thing around 5k your gonna smack the heads :nono: , there are much better ways to get higher compression ratio, you cant compromise your quench like that, with different heads i would say that you will likely be around 410-420 but right now if you get it running right you might get 330-350hp not much more, those heads just dont flow, the 84 T/A is not likely 3200 with driver unless the driver weighs 0lbs, cause that and the camaro (87 Z28 is what i have) are 3150-3350 depending on options mine is about 3450 wtih me in it (im about 220) that 700R4 (i love them) is garbage stock cant handle over 300-325tq go to monster transmissions.com and get one of there rebuild kits, if you feel like tackling that your self or they sell a good one for 1200, stall with that cam needs to be up around 3500 for the best performance you could even go to 4000. what rearend? the crappy 7.5 with stock G80 "posi", that will be what breaks in the rear, you mentioned that it had 3.42 gears is that aftermarket, cause non of the 82-92 F-bodies came with larger than 3.23's and very few came with those (very few) most IROC's came with the 3.08's, i would advise you to atleast get a better set of gears and a good posi, like Eaton, aurburn not as reliable with the cones, and eaton you can rebuild aurburn you cant, good luck, like i said i have a 87 Z28 so i have already run into all these problems :D
 
#23 ·
like i said im not totally sure about fuel pressure but when i start to rev it
and it just backfires i already set time to 32 deg seems to like that any less it dont want to run when i was assembling the engine i have adjustable crank gear was a cloyes dual roller had a square a triangle and circle they were
-4 0 +4 i set it to zero so i dont know why else the engine is running like it is cause it ran fine before it blew up with the same combo now its running like a turd i lined up 1 at tdc put the cam in lined up the dots and assembled did i miss anything ? when i had it apart ?

i remember having an old Holley 600 on there back when i first got the engine and i took that carb off and put it on another buddies 350 and the fuel pump blew past the acc pump put it back on mine and it didn't do it he was running 6 psi on the Gage ... thought it was odd that it would do that .. now im using the same fuel pump now as i was then could it be dying ? cause when i crank it really isent alot of pressure comming out of that hose its more like a slow stream im using 3/8 fuel hose :confused: i have never had this much trouble getting a sbc 350 going im going to hook up a vac gage tomorrow see what i have thats another thing i think i have low vacuum im just going to confirm it i have no power breaks almost NONE ... yes i will be yanking those heads off ... but i have to get the car movable first dart pro 1 heads . are what i want ... so ive been trying to call demon to see what they need for pressure but i cant seem to get the time right ... eastern time dam them ... :smash:
 
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