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My first 350 build

16K views 135 replies 11 participants last post by  prostreet6t9 
#1 · (Edited)
Ok so ive decided to build a SBC 350 for nitrous. The goals are a 200-300 shot. For now i guess let me just tackle the bottom end as it will be a while to fund this motor and right now im at phase one, having the block machined, And purchasing a rotating assembly. The block is an "010" 68-76
4-bolt main.

This car will be a track car with very minimal street driving. I dont even have a car as of yet. First i plan to build the motor and then go from there.

I beleive i need to run an all forged rotating assembly correct? I also beleive i want a 10:1 or less compression (Id prefer to run 91). I was told for my power goals of 600+hp i will have to run H beam rods, This correct? Also the machinist guy tells me i should balance the Rotating assembly. Is this a power thing or a reliability thing? I want the motor reliable but i cant afford to do every little trick thing to make maximum power. Anything else i should look for or watch out for is much appreciated.

Also this is my first post so hello everyone. Im not here to suck up your info and scoot. If all goes well some day i can contribute usefull info of my own. Maybe this thread can continue throughout my build from start to finnish.

-Kenny
 
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#2 ·
hello and welcome.First,you are starting at the wrong end of the car.
or better yet,get a car, set up the suspension(or buy a used rolling chasis)driveline and engine need to be matched for racing.
RE: balancing=mandatory and yes it does add a small amount of horse power.
Racing and budget? start with a car,,,,
 
#3 ·
Well part of the reason im starting with the motor is i live in an apartment with a small single car garage. Im doing this mainly for something to do. The car kind of has to come second as i will likely be building iy in a friends garage and dont want a car with no motor taking up his garage for a long time while i slowly build it.

My budget for the motor is bassically unlimited as ill just throw money at it check by check. but id like to have the motor completed in 9 months or so. Calculate that with my available income and it would ideally be around a $3500 motor. If that price is unrealistic ill just have to extend the build time.
 
#36 ·
My budget for the motor is bassically unlimited as ill just throw money at it check by check. but id like to have the motor completed in 9 months or so. Calculate that with my available income and it would ideally be around a $3500 motor. If that price is unrealistic ill just have to extend the build time.
The budget for the engine is "basically unlimited" and he's going to throw money at it check to check.So this opens a door to one school of thought.

Then a time frame of only"9 months". I am thinking it is going to take longer than that funds wise.

But a price point of $3500.

And him saying that if $3500 isn't enough,"I'll have to extend the build time". To that end I agree.

So here is what I am thinking.Certainly there are still new developments in first gen SBC's all the time.But all those are being overshadowed by the LSx series engines.Especially LSx series engines with power adders.I just don't want to suggest a first gen that he is spending as he can to have finish and over time have built,that gets run over with the tech from a LSx series engine.Is it going to cost him more??. Yes,yes it is. But as he can check to check build it,the long term investment would be better and closer to the current tech going on. I then is a matter of commitment to the build,but I believe a positive suggestion.:thumbup:
 
#6 ·
Near stock?... I know i can build an all after market cast rotating assembly bottom end for around 1200. Of course i cant use cast parts... but a stock 350 for 3500? The old saying "they saw me coming" would come to mind.

making my own motor mounting points etc in said car is not an issue. Infact i was considering putting the motor in a fox body mustang.
 
#8 ·
sorry K,maybe ask CnC what it costs to blue print a block? you need your pistons before you bore the block,therefore you need the heads before you choose the pistons. The block needs to besquared/decked/align honed after it was cleaned,threads chased,new frost plugs and cam bearings.
you will need the crank and rods and pistons to trial fit after boring before decking and squaring

Price out those parts and machine work,add 250-300 for balancing after the second or third trial fitting and measuring piston to valve clearance.
research for parts pricing is your job because your suppliers might be different from the ones I use here?
 
#9 ·
Right im still not certain on the exact process time line of what i need to do what. as of now my plans are have the block tested and then ask the machinist what parts he needs to move forward.

But again if he needs the entire rotating assembly... all my questions above come into play. If heads are also needed to complete the machining process what stats am i looking for in a head? High cc Low cc? Big exhaust valves? etc.

I dont mean to throw a million questions out.
 
#17 ·
Kenny , I don't want to hurt your feelings but I'm not gonna hold nothing back. If you are interested in building a race motor how about getting some reading material. This may be a shock but building a race motor at the least cost will set you back about $10,000. Checkout the story on this build. http://www.onedirt.com/tech-stories/engine/bad-***-sport-mod-355-sbc-engine-build/. You won't have to have that much compression but you will need the same light weight parts. If you are going to have a machine shop build the motor for you check out these motors from CNC Motorsports. USRA Stock Car SB Chevy 350 Spec Stage 3 Race Engine - Race Engines | CNC Motorsports | Car Parts | Truck Parts | Competition Engines. Those CompStar lightweight cranks are sold by Callies.
 
#19 ·
I understand you can throw as much money as your heart desires at a motor. But are you saying its not possible to build a mild reliable nitrous motor for a good amount less then 10k? With what ive seen online for parts id have to do some work spending 10k. But im new to this like i said so maybe theres a lot im missing. The first link dosent work for me.
 
#21 · (Edited)
No riot, im still learning. Ive always heard 4 bolts the way to go so i did. Even my machinist was glad to hear i was planning on using a 4 bolt. Not saying he was right but yeah. Why is a 2 bolt better with nitrous?

And in the not trying to start a riot fashion im curious, are you guys playing it VERY safe with your recommendations? I ask because a 600whp honda motor is really not that impressive. They resleeve the motor and make 800whp all the time. I decided to shoot for 600hp because it seems like a very mild build for a 350. Am i wrong in that assumption? calling a 600hp 350 a "Race Motor" seems extreme. Its just a little nitrous on a 350. I just want to drive down the track on the weekends. 12's dosent seem like a race car to me. Im assuming thats the ballpark id be in with that power... maybe high 11's with a heavy tail wind.

In this thread 600hp seems like a fortune fed ground breaking race motor build. Then a couple threads down $3k gets you 400hp no problems all motor. whats going on here? lol

Please put it into perspective for me. Maybe i should rethink my options before its too late. Is it cheaper to build a 600hp motor with no power adders because i dont have to go through all the beefing up to keep it reliable on nitrous?
 
#25 ·
Everyone has an opinion. Some people have years of experience, and they know some stuff that works, and some stuff that doesn't. You will have to read all these posts, and decide for yourself what you want to do.
There is no easy answer, and there are many ways to do the same things. The only thing anyone can do to help you, is try to keep you from making the obvious major mistakes that most inexperienced engine builders make.
Also, machinists all have their own ideas. And oftentimes they contradict each other. So it is important for YOU to do your own research. That will serve to protect you from the bull*****ters out there.
My thoughts on your project:
600hp from a reasonably-priced 350 small block is a stretch. Don't focus on a specific power number. Instead, focus on building the best engine your budget and time-frame allows. 4-bolt block is fine. No more than .030 over. You will want to run a steel crank and forged pistons. You do not need H-beam rods. But you do need "good" rods. You also need ARP bolts everywhere on this engine. You WILL need to have it custom balanced. You should have the line bore checked. You should have the block decked. I would go with some good aluminum heads like AFR. Single plane intake like a Victor Jr. Decide your target RPM range and pick a cam that works in that range. The higher the RPM, the more expensive your engine needs to be. I would stay under 7,000rpm.
Run a mechanical lifter flat-tappet cam with full roller rockers. Double roller chain. GOOD oil pan. ( Not a chrome china stamped POS ) MSD 6AL or better ignition. Good fuel pump. If your pump is high pressure, run a regulator and a splitter for your nitrous system. I would not go over 200 on the kit. 150 would actually be better. They make good plate systems that run on 5-6psi fuel pressure. Your target compression ratio should be 10:1 if you plan to run pump gas. Be advised, you will have to pull some timing out when you spray it. ( Mixing some race-gas will make it run a little better. ) 750cfm race carb on the single plane. Good full length headers with at least 2 1/2" exhaust pipes.
This setup would be respectable, and not cost you an arm and a leg. Also be fairly reliable. The MSD 6AL would keep you from accidentally overreving it. Your machinist needs to setup all the clearances, ring gaps, and cam bearings. He also needs to do all the block work. YOU can do the assembly, if you are good with a torque wrench, and you understand pre-lube and proper sealants.
Your big-ticket items will be the aluminum heads, carb, the machine shop bill, and your crank-rods-pistons.
This motor could theoretically make over 400hp + 150 shot of spray.
( Would get you in the ballpark. ) PRICE? Maybe $5,000 or so, including the nitrous kit, but plan to spend more. Unexpected expenses always come up during the build.
I seen people buy a brand new STOCK 350 crate motor for $1,600... put a few bolt-ons on it: cam+springs, intake, carb, headers, MSD ignition... top it off with a 100hp nitrous kit, and go racing with much success in a LIGHT CAR. ( Like a VEGA, or even a Nova )
The thing is, if your chassis is heavy, you won't be quick. And the rest of your setup is just as important as the engine. The weight of your car, the tranny/converter, rear-end/tire setup and gearing is all critically important.
It all has to MATCH.
We used to be able to build some cool budget racers back in the day, but good rollers are getting harder to find, and prices have gone WAY up in the last 10 years on performance parts.
Good luck.
 
#27 ·
When talking about building a mild 300-400hp motor your talking about a 355, using aftermarket cast steel crank, 4340 I-Beam rods, hypereutectic pistons, 8740 or Arp2000 rod bolts. P-series main & rod bearingsfor about $900 in a 30 year old cast iron block. Some jump to the 383 ci. to gain extra cubic inches. Some go as far to install a set of $1200-$1500 aluminum heads usually not done on a budget. When you talk of 200-300 shot of nitrous this changes everything. You then want a 4340 forged steel crank, H-Beam 4340 alloy steel rod with Arp L19 hardware, forged pistons, H-series rod & main bearings. Usually at around 600 hp you start thinking about a aftermarket dart block. You then will have a choice of the stroke you want to use. Here is an example of a rotating assembly the average hotrodder would use. Scat Engine Rotating Assemblies 1-40010BI - SummitRacing.com. At $1900 then probably $600-$800 for block prep. Engine gasket kit ??? You then have the cam selection $350 non-roller or $1000 roller. Lifters. Valve springs and retainer with locks. Oil pump. Timing chain & gears set. Intake manifold and carburetor. Reworked ported heads or new aluminum heads. You said you would have a machinist to assembly it $2000. Sit down and make a parts list of what you want to work with and then start getting prices is the best way to start.
 
#29 ·
When you talk of 200-300 shot of nitrous this changes everything.
AMEN brother.

He is absolutely correct. Which is why I suggested you run a 150hp plate kit. Keep it simple, and keep the costs down. Keep it reliable.
You said you are in this for the "fun factor". It's not "fun" when you trash your new engine because you are trying to run too much nitrous, and you don't have all your ducks in a row.
 
#30 ·
I do the same thing as most guys who has built cars.I tend to tell how much it costs and end up discouraging a guy just trying to start out.

So here is my advise of over 40yrs of racing.Don't build something you couldn't afford to replace.If that scales your plans back some it is for good reasons.
 
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#35 · (Edited)
If you want to have the most fun with nitrous,, build a cheap *&^% motor that you won't cry over if/when it fails. It will only fail from a tuning mistake.
If a $7000 short block with all the goodies, fails, How much fun is that.

but if a $800 350 short block fails,, you can laugh and learn and do it again.

Learn to build you own simple basic 350's
A near stock motor with a big cam, good heads etc will go like hell and take a ton of nitrous.

couple keys high rpm from launch to finish. Do not launch at a low rpm on nitrous.
high stall converter.
Big duration cam that can rev and shifts the power and cylinder pressure up high.
Solid flat tappet is fine.
Get the exhaust out. big exhaust, big exhaust duration.
Good heads You need flow
good basic valvetain,, it has to rev
Good high octane fuel 110+ race gas.
Don;t be afraid to hit it hard. It will take it.
Large piston rind end gaps, larger piston to wall clearance
Watch the timing on nitrous... nitrous speeds up the combustion.
A tunnel ram works really well with nitrous..
I like the idea. If i can get away with a cast rotating assembly thats cool. On my CRX on nitrous id launch around 3k and stay 3/4 throttle until it hooked up and then go WOT to spray. It was on a WOT switch.

Will 110 save me some money on parts or is it more of a safety thing. For example will running 110 with a good top end make it capable of running a cast assembly?
 
#37 ·
The guy doesnt even have a car to put the engine in,,,, He should take the 3500 and buy a clean V-8 late 90s Camaro and take it to the track the day after he buys it.On street tires and stock trim it will get him down the track with very little costs. Buy tires as required and update and improve as budget allows...
Building a gen 1 small block for maybe a fox car in the future? seriously?
 
#38 ·
To each their own but screwing around with a clunker with unknown cans of worms every where dosent sound like much fun. Sounds like more of a money pitt then just building it totally right the first time. Why spend money on parts on a running car i dont plan to use? My dodge neon is as fast as a stock 90's camaro...just saying..
 
#40 ·
I hope you are successful in your quest. At mission raceway we have an old Mustang with a 355 chevy in it.mid 10s,beautiful car--expensive build.
We also have a 77 Camaro with a 383,the kind with the distributor in the front of the engine.I think its a 13 second street car,low budget,just did it because he thought he could.
Engine swapping is what hot rodding is all about. some ideas are practical,some are just whims.Can it be done+yes,then ask why you would do that? are there better ideas? what will this project cost when done? what will you have when its finished? what will it be worth?
My project is a very good example of what is not a good idea,but I like it,so I did it.

Hope that w/e you have at the end is what you really really want
 
#41 ·
This may sound like a VERY strange idea, but I'd build your car to handle that power, then build a good turbo and induction system. Run that on a stock long block with maybe a solid flat tappet cam swap. If and when it pops you just need another $300 long block. BTW, for 600fwhp you only need a modest 10-15 pounds of boost. Turbos are a LOT easier on an engine than nitrous too.

Its about the cheapest way to get into the 10s and STAY there.
 
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#50 · (Edited)
If/when you choose to build a expensive so called bullet proof motor, you had best be fully prepared
to waste that money spent if you make a simple boo boo on a big shot.

Cause it will come unglued. How many of those are you gong to build and keep smiling?

Yep, i am doing my best with what little i know and the machinist to get it right regaurdless of the fact that im putting expensive parts in it. He said he is going to bore it a tad more then typical to make room for expansion for one example.

The machinist is very adamant that i use H beam rods for the power im looking for.

If i get away with 2k in the bottom end i think im lookin good. As some have said previously its not going to be cheap for what im trying to do. Its looking like a $5k motor on a good day. Its ok though. I know what i want, and im going to make it happen the best way i know how.
 
#45 ·
I dont know but if this was my build I would start with car get one that runs so dont have sit in a buddy shop go ahead and fix all the weak points in car because dont care what car you buy with 600 hp you will be replacing stuff axles gears tires shocks suspension drive shaft you not just going drop 600 hp in and go wish it was like that but all you going do is smoke off some tires and still prob get out run by ur neon if you want the motor to be 600 hp.with 200 to 300 shot and stay together it will cost more than 3500 and I would never. Put 300 shot on gm block I would be using dart I have seen what happens when one comes apart with 200 shot and it wasent pretty can only imagine 300 just my 2cents and there is a lot of hidden cost to a motor like that also with timing box to retard good trans for that power nitrous stall big carb by time you done you will have more in the car than you think it happens to use all.
 
#46 ·
We run 114 race gas when we use the bottle on our BBC 632. But a clear understanding of how hard nitrous is on parts also come into play.No way do we run the bottle from over 2,500 out the back door.In fact the button and how long the nitrous is run is on a timer.Mid lap using nitrous of only .002 netted in the 1/8 4.50's@ 150 mph in a RED.
I disagree it's hard to play catch up.In my career I can tell you a number of times I lost to being mph'er.

I totally agree with Cobalt in that 800 hp on a stock block is risky best case or not.
 
#48 ·
20 yrs of 9.90 racing where N/A was used with a glide/brake.Those launches are as hard or harder than nitrous.Pretty much all strokers.Good friend of ours lost his good engine early in the season.Forced him to race a cast crank engine.He held his breath on each launch for the whole season.That thing was a grenade with the pin pulled.Torn it down at the end of the yr and junked it.It was trash.

Point being is we shouldn't advise guys of our high risk adventures many of which have only enough money for the one engine they are asking about.Thing with that high risk is then it is much better to be "lucky" than good.The idea of what? At first stated 800hp and then 1300 hp on a stock block/cast crank is just not logical.
 
#49 · (Edited)
This is a stratagy mistake... make the car hook right from the starting line. launch the car at a very high rpm to avoid nitrous shock. Over torqing the engine, bending connecting rods.
You could have covered the 1/4 mile qucker, using a smaller shot all the way down the track.
It's hard to play catchup.
Sorry i should have specified it was a street car. Spraying on street tires on the street out of the hole isnt an option. Doing that would just send it directly to redline faster then a street bike revs up. A smaller shot would have helped for the first couple gears but the top end really did makeup for it. I remember racing a moderatly modified EVO. He destroyed me out of the hole and at about half track i went by him like he was standing still.
 
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#53 ·
I was running falcon azenis not 500 treadwear tires off grandmas oldsmobile. Only time i had an issue was when upon turning around to line up my right front rolled through some dirt. a weak burnout didnt clean it well enough. launched and was steering left and still turning right towards the shiny ZO6 i was racing so i had to get out of it. I thought for sure i broke an axle. took me a couple days mentally playing it over to figure it out. A better tire would have only made it a worse case in that situation.

You can get killed 1000 different was street racing. This is why i dont recomend it. We were all young and dumb.
 
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