Thread: My first build

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i am currently driving a 1993 gmc sierra 1500 regular cab long box 2 wheel drive with a 305 CI in it. I have recentley bought a 350 CI TBI used. It would be nice if it was sitting at about 400 hp, how can i get it there? what pistons would you go with? what camshaft ratio? should i get new heads or machine the old ones? How do i go about building a 400hp motor?

The GM TBI is a reliable unit but pretty limited in terms of performance. It cant take a lot of cam duration and you're definitley going to need a healthier cam if you're going to make 400hp. For 400hp you'll need a sizeable amount of engine work and performance parts. A stock 350 TBI non-vortec engine made about 210 hp.

Personally I'd save the money and do something like this.
325 Chevy Small Block Engine - Bolt On A Cam And Heads And Add 120+HP - Car Craft Magazine

Welcome to CHR!

You may want to see a parallel thread that advocates a BBC which is a sure bet for 400+ horsepower and when all said and done may be a good choice. I've always built small blocks but we have some great BBC guys here (Pat McCarthy is the world's best!). In that you have already bought a 350, here's my two cents on a 383 build and a few tips that I’ve continued to use for over 40 years with a proven combination of off-the-shelf components that will net you well over 450 horsepower and 460 plus foot pounds of torque.

As a side note: If you’re going to run this with an automatic my choice would be a well built 200R4 as it’s nearly identical to the TH350 and you can use your existing drive shaft. You could also use a 700R4 – your choice really – with the key being well built. Both transmissions have a low first gear and overdrive to give the 383 a nice launch as well as decent street manners even on the freeway (stay with 3:90 gears in the rear end and shoot for tires with a 30” - 33” diameter, 285/60-18 would be perfect). In either case, go with a 2500-2700RPM stall converter.

The components I have listed below are flat tappet, but you could certainly substitute a roller cam (with similar characteristics) and valve train if your budget allows such.

First and foremost – find a good machine shop where you can talk to the technician who will be doing the work. The prep on your block is critical. The 383 can be a screamer if built correctly, but heaven help you if clearances are not correct as the whole thing will come apart and you’ll have one very expensive door stop! Make sure that the technician has built many 383 motors. I know everyone has to learn somewhere – but you don’t want it to be your engine. The block doesn’t have to be a four bolt unless you’re going to race it real hard.

That said – have the block cleaned and tested – no need to build a block that has cracks or cannot be squared. Make sure that the machine shop understands that you’ll be building a screamer and that you want to have the crank journals align bored and the decks cut to 9.003” – this is an important measurement!! Have the machine shop install new cam bearings and new brass freeze plugs. Also have the machinist go over the location of all the galley plugs with you so you know where they are and that they have been properly installed. When you get the block back from the machine shop make sure you really scrub that baby down with hot soapy water. I like Dawn dish washing liquid and water straight from the bottom of the water heater. Put the block on the engine stand and dry with compressed air really well. Make sure you have a 55 degree or warmer day and paint the inside of the engine. I use Glyptal. Its $50 a quart from Eastwood – buy the brush on (versus aerosol) - a quart will do the job real nice (I use the disposable “China” bristle brushes from Harbor Freight). Also paint the exterior at this time too. Let everything dry real well – at least 48 hours, preferably in a warm garage.

Rotating assemblies are really your choice. Eagle makes a kit that includes crank, flexplate, damper, rods, bearings, pistons and rings for about $850. Part number from Summit is ESP-B13005E030. It’s probably fine for your application – uses a -7cc flat top and with the deck height recommended (remember that 9.003” measurement?) above should keep you in the 10-10.5:1 compression ratio with a .041 head gasket (see below for part number). Have your machinist press the pistons and rods together – it’s a bit tricky if you’ve not done it a lot and you need a press.

Use lots of good assembly lube (I like Red Line – carry over from old two stroke days!). Keep your hands really clean and wipe thing as you go (remember I told you to paint the engine? Lot’s easier to keep nice and clean with fresh paint inside and out!)

Oil pan assembly – Milodon 30901 fits stroker motors – might need a bit of adjustment with Eagle rods. Use Milodon 18750 oil pump with a 18314 pickup. Use Milodon 23050 oil pump drive shaft and 41000 one piece gasket (some may disagree – but I’ve never had an issue with the one piece when installed as a part of the original build when the engine is on a stand).. Milodon 81300 is an oil pan stud bolt kit – worth the $20 for ease of assembly.

Top the engine off with the components listed below:
AFR 1040 195 Street Eliminator heads
Double roller timing set - Summit is fine
Comp Cams 7972-16 chrome moly 5/16-inch pushrods
Comp Cams 812-16 lifters
Comp Cams 1305-16 Pro Magnum Roller rockers 1.60
Comp Cams 12-250-3 Xtreme Energy hydraulic cam XE284H - Duration @ 0.050": 240° / 246°, .507" / .510" lift
Edelbrock 2975 Victor Jr. intake manifold with a Demon 5402010 Mighty Demon 850 Carburetor
(Alternately, en Edelbrock Performer RPM and 750 carburetor will save a couple hundred dollars)
Fel-Pro 1205 intake manifold gasket
Fel-Pro 1003 head gasket
HEI Ignition - stock Chevy is a good unit - pair with a MSD ignition (stay away from Accel anything – my opinion)

Stop working when you get tired and you’ll save the headache of having to redo something. I still keep a log sheet on an engine and note everything I’ve done before I quit for the day – of late I’ve started taking pictures with a digital camera then have a visual record as well. It makes it a whole lot easier to ‘take-up-where-I-left-off, especially if there are a couple days between working the engine.

Have Fun,
Glenn

Originally Posted by green machine

i am currently driving a 1993 gmc sierra 1500 regular cab long box 2 wheel drive with a 305 CI in it. I have recentley bought a 350 CI TBI used. It would be nice if it was sitting at about 400 hp, how can i get it there? what pistons would you go with? what camshaft ratio? should i get new heads or machine the old ones? How do i go about building a 400hp motor?

This will be an exercise in futility that will leave you broke with a bad attitude. Curb weight of your truck is 4001 lbs. Figuring you and a buddy weigh 350 together, that puts the weight of the truck at 4,351 lbs. By the time you spend money on engine, converter, trans and rear end upgrades, you're gonna be very upset when some Ricky Racer in an 1800 cc Honda with a $500 boneyard turbo setup hands you your azz on a plate.

Begin with a lighter vehicle, like maybe an S10/S15. My son drove a '72 Chevy Luv truck with a bone-stock (no headers either) 455 Olds/TH400 in it when he was in high school. It went low 13's with a stock converter through a narrowed Olds rear w/3.90 gears hung on leaf springs.

Your reference to "camshaft ratio" tells me that you know little about building any kind of motor, so you will need to upgrade your education before you begin adding soup to anything. Begin with some books by David Vizard.

listen to this man. even with 400 hp the truck would be a dog .

I bought a 93 GMC in 93 still drive it today (Daily driver) 350 tbi I wouldn't waste my time building a small block for it to much money to haul that weight around. I don't know what your intentions are but you have a nice truck but not a nice racer. Stock its quick enough to get out of its own way but crazy to race it.

Ouch – Are we’re being kinda rough on this guy? Maybe I’m missing something here but he’s already got the truck and just bought a 350 TBI and is looking to use it as a base to replace his lil’ ol’ 305 wheezer. He didn’t mention racing or a budget, rather wanting to build 400 horsepower (over twice what the 305 would make on its best day) and asked for help.

I certainly don’t want to pick a fight with either Tech or Shine (both of whom I greatly respect) but maybe this guy just wants the experience of “building a motor” and having a great cruzin’ truck. I’ve driven my share of warmed up SBC trucks and while they’ve not held a candle to a 502 big block Chevelle, they can be fun to drive to the local A&W or the lumber yard. Hope we haven’t scared him off.

Regards All,
Glenn

Originally Posted by glennsexton

Ouch – Are we’re being kinda rough on this guy? Maybe I’m missing something here but he’s already got the truck and just bought a 350 TBI and is looking to use it as a base to replace his lil’ ol’ 305 wheezer.

Glenn, you answered his question perfectly, it's just that I see the whole scenario a little differently. With the OP asking how to reach 400 hp, the motor you laid out for him would easily eclipse that number, but with all the upgrades that would be necessary to make the whole mess work, I think he would be disappointed. I see $10,000 in parts and labor invested in a slow truck. There are no flies on you buddy, so please don't take offense.

93 still TBI ? or was 95 first year for vortec ? built a dozens of each any ways if TBI you can not used any thing but a stock cam the Map and computer willl not take a up grade on cam . mass air you can use a much bigger cam with some work but can be done . mark 6 454 out to 489/496 will get you close to 400 hp and a boat load of tq .but would have to upgrade injectors /bore out intake for bigger thottle body . computer /harness out of a vtech 454 truck .i have a customer that just went threw all this with a mark 6 454 . building the engine is not hard but getting it tune in may take time

thanx a lot for the advice, and that is correct all i am looking to do is to get experience in rebuilding a motor. Im not going to drag it i just want something thats a little better then my stock 305 CI. So it dose not need to be 400 hp but it would be a lot nicer then what i got now. i just want something that will be fast and fun to drive. I have nothing but time to do it. i found a guy in the area to machine the block, i have been recommended to go to him by many people he does high hp motors i plan on going to talk to him some point next week.

Glen-all due respect.I disagree with even the most basic builds and the use of Eagle.

I know that there have been some issues with Eagle however, in my opinion; Eagle and Scat are decent entry level products and fine for folks who are not going racing every weekend. That said it’s always a good idea to check the fit and finish of Eagle (and Scat [or any machined part for that matter]) cranks and rods before final installation.

I talked with Eagle’s tech rep at a show and according to him; both Eagle and Scat cranks and rods start their lives in China where they are cast/forged and then shipped to the United States for the final machining and finish.

Buying parts from GM, GMSPO or GMPP is no guarantee that the parts were made in the United States. GM, Ford, and Chrysler all have parts made in China, Mexico, Canada, etc. I have purchased GM cranks and rods that have “Made in Mexico” tags on them.

Key here is to check things out and verify proper clearances. On a “first build” it would be wise to have your machinist walk you through the process – it would be money well spent and I find most real professionals will provide this as a service to someone who wants to learn.

Another plus of buying from Summit or a reputable first tier local supplier is if you find a flaw, they will make it right - or such has been my experience as one who now only builds an occasional motor. Pat, Jerry and those who do this for a living - building a coupe a week - have a much different perspective as well as being able to correct the alignment or finishing issues immediately in-house.

Regards All,
Glenn

Originally Posted by glennsexton

I talked with Eagle’s tech rep at a show and according to him; both Eagle and Scat cranks and rods start their lives in China where they are cast/forged and then shipped to the United States for the final machining and finish.

Regards All,
Glenn

You are certainly correct, and if we all want to go in on a group buy we can compete with Eagle and Scat (if we're willing to buy 20,000 at a time from these Folks)-notice their part numbers and Eagle's are just about identical-

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The thing with Eagle is a QC issues from taper on journals to the cranks breaking behind number two main bearing.Some right out the box needed to be machined 10/10 to make them right.
$200 to $300 can and does make a huge difference when buying parts like that.I am a huge fan of Howards built here and machined here. It's not so much where it is built,but a bigger bang for the money spent. So if a guy is building a engine and is short of that amount,I suggest he saves alittle more and that will come back to him ten fold over time.

i seen scat take 1000HP so it just not low buck stuff same with this list PBM/Scat .Cat .Eagle .Elgin .Manley Wheeler . Pro comp . Ohio crank. RPM.PEP.Comp star .and another dozen or so all forging come from china and i used all of them many times on this list and many no name yellow box stuff . to say its all the same is not true .to say that scat is just like eagle is not true and asking a guy from eagle if his stuff is the same as scat .is like asking a guy at McDonalds if his burgers are like Burger king ? well they both come from beef ???. well you hope ? eagle rods are ok there crank are far from the finish of a scat . there are thing about eagle i do not like and could make a list on here about there bolts in there rods to the finish on there cranks and how bad some of the finish is on the raw parts of there cranks were scats look as good as a 1800. callies magnum