Hot Rod Forum banner

350 engine overhaul needs guidence

3K views 34 replies 10 participants last post by  J. E. Allison 
#1 · (Edited)
I've got a 350 in my 1980 chevy heavy half ton. I just bought the truck and the engine is getting to be pretty old. I plan on overhauling the truck. I've got a few of the basics done and now I am wanting to do the engine/transmission before I get to much farther. the transmission is a pretty newly rebuilt th350 with lockup torque converter. Has twelve bolt rear end and 3.08 gears. I was going to get a new block but decided to go cheaper with the one it has. As far as I know it is the original block which I would think is a 2 bolt main. This is my first project and engine build. I want it to be slightly more wild than mild. ATLEAST around 325 horsepower and 375 torque. But would prefer more in the 400hp and 450tq range. I like it pretty loud and have a nice thump and rough idle to it. However I want to have somewhat of a guess on my parts and such before I pull the motor and get into it. So assuming it's a two bolt main how much would that affect me making more power in the engine? what should I try and keep the power under to be safe. I plan on doing in this in the next 3 months or so. I want to stay under $2,000 and the cheaper the better. I could go above but would like to stay in budget. Needs to be pretty reliable too. And have it run on pump gas too. I am thinking I will need to get it bored .030 or .040 over. What would be an estimate on the cost of that? Is there any other machine work that I might need/consider? I think I am going to run edelbrock performer rpm heads, camshaft, and intake. Just to know I will have a good combo. Other than that I am not sure what to do and what additional parts are needed and what, if anything, I can reuse. I do have a performer eps intake now that I would like to reuse and save money if I could. As well as a brand new edelbrock 600 carb that I would like to use if only temporarily or just sell. So basically I need opinions and information on what other parts I need and what should I consider purchasing to be making the power I want for under my budget. Estimated figures on power and price would be nice. Thanks for all your help! especially if you read all of this! Oh and also would kind of stall converter would I be needing? Could I get away with stock? I need to have this setup complete and all the components of the drive train to be able to work together. I will not be needing any accessories (alternator, etc.), valve covers, or an aircleaner. I also have brand new HEI distributer, headers, and flowmasters. I know that some of this also depends on what I find once I get in there and tear it down but give me a rough guesstimate. :) Also 3.73 gears or so and shift kit are planned on being put in a little later or about the same time.
 
See less See more
#2 ·
Identify the motor

First thing you need to do is identify the block. There are casting numbers on the block that will tell you exactly what you have. The main bearing have a lot to do with your build, but often they don't contribute as much as some builders want to think. In very high hp and high torque setups the 4 bolt main keeps the crank stable as it tries twist up. In high RPM applications the 4 bolt mains keep the crank from gyrating out of the bearings. So it has it's application. To me, if I'm buying the only reason I care if I am getting a 4 bolt is that I might overhaul one someday and I will have a more versatile block to work with. As far as building up a two bolt, I don't have any heartburn building up a high performance motor using a two bolt main. What you need to know here is don't build more than a street and strip with a two bolt. You can get a four bolt for just a hand full of bucks and start the build off right. There also exist a ductile iron bearing cap designed to convert 2 bolt to 4 bolt, when you have your block cleaned, magna-fluxed and honed, they can aligne bore the new bearing caps for you. This is a cheap way to get a four bolt.

Any overhaul is going to cost you some money, so its important to get ahead of it. The last one I did came out very well. I will tell you how I did it so you can glean from it what you want. Read my next post. I don't want to make this one to long.
 
#3 · (Edited)
Yeah Ive been meaning to check the block number. Where would it be at? No I wouldn't build anything more than that on this block. If I ever wanted more (which right now I don't) I'd go to a 4 bolt. If I decided to get a 4 bolt now I would do it the most cost efficient way. My only reason for sticking with the 2 is to cut corners on the cost. I just figure I should have somewhat of a budget number goal. The budget I have set is below the actual funds I have. That way I have some room if I end up going over or have any surprises. But I'm not quite sure how cost will be for that kind of machine work. Thanks for the help too by the way. I am fairly new to this.
 
#4 ·
staying within your 2000 dollar budget wont be easy if you're trying to reach 400hp. you will need to look up the clock castng numbers to know what you have, but you will also know what you when you tear it down. a 2 bolt main is nothing to be worried about when building a motor under 450hp. IMHO i would stay away from the edelbrock heads, if you are on a budget look into some RHS pro torker heads or thier pro action heads but since you are running a 350 and i dont think you plan on spinning over 5500-6000 you wont need anything over 170-180cc heads. since you are looking at trying to hit 450tq i would look into both an aftermarket crank and rods, and of coarse you will need some hyper pistons, since you want to stay with pump gas should try and keep your compression around 9.3:1-9.8:1 if you stay in this area it would be easy to run it off of 89-91 octane, depending on how much decking needs to be done you should be looking at around a 18cc D dish piston with 64cc heads. you wont be able run a stock stall with the cam it will take to make 400hp out of a 350, about the smallest you'll be able to get away with would be about a 2500 stall, i might would look more into a 3000 stall but that will all also depend on what cam you chose. since this is going into a 4500-5000lbs truck i would look at a cam around 218-228 duration @ .050 as you will still want to keep the power down low, with this type of cam you will need to go after a good set of heads like the ones i mentioned before to reach your power goals but it is still very possible to atain. you will need to go with the 3.73's on this truck and build otherwise this truck will act like a dog till it gets to it's power band
 
#5 ·
The way I did it!

http://www.americanhotrodsolutions.com/iron_4_bolt_main_bearing_caps.htm

http://www.amazon.com/Engine-Builders-Handbook-Tom-Monroe/dp/1557882452/ref=pd_sim_b_4

Here are a couple of websites you might be interested in.

I like the way you are thinking but many guys are real pros and like to make personalization's that make life a little more difficult or expensive. I like edelbrock products and I like the way they have the performer line already matched up for builders like yourself. It makes life easy, just pick your level and get with it.

Idea one, have you thought of getting a brand new short block from Chevrolet for your build? Look it up and see what a brand new short block cost from them. you might be amazed at how cheap you can get it. If you are not impressed go to this web site and see if you are impressed http://www.jegs.com/i/GM-Performance/809/10067353K1/10002/-1?parentProductId=752506

if you don't like that just look around for what you might like. 2 grand will go a long way if you spend it right. Like the above link would allow you to sell all that stuff hove have on E-bay or Craigs list to offset everything you will spend on that kit. Sound attractive?

Now if that is to rich for your blood, I cant help you much. But if you just want to build up something special just to say you built it then that is different.

In that case I would start by looking at some professional crate motor builders and look to see what they have used in their motors. there are a multitude of engine builders out there that provide motors to all kinds of hotrodders. you can read what they have done. and they will even tell you what parts they put in them. Here is an example:

http://www.proformanceunlimited.com/specs/327/327_375_carb.html

Spend some time going over this and write back and I can tell you how to afford this stuff, there is a way believe it or not. personally I like the jegs combo for the price and what you get.....
 
#6 ·
you can expect to spend something like this for this build:
aftermarket 355 kit= 700.00 / a possibly better route 383 kit= 850.00
machine work to the block and rebalancing of the rotating assy= 550.00-750.00
decent heads= 850.00-1000.00 (do your homework before you buy)
complete valve train (hyd f/t)= 300.00
gaskets= 50.00-75.00
intake and carb (RPM, 650dp)= 500.00 (sell the ones you have)

so your homework on these parts, just because a name is big doesn't mean they are better. RHS or DART are IMO the best 2 iron heads makers there is out there on the market, and if you're gonna buy a set of cheaper alm heads then go after the Brodix IK180's. with expectations of 400hp i wouldn't go with an eddy 600 carb, i would atleast go with a holley 650 vac sec, if not a 650 double pumper. i haven't added all this up but i would guess it to be somewhere around 3500.00 or so
 
#7 ·
Those links did help! Thank you! Yeah I just wanted to have a good combo that's why I wanted the edlebrock combo. The name brand does not matter to me as long as they are of decent quality. I wouldn't mind going with personalized parts if I can get a good idea of which parts go well together. I was thinking crate but I think I want to go more into building it myself. No matter what parts I decide to get I will be looking around craigslist and ebay for deals. I have actually looked at what was in a few crate engines. I wouldn't even know which one to copy if I were to go that route. I have looked into short blocks as well. But by the sounds of it I should be okay running the block I have now. Which way would be more cost effective? I know that if I did start with a new short block It wouldn't put my truck out of service so I could still drive it around with the 350 that is in it. Also it would save me the hassle of going to a machine shop. I have done some research on some of this but I can't always find the answers I am looking for. And thank you for the price quotes. I'll do some more research on the price of things and if I can find deals on them once I have an idea of what to go with. So for sure go with a lower duration camshaft to keep power low? I want most of my power in the low to mid range. I have come across some decent looking heads in the 600-700 dollar range. Although I wouldn't be completely sure of how nice they are. I know there are a bunch of parts out there and it's just hard to know what to get and go with, and what works with what, that gives me such broad options that I have trouble knowing what I would want or what would be good.
 
#9 ·
80chevybigten said:
Those links did help! Thank you! Yeah I just wanted to have a good combo that's why I wanted the edlebrock combo. The name brand does not matter to me as long as they are of decent quality. I wouldn't mind going with personalized parts if I can get a good idea of which parts go well together. I was thinking crate but I think I want to go more into building it myself. No matter what parts I decide to get I will be looking around craigslist and ebay for deals. I have actually looked at what was in a few crate engines. I wouldn't even know which one to copy if I were to go that route. I have looked into short blocks as well. But by the sounds of it I should be okay running the block I have now. Which way would be more cost effective? I know that if I did start with a new short block It wouldn't put my truck out of service so I could still drive it around with the 350 that is in it. Also it would save me the hassle of going to a machine shop. I have done some research on some of this but I can't always find the answers I am looking for. And thank you for the price quotes. I'll do some more research on the price of things and if I can find deals on them once I have an idea of what to go with. So for sure go with a lower duration camshaft to keep power low? I want most of my power in the low to mid range. I have come across some decent looking heads in the 600-700 dollar range. Although I wouldn't be completely sure of how nice they are. I know there are a bunch of parts out there and it's just hard to know what to get and go with, and what works with what, that gives me such broad options that I have trouble knowing what I would want or what would be good.
I'm looking for somthing for you right now, i will be back!
 
#11 ·
Do not, i repeat do not buy one of the "hencho in Mexico" Mr. Goodwrench 350's like the one posted above for 2K, these motor's have had numours problems with quality as they are out sourced to be built in mexico. you just wanted to put a another close to stock engine in your truck i might would say go for it with this motor (not really, but i can see where some may do this) but if you want more power out of these motors you will need to redo the whole top end as well as these motors are built with the crappy O dished pistons that have a horrible quench pad, you want a D dished piston as the flat part before the D is the quench pad and has far better burn charactaristics. it was mention that you could sell the parts off this motor that you dont want, you wont get much for all of them, maybe 300.00 as they are very undesirable part, you might a 100-150 for the heads and then you might get another 100 for the cam and lifters and that would be it. you will need to build this motor or have a machine shop build it for you but this is going to cost you another 500.00-700.00. and like i said look up the perfomance from products before you buy them, dont just buy something because it's from a big company

take a look at the heads flow numbers of the heads i mentioned and the heads that you are looking at on this website, or you can also look on RHS's website for their flow numbers, as a general rule of thum i take about 2.5-5% off of the flow numbers to get a more acurate number as most all companies will test their heads with a 4.200" bore so that the numbers look more inflated.

look at this website, click chevy and look all the different heads you thought of running:
http://users.erols.com/srweiss/tablehdc.htm
 
#12 ·
Yeah I wouldn't go that route anyway. If I can I would like to sell them. If only for a few bucks it is better than having them lying around here. I am very thorough in researching and getting info before I buy products especially when it comes to my vehicle. Name brand is not a factor. Oh wow! That chart will come in handy! Thank you for the info.
 
#13 ·
350 engine overhaul needs guidance

i've done exactly what u want 2 do. the 2 bolt block is fine under 500 horse. w/ the edelbrock combo (RPM) you've chosen, youll reach your goals. as time went on, i went to a vic jr intake, and as i started port matching the vic jr 2 a fel-pro 1205 intake gasket, i said screw it, and hogged out both the intake, and heads 2 a 1206. this eventually brought me from low 12's 2 a best of 11.64, in a 3444# camaro. 2 bolt mains rock,as long as u are not a circle jerk,as extended hi-rpm's can make the caps walk. 79z
 
#14 ·
If I were truly on a tight budget, I'd use the Vortec heads on the existing short block (FWIW probably a 4-bolt).

Bore the block 0.030 for moly inlay rings and hyper cast pistons. Turn the crank if it needs it, bearings and gaskets. Get a 3-angle valve job done on the heads.

For the rest (along w/ the Vortec heads from the junk yard, craigs, etc.), add a Vortec intake (RPM if using a square bore carb, Performer-type if a spread bore) and a cam w/around 222-224 degrees duration @ 0.050", 110 LSA and around .460" to .480 lift.

No great amount of work is required to get the heads to handle that lift- just taking a little off the retainer bottoms and a switch to the "Z-28" stock diameter springs.

Dial in the HEI's timing curve and rebuild the Q-jet. Timing set and oil pump, couple rattle cans of paint for the OEM covers and block.

Fresh plugs, wires, cap, rotor, PCV valve, belts, hoses, coolant, oil and filter, etc. etc., etc. This short run-down isn't meant to have every little detail, just a broad view.

Let the HP/TQ fall where it may...
 
#15 ·
my87Z said:
Do not, i repeat do not buy one of the "hencho in Mexico" Mr. Goodwrench 350's like the one posted above for 2K, these motor's have had numours problems with quality as they are out sourced to be built in mexico. you just wanted to put a another close to stock engine in your truck i might would say go for it with this motor (not really, but i can see where some may do this) but if you want more power out of these motors you will need to redo the whole top end as well as these motors are built with the crappy O dished pistons that have a horrible quench pad, you want a D dished piston as the flat part before the D is the quench pad and has far better burn charactaristics. it was mention that you could sell the parts off this motor that you dont want, you wont get much for all of them, maybe 300.00 as they are very undesirable part, you might a 100-150 for the heads and then you might get another 100 for the cam and lifters and that would be it. you will need to build this motor or have a machine shop build it for you but this is going to cost you another 500.00-700.00. and like i said look up the perfomance from products before you buy them, dont just buy something because it's from a big company

take a look at the heads flow numbers of the heads i mentioned and the heads that you are looking at on this website, or you can also look on RHS's website for their flow numbers, as a general rule of thum i take about 2.5-5% off of the flow numbers to get a more acurate number as most all companies will test their heads with a 4.200" bore so that the numbers look more inflated.

look at this website, click chevy and look all the different heads you thought of running:
http://users.erols.com/srweiss/tablehdc.htm
Do your own research builder! I don't know that these motors are built in mexico, china, or canada. I have a production 454 in my suburban, it's bad *** and is pulling hard at 250,000 miles. I like stuff made in america and your old block may have been made in america, or may not have been. I wish i knew. But GM does not make cheap motors, the chevrolet short block is and has been the baddest most durable and capable motor on this earth for many years, If GM is making them in mexico you can bet your bottom dollar they are making them with the best steel and the best machining available. in fact the plants and equipment are new enough that the product might exceed what we make in the states. I know that pisses people off. and it does me too but the fact is that is the world we live in today is different and it aint going back to the way it was. Check with the chevy dealership in your area and see what he will sell a new chevy short block to you for and try to find out where it's made. If you think about it, how much does it take to make a short block? I think that the package from JEGS is probably a pretty fair deal. Just cause you pay 5 grand for an engine dont make it better. Good luck, by the way you might want to go to the GM performance parts website and download a catalog.
 
#16 ·
There is a very high probability that the Jegs motor is made in Mexico. That is a frustrating part of our life these days. but guess what, the one in your truck was probably made there too. Any parts that you buy to rebuild that motor will probably not be made int eh United states. So dont get all distracted on that issue, WHAT YOU DONT WANT IS A BACK YARD REBUILD, OR AN AUTOZONE SPECIAL. Good luck
 
#17 · (Edited)
I don't have an issue where it is built but I don't think I will run with a crate. I'll have to see about getting a block from them if I can get one cheap. But yes Gm performance parts has their engines made in a plant in mexico. It is stated somewhere on their website. I've never heard bad things about them though. I would buy a block from them. But anyway thanks for your help. I'll keep looking around. And to the above can you get pretty decent numbers out of vortecs? I heard they do pretty well. But I don't want to have to get them to a machine shop if I can just buy a set of heads for about the same price and be done with it.
 
#18 ·
80chevybigten said:
And to the above can you get pretty decent numbers out of vortecs? I heard they do pretty well. But I don't want to have to get them to a machine shop if I can just buy a set of heads for about the smae price and be done with it.
400 to 420 HP/TQ from unported, stock heads- w/the right cam and engine combination should be possible. Preferably a '86-up roller block would be the foundation, regardless.

If you can afford aftermarket heads, the sky (or your budget! lol) is the limit.
 
#19 ·
I still am not sure about the block issue. So to get the one I have now is going to be around $400+ to get reconditioned I'd just get a new block. It is the orginal block from '80 with the stock heads now. I'd kind of just like a new block to start my build and just build it over a month or two as I find good deals and things. And just leave the engine that is in it alone until I'm ready to swap.
 
#20 ·
I noticed when I reread your paragraph, that the sound is of some import.

Do yourself a favor. Don't get sucked into the "Bad-A" sound deal. :rolleyes: Build the engine to suit your needs- if sound is a high priority, just go to the Comp site and get a Super duper Thumper (or whatever they're calling it) lock the distributor w/36 total and be done w/it and save yourself (and us) the time of working out a GOOD engine for you.

This is not meant to be mean, or to belittle you in ANY way. It's just how things are. I apologise if I've read too much into the sound deal, but it's important, IMHO.

Most engines when built correctly, will 'sound' just fine. But to purposely build an engine for the way it sounds, w/o full regard for the performance, will have its *** handed to it by a seemingly lesser 'sounding' engine.

Just so you know... ;)
 
#21 ·
Meh No matter how I build it, it will sound good to me. I love the way it sounds now as stock! So as far as sound it's not an issue, as you said any engine build correctly will sound fine. I'm more into the performance part of it. So just regard that :D I am finding vortec heads pretty cheap or I could just go to a junk yard, and they seem pretty appealing, but don't they have to have some work done to them to go on a earlier model block?
 
#22 ·
80chevybigten said:
I am finding vortec heads pretty cheap or I could just go to a junk yard, but don't they have to have some work done to them to go on a earlier model block?
There are two main issues w/the Vortec heads in stock form.

First is the valve lift is somewhat limited. This can be overcome in a variety of ways, some costing more than others. The cheapest way is known by "ghetto grinding" (google it) the retainers on their bottoms and swapping out the valve seals and stock springs for different seals and inexpensive "Z-28" springs. This will get you around .480"- .500" lift capability w/o much expenditure.

Or, going a step further, Comp sells a beehive spring and matching retainer that will give you all you need in that regard. The valve guide boss needs to be cut down in height and diameter to best utilize this set-up.

The other thing is a Vortec-specific intake manifold needs to be used.

Vortec heads use a self-aligning rocker arm. Be sure to get them w/the heads if you buy a used set.

Other than that, the Vortec heads are a bolt-on. They do have pressed studs, so there is that limitation unless they are machined for screw in studs. This is where things start to get expensive, and where aftermarket heads start to make more sense.
 
#23 · (Edited)
Yeah I was thinking after all of that aftermarket heads might be easier. But what kind of extra work would need to be done to a kit like this? http://www.summitracing.com/parts/EDL-2098/
I'd probably use similar parts to this kit if I were to go vortec. I just don't want to deal with all the extra machining and things.
Although the RHS heads look to be pretty decent as well. I am not sure what intake runner and combustion chamber size I would want. I was thinking somewhere in the 180cc and 64cc range.
 
#24 ·
this kit would do the trick but i'm not in favor of buying top end kits, i prefer to pick out my cam, if not have it custom ground. i told you my opinion on the eddy heads but as for intakes they are the leaders, i'm also not fond of the eddy carbs except for a very mild street application. i mentioned before that you probably wont be truning this motor over 5500rpm, and since it is a 350 a set of 170cc heads would do just fine, but 180cc heads will give you a little more top end, and wont sacrifice to much low end as they are still not large runners. your combustion chamber size need to be figured out when you figure out what pistons and compression ratio you want to run, i told you before that a set of 18cc D dished piston with 64cc heads will give you around 9.5:1 depending on what need to be done to the deck. if you do get another block you will still need to have it looked and likely machined, but if you do you could kill two birds with one stone and go after a 96'-00' vortec 5.7L out of GM's 1500 truck line, you would spend less money this route and vortecs are a great head for a street motor, you will spend roughly 400-600 on all the machine work (that i would want done to them) so for the block and heads you would be looking at about 1000.00 in machine work, but i would still be cheaper than buying new heads and having the block you have now machined. you could also probably get away with reusing the stock crank and rods out of these motors as they can handle about 400hp, that would save you some more money, you can get the pistons for about 250-350.00, bearings another 75.00, gaskets another 75.00, vortec intake= 200 (better if you find one used) 650 vac sec carb=300, cam, timing chain, push rods=300, reuse the stock lifters, and rockers, and there you have a 375-400hp motor
 
#25 ·
80chevybigten said:
Yeah I was thinking after all of that aftermarket heads might be easier. But what kind of extra work would need to be done to a kit like this? http://www.summitracing.com/parts/EDL-2098/
I'd probably use similar parts to this kit if I were to go vortec. I just don't want to deal with all the extra machining and things.
Although the RHS heads look to be pretty decent as well. I am not sure what intake runner and combustion chamber size I would want. I was thinking somewhere in the 180cc and 64cc range.
One time you're talking about a $2K budget, then you link a top end "kit" costing $1700, before doing anything to the bottom end. To get you just 410 HP.

Bottom line: If you're looking for easy- buy a kit.

If you're looking to maximize your budget, you will need to get dirty. And "deal with all the extra machining and things."

There are as many ways to go about this as there are guys w/opinions. You should give some hard thought to your wants, needs and budget.

Your original 325/375 engine can be built for the $2K, using the Vortecs, unmodified. 400-plus HP is another thing altogether.

Be realistic w/your goals and budget, then we can pin your options down pretty close for you. But as it is, you're all over the map w/this deal.
 
#26 ·
just get started

Get an engine stand, a good block, and start building. Part of the fun is ordering your parts and receiving them. I have found myself receiving parts on friday afternoon, and working until 2:00 am talking with friends, and having a few beers. That is part of the fun. If it takes 90 days to build, so be it, that is 90 days of real fun. Get that book I showed you or check it out from your library. To do the whole thing for 2K you are going to need to be very judicious and frugal to come up with what it is that you want. but that will give you great satisfaction. I rather have my carb rebuilt locally, than I would pay two prices for one built by who knows where. those are the decisions you will make. Don't be worried about getting into the project, It will all come to you once you decide what it is you want. And one thing you must remember is that there is no part that does not have a home. And if it aint in it's home when you finish, you gotta go back and put it in. So don't leave any parts out. First thing you know you will have a very satisfactory motor that you can call all your own. And you will know more than most people about motors and building them.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top