Tips for Rebuilding 350 for Firebird

[poopapooman]

Hi
I recently pulled a 350 from a 77 Caprice Station Wagon at my grandfather’s farm. The car has been sitting since the mid 80s but according to my father and uncles the engine ran and drove fine when it was sat. The reason my family sat a perfectly running car was because the car was given to them by a wealthy women up the road who was sick of the other problems with the car. The car had broken door handles and the interior was garbage. After further asking, I found out that the car had a relatively new engine in it because the old one was blown and she had a new one put in. the block is blue which could mean nothing but a pretty good mechanic told me that these blocks were good and generally were not put in by gm (he could be wrong so don’t take my word for it). After pulling the engine I turned the crank with a tire arm and a pipe for leverage to check for compression, it had compression.

I plan on rebuilding this engine for performance, so I’m not going to just throw in some new oil and springs and run it. I plan on pretty much buying everything new that I can (maybe not the heads $$$$). Currently I have taken everything off down to the heads and block.
Originally I wanted to stroke it to a 383 but I took off the oil pan and it’s only a 2 bolt. Now I know many people have different opinions about stroking a 2 bolt but I don’t want my post to turn into a 2 bolts aren’t strong enough argument. I look at it like this, I can still build a pretty decent 350 and since I’m only a college student and can’t afford to put money into an engine that might blow in a year or two. I plan on dropping this engine in my 92 firebird which is going to be a street/strip car, mostly street for I might just take it to the track for qaurter mile times. I want to build this engine best for stoplight to stoplight street racing (low to mid power) and would be willing to compromise power for high speed racing. I look at it this way: an unsafe start ticket is nothing to worry about compared to a 150 in a 65 ticket.

Now that I got the background and planning info out of the way here’s where I could use some tips. I know from researching and reading some info on engine rebuilding but I don’t have any 1st hand experience like many of you gear heads on this site have. I do have an uncle that is a very decent mechanic and has rebuilt engines many times but he lacks new technology info and the initiative to build a fast car. he’s kind of one of those old gurus that puts down everything saying things like "your car is fine the way it is" and complaining how much work everything is. But I bet if he looked back at when he was young he be doing the same thing as me. he admitted he’d help me rebuild the engine and use his garage but when it comes to taking the right path and choosing the right parts I would like better advise otherwise the engine would be a late 70s 350 with stock parts.

My first question is about magnafluxing. Since the engine reportedly ran and had compression should I spend the money to magnaflux the block?

Now I know there may be cylinder ware and a machinist may recommend boring to a certain point, but say the cylinders are pretty good. What should I have the engine bored to? I was thinking 30 over but maybe I could go 40. Someone told me never to go like 50 or more over unless you plan blowing your motor in a year but I think he was only talking about off-road drag cars. Remember it’s a 2 bolt.

Since it’s a 2 bolt. Maybe I can strengthen up the main by having splayed caps installed. Does anyone know if machine shops do this? Price? Would it be worth it?

Now I know prices can be cheaper and more comfortable knowing parts will fit by buying a rebuild kit but if I can spend a little more money to get the best performance possible by buying parts separately than I will. Now money is a problem but I’m a very good saver and would rather get the best performance I can while I have the engine on a stand and not in the car. I don’t want to think back in a couple years saying I wish I went with these pistons or cam...ECT. Can anyone recommend any rebuild kits; I don’t care about emission testing since in NY, inspections are easy and I have many friends, so if the kit is meant for strip only and puts out more power so be it(its not like California here). Also if anyone has gone thru this b4 and recommends buying parts separately then let me know.

Not sure what I should do with the heads. I know I can port and polish them but it would be a little tougher since they’re iron heads or I could spend a grand for good heads. What do u guys recommend and how much more power can I get by buying new heads rather than to port and polishing them.

Next thing is cam. Many builders recommend choosing your bottom end parts and heads first. Which sounds like a good idea. But after looking around at cams I became confused about their specs. I’m not sure which cams are better for low to mid power because of their specs say for instance a cam offers 1200 - 4200 rpms 260 duration .427 lift and 110 lobe separation. Now correct me if I’m wrong but the confusing part is that when you’re at a stand still and you accelerate your not shifting till the power band so you need your power at higher rpms. I know I may sound stupid but I’ve been trying to understand cams for awhile and I’m still a bit confused. I slightly understand the other specs but I’m still not sure what the better range of numbers is for duration, lift and lobe separation to get the best low to mid end power. So if someone could give me number ranges for these specs to get the best low to mid power that would be great.

Now I could be wrong but I think intake and carb are pretty easy. Just choose the intake and carb that offer the best cfm air intake and consider clearance.

I’m sure somebody out there has put and older style carbed 350 in a thirdgen firebird so can anybody offer advise on the oil pan and headers for clearance issues? I don’t think there’s any difference of third gens but mine is a 92 if there is.

I know I’m going to have to get new motor mounts but that’s pretty simple.

It’s kind of early to think about transmission and rear-end but many say it’s good to have your drive train planned out in order to get the best of what u want from your car. In my situation I want a car that can get from 0-60 fast. My firebird is an automatic but as we all know there is already a hole above the tranny because the auto shifter is on the floor. Is the hole in the right location and big enough to put a manual tranny in? Many have told me it’s a pain to put a clutch and tranny lines in but would it be worth it?

I know the higher the gear ratio the faster off the line the car will be but I don’t want to be only able to go 60mph and I don’t want the wheels to spin only at the touch of the gas for that would cause me to loose races.

For the power the motor will have a stock tranny and rear-end would obviously be a bad idea. So can anyone let me know if it’s worth it to rebuild a tranny and rear-end with stronger aftermarket parts or buy an aftermarket tranny and rear-end? What are the better quality aftermarket transmissions and rear ends out there?

I m sorry about the extremely long thread but I tried to explain everything so the people who may try to help me can actually offer answers instead of more questions because the author of the thread wasn’t specific enough.

Thanks,
Tim

[darndot]

I have a 350 SB that was bored .60 over. The only bad part is the block is done after this rebuild. You always want to do the minimum.

You might check some of the packages that come together as a kit. Heads, cams, and intakes work better if they designed to work with each other.

Welcome to GMi.

[Slideways]

I don't suppose I could convince you to put a Pontiac 350 in there, could I? I know they came with Chevy motors, but it would be cool to have '92 with an actual Pontiac in it. Nah, for your first build a small block Chevy is perfect. As for your questions, check out our www.carcraft.com and check out their tech articles. Those guys are all about budget builds, and the last thing you want to do on a first build is mismatch parts and waste money. If you read about an engine build and you like the power it made, duplicate it part for part and you can expect to make similar power. I think you should go mild with your parts choices, since high-lift cams will often not have enough vacuum to run your brakes at idle, and an engine in a street car will spend most of its time at low RPMs. Don't be tempted by high-end power and build a drag-race engine that needs a high-stall converter.

My $.02

[IROCNROL1]

My advice would be to visit the F-body sites and break your questions down a little. There are some people here that can answer your questions, but there are lots of them there, and they specialize in your particular car.

You might also add up what all those parts cost, and compare that to a GMPP crate engine, like a ZZ4. You might be surprised, especially if you put a price on your time. Also, if you are inexperienced, it makes a lot of sense to buy a complete, proven combination that already has the correct block, crank, heads, cam, and intake. Less time and less headaches=more fun.

Your engine is an unknown quantity. If you want to build it, check your engine and head numbers first, to see if it's a good starting point. Odds are, at least the heads are probably worthless from a performance standpoint. Two bolt blocks are OK for street performance, but the crank, rods, and pistons that you have probably aren't.

I could go on, but I'm not trying to discourage you. It's just that there are so many different ways to go, that you really should keep it as simple as possible and rely on advice from people who have been through what you are starting to get into. Good Luck!

[poopapooman]

Originally Posted by Slideways

I don't suppose I could convince you to put a Pontiac 350 in there, could I? I know they came with Chevy motors, but it would be cool to have '92 with an actual Pontiac in it. Nah, for your first build a small block Chevy is perfect. As for your questions, check out our www.carcraft.com and check out their tech articles. Those guys are all about budget builds, and the last thing you want to do on a first build is mismatch parts and waste money. If you read about an engine build and you like the power it made, duplicate it part for part and you can expect to make similar power. I think you should go mild with your parts choices, since high-lift cams will often not have enough vacuum to run your brakes at idle, and an engine in a street car will spend most of its time at low RPMs. Don't be tempted by high-end power and build a drag-race engine that needs a high-stall converter.

My $.02

It would be nice to have the Pontiac 350 but i was given the block and figured i'd save some bucks not having to buy a block.

[poopapooman]

Originally Posted by IROCNROL1

My advice would be to visit the F-body sites and break your questions down a little. There are some people here that can answer your questions, but there are lots of them there, and they specialize in your particular car.

You might also add up what all those parts cost, and compare that to a GMPP crate engine, like a ZZ4. You might be surprised, especially if you put a price on your time. Also, if you are inexperienced, it makes a lot of sense to buy a complete, proven combination that already has the correct block, crank, heads, cam, and intake. Less time and less headaches=more fun.

Your engine is an unknown quantity. If you want to build it, check your engine and head numbers first, to see if it's a good starting point. Odds are, at least the heads are probably worthless from a performance standpoint. Two bolt blocks are OK for street performance, but the crank, rods, and pistons that you have probably aren't.

I could go on, but I'm not trying to discourage you. It's just that there are so many different ways to go, that you really should keep it as simple as possible and rely on advice from people who have been through what you are starting to get into. Good Luck!

well the cheapest crate engine is around 3 grand and thats just a short block if they sold a complete engine for 3 grand then id consider. plus the specs arnt that great. id probably spend the same or less money rebuilding myself, the engine would be built to my standards and id be more proud if i built it myself.

as for the engine not having good crank, rods, pistons. i plan on replacing pretty much everythingexcept the block. if the heads are crappy i guess i'll have to buy new ones.

can the heads still be worthlesseven if i replace the rocker arms , springs averything and port and polish them?

[ockgator]

you can get a basic Goodwrench 350 for around $1500 or so... it's good for 240 hp but a mild cam, decent intake and headers will really wake it up, IIRC to the tune of around 300 or so HP, if you go that route you'll probably be $$$ ahead in the long run since you already have all the accessories you'll need(dist,water pump,etc)

2 bolts are good up to roughly 350HP and/or 5500 rpm

[poopapooman]

Originally Posted by ockgator

you can get a basic Goodwrench 350 for around $1500 or so... it's good for 240 hp but a mild cam, decent intake and headers will really wake it up, IIRC to the tune of around 300 or so HP, if you go that route you'll probably be $$$ ahead in the long run since you already have all the accessories you'll need(dist,water pump,etc)

2 bolts are good up to roughly 350HP and/or 5500 rpm

im sorry but guys im replacing everything, money is a problem but i want to know that i put everything i can in this rebuild.

i like the info but im pretty much sold on rebuilding the engine and just would like some tips on my questions so i dont make mistakes

even if u can only answer 1 question that helps me

u say that 2 bolts r good up to 350hp and 5500rpms which iv heard before but would splayed caps increase strength?

[nailhead425]

We'll start off by assuming that smog checks aren't an issue...

First thing I would do is get a number stamp set and stamp the numbers of each rod and cap before disassembly.

Take the block to the machine shop have them clean it, magniflux it and check the bores. At most you'll be out a couple hundred bucks. If the block is good, they'll give you and idea of how much overbore you need. Same goes for the crank and rods.

Your max overbore will depend on your block, not what anyone else says. Once they check it, you'll know. Generally speaking 0.060" over bore is max.

Don't worry about splaying the caps. Buy a main cap stud kit and put it out of your mind.

OE flat top pistons from late 60s-70 w/ 4 valve reliefs will net around 10.2:1 compression with 64 cc heads. These are typically called "claimer" pistons because they are cheap, cast, and generally used by circle track guys.

Pay the extra bucks to have the assembly balanced and blue-printed. Don't be afraid to ask the machine shop questions. Likewise, be honest with them about your intensions.

You'll need to check the casting number on your heads. If they are stock heads you'll have small valves and large combustion chambers. Look to replace them with O.E. 350-Vortec heads or World Products Torquer series. Both flow well enough for 300hp and are affordable.

For a first-timer I'd just get an Edelbrock cam, lifter, and timing chain set. The performer cam works great in this application, is easy to install and set up, and eliminates all the speculation.

I'd run a Performer intake (make sure it has a Vortec intake pattern if you use Vortec heads) and a 600cfm Edelbrock carb.

Holleys are great for top end power, but again Vic has spent lots of money developing his Performer kits, use all of the Edelbrock stuff and you'll be very pleased.

Your oil pan will fit, and run your large-cap HEI. Typically a 3" open element air cleaner will fit on top of the carb and intake, but always check FIRST!

For exhaust I'd get a F-body spec header system and a cat-back 3" exhaust system. Since you likely won't use a cat, put in a 3" test-pipe.

If you have the stock 700R4 trans (it was a v-8 car, right?) you can install a lock up switch for od only. TCI makes them. If you elect to run another trans, or your 700R4 is from a V-6 car, consider the TH350 from the wagon.
You'll need a torque arm mounting kit.

Your stock 7 5/8" rear 10-bolt is sort-of strong. Stick with a 235/60-r15 tire and a mild gear and you'll have a great balance. If you're keeping the 700R4, go with a 3.42 or 3.73 gear. If you're installing a TH350 go with 3.23-3.42.
A limited slip will help with traction, but also help save the rear end from a costly blow up. Remember your 7 5/8" 10-bolt has 28-spline axles if you're buying a limited slip unit.

Figure around 310hp/380 lbs ft, mid 13s in the quarter mile, and nice driveability.

[poopapooman]

Originally Posted by nailhead425

We'll start off by assuming that smog checks aren't an issue...

First thing I would do is get a number stamp set and stamp the numbers of each rod and cap before disassembly.

Take the block to the machine shop have them clean it, magniflux it and check the bores. At most you'll be out a couple hundred bucks. If the block is good, they'll give you and idea of how much overbore you need. Same goes for the crank and rods.

Your max overbore will depend on your block, not what anyone else says. Once they check it, you'll know. Generally speaking 0.060" over bore is max.

Don't worry about splaying the caps. Buy a main cap stud kit and put it out of your mind.

OE flat top pistons from late 60s-70 w/ 4 valve reliefs will net around 10.2:1 compression with 64 cc heads. These are typically called "claimer" pistons because they are cheap, cast, and generally used by circle track guys.

Pay the extra bucks to have the assembly balanced and blue-printed. Don't be afraid to ask the machine shop questions. Likewise, be honest with them about your intensions.

You'll need to check the casting number on your heads. If they are stock heads you'll have small valves and large combustion chambers. Look to replace them with O.E. 350-Vortec heads or World Products Torquer series. Both flow well enough for 300hp and are affordable.

For a first-timer I'd just get an Edelbrock cam, lifter, and timing chain set. The performer cam works great in this application, is easy to install and set up, and eliminates all the speculation.

I'd run a Performer intake (make sure it has a Vortec intake pattern if you use Vortec heads) and a 600cfm Edelbrock carb.

Holleys are great for top end power, but again Vic has spent lots of money developing his Performer kits, use all of the Edelbrock stuff and you'll be very pleased.

Your oil pan will fit, and run your large-cap HEI. Typically a 3" open element air cleaner will fit on top of the carb and intake, but always check FIRST!

For exhaust I'd get a F-body spec header system and a cat-back 3" exhaust system. Since you likely won't use a cat, put in a 3" test-pipe.

If you have the stock 700R4 trans (it was a v-8 car, right?) you can install a lock up switch for od only. TCI makes them. If you elect to run another trans, or your 700R4 is from a V-6 car, consider the TH350 from the wagon.
You'll need a torque arm mounting kit.

Your stock 7 5/8" rear 10-bolt is sort-of strong. Stick with a 235/60-r15 tire and a mild gear and you'll have a great balance. If you're keeping the 700R4, go with a 3.42 or 3.73 gear. If you're installing a TH350 go with 3.23-3.42.
A limited slip will help with traction, but also help save the rear end from a costly blow up. Remember your 7 5/8" 10-bolt has 28-spline axles if you're buying a limited slip unit.

Figure around 310hp/380 lbs ft, mid 13s in the quarter mile, and nice driveability.

-thanx for the long valuble post

-smog checks arnt an issue but 92s were supposed to have cats so when i get it inspected i might have to gut the cat and weld a pipe thru it. but most likely it wont be a problem in the worst case i can take the cat off after inspection.

-dont u think i should buy new connecting and pushrods meant handle more power?

-forged pistons are a little more money but are a lot more durable than cast do u think it would be worth it

-the bird has a v6, the tranny from the wagon is gone so i need to find a tranny

-the rearend in my bird is a limited slip and had 3.23 gears. i kinda planned on going with posi so i can burn rubber well.

-is that hp rating at the wheels or the crank?
-

[nailhead425]

If you have no trans, try to find an '87-'92 700R4 out of a Camaro/Firebird with V-8 and add the TCI or similar TQ converter lock up swtich. Or you can have a shop modify it to lock up in od only. Try to swap your 700R4 for exchange or part of the cost of a v-8 version. '93 up units won't work and pre-'87 units aren't as strong.

As long as the crank and rods check out okay at the machine shop, don't waste your money. For what you are looking to do, a set of ARP rod bolts and crank studs are plenty. In fact, 375hp is still safe, so there is a sizeable margin for error. Don't get forged pistons. They cost more, require looser piston to wall clearance and are not needed. If you think you might run a little more power, bigger cam, or nitrous, try hypereutectic pistons. They are lighter than forged, good for more HP and mid-priced alternative.

Cats are pretty cheap and readily available. So, if you have inspection, do yourself a favor and tune it right and run a 3" cat. You'll notice very little, if any decrease in power and it won't stink (a clue you've got a built engine).
**Of course I don't condone the defeat of any emission control device**

If the limited slip in the rear axle is still sound, don't change it or add another. Posi is a GM name, like Sure-Grip, Trac-Lok, etc. If the limited slip unit is weak, most diff shops can rebuild them. Don't add a detroit locker, ez-locker, ARB or any other positive locking diff. Keep a clutch type limited slip. This is help keep you from chunking the rear end.

The HP is approximate for the crankshaft. The RWHP depends on trans, gearing, tires, etc.

[69Chevy]

Originally Posted by poopapooman

im sorry but guys im replacing everything, money is a problem but i want to know that i put everything i can in this rebuild

I replaced everything but the block, oil pan and timing cover when I built my 383 Stroker in my 69 C/10. it came to around $5500, including exhaust system. The engine lasted 14 months before eating up 9 lifters sending metal through everything. No matter what you decide to do make sure you have a GOOD machine shop do all the work. That and the guy that helped me assemble mine was the downfall.

Otherwise I'd say having 350 hp in a Firebird would be fairly quick, I have a 84 T/A and it was fun with the original measly 190 hp 305 and the rebuilt (cheaply) 305 I bought to put in it. I got the engine already built form a machine shop that had been pulled out of a mid 80's pickup after about 2000 miles. It dropped right in as far as oil pan clearance. I did away with all the emissions junk- A.I.R., cats, etc. I also replaced the stock computer controlled carb (CCC) with a rebuilt Quadra-Jet. I left the stock exhaust manifolds on it, I previously had true duels ran out the back so I left that as well. Naturally the Check Engine light was on, but I had expected that. It needed some burnt out dash light bulbs replaced anyways so I went ahead and pulled out the engine light bulb, no more light!

That engine lasted about a year before flattening out the cam, I moved on to my C/10 and stroker while my T/A sits. I do have a 97 Vortec long block(spun a rod bearing and destroyed the crank) that I plan on rebuilding to maybe a max of 400hp to put into the T/A. It will have to wait on the stroker though. Story of my life.

Good luck with whatever you decide and be sure to keep us posted on progress!! Welcome to GMi too!

[howpeculiar]

FOr starters, you can forget the heads that are on that smog era motor. ALso, 2 bolts have been known to hold up to 600hp. Get a stud kit. Look into a nice windage tray as well, every little bit helps. For a gas pump driver, don't look at a static CR that will go past your available fuel. If you can get 93, then look at 10:1 to 10.5:1 as a practical iron head limit. Costwise, you would probably come out ahead buying a top end kit from Edelbrock or Holley. They offer matched components for a given displacement with actual tested results that you can count on. They both offer kits that include heads, cam, intake, and carb. Good way to go for around $2200. If you follow that route (which nets you aluminum heads), just follow their reccomendation for final CR and buy your pistons accordingly. I highly recomend the kit route for anyone that isn't locked into a specific component (if you had a set of good heads already, that would defeat the savings). GET YOUR BLOCK MAGNAFLUXED! Don't ever, ever, ever skip that step. Just because the engine ran in 140hp trim, does not mean there isn't a stress fracture somewhere dying to cause you grief at 450hp... If you plan on more than .040 bore, pay for a sonic inspection as well. Better to find out now if your block can handle the load. You can fit almost anything in your engine bay, and I would recomend you stick with an HEI based distributor unless you are planning on spinning the engine over 5500rpm all the time. You will notice that the motor mounts for the 2.8L (or 3.1, same engine) that was in it are not the same as for the SBC. I would suggest you get a tubular K member. What are you going to do for your accesories?

[poopapooman]

sorry for the long delay had some troubles in college. i have reconsidered what i want to do with the 350 block. even though its a 2 bolt main i want to stroke it to a 383. i think it'l be okay bc im building it for a street car emphasizing low end torque. i know people may question why i want to sacrifice top end power for low end power this is because i want to be able to beet other cars on low traffic roads around me with 8th to 1/4 mile straight patches. so i guess what im tryin to say is i want to build my 383 to be the best at 8th to qaurter mile street racing.

Now i know b4 i said that im on a budget, but not to take your guys advice for granted but i want to do more than keep the stock bottom end and throw on top end stuff. i pretty much wanna make my own crate engine using the old block. now i know i could probably buy a crate engine for the same price but it wont match my specific specs for low end power i want. i want to be able to go to the gas station for fuel so i need it to run on pump gas.(around here they have 87, 91 and 93). from what iv heard u cannot go much over 10:1 compression on pump gas or you'll detonate.

Now i know to raise compression several methods can be done and i know to build a 383 u need to bore the cylinders 30 over. the other ways to build up compression that i know are to deck the block, small cc chamber in head and a thinner head gasket. i want to find the cheapest way to get around 10:1 compression unless i can go more on pump gas.

so ideally if i was a millionare which parts would i buy to build the fastest 383 for 8th to 1/4 mile street races. after getting this info i can understand the manufaturers specifications on the elite parts in which i can shop around and make compromises between performance, quality and prices.

from looking around iv found a kit that is probably ideal for my situation if u can suggest better go ahead

Northern Auto Parts :Chevy 383 Stroker Engine Kit - HP383KHW Hypereutectic Piston W/Crank

http://www.northernautoparts.com/Pro...ctModelId=1674

[nailhead425]

A typical 383 requires a 0.030" overbore. But depending on the condition of your block you may need a 0.040" overbore. Either way, the machine shop will tell you. With a flat-top, 4-valve relief piston, in a .030" overbore, you'll have around 10.4:1 with 64cc heads and a normal 0.038" gasket. A thicker gasket will drop your compression to around 10.2:1. With 76 cc heads you'll be around 9.5:1 with a regular comp gasket, 9.7:1 with a thin metal gasket.

How much compression you can run with pump gas depends on alot of factors, most importantly cam lobe seperation angle and overlap.

Consult cam manufacturers and your machine shop for the best advise regarding duration, lift and most importantly Lobe Seperation Angle.