91 tbi 350 is trashed, time for 383. Where to start?

[sport91]

So it appears the motor in my 91 sport has decided to lock up, got a few trick to see if we can change this but Im pretty doubtful it will happen.

I have read around enough to know that if you are gonna do anything more than a normal rebuild on these motors the 383 is worth the little extra cash it takes to do.

My question is where do I start??? Im clueless as to what this involves :o
Crank? Pistons? New intake and throttle body??? A kit to do this would make my day :cool:

Someone please enlighten me and links to products needed are very appreciated.

Thanks in advance

Scott

[powermatt99]

http://www.chevymania.com/tech/383.htm

This has some good info. Its at least a starting point.

[D-BoB'91]

Eagle makes a balanced 383 kit that comes with everything...check out summit or jegs. I've got a '91 Sport that is about to get the stroker upgrade and I'll probably do the roller conversion at the same time. :rocking:

[1BadZ71Tahoe]

Eagle makes a balanced 383 kit that comes with everything...check out summit or jegs. I've got a '91 Sport that is about to get the stroker upgrade and I'll probably do the roller conversion at the same time. :rocking:

I can vouche that the Eagle 383 Stroker 4340 Forged and Internally Balanced assembly is the most superior hunk of metal i've purchased in a long while. Well worth the money to even get a street cast version. :cool:

Edit: My machinist had to hardly touch anything to get the assembly in balance, but went the extra mile to be within hundredths of a gram. Prepping the block via hot tank, magnaflux, then bored .030 over and oil valley getting notched plus if you want a roller cam you'll have to get your lifter valley drilled and tapped out for your spider retainer.

As for what to buy, we need a whole budget for the build. you can spend anywhere from $1,500.00 to $15,000.00

- B

[sport91]

ID like to keep it around the 1800-2500 if possible including machine work. Not looking to make any passes ayt the strip but if I have to go through this motor I would at least like to come back better than what it started as.
I know alot of my investment will depend on looking machine shop prices as well.

[sport91]

Those kits dont look too bad, is there anything different I have to look for on this motor compared to an older 350 or is the only real difference the centerbolt heads and intake?

And thanks for your help guys.

[D-BoB'91]

Those kits dont look too bad, is there anything different I have to look for on this motor compared to an older 350 or is the only real difference the centerbolt heads and intake?

And thanks for your help guys.
Pre-'87 had the 2 piece rear main seal...after got the 1-piece, as well as, the provisions to go roller. All the cars after '87 got the roller cams, but the trucks only have the provisions and not the equipment. You can easily find what you need to do the conversion though...I believe it's roller cam, roller lifters, pushrods, spider, and timing chain. Might want to check though :dunno:

Like 1BadZ71Tahoe said, you will have to get the lifter valleys drilled and tapped if you go the roller route...unless you get lucky like me. My TBI block already has the lifter valleys drilled and tapped. :thumbup:

[1BadZ71Tahoe]

Pre-'87 had the 2 piece rear main seal...after got the 1-piece, as well as, the provisions to go roller. All the cars after '87 got the roller cams, but the trucks only have the provisions and not the equipment. You can easily find what you need to do the conversion though...I believe it's roller cam, roller lifters, pushrods, spider, and timing chain. Might want to check though :dunno:

Like 1BadZ71Tahoe said, you will have to get the lifter valleys drilled and tapped if you go the roller route...unless you get lucky like me. My TBI block already has the lifter valleys drilled and tapped. :thumbup:

My only correction to your above statement is that there is no rhyme or reason to the truck lifter valley tapping. I have pulled the intake manifold off two 88+ blocks from trucks and neither had provisions. Some do, but not ALL.

- B

As far as the original poster, i would go with an Eagle Cast 383 stroker kit. There are two different styles of balance. Internal and External. If you plan on having your transmission changed, you'll want an internal. I think you'll be fine with an externally balanced engine where the damper and flexplate are used to keep the assembly in balance. it's already balanced from the factory so your machine shop will only have to do what I have suggested in my above post.

Get Clevite 77 rod and main bearings, and as much additional ARP hardware as you can afford.

Do you want to do anything to the top end?

383 Stroker External Balance: 800ish
Machine work: 200ish
clevite bearings and arp hardware: 100ish+

With the remaining you may opt to upgrade your heads, intake manifold, cam, throttle body or all the above depending on how much more you sink into it.

keep asking i have no problem helping.

- B

EDIT: You'll also have to be very versed in getting the correct compression ratio for your engine: http://www.fullsizechevy.com/forums/general-discussion/performance/279598-rebuilding-383-want-least-500hp-better.html

[sport91]

I have already swapped in a th350 so i should go with internal correct?
I plan on doing the 454 TB upgrade and most likely an intake. Not sure on the heads as that will throw me alittle over budget but i know its a very important thing i would be looking over as well.
You guys are VERY helpful and thanks for the links.

[1BadZ71Tahoe]

I have already swapped in a th350 so i should go with internal correct?
I plan on doing the 454 TB upgrade and most likely an intake. Not sure on the heads as that will throw me alittle over budget but i know its a very important thing i would be looking over as well.
You guys are VERY helpful and thanks for the links.

If you have a th350 all ready to run, external is how i would go IF your swapping them in at the same time. The point of an internally balanced engine is the fact that it balances it all without the need for a dampner and flexplate to balance it, you can run any combo of the two you want. Does that make sense? I hope so.

For instance, the reason i got an internally balanced engine was due to the fact that i had been running a 700r4, and swapped to a Keisler Automotive 6 Speed double overdrive transmission, and didn't want to worry about getting it rebalanced when I changed FROM my auto TO my stick. Had it been externally balanced, i couldn't run the 6 speed because the flexplate/dampner combo from the engine build is what's keeping it in balance. Pulling that flexplate for a different style one is going to throw everything off.

EDIT: Your running the th350 already so you can go with either combination. External is almost always cheaper.

- B

[sport91]

Gotcha, looks like external it is.

[Tbi-MAX]

hey, i know your waiting on my writeup and all, but i hadnt got around to it yet... but yes, your are in the right direction, external balance..

Eagle makes great cranks... i got the cast street version, not forged, cause ill never need forged.. when its all said and done, budget 2600 or so.. and i mean, thats for vortec heads, all the way down to the new oil pan... PM me for more information..

you will need a 1 piece rear main seal for your block, which is better than the 2 piece. make sure your crank is 1 piece, you will also need a 350 flexplate, NOT a 400. 400 flexplates are for 2 piece mains.. my eagle crank uses a 350 flexplate, and a 400 balancer and is a 1 piece crank.. its a 383 crank! journals and everything to fit a 350, but its basically a 400 crank.

the vortec heads are a must! you have plenty cam choices, but to keep it within budget i left my flat tappet, even though, i had all provisions for roller... and to the contrary, flat tappets spins fast enough for me. i would do roller if you want 500 or so horses...

find yourself a good machine shop 1st, thats willing to do the build, and who has built strokers before. they will know what exactly needs to be clearenced... also you will need a deeper oil pan for the bigger stroke.. the machine work should be as low as 250 for bore, horn, plugs, tanked... or 5-600 for them to build the entire short block.

[sport91]

Awesome info so far, now my next question has to do with boring the block. What do I NEED to do and what CAN I do as an option for larger displacement. This is gonna be a slow build process as the truck isnt my daily driver and if my wife see hows much this is gonna cost im gonna have ot buy her alot of purses :) So im flying under the radar.

[Tbi-MAX]

i believe .30 over is what the vote is for, which makes it a 383. you can opt for as much as .40 or .60 over i believe. this makes it alot bigger than a 383, i don't know the exact numbers, but it also thins the cylinder walls, making the block less durable. so i wouldn't recommend getting the biggest bore. .30 over with the stroke of the 400 crank, 3.75 will be alot enough for you...

[1BadZ71Tahoe]

i believe .30 over is what the vote is for, which makes it a 383. you can opt for as much as .40 or .60 over i believe. this makes it alot bigger than a 383, i don't know the exact numbers, but it also thins the cylinder walls, making the block less durable. so i wouldn't recommend getting the biggest bore. .30 over with the stroke of the 400 crank, 3.75 will be alot enough for you...

I've been debating boring out my 1983 G30 4 Bolt Main Block to .60 over, which would then make it a 396 stroker. :eek:

[dag]

i just order a 383 from motorcrateenines, off ebay..got this link off of tbichip. the just arived at my door. they have different engines avaiable and good prices. i upgraded on heads over stock better cam and rockers

[oldred95]

If its not a roller block you'll want to convert it to one. I wouldn't even mess with a flat tappet cam anymore with the chit for oil they today. Get some vortec heads, port them, get them machined to handle more lift, maybe even bigger valves too. If you do all that you'll need a new intake and Fast305's latest find is that a victor Jr. single plane 2 barrel intake is just badass on a vortec headed big cammed TBI engine. And if you do all that you'll damn sure need a 454 TBI, bigger fuel pump, and lots of tuning.

[Chrisbequick]

I've been debating boring out my 1983 G30 4 Bolt Main Block to .60 over, which would then make it a 396 stroker. :eek:

No it doesn't. A 396 small-block has a 3.875" stroke on a 4.030 bore. A .60 over 350 with a 3.75" stroke has a 388ci displacement.

-Chris

[Fleaz71]

Wow.. I am beyond impressed with the knowledge that has been mentioned in this thread and around this site. It is encouraging to see.

Sorry, off topic, but I had to say it.

Please continue!