hi all who still thread here, got an odd question...well maybe not so odd...i know some engine stuff.....like mechanical not tech stuff...so. in an iroc i once owned it was a 350...i think.....but it was way more powerful and smooth than an L98. first thing, i once needed to change the flexplate. the L98 plate wouldnt fit crank was too big for the hole. 305 iroc didnt fit either. nothing did except an old dusty box i got from cap thatwas for a caprice 350 diesel. then i had to cut the weight off the plate, as it threw the balance off (serious vibration) the old chewed up plate didnt have a weight either.

but also it didnt have centerbolt valve covers which from what i heard an l98 would have had. also i was told it looked like the wrong waterpump for an l98 yet an l98 pump did work as i had to replace the pump. it had l98 smog stuff but the pulley brackets were too old to be l98. also it had a like 88 89 MAF on the intake. it didnt go numb at 3500. went like a rocket. idled smooth you could put a drink on top of the tpi and it wouldnt fall off..or move.....ive heard vortech heads would make it smooth like that.

biggest thing was it was an 86 ...wasnt supposed to have a 350....obviously a swap. so i guess the question is, could any SBC use the TPI? what was up with the crank? older block? truck motor? even older camaro motor? id love to clone this motor as it was powerful, loud and very solid, ran better than it looked thats for sure....maybe those grooved head covers are a hint? plus i looked for the block number where iroc ones should be.....NONE found! so if anyone wants to look at the pic with the points i mentioned and take a guess as to what it could be? im thinking it wasnt an L98

 

Your engine looks stock. I pulled this engine in the pic below from a bone stock '85 Iroc a few months back, same grooved valve covers, and it pulled pretty well for what it was, but it was definitely a 305. Yes, TPI can be used on any SBC. If you believe the engine to be different in size, pull the numbers off of the block and look them up...

 

im sorry, no disrespect you probably know more than me on it....NO way that was a stock 305. i cant even believe its a 305 at all. i killed a stickshifted firebird with the 305tpi. he was a decent driver. i beat him pretty good. his had some bolt ons as well. i looked up the stats on the 86 305. i just cant see it. not without a WICKED cam, which it didnt have, idle wasnt lumpy.....very smooth actually. it was compared with a 350 iroc and it had more power than one that DID have the L98 it was supposed to. didnt have center bolts either. my monte had a 305 and it did. plus then why would the 305 iroc flexplate not fit? most of my research indicates a 305 ISNT worth a crank change.....not to mention stats said the 86 305 tpi was the weakest and least desireable (weaker cam).that crank shaft thing is the biggest smelling rat could you even put in a crank that would need a 350 flexplate? a 350 diesel one no less? i ate 5.0 gts ALL day.(took atleast an L98 to do that) im tryin to figure out what kinda frankenstein motor it is. its gotta be. oh also.....i searched BOTH locations where an iroc block number would be.....non exsistant.it wasnt behind the alt. as well as not under the heads on the firewall side driver or passenger....(maybe a crate motor?) so if tpis can fit on other SBC's i was just tryin to see if i could narrow it down if only certain blocks could use the TPI but it seems thats pretty open. this car was supposed to be a 305 tpi. im thinking swap. without heavy mods the 305 in 86 couldnt do what this one did.

 

Just because you beat a "stick shifted firebird" doesn't mean anything. My 5 speed TPI Trans Am runs high 16s. Without having the motor in front of you, there's no way to know what it was. If you bought the car new, then it was an LB9 305. If you bought it used, then who the hell knows what was in there.

The flexplate situation doesn't tell us much either. A stock 86 has the 1 piece rear main seal block. Any 85-older block would require a 153 tooth flywheel for a 2 piece block.

 

well it seems a little odd to me if its a stock lb9 then why would the lb9 flexplate not fit? neither would an L98.....the middle hole was too small for the crank, and if i recall the bolt pattern wasnt right in one of them...so what same block changed crank? different block n crank with lb9 heads n tpi? but would that make it faster than an L98? it was.... so if it was an lb9 would it be possible to mod it enough to do what this one could do? yes ofcourse i bought it used or i wouldnt be asking so many questions. everything i could confirm was the bolt on stuff K&n air, accel dist to plugs. and the flowmaster exhaust. idle wasnt lumpy enough for a radical cam. so the idea was to find out if it was an lb9 what was done to it to make it accelerate faster and run smoother than a confirmed L98 (my old friends 88 w/tpi 700r4) mine also didnt go numb at 3500 as ive heard stock tpi's do. just trying to piece together a little mystery thats all. ive read tpis can bolt up to gen1 SBC so like...a truck block? older camaro? i know what was SUPPOSED to be in this car, i just highly doubt thats what it was


Street lethal....it LOOKS stock. but no way it ran like stock...too much power to believe its a stock lb9. tryin to figure this out a little....

 

I hear what your saying, and I am not saying you have a 305, but remember, all it really takes to wake up the 305 is to advance the cam timing, and tune your fueling and spark advance in the chip. You would be surprised how that alone will really wake up that little engine...

 

I have no doubt that you know how a 350 should feel. And a 305. But you might be mistaken. If the 305 was tuned, that can be enough to give the placebo "felt like a 350" affect.

 

ok, youve got a good point street. the crankshaft thing baffles me so with what your suggesting to me....the light tuning, along with the decent ignition/air/exhaust would do all that?

hawk...i also see what you say. but ive owned a few different motors and learned how they acted...tuning, honestly...AND I WILL take the beating for it....the motor i enjoyed most was the 400M in my old 78 f250. that motor could PULL! its downfall was the c6. ALSO tho to stay on the point. i owned a 67 firebird that had a chevy 350 (4 bolt main) so yes im definitely familiar with a 350's feel, the bird had a turbo 350 tho. dont know if that would make a difference, and it was carbed...but a holley intake as well as carb, headers and as great as that 350 was this "frankenmotor" as im calling it was just better. hey IF it is an lb9 as long as i knew what was done to it to clone it id be VERY happy with it.

so i guess next question....could you change the crank?(would that matter much?) or could you do like an older 305/350 with the lb9 top end? even just the covers? the guy i bought it from had invoices that proved a portmatch (those could be from anywhere or another car. i looked it over once and put it away). plus another person i asked about said a cam and vortec heads would cause the super smooth idle and top end life as well as the smooth acceleration it had

 

Like Jim said above;
when GM went to the 1 pce seal crank engine in '86 , they had to put the balance weight on the flywheel
so they changed the flywheel bolt pattern on the crankshaft and the size of the center hole so you can't accidentally put a late balance flywheel on a early ( 2 pce ) crank engine as you tried to do and vice versa to prevent the wrong balance flywheel being used

 

wow. ok forget it. try to understand something and you get treated like an idiot. OBVIOUSLY it was the wrong FLEXPLATE. wasnt a flywheel....those go on manuals,also i was 23 at the time.didnt know much about these engines.

SO the question i was getting towards, thats been misunderstood twice. SO if an l98 flexplate didnt fit....and an lb9 didnt either....why was the plate that DID fit an OEM sbc 350 diesel,different block? or different crank?

plus once the 350 diesel plate was installed i had to hack the weight off as the motor was horribly out of balance once the weight was removed. WHATEVER motor it was must be pre 86 or atleast the block.

86 lb9 needed the weight. the weight made this motor angry....so....PRE 86 305? all i wanted to know was what was done to this engine as it was way more potent than the stock figures on the 86 LB9. or what motor was it because it was seemingly too potent. so thanks to the guys that atleast tried to help rather than just try to tell me what an idiot i am

 

All sbc chevy heads after 86 or 87 had centerbolt valve covers.
All 86+ sbc's used the newer design Flywheel or Flexplate bolt/hub pattern.
All 85 and down sbc's used the older design flywheel or flexplate bolt/hub pattern.

The only thing you've figured out is that it was an older motor. 85 or older.

Do you still have it? You can pull the valve cover and we can see what cylinder heads are on it. That's a huge part of making power.

Displacement determines potential, or more accurately, its ability to produce torque (as in amount of force applied to the ground). The heads, cam, and intake etc determine how fast it can apply that torque, because they determine how much air can flow through the engine.

So find out what cylinder heads it has.

There's a chance it might be an old 400. Or maybe an old 383. But with the perimeter bolt factory heads, it's almost a given that the heads are garbage or at best mediocre. So with that being the case it could feel peppier because it's geared better (maybe someone put some 3.73's in the diff?) or because its a 400/383.

BTW, 350 and 305 cranks from the same year are nearly identical. The only difference is the counterweights are slightly different for a 350 because the pistons are heavier. The stroke and design is otherwise the same.

And there's a million different ways to build a fast chevy. Doing it with 85 and older factory heads isnt one of the better ones. So if you just want a fast smallblock, just do some research. You can probably make a 400hp 350 with some AFR 180 heads and and an XR276 camshaft. Would outrun anything with factory heads unless they had some truly magical port work on them. Do that with a 383 and you'll make even more.

 

ok now were getting somewhere. well your take sounds good, sadly no i dont have this actual one but the point of all this is to do it again, this car was a SERIOUS blast to drive. but wasnt a horrible pig on gas. plenty of low end power would suck ya into the seats hard. but up on the highway she still had top end pull...didnt go numb after 3500 like i heard tpis do stock. but wasnt high strung. and maybe with the knowledge of this, it could even be improved (like what u said about heads)

so...i had an old work slip....they were ported/polished. but there was all this:

K&n air/oil
accel EVERYTHING dist to plugs
maf foil was punched out. (also i heard from someone else the maf on the intake like that was 88..89.)
another thought just occured to me. when was the lt1 first introduced? your take is showing 85 older....but i was told it was NOT an lt1 because the dist was in the wrong place. i was also told lt1 and tpi was impossible but an older one possible?

ok what else.....ok your gearing adding life makes sence, my speedo was off by ten. speedo said 40....police radar trap said 30. (rear end change?) but to what is what i dont know it was definitely posi. there were no shortage of people requesting smoke shows. and since i was a younger guy then. and she was so happy to oblige (you didnt even have to keep the brake down....just used it to break traction....then floor it...shed stay put till ya smacked her up to 2nd....then shed catch grip and take off like a rocket.

also, her 700r4 was built up some, shift kit. upgraded shiftbands (were called red bands?) highway...she wasnt screaming...im just cruising....glance to the speedo 110....ok lets see if shes got any more....not even to the floor...she jumped to 120 pretty quick and seemed like she had more...i just backed out so i wouldnt get arrested or killed (im no pro but i am an ok driver.....early 20s.....pretty immature due to being wowed by her power. never even came close to losing control of her....never hit anything.)

so there was all the bolt ons played with tranny and an obviously messed with motor, made for one hell of a fun camaro im just trying to narrow down what is what so i can live that again.

oh and i think youre right about the year figures too. i had an 87 monte ss with the 305 H.O. and it was center bolts. oh yea...and that was the carbed 305. few bolt ons....couldnt get anywhere NEAR the iroc. well sadly enough the poor old monte got smoked by my wifes 04 grand am gt 3400 ram air. and probably half the weight..well not half...but you know.....


Oh...edit: the only reason im asking about lt1. when i bought it from the previous owner, he claimed it was an lt1. ive heard theres no way for that..... whatever block that was. i want another. then improve it with better heads ive heard alot about vortec heads. someone else i talked to said that may explain its smooth idle and life after 3500...well he said cam/head combo. IF it was cammed which i honestly dont know.....it was mild, her idle wasnt lumpy sounded good, but smooth

 

LT1's are generation II smallblocks. Many of hte parts interchange, but very important ones do not. Such as the distributor and water pump. The Gen I smallblock was in production since the 50's, and stayed in new vehicles until the late 90s with the Vortec 350s. The Gen II smallblock was introduced in 92 in the vettes, and 93 in the f-bodies, then the Gen III LS family was introduced in 97 in the vettes, 98 in the f-bodies and is a complete radical departure from Gen I and Gen II engines. The main difference between the Gen I engines and Gen II is that the Gen II engines (LT1 and the baby LT1) have a reverse-flow cooling design, which puts cold coolant through the cylinder heads first and then into the block. Because of this difference the coolant ports in the heads, intake, and block are slightly different. They also changed to a front mounted distributor called the optispark that was driven by the camshaft. Its way more accurate, in fact probably the best distributor the world has ever seen. The problem is that thew ater pump is mounted on top of it and we all know what happens when water and high voltages mix. They are very failure-prone and expensive.

Heres a picture of a fancy aftermarket version and you can see what I mean:



So in short, if it had a distributor in the back with a TPI on it, it's impossible that it was an LT1, because you cant put a TPI onto LT1 heads and you honestly wouldnt want to, the LT1 intake is far superior to the TPI.

Some good 3.73 gears would do most of what you describe. Many of these cars are strangled by awful gas mileage oriented highway gears. Some 3.42's or 3.73s will REALLY wake one up.

Personally I think you may have gotten some 400 or 383 that was bolted up under a TPI system. It should be even more strangled at high RPMs than a 305 or 350, but it will make so much torque you may not notice.

 

Because after having it explained to you twice , you still didn't understand that it is the age of the engine ( crank type ) that determines fitment ;not what model engine the flexplate / flywheel came off
As you found out, a GM 350 diesel has same crank bolt pattern as pre '86 305 and 350 ( as well as 283, 302 ,307, 327 )

 

i wasnt disputing that. all ive been trying to figure out....it it didnt seem to be an LB9. so maybe an L98, signs are pointing to no....so i was wondering what it was then if it was THE STOCK engine it was supposed to have. then the 86 Lb9 flexplate would have fit. it didnt. so. since it OBVIOUSLY isnt THE CORRECT motor so now, an L98 would have been later as the chances of the 86 L98 is pretty near impossible.....out of 50 i got one? doubt it. so....an 85 lb9? maybe. as ive said to vortec. im trying to narrow down what it could be. so when i do save my pennies and get another 3rd gen, i can build, and maybe improve on what was done. and make a massively fun car even more fun......SO, Vortec

i am tickled about maybe a 400/383. hell even if it turned out to be an 85 lb9 thats not bad either.......when the kid told me it was an LT1 i already knew no way.

so. then if they tossed it to 383 in the back would that cause the speedo innaccuracy? i would have said 4.11 BUT she didnt top out too soon. best i did was 120. she had more. youre idea of it being more strangled at high rpm does make sence, if shes pullin hard enough. but she did sound strong and didnt sound choked. it pulled ALL the way to the redline. so somehow it had the best of both...improved accel without top end loss. but since i never totally topped it. i dont know where that is, i do remember the kid i bought it from said if i wanna race people, take em on the highway. he coulda been talking out his rear. im getting closer to knowing what to build in my next iroc. that baby was soooooo much fun. even if i could improve on it =) just be all the more fun


oh and. the sensor on the intake. somone told me being upthere was like 88-89 so if the blocks lookin 85 or before would that work? not sure it matters really. the 85 lb9 up a few posts didnt have the airbox so i couldnt say .....i looked a a couple engine shots and i dont see that maf sensor on the intake like mine is....so we pickin and mixing parts eras as well?

 

If it was an older engine then the TPI was still newer than it was, meaning the TPI was bolted on top of something else, which is more than possible. Unless of course it was just an 85 LB9, but you seem adamant that it wasn't. I can only go by what you say on that front, so if it truly had that much more power than any LB9 then...

And yes, shorter ratio gears like some 3.42's, 3.73's, or even 4.11's will make a HUGE difference at all RPMs compared to the stock 2.73's or 3.08s or even 3.23's that are so common. Also remember that these tachometers in these cars are notorious for being inaccurate and reading high, so when you say it pulled all the way to redline it may have just been an improperly indicated redline, which on most tachs is still just 4500 RPMs, or 5,000.

Shorter gears will make the car pull harder everywhere, and will make it much easier to break traction from a stop too. And there are guys who run 4.56 gears with turbo 350s at the track and run 130 mph trap speeds. You can still go fast, it's just that the cruising RPM for interstate speeds is a little higher than usual, usually by 300-700 RPMs or so, which may or may not be noticeable if you werent there to see the difference before and after.

 

Didn't GM put what they called an LT1 engine in some older Vettes(70's). If I remember correctly it was just a powerful 350 gen 1 motor. With the info given this sounds like a possibility. I do not believe they were referring to the modern LT1.
It would have been simple to put the 305 TPI on it and swap injectors. May not be perfect but would run.

 

well when i bought it from the guy thats what i was maybe thinking, i admit i thought no way. but then thats why i was asking how far back the lt1's went. cause yea i remember him telling me that it was an Lt1. so maybe the only was possible was it had to be an OLD one, i just found this on another message board. smokin vetter .com i think it was called:

The original high-performance LT1 engine, a 350-cu.-in. "Small Block," was introduced in 1970. It generated 370 horsepower, actually that quote was on a corvette generations site, HERES what smokinvette.com had to say:

When talking about the GM LT1 engine there is little doubt that most will associate the small block powerhouse with the Chevy Corvette. But the engine made its way into several GM models and though most notable for then power it delivered to the Corvette, it also powered other GM sports cars like the Camaro. The more known GM LT1 engine is the one that came out in 1992 and ran in GM cars until 1997. Though the engine was not the same, it was actually GM’s second go around with the name as in 1970 there was in fact an “LT-1” engine that was produced by GM. Understandably because more time had passed since 1970 there was a huge evolution in the new generation LT1 engine.


and someone else i talked to said something about those valve covers reminded him of a way older 350. so i think we may be on to something here. when he said it was an LT1 he never said anything about generation. so NO WAY this is a MODERN lt1. i mean this isnt for certain either. also ive heard a few people say that tpi will work with almost ANY gen 1 SBC. so i think im gonna have to study this more. i mean really this engine had some power.......so 1st gen Lt1 is very possible now but if thats the case....may be hard to come up with another one then. im gonna go now and look at some 1st Gen lt1's and see what they look like, valve covers etc. then if thats the case would the whole 85 LB9 top end bolt up?

if it was a 1st gen Lt1 it would explain alot.

 

HEY take a lookie at what i found according to this, this is a 1st gen LT1 look when the DIST is. hmmmm wow, im kinda getting excited now. when he said LT1 he must have meant first gen. SO.....he was i think the third owner......when i bought it it was registered in Sandown NH. i did a carfax one day for the heck of it, and it had changed hands atleast 3 times before me, so now way this kid could have done it, he admitted he knew oil changes and the like, SO if someone did have a 1st gen lt1 and put it in, it was done before this kid. NO way he put it in. but one of the previous owners did it, with how well she ran. whoever did do it KNEW what they were doing, with how much power she had, even with an automatic if you had a lil sand in the road , the first day i bought it, i can admit i was beatin on her a little, new car see what she can do.....i was on a rural back road, lots of sand from winter i went to show my new friend to my brother in law. so leaving his son was BEGGING me for a smokeshow. so ofcourse i obliged him. so i held her on the brake for maybe less than 10 seconds, got em spinning good, got off the brake and just floored it, the first curve in the road was 750-900 feet away so on this sandy road, when i let the brake off. her rear started swaying left.......but still going forward, turned in a little.....the turned it the other way.....the rear end swung right.......going forward and picking up speed.....so then i turned into that to not go around. went to check up and backed out of the gas, as too as she was dead center straight. then back on the gas. she checked right up....then went foward like a rocket, had to climb all over the brake to not crash in the corner. so essentially she was drifting.......and they say that first gen lt1 was a powerhouse. so.....maybe here....i dont mind Infernal Vortex's idea of a 383/400 but yea, DEFINITELY A 1st Gen small block, we ALL seem to agree there. so here take a look at this:


OH and a thought kinda just clicked into place. this may explain why it wanted an a first gen SBC flexplate, and didnt want anything to to with L98's OR lb9's. there was no way i woulda thought to ask the guy for a 1st gen LT1 plate......back then i really didnt know they exsisted. well when i thought of LT1 i thought of what they actually call a GEN 2 Lt1 hmmmmm maybe finally on to something.

 

The 85 TPI would be a straight bolt on with the exception of injectors. The tune may be off some but it would run.

 

On the back on the block driver side there is a production number. Get it and look it up on this site:
http://www.nastyz28.com/sbchevy/sblock.php
The number is on a 'landing' where the driver side head meets the block.

 

wow, funny that exact same thing was pretty much just said, to a T. REALLY looks like were on to it here. so with better injectors......heads were port/polished. like infernal said before, it coulda been numb but it was pulling so hard i may not have noticed EVERYONE that rode in her always commented on the motor, other people ALWAYS said the motor was the best part of that car. other 3rd gen entusiasts all said it was fast even for an Iroc. its kinda making more sence. but now im fearing it may be hard to do again if its true.....

 

Theres nothing special about a first gen LT-1 (the dash is in the original). Its a little fancier than other 350s of the time, but modern tech and parts are way better. It still used mediocre "camel hump" heads which everyone used back then. They're just not that great by modern standards. I think it just got a bigger cam, and it was an extremely rare engine. You could build a clone of it pretty easy if you wanted, but an L98 would probably put up better numbers if you tested them by the same criteria, either SAE net or SAE gross.

 

well that could be true too vortex since i thought it was originally an L98 anyway i was just getting jazzed by the site reviews. that vette one called it a power house. made more power stock than an L98. but i mean if you could get that from an L98 and more then that would be sweet. and eaiser to find. so i guess its narrowed down enough to know that lt1 if thats what it was is really sweet, but rare. so either find myself another L98 equipt iroc or if i get the lb9 be ready to swap it out. which if i did get one that had a lame motor, i could get it cheaper. my brother works with gen1 V8s alot, he has a 79 impala aerocoupe with a 327 vette motor. and the parts donor has a 283 out of i think a 63 impala....hes done motorswaps before. has a good engine lift and air tools. so with his help i think it wouldnt be hard to do, hardest part will be to scrape up the green its gonna take, i mean even its an L98 not too long ago my local pick a part yard was selling an l98 with harness and comp for just under 300. so find a lame duck or a 305 that needs an engine. id be well on my way i just definitely want an 86 or later to start with, i love the 16's favorite iroc/3rd gen wheel hands down, i even had a set of z28 15's on my monte SS. i swear just cause i liked it, the next one would look like my old friend

 

I could be wrong but didn't the lt-1 have aluminum heads? I thought that's what made it special.

 

well that may be gen II but im NOT an lt1 expert, or even a tpi, i can do the mechanical stuff, grunt work. but ask me why and im DUH like recently i helped my brother with a posi swap with his 79 impala. i removed it for him myself, not much to it. him im gonna look up gen 1 Lt1 heads now, well either way what they were they were ported and polished to that block. so i hear tell that will make things smoother, honestly i couldnt tell you, but the heads were painted like the block, they didnt LOOK aluminum to me, that part i may never know unless i tracked her down. ALSO i did look for a block number when i did have it. COULDNT find one where the iroc ones would be, non iroc block would answer that, i had to pull the alt to check there. and i felt around behind the firewall(drivers) and couldnt find ANY numbers.....hmmm maybe a hot motor?

 

Because as Vortex said above they used a different Hp rating system back then
Test it under today's testing standards ( that a L98 rated under ) and it wouldn't look so fancy

Nope
what made it " special " was the high compression and lumpy cam

 

If it was an 86 it was originally equipped with an LB9 305. Those old sites have a lot of nostalgia-based romanticism around those old cars. Modern technology has far surpassed them. If you take even the craziest big block equipped muscle cars of the late 60's and early 70's they were doing REALLY well to break into the 13's and a bolt on L98 can do that easy. Those old school guys either dont realize they're outdated, or they are merely comparing powerplants of that era to other powerplants of that era. The LT-1 was by far one of the crazier, remarkable ones, but you can do better today.


Stop getting hung up on "came from a vette" or "Came from an impala" or chevelle or whatever. That really doesnt mean much, most of those old parts were either mediocre or garbage by today's standards. After 73 they were pretty much unanimously garbage across the board until the mid 80s Camaros and Corvettes. You need to stop looking at motors from ANY old car, and start looking at something like a Vortec 350 from a 96-98 truck. They are FAR better engines than that old school stuff for a whole plethora of reasons. Just make sure its from a 96+ truck, not a 88-95 truck.

Pretty sure it just had camel humps. Aluminum heads were pretty crazy tech and I dont think any stock Chevy's got them until the L98 corvettes in the late 80's. Aftermarket aluminum heads didnt start showing up all over the place until after that even. The 92-97 Gen II smallblock LT1's had aluminum heads for some years, iron heads for others.


It's amazing how quickly the technology evolved and developed over the past 20 years from exotic race only stuff no one could afford to stuff nearly anyone can get these days. The reason those old camel humps have the reputation they have is because they were used in cars people were nostalgic for, and the otherh alf because the 73+ years were so badly crippled by emissions, gas mileage, and fuel regulations and they had to severely limit power output to make their cars legal for sale. They camelhumps were the ONLY good heads around for 20+ years. It wasnt until the mid 80s with the IROCs that people had performance numbers that competed with those old cars, and at that point so many people were nostalgic over them and so many of them had huge big blocks with lots of torque (and very little horsepower, like the 78ish Pontiac 455's that made 180 hp) that the just as fast IROC 305's and 350's just couldn't compete with rosy memories and modern souped up, cammed up, bolt on super muscle cars of the era which were nowhere near stock at that poitn. The reasons people love the old stuff is psychological, not technical or performance reasons.

Also, after 72 or 73, around that same time, they switched from SAE gross to SAE net horsepower rating standards, which lead to an immediate, and drastic drop in horsepower figures just because of the testing methodology. SAE gross and net both measure horsepower at the flywheel, but SAE Net (What was used from 73 and up) measures horsepower with all the accessories, factory induction system, factory exhaust, and factory emissions equipment etc. SAE gross measures with headers, ideal exhaust setups, ideal intake setups, huge carbs, no accessories at all, etc. The engines didnt even turn their own water pumps. The engine you ended up with in your ride could be ENTIRELY different from the one that got tested by the SAE. Plus the move to unleaded fuel demanded far lower compression ratios, and that kills potential power also. It was a perfect storm of performance killing regulations that all struck at the same time, and so the legacy of the muscle car era has become very, VERY rosy in comparison to what it was and what we have today.

Am I wrong, or is the LT-1 the 350 that got the cam that GM used in the DZ302 Z/28s? If so that cam is WAY too radical for a street car, even in a 350. Definitely wouldnt work well with any tuned port system and would have a very lumpy idle, so the odds that the engine in question is an LT-1 is very, very, very low.




To the OP, these are just engines. There's nothing magical bout them because of the car they were bolted to. They werej ust made of different parts that helped or hurt performance in different ways. More displacment is more torque. Bigger cams, intakes, and head ports means more horsepower from that torque. It's easy to make a fast smallblock.

Today you can build a 383 bottom end for $2k if you piece it together on your own. Use a Vortec 350 block as a base and then you can use a roller cam like an XR276. Run some Comp 26918 beehive springs, and then run a vortec base on your TPI and you'll have a TPI pushing CRAZY torque numbers and probably 300-350 estimated SAE net horsepower. If you get a Holley Stealth Ram intake or the likes, or go carb (Which I wouldn't recommend in an already fuel injected car) you could make up to 400hp with that setup easy. The TPI will kill top end horsepower and make more low end torque, but either way it will move like you wouldnt believe and have tons of torque.

$2k for 383 shortblock, including the cost of a Vortec L31 core
XR276 cam + springs - $500
Random head finish work like screw in studs, and maybe some decent rocker arms - $600
Vortec TPI base - $400

A beast of an engine for $3500 that will SMOKE any rebuilt "from a vette/chevelle/whatever" engine for about the same money.

The biggest factors in building a performance smallblock these day

1. Start with at least 350 cubic inches just to get hte most out of your money
2. Get some decent heads. If you want to go cheap, use some L31 Vortec heads (906 or 062 casting numbers). Some corvette 113 aluminum heads aren't bad either, but they will make stock TPI type power levels. If you go AFR or other decent aftermarket casting aluminum heads you will make 50-100 more horsepower than that depending on the rest of the setup.
3. Use a modern roller camshaft like the XR276.

The best cheeeep way to hit decent power numbers in a 350 + Vortec heads + LT4 hotcam. Will smoke any of those classic muscle cars, but not quite as badly as my previously mentioned combination.

And here's what I find craxzy about your other post. An engine is a combination of parts. Most of which tune the power band for higher or lower RPMs. Higher RPM torque is what makes horsepower, lower RPM torque is what makes... lower RPM torque. You can build a high strung NASCAR-esque 800 hp 350 if you spend enough money and tune every part to work at 5000-8000 RPMs, but it's expensive, impractical, and unreliable.

What you're saying is you had a smooth idle (meaning a small cam), lots of low end torque(fits with a small cam), and lots of high end horsepower(would require modern fancy heads and a large cam), AND you had a TPI (which chokes large cams). Something has to give there. Even a stock 400 smallblock (the MOST POWERFUL 400s were rated at 200 SAE net horsepower) will be choked at higher RPM's with a TPI on top due to its design emphasis on creating low RPM power. So I dont think this motor was nearly as powerful as you remember, and I have no doubt in my mind a good modern roller cam 350 will beat it regardless of how fast it really was if it had factory iron perimeter bolt heads on it and a TPI.

http://www.chevyhiperformance.com/te...cam_355_build/

http://www.chevyhiperformance.com/te...e_roller_cams/

http://www.chevyhiperformance.com/howto/97458/

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


Read those articles and you will do a LOT better off for a lot less money than you will if you dont read them.

 

Take off the rocker covers and tell us what heads are on it.


Take it to the track and see what it runs.

 

certainly would if i could. i sold her. tried to find her to get her back nothin doing. the perpose of me asking all the questions is to replicate. ive been watching craigslist for a lil while now, plenty of candidates. couple with bad motors, decent body i can scoop up around a grand. with a V6 car i know the suspension will bring the bill up, but one close to me, a 92 RS with a 6. motor doesnt run but the body is cherry. they want 1000 flat.

so that. coulpled with an encouraged L98 or something of the like.which leads me to:

vortex i believe you completely on the newer tech being better. problem with that is i dont have 3k to sink into a motor alone. cloning/improving the motor i had will be more than enough to keep me happy. probably wanna go with an L98 with a decent block i can have more in the budget for decent heads. but with three kids i certainly wont be setting any speed records on the build

 

How you plan on doing that given that after all this talk nobody ( especially you ) knows what engine/ combo you used to have?

 

close enough, with discussions it was way narrowed down. 85 or older sbc got plenty of choices there now. but still with the info thrown around trying to figure it out theres plenty of info to build up a tough motor anyway. the 350 that was in my 67 firebird was a 70's truck block, carbed it had plenty. that also did have a mild cam headers ETC yea somethin new would eat it. but still a 67.... that was a fun car. even the 400 in my 78 truck was good a cam n good carb would have made it good in something lighter

 

Those truck engines from the 70s all made around 140-200hp. 200 was the peak of the 400 smallblocks I believe. A FACTORY L98 makes 225-250. More than ANY 350 made before 86, and arguably more than any of the ones made in the late 60's because they measured horsepower so differently then.

Your best bet is to get a factory L98. It is literally the best 350 you can get after a 96-98 truck 350 (which requires an expensive intake manifold base for the TPI) and the 87-91 vette L98's. The other advantage of these 87 and up engines is the roller cams which increase reliability and give you huge power potential. I would take a roller cam LB9 any day over a 85 and earlier sbc of any type. The 305 LB9's made 190-215hp, which is more than the vast majority of those 73-84 chevy smallblocks made.

 

All that was determined was an early block that ran real good for certain. I have driven a early LT-1 (clone) w/ a Muncie 4sp. It ran good yes but it was still just comparable (considering weight) to my current truck.
I agree totally to build a roller cam block. Choose a cam wisely and back it up with some good flowing heads. It will be strong and reliable.

 

yes an L98 is obtainable around here. a local pick a part place was sellin one with its cpu n all for somewhere around 300. tagged as out of an 88 camaro. the vette L98s have better heads. theres enough 350tpi's around but the nicer they are the higher the price tag. i mean as long as its a 3rd gen v8 setup i can find one cheaper. definitely prefer iroc but doesnt have to be

 

I'm not even sure we've determined that much. We know it was an early block, but only his Butt-O-Meter is telling us how it ran. I've had a few cars that my butt-o-meter told me were fast, but real world track numbers told me different.

 

Had an LT-1 350 in a 1970 GMC Camper Special, first Gen 350... Old days they called them 350/350 this was a special order by the GM Eng. down the street when I was a kid. traded my Honda 70 trail bike and 400 bucks for it... lol I think it had like 10 to 1 compression & lumpy cam with the camel back heads it had a 4:11 gear and a 4speed where granny gear would only do like 10MPH 2nd would scream and 3rd... 4th was like BbLlaa over drive, But I would spank vet's and Camaro's for the first 100yds... Before I put Camaro bucket seats in it if I was doing 50MPH in 3rd and stomped the gas and let off fast the passenger's head would smack the back window, Needless to say my right arm hurt from my bud's punching me in the arm for Smacking them up side the head like that ... lol :-P
Also I am building a 1994' GMC Two door Yukon 4x4. Swapped out 6Lugs to 3/4ton 8lugs 4.11 axles,trans up to a 4L80E, 3200stall bullet aluminum, 3/4ton T-Case, flip kit, LoweringKeys on the IFS axle,frame C notched @ rear diff. Old school 383 forged 4bolt main,1pc rear seal,roller cam & roller tipped 1.6 rockers, lift comes in at about 520/530, AEMController/ECM & Engine Position Module replacing the distributor, LS-1coil on plug, Holly Stealth Ram Jet, Trick Flow Twisted Wedge Heads portedpolished and flowed, intake valve cantered to 13deg's from 23deg's, JBAstainless Headers, Cal-Trak Bars, Bilstein shocks, Bridgestone Blizzaks,Kenwood, Polk MoMo's and Infinity speakers 16 total, 1350watts component 3amps16 speaker's.

 

If you remember .... I would like to know what Throttle Body that is on it... most I have seen have Two 52mm or 58mm blades not one like in the picture ???