# 350 small block chevy motor in 300zx??



## rhythmicSTIMULUS (Apr 12, 2005)

Please note that I'm very much against this idea, but my boss and my co-worker keep trying to convince me that it would be cheaper and better(performance-wise) to throw a 350sbc into the 300zx that I have instead of refurbishing the turbo motor. As it is, I need to buy new lifters, new motor and transmission mounts, new gasket set, new brake lines(the rubber portions) new oil seals front and rear, new water pump, oil pump, and timing belts. I also need to pay for a valve job. What I need to know, is whether or not anyone has tried to put a small block into a 300zx before, and if so how much it would cost me, because I'm looking at an estimated $1,200 right now, and they keep telling me I could do the small block conversion for more like $1,000 and have twice the horsepower.


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## ICP Sux0rZ! (Jan 10, 2005)

http://www.az-zbum.com/modification.engine.swap.shtml


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## JAMESZ (Mar 12, 2004)

If it was an NA Z31 I would say go for it, but if you already have a VG30ET I would just build it up.


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## AZ-ZBum (Nov 21, 2004)

The above car was a turbo before the motor blew. But the owner already had a SBC 240Z, so he also knew what he was doing. Note that he even kept the factory cruise control.


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## LostLucian (Sep 20, 2005)

I have a 88 nissan pulsar that will have a 305 (not a type-o, i mean 305 cubic inch not 350ci) chevrolet engine, i will be installing my own transmission and drivetraign system, converting the entire are from a front wheel 5 spd system to a rear wheel 3 speed overdrive system. thankfully, i am not a new comer to chevrolets, i have owned a 79 camaro, a 65 impala sprt, a 88 chevrolet, and a cavalier beforehand (the cavy wasnt stock either  ) 

[email protected]


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## Asleep (Jan 19, 2003)

LostLucian said:


> I have a 88 nissan pulsar that will have a 305 (not a type-o, i mean 305 cubic inch not 350ci) chevrolet engine, i will be installing my own transmission and drivetraign system, converting the entire are from a front wheel 5 spd system to a rear wheel 3 speed overdrive system. thankfully, i am not a new comer to chevrolets, i have owned a 79 camaro, a 65 impala sprt, a 88 chevrolet, and a cavalier beforehand (the cavy wasnt stock either  )
> 
> [email protected]


for not being new to the chevy world, why in the world are you going with a 305 over a 350?? thats a total waste of money when you consider the 305 is such a weak contender compared to a 350. not only that, but what 3spd od system are YOU talking about? chevy's od tranny is a 4 spd, not a 3. im sorry, but you actually do sound kind of newbish to chevy's.


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## Asleep (Jan 19, 2003)

ICP Sux0rZ! said:


> http://www.az-zbum.com/modification.engine.swap.shtml


i missed the day that this car was brought out to an az get-to-gether... i heard about it afterwards, would have been nice to see in person.


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## AZ-ZBum (Nov 21, 2004)

AsleepAltima said:


> for not being new to the chevy world, why in the world are you going with a 305 over a 350?? thats a total waste of money when you consider the 305 is such a weak contender compared to a 350. not only that, but what 3spd od system are YOU talking about? chevy's od tranny is a 4 spd, not a 3. im sorry, but you actually do sound kind of newbish to chevy's.


Now I'm sure someone will correct me, but isn't the 305 the same size block as the 350?

From what I remember while studying engine options before I ended up not buying a K1500 a few years back, the 305 had the lower towing capacity of the V6 and worse fuel economy than the 350. It just didn't make any sense to choose the 305 over either.

And when was that car at an AZ show? Damnit. I would have loved to have seen it as well. All I know is he's from Houston.


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## Asleep (Jan 19, 2003)

AZ-ZBum said:


> Now I'm sure someone will correct me, but isn't the 305 the same size block as the 350?
> 
> From what I remember while studying engine options before I ended up not buying a K1500 a few years back, the 305 had the lower towing capacity of the V6 and worse fuel economy than the 350. It just didn't make any sense to choose the 305 over either.
> 
> And when was that car at an AZ show? Damnit. I would have loved to have seen it as well. All I know is he's from Houston.


the 305 and the 350 externally are the same exact size. the 305 is less reliable, less economical and less powerful. for the extra 100 dollars or so, it doesnt make sense to go with the 305. 
as for the z, if thats the same z my buddies told me about, it was at sco about a month ago. maybe its a different z, im not sure, but i know there was a vette powered z there. 
funny seeing you here on nf, i thought you were primarily az240sx material.


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## LostLucian (Sep 20, 2005)

ecternally they are not the same in some cases, and also,t he 350's belive it or not are just as reliable as the 305's the only differnce is that for more then 100bucks you pay to get a 4-bolt main block instead of a 2-bolt main block which are hard to come by anymore for original motors, and new ones cost a good mint. the 305 and 350 use differnt starters more often then not, the 350 version of the starter is more beefed up to turn the pistons, which measure 4 inchs as opposed to the 3.5 inch bores of the 305. i do own a 350 4-bolt main engine block, but i dont want to waste it on a nissan body, only for a real purpose built car, not a daily driver weekend car.


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## LostLucian (Sep 20, 2005)

to skip to my bottem line, 305s are everywhere, and if wanted, the blocks can be heavily modified to fit the specs on the 350, and for those of you who dont know, the 305/350's share the same crank and what not, just the pistons differ, my 305 will inclue 350 heads, larger bores on the cylinders, lighter crank, and beefed up rods. why use the 305? quick frankly, i beat the shit out of my engines, and 305s are cheap to replace! lol (about $200 to $500 less for remanufactured block usually, and $50 less in a junkyard.)


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## Zen31ZR (Mar 24, 2004)

305 and 350 are the same block. The bore is slightly different, is all. You can bore the 305 out to accept the 350 pistons and it works perfectly. 

1st number is bore, 2nd is stroke

305 = 3.740" x 3.48"

350 = 4.000" x 3.48"

I'd take the 305, personally, because it'll rev quicker. The only difference between the 305 and the 350, is the 305 is low on torque, for the obvious reason. The 305 was only a bit short on the Hp from a 350. This comparing the 2 motors via the 89 IROC-Z, which I have experience with. The 350 only had 15 more Hp than the 305, but torque was alot higher. Easily cured with a supercharger, and the 305 has better throttle response. If you're looking at an LT1 or an LS1, then all bets are off, but if your swapping in one of the older TPI units, my bet is on the 305.


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## LostLucian (Sep 20, 2005)

your right, think about it as a air/fuel ratio, the 350 bores allow the normal aspirated air to fit more air to as much fuel as the less airid mix in the 305 engine, however the supercharger or whatever combo of forced induction your pick solves this by shoving more air in less area, in this case, a 305 disposable engine with a supercharged carb set-up will use little amount of gas, produce more power then a normal 350. carburated versions are preferred however because its basic fact that carbs atomize fuel better then fuel injection however fuel injection is better for gas mileage. the lack of horsepower is explained by this, and the loss of torque is given here because the less bang the cylinder makes results in less torque to the drivetrain.


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## Asleep (Jan 19, 2003)

when it comes to the 305 vs 350 debate - NO ONE in their right mind would pick a 305 over the 350. the slight revability of the 305 over the 350 is not worth the tq loss or the hp difference of the 350. its too easy to find high hp 350's than it is to find a high hp 305, especially if youre looking at carb'd applications. 350's are not all 4 bolt mains either. the 375hp 350 in my truck is a 2 bolt. when i was shopping for an engine to go into my s15, i thought about a 305 but it just doesnt make sense when i could spend about a 100 dollars more and get that much more out of it.


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## himilefrontier (Jan 21, 2003)

AsleepAltima said:


> when it comes to the 305 vs 350 debate - NO ONE in their right mind would pick a 305 over the 350. the slight revability of the 305 over the 350 is not worth the tq loss or the hp difference of the 350. its too easy to find high hp 350's than it is to find a high hp 305, especially if youre looking at carb'd applications. 350's are not all 4 bolt mains either. the 375hp 350 in my truck is a 2 bolt. when i was shopping for an engine to go into my s15, i thought about a 305 but it just doesnt make sense when i could spend about a 100 dollars more and get that much more out of it.


There is no revability benefit to a 305 over a 350. Both have the same rods and crank; the only difference being that the counterweights are drilled differently ofr the weight variation of the pistons between the two. Most 350's and all 305's are 2 bolt main engines, the 4 bolts are mostly found in the RPO codes LT-1 ( 1970-73), L48 ( 1967-70 350 4 bbl engine rated at 290-300 hp depending on application), L82 ( late 70's Corvette and Z-28 IIRC) and most truck applications. The 4 bolt main block 350 was only used in 1 application in the "2G" engines produced from 1980 (?) to 1986 and that was the L98 in the Corvette. (2G engines are made with a left rather than right hand dipstick, and have double drilled exhaust flanges on the ends of the heads). The 3rd gen engines are made from 1987( some late 1986) until 2000 or so and had the one piece rear main seal, centerbolt valvecovers, most had roller cams and the accompanying valley spider and cam thrust plate, and the bolt angle of the center 2 intake manifold bolts is slightly different than earlier engines. The biggest redesign came in 1992 with the addition of the LT1 ( notice it is not an LT-1). This came with the opti-spark distributor on the crank, timing chain driven water pump and reverse flow cooling. The only variation of this generation to have 4 bolt mains is the Corvette version, all others are 2 bolt. These came only in 265 and 350 CI displacements.
Other interesting trivia: The SBC did not have a oil filter boss until 1957 and earlier versions had a optional canister filter that mounted to the intake manifold! The SBC was the world's 2nd fuel injected engine in 1957 ( the 1954 Mercedes Gullwing was first and the first car with EFI was a 1958 Chrysler); Chevy II blocks had different oil filter bosses than standard SBC's, and all SBC's have the same mounting ears, so a 1997 Camaro LT1 350 ( last passenger car variant) will bolt right in to a 1955. The SBC was produced in production US cars from 1955 through at least 2000 with the fullsize Express vans getting it last. Displacements of the production SBC are as follows: 262.5, 265,267,283, 302,305,307, 327, 350 and 400 CI. The 302,327, 350 and 400 were the only ones available with 4 bolt mains. Sorry if I am a little off on any of this, but I was doing it from memory.


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## AZ-ZBum (Nov 21, 2004)

AsleepAltima said:


> funny seeing you here on nf, i thought you were primarily az240sx material.


read some of the other posts. I'm about to be booted from here for being too short and sweet. I guess some people can't understand learning by reading vs posting in a 12 year old chatroom.


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## Zen31ZR (Mar 24, 2004)

himilefrontier said:


> There is no revability benefit to a 305 over a 350. Both have the same rods and crank; the only difference being that the counterweights are drilled differently ofr the weight variation of the pistons between the two. Most 350's and all 305's are 2 bolt main engines, the 4 bolts are mostly found in the RPO codes LT-1 ( 1970-73), L48 ( 1967-70 350 4 bbl engine rated at 290-300 hp depending on application), L82 ( late 70's Corvette and Z-28 IIRC) and most truck applications. The 4 bolt main block 350 was only used in 1 application in the "2G" engines produced from 1980 (?) to 1986 and that was the L98 in the Corvette. (2G engines are made with a left rather than right hand dipstick, and have double drilled exhaust flanges on the ends of the heads). The 3rd gen engines are made from 1987( some late 1986) until 2000 or so and had the one piece rear main seal, centerbolt valvecovers, most had roller cams and the accompanying valley spider and cam thrust plate, and the bolt angle of the center 2 intake manifold bolts is slightly different than earlier engines. The biggest redesign came in 1992 with the addition of the LT1 ( notice it is not an LT-1). This came with the opti-spark distributor on the crank, timing chain driven water pump and reverse flow cooling. The only variation of this generation to have 4 bolt mains is the Corvette version, all others are 2 bolt. These came only in 265 and 350 CI displacements.
> Other interesting trivia: The SBC did not have a oil filter boss until 1957 and earlier versions had a optional canister filter that mounted to the intake manifold! The SBC was the world's 2nd fuel injected engine in 1957 ( the 1954 Mercedes Gullwing was first and the first car with EFI was a 1958 Chrysler); Chevy II blocks had different oil filter bosses than standard SBC's, and all SBC's have the same mounting ears, so a 1997 Camaro LT1 350 ( last passenger car variant) will bolt right in to a 1955. The SBC was produced in production US cars from 1955 through at least 2000 with the fullsize Express vans getting it last. Displacements of the production SBC are as follows: 262.5, 265,267,283, 302,305,307, 327, 350 and 400 CI. The 302,327, 350 and 400 were the only ones available with 4 bolt mains. Sorry if I am a little off on any of this, but I was doing it from memory.


Lookin good for the most part, except the early 80s Corvetter engines had minor differences from the regular run of the mill units. I think centerbolt valve covers started in early 86, and the 85 'Vettes had aluminum heads. And as far as a 4-bolt main 350, I have never seen one and I've been in a lot of 350s. Most 5.7 and up crate engines are 4 bolt, but most street 350s are not. Near as I could remember, the caps and block could be drilled for 4 bolt, though. But generally the 2 bolt was plenty strong for most applications. Oh yeah, and the Opti-spark was driven off the cam housing. Otherwise, I'm impressed. Not too many people can cut a 5.7 history lesson down to size like that. :thumbup:


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## Zen31ZR (Mar 24, 2004)

AZ-ZBum said:


> read some of the other posts. I'm about to be booted from here for being too short and sweet. I guess some people can't understand learning by reading vs posting in a 12 year old chatroom.


Sure but getting people to search is like pulling crocodile teeth. And you're doing much better lately.


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## Asleep (Jan 19, 2003)

Zen31ZR said:


> Lookin good for the most part, except the early 80s Corvetter engines had minor differences from the regular run of the mill units. I think centerbolt valve covers started in early 86, and the 85 'Vettes had aluminum heads. And as far as a 4-bolt main 350, I have never seen one and I've been in a lot of 350s. Most 5.7 and up crate engines are 4 bolt, but most street 350s are not. Near as I could remember, the caps and block could be drilled for 4 bolt, though. But generally the 2 bolt was plenty strong for most applications. Oh yeah, and the Opti-spark was driven off the cam housing. Otherwise, I'm impressed. Not too many people can cut a 5.7 history lesson down to size like that. :thumbup:


yeah i gotta agree. pretty good knowledge thrown down there. ive got a 4bolt main 350 block sitting in the back of my truck right now. dont know what year it is though. the engine i have in my truck happens to be a passenger side dipstick engine. came out of a 1984 hd app. had it built here in az and it runs like a beast.


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## Zen31ZR (Mar 24, 2004)

AsleepAltima said:


> yeah i gotta agree. pretty good knowledge thrown down there. ive got a 4bolt main 350 block sitting in the back of my truck right now. dont know what year it is though. the engine i have in my truck happens to be a passenger side dipstick engine. came out of a 1984 hd app. had it built here in az and it runs like a beast.


Might be out of a Corvette, supposedly they are all 4-bolts. Last 5.7 engine I played with was the LT1 in my 97 Camaro. It was a beast too, amazing engine I think. Last of the iron blocks, IMO a lot stronger than the LS1 especially when it comes to supercharging. Wish I still had that car, it was a lot of fun.


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## LostLucian (Sep 20, 2005)

I wont disagree with you on the 350 over a 305 with anyone int he right mind, but where i am at (middle of iowa) good 350's are hard to come by and with a little to no money budget for me. the plentiful and still useful 305 is good enough to employ in a car until a 350 can be built or bought to fill the application. around here, small time dirt track racers and demo cars use up the larger small block engines like no tomorrow, so to find a 350 383 stroker, or a 400 small block is rare to see them out in the open. leaving two options, get a junked out fuel injection motor and have it all swapped in or convert it to carburated, or use the plentiful 305 to get your project off the ground. and its just simple to employ a 305 into a project car to get it set-up. i wont doubt you, but this is the method we use here, my cousin did this to his 92 camaro, and it uses a 305 witha ll the stuff you would use on a high output 350, he is just lacking a block too.


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## zak187 (Jan 15, 2005)

how sweet would a lt5 be in a z?


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## Zen31ZR (Mar 24, 2004)

zak187 said:


> how sweet would a lt5 be in a z?


The LT5 is incredibly wide, I don't think it would fit under the hood.


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## zak187 (Jan 15, 2005)

yea it is a large motor


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## himilefrontier (Jan 21, 2003)

Another downside of the 305's, particularly the later 80's L03's ( TBI, 170HP) is the cylinder heads have part of the intake port obscured around the valve bowl, in a misguided effort to induce swirl and reduce emissions. The 305 is by no means a perfect engine , but it is buildable for decent power now due to the introduction of the World Products S/R Torquer 305 heads which are cast specifically to put a decent sized set of valves in the small cylinder. The small cylider size is a big liability on these engines, but not because of the actual displacement. The small bore limits the amount of air that can enter because of the valve sizes required in a 2 valve head.This limits power. If you look at any good 4 valve 4 cylinder, it produces far better specific output with much smaller bores than a 305. If you overcome the valve sizing hurdle, the 305 can be built to produce decent power with low cost.

Oh, and another good head that may work on the 305 is the excellent L34 Vortec head used on late 90's light trucks. It has only a 1.94 intake valve, but actually has flow numbers superior to the first generation "Bowtie" heads. These heads are excellent on any SBC that can take them as they have excellent high swirl chambers, and are so efficient that they only require 28 degrees of initial timing as opposed to the old standard of 38! They are cheap too. New sets cost under $600 with valves and springs already installed. They have only 3 drawbacks I can remember: the intake bolts are installed straight down like a Ford Windsor V8 and so they will not accept a standard SBC intake ( But IIRC, Scoggin Dickey has them available drilled for standard intakes), they are Iron and thus not light, and the valvesprings can only deal with .450 lift.

Oh, I thought of another possibility for heads: L98 Corvette aluminum units from 1986 on up ( I worked on a 1985 Vette and it did not have aluminum heads that I can recall). A variant of these was sold on the ZZ4 crate engines too, and their 58cc chamber would provide decent compression as most 305's also had small chamber heads. I can't verify that they work, but I seem to remember reading a story in Hot Rod back in 1986 or 87 where they built a 305 with a set.

My history with SBC's includes a 1970 406 powered 1984 Z-28 I built for a freind and my own 1985 Olds Cutlass with a mild 1977 355 that has the S/R Torquer heads and a Performer intake, HEI, and soon to have a Q-Jet.


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## Zen31ZR (Mar 24, 2004)

himilefrontier said:


> ( I worked on a 1985 Vette and it did not have aluminum heads that I can recall)


Mid-late 85, as I recall, and not _all_ Corvettes got them. Typical GM weirdness. They pulled a similar stunt with the LT5 (actually Mercruiser did) where there were 2 different types of heads on the same motor. This happened in 94-95 as I recall. I had both an ('87) 305 and an ('89) 350 TPI powered IROC-Zs, they both were pretty fast. I wouldn't call the 305 a slouch by any means.

I guess if he has access to more 305s than 350s, he has to do what he has to do. Both are common in junkyards around th ecountry, and given the minor price difference, I'd sooner pick the 350, myself.


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## himilefrontier (Jan 21, 2003)

I was going to edit my previous post, but for some reason, the "EDIT" button is not there. The reason why is that I mis stated initial timing as 39 and 28, I meant to say total timing. 
Also, the biggest reliability problem with 305's is with the earlier vesions. The problem was the cam cores were made of too soft a material and tended to go flat. This applies to all carburated flat tappet 305's (LG4 et al) except for the 1983-1985 L69 "HO" engines which used 350 cams instead.


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## Zen31ZR (Mar 24, 2004)

himilefrontier said:


> I was going to edit my previous post, but for some reason, the "EDIT" button is not there. The reason why is that I mis stated initial timing as 39 and 28, I meant to say total timing.
> Also, the biggest reliability problem with 305's is with the earlier vesions. The problem was the cam cores were made of too soft a material and tended to go flat. This applies to all carburated flat tappet 305's (LG4 et al) except for the 1983-1985 L69 "HO" engines which used 350 cams instead.


 Friend of mine had an 83 chevy wagon with a 5.7 and some of the cam lobes went flat on it. I heard that was a problem with both the 305 and the 350 til the roller-cam motors came along.


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## Marc Z31 (Jul 25, 2004)

LostLucian said:


> ecternally they are not the same in some cases, and also,t he 350's belive it or not are just as reliable as the 305's the only differnce is that for more then 100bucks you pay to get a 4-bolt main block instead of a 2-bolt main block which are hard to come by anymore for original motors, and new ones cost a good mint. the 305 and 350 use differnt starters more often then not, the 350 version of the starter is more beefed up to turn the pistons, which measure 4 inchs as opposed to the 3.5 inch bores of the 305. i do own a 350 4-bolt main engine block, but i dont want to waste it on a nissan body, only for a real purpose built car, not a daily driver weekend car.


Not to be a dick, but the 305 and the 350 are EXACTLY the same externally. They use the same flywheel, pulleys, distributor, starter, water pump, oil pan, the crankshafts are interchangable, they use the same intake manifold and exhaust manifolds, everything is the same, save the bore and stroke. The bore on a 350 is 4.00 inches (you were correct), but the bore on the 305 is 3.875 inches (1/8 inch shy of the 350). 

the reason for a beefed up starter would not be larger pistons, as the increased weight is neglegible. A better starter would be for high compression. They made 350 engines with 2 bolt mains as well. they never made a 305 with a 4 bolt though.


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## Marc Z31 (Jul 25, 2004)

Zen31ZR said:


> The LT5 is incredibly wide, I don't think it would fit under the hood.


The LT-5 will run you about $25000, and they stopped making replacement parts for them as well. The throttle bodies on those cars are cool (2 small butterflies and 1 large one) and the fact that it's a fucking DOHC 5.7L.


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## zak187 (Jan 15, 2005)

Marc Z31 said:


> The LT-5 will run you about $25000, and they stopped making replacement parts for them as well. The throttle bodies on those cars are cool (2 small butterflies and 1 large one) and the fact that it's a fucking DOHC 5.7L.



thats a lot of money. you can buy a zr1 for under 40. i plan to build a DOHC 5.0 for the mustang with in a year or so. got any throttle body pics?


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## Zen31ZR (Mar 24, 2004)

Marc Z31 said:


> The LT-5 will run you about $25000, and they stopped making replacement parts for them as well. The throttle bodies on those cars are cool (2 small butterflies and 1 large one) and the fact that it's a fucking DOHC 5.7L.


Last LT5 was put in a Corvette in '95. Federal law mandates replacement parts be made for 10 years following end of regular production, so at the end of this year parts production _might_ stop. Not to mention that was a Mercruiser boat engine, in use since that time as well. Replacement parts won't be a problem. Expensive, since the total number of ZR1s built didn't clear 50,000, but they should still be findable.


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## 53sled (Sep 4, 2009)

LostLucian said:


> I have a 88 nissan pulsar that will have a 305 (not a type-o, i mean 305 cubic inch not 350ci) chevrolet engine, i will be installing my own transmission and drivetraign system, converting the entire are from a front wheel 5 spd system to a rear wheel 3 speed overdrive system. thankfully, i am not a new comer to chevrolets, i have owned a 79 camaro, a 65 impala sprt, a 88 chevrolet, and a cavalier beforehand (the cavy wasnt stock either  )
> 
> [email protected]


I was just looking for engine swap ideas and found this. I call bullshit, 4 years later.
:newbie:



Zen31ZR said:


> 305 and 350 are the same block. The bore is slightly different, is all. You can bore the 305 out to accept the 350 pistons and it works perfectly.
> 
> 1st number is bore, 2nd is stroke
> 
> ...


You are a fool. the extra .26 bore unshrouds the valves and allows MUCH better head choices.


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## Asleep (Jan 19, 2003)

wow, you just bumped a 4 yr old thread and called HIM a fool...


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