honerablefroggy

Right now I have a 350, and its nice, but Im wanting to go with something a little more gas friendly. Ive been offered a 327 out of an old corvette for a bargain, and I was wondering, for a daily driver, does a 302 have the torque needed? I can get a 283 crank pretty easily. I know both can rev, and I like the small journals. What Im looking for is a (relativly) gas efficiant engine (Im going to be commuting 50 miles every day starting in august) that gets 15-18 mpg in overdrive, but makes enough power up high that I can hold my own in a race. Im hoping for high 13-low 14 seconds, which should be possible with vortech heads and a 100hp shot of funny gas. which would you reccomend? also, how do the small journals hold up to N2O?

Air_Adam

The 302 is.. well... I won't say a bad street engine, but it has very, very little low end torque. It was meant to run up above 6000 rpm, like in Trans Am road racing in the '60s.

The 327 is a better street engine, mainly because of the longer stroke, which makes more low end grunt.

They both have great power at high rpm. The '69 Z/28 (the 302) made around 330 hp (SAE measured in a magazine article) at 6500 rpm. A similar 327 would be a little higher hp at a lower peak rpm, but not much different.

The 302, 327, and 350 are all about the same for MPG, but the 350 will make the most power of the 3, but at the lowest rpm.

Look at the 305 and 350 motors in 3rdGens. They aren't more than 1 or 2 mpg different in any given year, so the difference between the 327 and 350 would be even less.

BUT... if this 327 really is out of a Corvette and has most of the original parts (ex. heads, intake, cam), then you are best off to sell this engine for 2 reasons:

1. If its got the original heads, you probably can't bolt up any accesory brackets.

2. You could very easily make an OBSCENE amount of money from this engine by selling it to someone restoring a vintage Corvette. If its one of the hot ones, it could easily get you a few thousand bucks.

ede

keep the 350, you'll make more power and there won't be enough differance in milage to matter

iroc22

The difference in the length of the stroke will hardly change the power peaks in the RPM band or the amount of torque the engine produces. The way you build the engine will depend on how it revs and where it makes it's power. Toss some smogger heads and a low lift cam on a 302 and we will see how high it revs and where its torque peaks.

From a mechanical standpoint the 327 is a good combination of stroke and bore but I'm sure you are not fine tuning the power curves on a dyno for some sort of circle track or NASCAR racing so really it is an insignificant feature to lose the extra power from the extra displacement. Stick with the 350.

Air_Adam

If you built two engines EXACTLY the same, one being a 302 and one a 350, the 350's peak HP and Torque WILL peak at a lower rpm than the 302's HP and Torque will. Its a proven fact.

the '69 Z/28 and the '70 LT-1 are perfect examples. They are identical in every way; heads, cam, exhaust, intake, carb, compression ratio, etc etc.. and the 350 does make more hp and torque, but at a LOWER rpm. The Z/28 peaks in hp around 6000-6500 rpm, and torque around 5000rpm.
The LT-1 peaks in hp around 5500-6000rpm and torque around 4000-4500 rpm.

These (Z/28 and LT-1) are IDENTICAL engines in every single way, except the stroke. The stroke difference of 0.48" made a drastic difference in HP, Torque and the rpms at which both peaked. period.

86BirdSE

I personally doubt there will be much of a gas mileage improvement with a 327 or 302.

I would look into a MSD type ignition with a hot spark and smaller carb (600 cfm) as well as keeping it all in tune... I put new plugs and air filter in every 12 months regardless of my mileage. Be sure all of your basics like plugs, wires, coil, o2 sensor, filters, etc. etc are new before swapping in another motor. Also, check your cat. convertor. Any thing wrong with it on these cars will cause poor fuel mileage.

I did a swap of a 305tbi to 350tbi in a chevy van and actually saw an INCREASE in mileage because the 350 didn't have to rev as high to get the beast moving.

jmiller

I owned a 69' Z28, bought it new in 69'. I drag raced it for 2 years in a stock class. A 302 is NOT a good street engine. It is totally dead in power unless above 5800 rpms. Eats plugs regularly, and gets horrible gas mileage. I would shift mine at 7800 rpms. I had 5.38's in the rear end and ran 12.5 at 108 mph. My car was only .4 tenths off the world record in AHRA formula 1 "I" stock. I agree with the others, a 350 will do much better than even a 327 for what you want.

honerablefroggy

ok, heres the plan then

Im gonna go with a 350, but Im building it my way (I dont know anything about the bottom end of my current engine, so im gonna build one from scratch)

As for the gas mileage situation, Im thinking about getting hooker comp headers, MSD 6AL with timing control (so I can run 87 or 89 during the week). and picking up a 670 cfm holley street avenger. That coupled with a tuneup should help me with a few MPG, hopefully I wont have to sell my baby. any other suggestions on how to get better mileage?

iroc22

Yeah it is a proven fact that's why I said: "The difference in the length of the stroke will hardly change the power peaks..."

Those two engines are terrible examples. First off GM didn't even give the public the correct hp/tq ratings even and I have never seen any side by side dynos of those two engines (if you have found dyno sheets of the two STOCK let me know). Secondly the most often dubbed erroneous ratings that GM gave us put these two engines at: 1969 302ci 290hp@5800rpm and 290tq@4800rpm while the higer compression 1970 LT1 (or the more popular way of displaying it; LT-1) was rated at 370@6000rpm and 380tq@4800rpm. And although those may be incorrect to a certain degree, those numbers are straight from GM.

They are supposed to be indentical engines as per GM again, but I have talked to a few people who have disassembled and had hands on experience with these two engines and have claimed that they carry some different parts. I'm not going to comment on the differences between the LT1 and Z28 engines since I do not know for sure whether the 'indentical' claims are correct.

five7kid

iTrader: (14)

The '69 Z28 302 and '70-1/2 Z28 LT-1 were hardly the same engines with different strokes. About the only common part was the block. The LT-1 heads were the first production angle-plugs. The cam was different.

The carbs were the same, though.

The 7800-RPM 302 is also a poor example for this discussion. It didn't turn those R's off the showroom floor. The home-made 302 I had, from a 327 block and 283 crank with LT-1 cam & heads, didn't have power below 2500, but it wouldn't pull above 6500, either.

It's the same old SBC story - if you want to make up for the reduced torque of a 302 vs. a 350 because of the shorter stroke, use a shorter duration cam & keep intake velocity up. If you want to make up for the reduced power of a 302 vs. a 350 because of reduced displacement, you maximize upper RPM power with gobs of duration and air flow.

If you want to maximize economy, consider a 305.

chevymad

I always find these 302 discussions pretty funny. I mean everybody says it cant be made into a decent street engine.. yet it has the exact same bore and stroke as the 5.0 mustang used. And we all know how good they were. So you guys saying Ford knows how to build a better motor than chevy or what?

jmiller

I beg to disagree. My 69' Z28 would easily turn over 7500 rpms stock. You have to put yourself into the days when gas was leaded, and Chevron sold custom supreme (white pump) 105 octane fuel for 33 cents a gallon!!!! The camshaft if adjusted down to .024/.026 would easily turn those r's. I ran my car in a stock IHRA class, but my car was totally legal to run "STOCK OPTIONAL". The only thing I did to my Z28 is add headers and slicks. I did NOT alter the motor!!!! Anyone knows that the advantage of a short stroked motor is to build it for top-end, which can't be done now with crap gas!!!! So why waste your time with it!!!! Go with the modern tech. and build low rpm motors with tons of power down low. I have a 67' Camaro with a stock ZZ4 TPI setup 700R4 get 20 MPG and with street tires turned 13.59 at 101. My point is I didn't waste my time trying to bring back old tech. that won't work the way they were intended to be!! And the gentleman that mentioned the LT1 and 302 were not the same is absolutely correct. A 70'Camaro with an LT! in it couldn't come close to running along side a 302. I saw them at the drags in 1970 and 71' .

wsp1970

I don't want to get into the middle of the horse power war here(LOL!), but if you do want to build an inexpensive 302 chevy, use a 350 block and a 262 crank. The 262 was a 305 block with a 3 inch crank. It will have the large journals and work in a 350 block. The 262 was made in the late 70's and maybe the early 80's. You should be able to get a remanufactured 262 crank from the machine shop that does the work for you (if they are also a parts house).

As for power, well I hate to say it, but, the Ford guys got somthin goin on there. Personaly, I like the 355, and would stick to the 350. I don't beleive that you would save much on gas buy going with less cid. I think that gas mileage is relative to how much you open your secondaries.

iroc22

Actually it was a 3.10" crank. Very close to the 302 crank though.

wsp1970

I don't know, I think I remember here in the last year that Car Craft Mag stated it had a three inch crank.

Here is the math


3.736(bore) / 2 = 1.868(radius)

1.868 X 1.868 = 3.48

3.48 X 3.141(pi) = 10.9

10.9 X 3(stroke) = 32.7

32.7 X 8(cylinders) = 261.6(cid)

Thats a 262.

If it had a 3.10 crank it would be a 271.

Check it out <http://www.aces.edu/~gparmer/sbc.html>

The 262 you are refering to was made in the 60's. The website listed above calls it a 263, but in a Malibu that I had, it was listed on the sticker on the fan shroud as a 262.

iroc22

Show me a Chevy that had a 262 V8 in the 60's and I'll give you my car.

The 262 V8 was produced from 75-76 with a 3.671" bore and 3.10" stroke. Simple as that.

You may be confused by the 265; produced 55-56 with a 3.750" bore and 3.00" stroke.

Or to stir the pot even more maybe the 267 (found in millions of Malibu's and Regal's continent wide) produced 79-81 with a 3.500" bore and 3.48" stroke.

wsp1970

I am so sorry for questioning your authority on this matter, maybe if I could just touch the hem of your pocket protector then someday I could be just like you. :hail:

iroc22

Just because you were completely wrong doesn't mean you have to be so bitter

86BirdSE

was asked.

Keep your cap and rotor fresh, and use one with brass terminals.

Low Ohm resistance wires, a hotter coil and fresh standard AC Delco plugs with a 060 gap, replaced yearly.

Clean Fuel filter (every 2 years)

Fresh 10W30 or 10W40 oil and the big filter (AC PF1218) Syn. oil is supposed to give you better MPG, but changing you oil every 2500 if you drive hard is much better than leaving syn oil in for 5000 miles or more.

Spray down your carb with carb cleaner at every oil change

Make sure all those vacuum hoses are in good order

New PCV Valve and Breather Element.

Change your tranny fluid and filter yearly.

Clean Air Filter (if it's paper, change it yearly, if it's a cotton gauze or foam clean it every 6 months.

Get a wheel alignment. It alone is worth a good 2 MPG on the highway.

and the #1 thing? Don't drive it hard at every stop sign and traffic light. There you'll be able to see your biggest difference.

Black363IROCZ

why can't a chevy 302 make any low end power when a ford 302 can? your arguements don't make sense. a Ford 302 is the same motor (bore x stroke) as the chevy one yet I hear everyone talking about how "unstreetable" a built 302 is. Ford guys have tons of built 302s that are quite streetable. it's all about matching parts and building it right. I think a 5.0 SBC (302) would be quite a good motor to throw into a 3rd gen.

cdartz

Nobody has mentioned this so I will. You are concerned with saving money by increasing your fuel mileage by doing an engine swap. That makes no sense to me. It's going to end up costing you a lot of money to build an engine. Just think about how long it's going to take for the minimal fuel savings to make up for the cost of the new engine. In my opinion it's a complete waste of cash. Just tune the engine you've got. If fuel mileage is that great a concern then you are driving the wrong kind of car. Go buy a 4-cylinder Honda.

Cronic3rd

Have you thought about swapping to fuel infection? With the correct parts TPI canmake good power and mileage. And it is cheap to obtain.

wesilva

iTrader: (35)

I think your plan to stick with the 350 and improve on it is wise. I have a carbed Vortec headed 406 in a 6000 lb Suburban that gets that kind of mileage! Are you running a loose converter? If you need MPG's your going to have to ditch the 750 DP. I'm running a Holley Truck Avenger 670 on the 406 and it makes great power that would probably put my thirdgen in the high 13's. I would improve on the 350 to make 290 to 305 RWHP. That's enough to give you the 1/4 mile you want provided you can put the power down. Try to put your power curve to where the meat of your torque is in a streetable range. It has been said that good MPG's is more a function of rpm than cubic inches. My overdriven (700R4) 406 has proven that to me.

Kingtal0n

Sheesh its about time! No one this entire post said shnit about fuel infection..

pick up a TPI setup from a junkyard or have Tacreations send you one, have the injectors cleaned and maybe pick up a chip burning setup so you can mod the motor effectivelly and DRIVE IT.

People with batchfire TPI in good tune ALWAYS pull better than 20 MPG highway, and usually in the 15-25MPG city.

Hell on my setup right before it overheated (255, ported TPI, XE262Cam, 170CC Perf RPM Heads ) I was getting 28MPG highway and averaging 20MPG city! I picked up the TPI setup from a junkyard vette (to fit my pre-86 heads) for $100, some new injectors and weee..... oh yeah and an $820 aftermarket ECU because i wanted to run 14PSI of boost reliably..

so i could have a pump gas 600RWHP daily driver that gets 28 MPG. thank you fuel infection.

jmiller

My point exactly!!! My 67' Camaro's TPI system is from the junkyard out of a 88' Z28. I installed it 4 years ago and have had NO problems ever.

Black363IROCZ

you could use TPI on a 302 without having it choke out around 5500 rpm like it does on a large 350. it'd actually be a great induction system on a built 302, provided it was ported and had a fuel system and52mm throttlebody to support it.

BIRD91ZRAG

iTrader: (1)

The 69 DZ 302 motor and the 70 LT1 actually have quite a few common parts.....
186 casting heads, the difference being screw-in studs and guide plates on the 70 heads.
Intake manifold is the same casting.
"pink" floating connecting rods
Solid lifter camshaft.

The heads are much better suited to the 350, as the large ports are the main reason for the 302 being a pig below 3000. The 302 will rev reliably over 7000, BT,DT. The 2nd gen Z was a much better driving car, even if it wasn't as fast.

I speak from experience, I've had them both.

Air_Adam

THANK YOU!!!

See? The LT1 and the Z/28 are basically the same engines! These are the common parts between the two that I know of

- Same head castings
- Same pistons (different CH though)
- Same intake manifold casting
- Same camshaft, solid lifter
- Same rods
- Same carb
- Same exhaust manifolds (Optional headers for Z/28 in '67-69 though)
- Same exhaust system components
- Same ignition system
- Same pan and windage tray
- Same block casting, 4 bolt mains (for most LT1s)
- Same emitions equipment

BIRD91ZRAG is right though... most of these parts were much better suited to the 350 than the 302. For street use, anyway.

Kiwi-85IROC

quote:
--------------------------------------------------------------------------------
Originally posted by jmiller
I have a 67' Camaro with a stock ZZ4 TPI setup 700R4 get 20 MPG and with street tires turned 13.59 at 101. My point is I didn't waste my time trying to bring back old tech. that won't work the way they were intended to be!!
--------------------------------------------------------------------------------



Hehe jmiller mate

jmiller

Here are pictures of my junkyard 88' TPI installed in my 67' Camaro with a stock ZZ4. I also have an 87' IROC.

jmiller

At the drags last year

jmiller

And my 87' IROC

Matt_Ky

DZ 302 and 327 not good street engines!

zerotosixtyV8

lol, apparently people are saying that, 302 is a GREAT motor but a 302 WON'T get better fuel economy than 350. because it is a higher RPM motor it won't get the fuel economy that a lower turning motor will get, so it'd get the same if not less fuel economy because of its operating speed. but you can make a 302 just as streetable as a 350, it's just more work and expense cause you'd HAVE to get a 302 crank if you've got a 69-up block, if you've got a 67-down 327 block, you'd have to find a solid 283 crank to use and you can only use 302 specific pistons. I think it'd be a fun motor to replace a 305 with cause you can keep the 5.0L displacement but have some very nice power. if you've got a 350 keep it, you can do 500 HP with it for less than you could a 327 or 302. and whoever said a 327 is a poor street engine what on EARTH are you smoking??? GM thought it was a great street engine for over a decade and so did people who bought them and raced them. yeah yeah I know they went to a 350, but that doesn't negate the 327 being just fine! there is a bloke I know of with a blown H/C/E 327 in an old Chevy running low 10s!

Matt_Ky

Ditto!!! I couldn' agree more. We easily ran low 12's on Friday and Saturday nights at BB Park in Bowling Green (my hometown) in our daily 302/327 drivers to high school.
Of course, gas was 35-50 cents a gallon

zerotosixtyV8

lol and had lead in it making 14:1 compression streetable

trickedout02

Stock the Chevy 302 pumped out 400+ hp and 400+ torque... Chevy rated it at over 300 hp and 300 torque, which was later corrected by car and driver... I hear people dissin' the chevy 302's grab a stock 302 chevy and dyno, that's the only true test, also keep in mind, chevy is known for lyin' about how much hp and torque there engines pushes out, always going lower, for the purposes of insurance and value, they wanted to make these vehicles affordable pony cars. Look up the history of the chevy 302 before dissing it...

heres a link, read the article about the z28 that has the 302...

http://www.musclecarclub.com/musclec...istory-1.shtml

RB83L69

Wow, what a steaming pile of excrement....

Those of us who were there at the time remember well that the stock rating for the 302 was 290 HP. In reality they did a little better than that, probably closer to 320 or so; but nowhere near 400. That's laughable.

Why won't this idea, that you can somehow make more power out of a given block by reducing the cubic inches by way of the stroke, ever go away? It's just ridiculous. It's so illogical, I guess people who aren't logical just have to fall for it.

Here's the 302 air cleaner decal. http://www.yearone.com/serverfiles/p...hid=821AC12078

jmiller

the 69' Z28 (302) was one of the only engines that was under rated by the factory, actual HP was around 330. I personally don't know why. I ran my 69' Z28 under 2 different drag race assoc.: NHRA and AHRA. Placement in stock classes was assigned by dividing the vehicles weight (3020 lbs) by the advertised HP (290). This placed my car (69' Z28) in the 10.0-10.5 ratio.
In 1970 when I was racing my car
NHRA ==== G Stock
world record was 12.3 held by a 69' Z28
NHRA tire limit was 7" cheater slicks
AHRA ==== I stock (formula 1 - 1 carb)
world record 11.95 held by a 69' Z28
AHRA tire limit NONE
don't remember the MPH but who cares in drag racing, the records are only ET's

My best time was 12.61 at 109. But my car was legal showroom stock NHRA and legal Stock Optional AHRA.
The only advantage of underrating HP was obviously drag racing and insurance, but Chevy didn't design and package the Z28 for drag racing, it's sole purpose was to qualify for Trans AM racing. Mark Donahue kicked *** in 1968 and 69'. When Chevy decided to put the LT1 (350) in the 1970 Camaro, Ford kicked it's *** and that was pretty much the end of Z28 Camaro domination. Keep in mind that the 1st gens were a lot lighter (2900-3050 lbs.) than the 1970. And for racing purposes, the 302 could and did outperform the LT1. Please also keep in mind that when racing back in the late 60's, the engines could not be modified!!! So don't argue that a 350 can be built to out perform a 302, when that was not allowed to be done. If you read the history of Trans AM racing back in the late 60's, the cars had to conform to production specifications!!!!, and you could not use any non-production parts.

zerotosixtyV8

lol, the older chevy 302 is subject to interpretation but it was intended for racing. the new Ford 302 EFI puts out HP was comparable to a 350 TPI and that's with heads that flow 140 cfm I hate ford as much as the next chevy guy, but that motor is no pushover.

Matt_Ky

400 HP from the production line!!
Ditto, 290 HP. However, you can't knock SBC's less than 350ci, the high winding 283 was the first engine to achieve the 1 HP per cubic inch bechmark in 1957 with a Rochester mechanical Ramjet Injection. The 283 would run circles around the W-block 348 (which eventually grew into the 409) and the 348 had 315hp. Some 327's made 360-375 HP straight from the factory. I believe the 1966-67 327 Novas made 350 HP.
Not sure I believe the 12.3 stated above as the NHRA record for a 302, but I could be wrong. It happens alot!
Of course, everything went to Heck in 1972-3 with
energy conservation, oil embargo, etc.

jmiller

I drag raced from 1966-1971. In 1969 I finally had enough money to buy a new 69' Z28. I raced it for almost 2 years at Lions drag strip (AHRA) and Irwindale (NHRA). I was running pretty close to the world record, believe me I knew what the class records were. Keep in mind that AHRA rules were more aggressive than NHRA. The main difference was the tire rule. NHRA rules required 7" cheater slicks, no slicks allowed. With 10" slicks my car would consistantly run 12.6-12.7 at Lions. With 7" cheaters let down to 4 lbs. (very scary ride) I could achieve 12.9's. Both Z28's that held the records were back east somewhere. The AHRA world record holder 11.95 ET was called "Jack the Giant Killer". It was hugger orange/white just like mine. There was about a .4 second diff between the NHRA and AHRA records, which is just about ALL tire.
I could not afford to do alot of the things you had to do to shave off the last 1/2 second. The only changes I made was headers, 5.38 rear gears, and a better clutch/pressure plate, no engine work other than tuning, but I never really ran into much competition at the track. Most cars were lucky to run within a second of the record!!!