Thread: 327 Sb

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WHAT IS THE DIFFERENCE BETWEEN A 1965 IMPALA 327 SB ENGINE AND A CORVETTE 327 SB? WHAT WOULD I HAVE TO DO TO AN IMPALA 1965 327 SB ENGINE TO MAKE IT COMPARIBLE OR BETTER THAN A 327 CORVETTE 327 SB? WOULD I HAVE TO CHANGE TO PISTONS, HEADS, ..ETC... AND IS THE CRANK SHAFT THE SAME? ANY ADVICE WOULD HELP.

Your question implies that there was only one version of the 327. Actually the Corvette could have had any one of four engines, L75/300hp, L79/350,L76/365, and L84/375. The Impala engine, if original, would likely be the L75, so those would be the same. To get to the others, generally, would take a head, cam, and induction change, along with compression change for the two higher hp versions.

THANKS MR. PARMENTER, I HOPE I DON'T SOUND IGNORANT, BUT WHAT IS INVOLVED IN A INDUCTION CHANGE? AND WHEN YOU SAY COMPRESSION CHANGE IS IT THE PISTONS AND VALVES? WHAT KIND OF MONEY ARE WE TALKING ABOUT IF I DO THIS?

I have a question for you guys. If a person can make 375 hp using NOS Chev parts, which is plenty for a street rod, why do you all become salesmen for the big buck aftermarket stuff? The everyday joe can not participate in the sport using your logic. In answer to the posted question, yes you can modify your 327 and yes you will be happy with the performance.

From reading your profile, it appears that you want to put this engine into your 55 Pickup, so I asume originality is not a major concern. I agree with Richard we could use a little more information to give you some answers that you can really use.

I'm going to go on the assumption that you want a "corvette engine" for the same reason most people do, bragging rights, and the notion that there was something magic about the engines that Chevy put in their little plastic cars (my apoligies to the vette guys out there, haven't had my first cup of coffee yet).

First the bragging rights thing. We used to have a saying in one of the shops I worked at "every small block is a vette motor and every (early) Hemi is a 392". Chevy made the SB in at least 8 different displacement, and Chryslers early Hemi had 13. You'd be amased how many people claimed to have either a Vette motor or the 392 (especially if the engine happened to be for sale, or they were hunting trophies at the car shows). In the case of either engine the castings are the same and without checking the numbers it's hard or impossible to verify wether it is or isn't what's claimed. I suspect most of the members of the CHR Old Geezers Club feel like I do when stranger tells them that that their car has a Vette engine in it ("yeah right, "). Frankly there are more "vette" engines in Hot Rods than Chevy ever produced.

As far as there being something magic about the Vette motors, as Bob points out the exact same engine could be ordered in a lot bodies other than the corvette. Yes with the right money, you can reproduce any Vette engine, pistons in the proper compression ratio, cams, heads and intakes are all available, just choose the combination you want based on the specs of the original engine.

The real question becomes do you really want to duplicate a mid 60's high preformance engine? Back in the "good old days" the factories produced some impressive high HP engines, the down side was they were really barely streetable. If you completly duplicate such an engine, you would likely have something in the 11 to 1 compression ratio area (to run it now you would need octane booster) with solid lifters that would need regular attention, and a dual point distributor that always a lot of fun to tune. It would make good HP numbers but be lacking in bottom end torque requiring deep gears and /or a high stall converter. Gas milage would not be something that you could brag about and it would likely have a tendency to run warm (New Mexico huh?).

My own opinion is that your first step should be to figure out how you REALISTICALLY want the truck to perform and how you plan on driving it. From there it's matching the correct parts and building the engine as a package. With that information, I'm sure the people here can provide some very good specifics on what combinations to use.

Tech, I cannot understand you. And that statement us totally unnecessary. I am from the old school when hotrodding meant figuring out what worked, not thowing dollars at it to make it work. You seem to doubt anyone who does not use modern parts.
If I do not know what I speak of, how was it that we got just as good times or some times better than the so called modern engines? Check your history. If you want to use the aftermarket heads, do so with my blessing, but do not tell someone who has stated that cost is a factor to also spend the bucks, OK?

I really appreciate all the advice and knowledge out there, if it wasn't for you guys, us begginers wouldn't know where to start. I pulled this 327 sb out of an 65 Impala, and yes I would like to put it in my 55 chevy p/u. I'v heard alot neat things a 327 can do, something about the crank in it. The reason why a 327 is my dad had one in his truck, it came out of a 65 or 64 vette, he had 202 camel hump heads don't know what cam but it had a radical idle especially when he uncapped his headers. He also had a possy track rearend, with a 4-speed munci, the engine was blueprinted and balanced. My father has passed away, and the truck will stay in arizona with the family. I liked to build my own hotrod similar or better. I want my engine to have a radical lope or idle I want to be able to slam those gears down a 3 quarter mile like my father did ( the first time he showed me how to drive that hotrod truck, it scared me, I was 16yrs old in highe school, I learned the respect for speed.) I would like to have a mean engine but also run a/c in it , cruise it around town, take it to car/truck shows, I don't ever think I'll be racing on a race track, maybe down main street light to light or out on that old high way, like we used to do it in high school. The engine doesn't have to be exactly like a vette engine, I just thought vette engines were the best, growing up with my dad and his red 55 chevy, to me his truck could beat anyone truck or car. So if any one of you hotroders can relate, please help me out on building an engine with 375 hp or more that can run A/C and not get hot, due to being here in NM, everything heats up, I would appreciate it.

I'm not sure what your refering to about the crank, Chevy used 2 different cranks in the 327, a large journal and a small journal. The difference being the size of the main journal diameter. Without getting into a big discussion about bearing speeds, it really doesn't matter as far a preformance goes, a small journal block requires small journal crank, and a large journal block requires the large crank.

As far as the combination you want to run in this day and age, I would recommend the following:

Do the best rebuild you can on the short block!!! If your going to spin the engine pretty tight, you want the engine to hold together.

1. Have the main bearing housing checked, and line bore if neccessary.

2. Have the crank checked and turn if necessary. If it has a cast crank, and funds permit switch to a steel crank. If the crank you have or are looking at won't clean up at .010 undersized disguard it. (With an engine that turns high RPM, the crank and rods can become the weak link and should be as strong as you can make them).

3. Have the rods checked (with the age of the engine, you'll likely find they need to be resized). It's a good idea to have them magnifluxed and if funds permit shot-peened to help eliminate the possibility of stress cracks.

4. Have the block bored the minimum necessary to clean up the cylinders (preferably .020 to.040 and no more .060). Choose pistons that will give you a 9-1 to 9.5-1 Compression ratio with what ever heads you decide to use. Higher compression will make more HP, but the problem becomes getting good fuel at the local gas station and the added heat generated by the engine. As far as pistions, unless your planning on running a supercharger or NOS I'd avoid forged pistons. Generally speaking they are heavier (which will directly affect how fast the engine winds up), and the added stregnth will not really be neccessary. A good set of cast pistion or preferably a set of hypereutectic will do just fine. Sent the rotating assembly along with the flywheel/flex-plate and balancer out to be balanced. Have new cam bearing installed, and use a good double roller timing chain and stock blue printed oil pump (I'd advise not using a HI volume oil pump if your going to spin the engine past 5500 RPM as it could drain the oil pan sump and starve the engine). I would advise against using trick parts like low tensions rings etc unless you are planning on this as a race only engine).

As far as the top end of the engine, which is what will determine how much HP you will make, I'd do the following:

1. SBC like to breath, So I would recommend heads with 2.02-1.60 valves. Chances are these are not what you have, so you have some choices on which way to go depending on your budget. The heads will be the most expensive part of the rebuild but if you want power this is where you make it.

a. Find a set of used 2.02 heads and have them reconditioned. In most cases the ones you'll find that the affordable ones will be worn out. Meaning new valves, guides, hardened seats, springs, etc. All in all this can be rather expensive.

b. Have your stock heads redone and over sized valves installed along with porting to take advantage of the new valves also a set of screw in studs should be added (Likely more expensive than re doing 2.02 heads)

c. Go with a new set of heads (with the number of aftermarket/OE heads available this may be the cheapest option in the long run.

2. Go with a cam in the .500 lift range with around a 290 degree duration. Go with a manifold that makes power in the 1500-6500 rpm range (edelbrock Preformer RPM or equivent) and top it with a 700-750 CFM carb.

3. Use headers that have 1 5/8 to 1 1/34" primary tubes, and a HP GM HEI or aftermarket electronic distributor.

4. Hang the biggest radiator you can find in front of the engine.

5. This combination will require either a manual transmission or an automatic with a stall converter (min 2500-2800 stall) and a set of gears 3.55 or deeper (depending on the tire size.)

To do it right speed/HP costs money. This is not a $300 rebuild, check with your local machine shops and parts suppliers to determine what this will cost in your local area. To REALLY make the HP numbers you want (and have an engine that will not blow up the 3rd stop sign you pull away from) your going to have make a realistic commintment on how much you want to spend.

I think for the majority of us (especially myself) cost is always a factor. When I was doing customer cars, the people who came in and didn't care how much it cost were few and far between (I think I had 2).

Even for the most "hands-on" of us, we all have our stregnths and weakness. I know of very few people who can do everything in house. Personally I can figure things out and fabricate, I enjoy assemblying engines and making things work together. (I know how to do machine work, but don't have the equiptment as I'm a mechanic, not a machinist). Other people may do upholstry or paint and body. Of course the more we can do for ourselves the cheaper the project will become.

Regardless of how much we spend on a project or engine or whatever there are certain things that need to be done to do it right. In the case of building a performance engine (especially one that is targeted to make a HP per cubic inch or more), certain things must be done to acheive that and make the engine live longer than 1 pass.

It dosen't matter if your rich or poor, if the engine needs big valve heads or a better intake or higher compression etc etc to make the power, that isn't going to change. I mentioned a few ways to do big valve heads in my post, but it dosen't mean that someones not going to find a set of good used units on E Bay, a swap meet, or from the neighbor down the street who's cash strapped. Bottom line isn't what they cost, it's a matter of if they will work and if the engine really needs them to make the HP levels desired.

If cost is not an object, I can pick up the cataloge, take the parts to the machine shop, assemble everything and build an impressive engine. If I'm doing it for myself and time is not a major factor, I will shop around, look at used parts (reconditioning them if/as necessary) and build an equally impressive motor for a lot less money. For me saving the money is important, but I also take a lot of pride in being able to do it. Regardless of which approach I take, I will still need the same parts no matter which method I use to collect them.

Going back to our stregnths and weakness (and the billfold sure fits in there) there are always alternatives, but they may be limited by what you want the final outcome to be. In this case the major limiting factor is making 375 streetable HP out of a 327. Doing that will drive what part have to be used, not how they are aquired.

PS thanks for the tip on the oil pump Streets (something that will definatley be filed away for future use).

I have the opportunity to buy a 400 sb chevy engine, already has high performance equipment in it, couldn't tell you right now what it has, but I trust this friend of mine, he has all the receipts to it, so that wont be a problem finding whats in it. The cost for the engine is 2,000$$. Would it be better to buy that engine or stick with the 327? Is the 400 sb better than a 327 engine or vise versa. I know to each his own, but what would you guys do out there, if you had the opportunity to go with a 327 or a 400sb, keep in mind I already own the 327. Could I put the 327 crank in the 400sb or is the 400sb crank better? If I'm going to spend the $$ to do it right, I would like to start out with one of these blocks.

Hey Mike there are some really good books that characterize and break down the small block. One I particularly like is "Chevrolet Small-Block V-8 Interchange Manual" David Lewis. I coppied it, cut it up and made a fammily tree of the small block and its components. the book is 11 years old but with newer publications and applications the small block tree is no sapling.

'Bout the only thing I haven't done is the babbet (only read about it and seen a few pictures). I have however adjusted (clearenced them) when overhualing tractor engines from the 20/30s.

Anyway back on topic, well Mike, you rased a whole new aspect to the way this subject is going. At one point the subject turned to the cost of building your 327 to get the HP levels you want. An old hot rodder "trick" has always been to swap in a bigger engine rather than build the current engine to higher HP levels. I was going to mention this in my previous post but it was getting pretty long.

Your apparently in the planning stage of this project, and now is the time to really look at your options. Half way through building the drive train is a bad and expensive time to change your mind on what you want to do. Now is the time time to define your vision and lock it in before you spend a lot of money. Decide what YOU (not your friends) want to have when your done.

1. Do you want to replicate your dads truck, down to running a SBC, or do you want to have a fast/quick truck and the drive train to do it is not really that important to you.

2. Are you planning on something to bring out and race or do you want something that you can also cruse and take reasonably long drives in (your AC question leads me to believe you want more of an impressive cruser than a race car). How important is streetability to you?

3. Are you willing to consider something other than a SBC?

4.. What is your time frame for doing this?

5. How much money are you willing to put in the project? The time and money go hand in hand in a lot of cases. If time is plentiful, you can look for good deals on parts and spread the dollars further.

6. Finally, just like the engine you need to look at the truck as a package. In my mispent youth back in the 60's you built a hot rod by either building the engine that was in the car, or doing an engine swap. Suspension changes, brake upgrades (I won't even get into the tires and wheels we were running) were not things that were considered. Frankly it's a wonder that many of us survived. When figuring out cost, you will also want to take into consideration proper suspension and drive train upgrades.

I know how I would build a 55 Chevy truck, but what do YOU want?

i have a 68 327 in my 57 chevy at least the block is the intake
and carb are edlebrock the cam is iski the angine is 9:1
the engine pulls that heavy chevy good enough for me and it
sounds good and still going strong after 16 years except for
a recent head rebuild including new stainless valves and hard
seats. 327 is my fovorite sb.

Im getting ready to get this 327 from this guy who took it out of his 65 Impala convertable, it is complete from 4 bbl rochester carb to exhaust manifolds, and even the flywheel. where do I find the numbers to research the numbers to see if it is a L75, L79, or what ever it may be.

Not mentioned in this discussion is that sometime around 1970 GM changed the way the H.P. was measured, so what does a 300 HP 327 compare to, say relative to a Goodwrench 350 with an Edelbrock manifold, 600 CFM carb and headers reputed to put out about 250 HP. Yes the 350 has a lower C.R. and the heads (882) flow less, but folks have told me that the difference in the way the older HP values were measured was about 50 HP less than the rated values compared to modern ratings. Other differences between 1968 and now are that the gas is much worse and that the 350 has more torque at lower rpm compared to the higher rpm performance of the 327. I guess the only way to compare "apples" to "apples" is to look at the dyno curves but looking at the price and octane of 2005 gas might also be useful.

Don Shillady
Retired Scientist/teen rodder