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Performance Engine Mods / Replacement for 87 Supreme Coupe?

Old December 22nd, 2008, 05:04 PM
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Performance Engine Mods / Replacement for 87 Supreme Coupe?

Hi --

I am the proud owner of an 87 Supreme Coupe that has a little rust, but it's worth saving! I like the car, but I would like a little more power than the factory 307. Have been told by a friend that some popular options for Olds power are the 330, the 350, the 425, and the 455. I have heard of Oldsmobile having built a 260 briefly, but am not sure it can do much better than my 307.

I am not interested in a big-block, as I think it might be too much power for the car. I am thinking a 330 would do nicely -- I have seen factory power ratings of 310-325 hp, which is enough for me. My questions concern compatibility with the car's factory configuration, as I would like the car to look pretty much stock after the conversion. I, however, am not particularly mechanically inclined and am seeking some advice.

First, are engine mounts and brackets for all small-block Oldsmobiles the same? If not, what differences are there?

Secondly, what parts, if any, can interchange between the small block Olds engines?

Third, can the 307's factory emissions controls and ECM be used to carburete a 330? My friend is thinking if bigger jets can be installed in the factory E4ME carb, the computer and oxygen sensors should see no difference.

One other question -- I have heard one conversion with small-block Chevrolets is to destroke a 305 block with a 327 bottom end. Is it possible to destroke a 307 block with these parts from a 330? If so, any ideas on performance increase over a standard 330?

My friend (more of a Buick expert than Olds) had thought of using a 4.0 Aurora V8 just for the sake of being different. Is this actually a real Oldsmobile engine, and if so, I know it is FWD, can it be used in a RWD application?


Thanks in advance for any advice given......
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Old December 22nd, 2008, 06:13 PM
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All small block Oldsmobile engines will be a direct swap into your car. I think the problem with a 330 is that they are harder to find than a 350 or 403. A 350 will be easier to find and probably cheaper.

All small blocks are exactly the same on the outside so everything will swap over. Use the same motor mounts for a 307.

A lot of things will interchange on all Olds engines. I think some of the different things are the accessory brackets between small blocks and big blocks, intake manifolds between big and small blocks, I think that is about it.

I have heard of people using the computer system with 350's, but I am pretty sure they need to be fairly stock with low compression to work. I am not sure what people do with the A.I.R. systems when they swap engines, they usually dont have the holes drilled in the heads for the air tubes.

I have no idea if destroking a 307 is possible or even worth it, probably not.

The 4.0 V8 was only used in Oldsmobile cars, but I am pretty sure it was just Oldsmobiles version of Cadillacs North Star engine.

I think I got most of this information correct, please dont hesitate to correct any of my info if I am wrong.
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Old December 22nd, 2008, 08:10 PM
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Originally Posted by dan2286 View Post
I have heard of people using the computer system with 350's, but I am pretty sure they need to be fairly stock with low compression to work. I am not sure what people do with the A.I.R. systems when they swap engines, they usually dont have the holes drilled in the heads for the air tubes.
I am curious.... how does the compression ratio affect the control system's compatibility? Does it have to do with the timing curve?

Also, my friend has me under the impression that the AIR system actually plumbs into the exhaust manifolds..... Does anyone make headers that allow this?

Originally Posted by dan2286 View Post
I have no idea if destroking a 307 is possible or even worth it, probably not.
Hmmm.... could be interesting to find out, I would think? Has anyone tried/heard of this, even?

Originally Posted by dan2286 View Post
The 4.0 V8 was only used in Oldsmobile cars, but I am pretty sure it was just Oldsmobiles version of Cadillacs North Star engine.
You probably are right, but neither I nor my friend have ever seen one to know for sure.
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Old December 23rd, 2008, 05:11 AM
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Welcome to our site. The 330 was produced in the fifties and is not the same as your eighties 307. I would recommend that you look for a 350, they can produce nice horsepower for a street car and you can find performance parts easier too. Forget about the 260 it is way too anemic. There are some threads discussing the 307 and what can and cannot be done to it, a simple search should reveal at least two threads on it.
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Old December 23rd, 2008, 05:20 AM
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This link should give you all the options:
http://tlentz.oldsgmail.com/more_power.html
Unfortunately, it is much more cost effective to drop in a 350, which I have heard can be made to run with the CCC system (with a few tweaks of course...)
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Old December 23rd, 2008, 08:16 AM
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Originally Posted by m_tanner_75 View Post
........ I have seen factory power ratings of 310-325 hp ........
Factory numbers can be (and usually are) misleading.

Originally Posted by m_tanner_75 View Post
........ are engine mounts and brackets for all small-block Oldsmobiles the same? ........
Yes

Originally Posted by m_tanner_75 View Post
........ can the 307's factory emissions controls and ECM be used ........
Yes. Commonly used with 350s.

Originally Posted by m_tanner_75 View Post
........ Is it possible to destroke a 307 block with these parts from a 330? ........
All "small block" Olds used the same 3.385" stroke. Differences in in displacement are due to bore diameters.

Originally Posted by m_tanner_75 View Post
........ Is this actually a real Oldsmobile engine, and if so, I know it is FWD, can it be used in a RWD application? ........
Yes and Yes. They work very well in "light" cars.

Originally Posted by Oldsguy View Post
........ 330 was produced in the fifties and is not the same as your eighties 307 ........
You have the 330 ('64-up) confused with the 303 ('49-'53)

Norm
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Old December 23rd, 2008, 09:10 AM
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Originally Posted by m_tanner_75 View Post
First, are engine mounts and brackets for all small-block Oldsmobiles the same?
Not always the same, but certainly interchangeable. The 307 mounts and accessory brackets will bolt directly to any small block Olds motor. Note that the brackets, pulleys, and water pump must be used as a matched set, otherwise the pulleys may not line up.

If not, what differences are there?
As noted above, the water pump length is matched to the accessory drives. More importantly, prior to the 1980s, Olds accessory brackets were designed to fit both big and small block motors. Since the main external difference between the two is the deck height, the brackets had two sets of holes where necessary to accommodate the difference. Since the BBO was long gone when the 307 was released, the brackets are SBO only, though they can be easily modified to fit a BBO. Note that the 403 Trans Am brackets are unique to the F-body installation.

Secondly, what parts, if any, can interchange between the small block Olds engines?
Pretty much all of them with a few exceptions. The late 307s used roller lifters with a 0.921" diameter. Most flat tappet Olds motors used 0.842" diameter lifters. Since the difference in displacements was the bore, the pistons obviously are different. The 403s used a beefier rod than the other SBO motors. 1977-up motors use 1/2" head bolts vs. 7/16" on earlier motors. The 330s were made with both 45 degree and 39 degree lifter bank angles (all 68-90 motors are 39 deg). The cam and pushrod length must be matched to the lifter bank angle. The pushrod holes in the heads are also slightly different as a result. Finally, the 1964 330s use a one-year-only shaft rocker setup.

Also, my friend has me under the impression that the AIR system actually plumbs into the exhaust manifolds..... Does anyone make headers that allow this?
Your friend must be familiar with Chevy motors. Olds motors run the A.I.R. tubes directly into the heads. Early heads will have the bosses but not the drilled and tapped holes for the A.I.R. manifolds.

One other question -- I have heard one conversion with small-block Chevrolets is to destroke a 305 block with a 327 bottom end. Is it possible to destroke a 307 block with these parts from a 330? If so, any ideas on performance increase over a standard 330?
As Norm pointed out, all Olds small blocks, including the 260, use the same stroke. The forged 330 crank drops into any SBO, with the proper balancing. How decreasing the displacement helps increase performance, at least for a street-driven engine, is a mystery to me. Since HP is a function of airflow, a smaller displacement engine must rev higher to make the same HP as a larger displacement engine. In my opinion, this is not an advantage on the street. Matching the HP vs. RPM curve to gearing and vehicle weight is very important in racing but can make for a peaky, hard to drive street car.

My friend (more of a Buick expert than Olds) had thought of using a 4.0 Aurora V8 just for the sake of being different. Is this actually a real Oldsmobile engine, and if so, I know it is FWD, can it be used in a RWD application?
The Aurora 4.0 liter motor is a version of the Northstar. Cadillac Hot Rod Fabricators (http://www.chrfab.com/) sells parts to swap them into RWD applications. The biggest problem is the water pump, which is driven off the back (driver's side) of the front cam. When you put the motor in a longitudinal orientation, the pump wants to occupy the same space as the brake booster in most cars. The usual solution is an electric pump, but I remain skeptical of those for long term street use.
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Old December 23rd, 2008, 12:50 PM
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Here's a fresh one --- can a 307 be bored out to a 350, or would this destroy the block?
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Old December 23rd, 2008, 02:41 PM
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Originally Posted by m_tanner_75 View Post
Here's a fresh one --- can a 307 be bored out to a 350, or would this destroy the block?
The difference in bore is over 1/4" (3.800" vs. 4.057"), so not even close.
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Old December 23rd, 2008, 02:52 PM
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Originally Posted by joe_padavano View Post
The Aurora 4.0 liter motor is a version of the Northstar. Cadillac Hot Rod Fabricators (http://www.chrfab.com/) sells parts to swap them into RWD applications. The biggest problem is the water pump, which is driven off the back (driver's side) of the front cam. When you put the motor in a longitudinal orientation, the pump wants to occupy the same space as the brake booster in most cars. The usual solution is an electric pump, but I remain skeptical of those for long term street use.

What about using Hydraboost instead of the vacuum brake booster. There is also a bellhousing out there to mate something like a Muncie 4 spd to a FWD engine. I have one.
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Old December 23rd, 2008, 03:49 PM
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Originally Posted by joe_padavano View Post
The difference in bore is over 1/4" (3.800" vs. 4.057"), so not even close.


Okay, now I'm confused. I was of the understanding that Olds engines all shared the same stroke, and that bore was the difference in displacement. Have also read that some race 307s are actually sleeved 350s. Now I'm being told that a 307 cannot be bored to 350. What gives? Are the blocks that different?
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Old December 23rd, 2008, 04:21 PM
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The 307's along with all the late 70's blocks are windowed light weight castings. Building one to the horse power level you are looking at would be ok but the block starts to flex with higher horse power engines so to make more power you have to use light weight parts. I think some of the 307's that are sleeved 350's use the older blocks so the block is more stable.
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Old December 23rd, 2008, 06:41 PM
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Originally Posted by The Stickman View Post
What about using Hydraboost instead of the vacuum brake booster. There is also a bellhousing out there to mate something like a Muncie 4 spd to a FWD engine. I have one.
Most current GM FWD motors use what is known as the "metric" bellhousing bolt pattern. This bolt pattern was originally used on the 60 degree Chevy V6 motors (the 2.8, 3.1, and 3.4 liter motors). The Series II and Series III Buick 3800 V6 motors use the same bolt pattern, as do some of the four cylinder motors. These motors were also used in RWD applications, mainly in the S-10 trucks and the fourth gen F-body cars. As a result, you can readily obtain manual trans bellhousings and 700R4 (and 4L60E) automatics for RWD applications with the same bolt pattern as these FWD motors.

The Aurora/Northstar uses a modified version of the metric bolt pattern. One bolt has been moved and the starter is located in the valley between the cylinder heads. CHRF sells modified S-10 automatics and manual trans bellhousings to use the Northstar motors for RWD applications. They also sell the correct M/T flywheels.

By the way, in addition to the Aurora/Northstar motors, the S-10 transmissions allow you to bolt a supercharged Buick 3800 or DOHC 3.4 liter motor into a RWD application. There's at least one G-body Cutlass with the 3800 SC drivetrain on the web. I also saw a very cool swap of the DOHC 3.4 into a Vega.
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Old December 23rd, 2008, 06:49 PM
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Originally Posted by m_tanner_75 View Post


Okay, now I'm confused. I was of the understanding that Olds engines all shared the same stroke, and that bore was the difference in displacement.
Correct. That's what I said. 307 = 3.800" bore, 350 = 4.057" bore. Both use a 3.385" stroke.

Have also read that some race 307s are actually sleeved 350s.
Also correct. You can add a sleeve to the larger 350 bore to reduce it to 3.800". You can't go the other way.

Now I'm being told that a 307 cannot be bored to 350. What gives? Are the blocks that different?
Yes the blocks are different. The casting cores are different so that the raw cylinder walls start out at a larger diameter for blocks that use a larger bore. If one casting were used to build everything from the 260 (3.500" bore) to the 403 (4.351" bore), the raw cylinder walls would need to be over 3/4" thick. Machining that much metal from a raw casting to get to a 403 is both uneconomical and can result in distortion during machining. Dedicated castings are used for each unique displacement.
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Old December 28th, 2008, 02:06 PM
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Before you drop in a new engine,
What is the gearing in your rear axle???
Most of these cars came with a 2.41 or so axle gear (my 78 had a 2.29!),
a change to a 3.23 - 3.73 will make the 307 feel like a new car.
REALLY.
You will think you found 50 hp.
This should be the first thing considered, in my opinion.
If you have already addressed this issue, great.
Jim

Last edited by Warhead; December 28th, 2008 at 02:09 PM.
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