). "9" has a .440/.440 lift cam, the "Y" is (forgot
exact numbers) more like a .370/.390 lift on the cam. Much wimpier.
The .440/.440 lift on the cam seems to be a new grind for Olds, the
closest to it was like 69 and older, but I cannot remember on what. No
clue on duration. I want to install a "9" cam into a 350, should make a
nice cam matched to 3.42 gears!!
The heads have different grinding specs, but that could be carried over,
so I cannot confirm what heads by the service manual as it does not list
casting numbers. The "Y" has a 30 degree cut on valves, the "9" has
45, or vice versa. One is designed for better flow at higher lift.
Typical for GM to do on high performance engines.
The carb is different in 85, the "Y" is 2 point adjust, the "9" is 3
point. Wish I knew what else was different!! The casting number on the
carb is different.
Exhaust manifolds are cast iron on "9" engines, while they are
tubular stainless steel for the "Y" 307. Although the cast iron
"log" type manifolds have been seen on a 1985 "Y" 307 with 7a
heads. I also pulled a set of cast iron manifolds off an early
80's Delta 88 with a 307 Y motor, 5a heads on that one.
Look in the book under engine rebuilding and see what you find to
compare, the "9" gets a lot of listing differently. Note them and
compare to "Y" 307. Much of what is found on the 307 "Y" is found on
the "N" 350, "N" you say? Diesel!
[ Thanks to Mike Rothe, Thomas Martin, Bill Reilly for this information. ]
1986 - 1988 307
As for performance, the '86-'88 rwd Cutlasses had an engine optimized for
low-end torque, so performance is great in the 500-3500rpm range;
unfortunately, the factory engine is pretty much optimized for that range,
so any additional "hot-rodding" would likely diminish performance, unless
you changed *everything* (cam, heads, intake, exhaust, carb, etc).
If you plan on leaving it completely stock, then this won't be a problem;
in fact, you can take pride in driving a factory "hot-rod", since that
little 307 has all the tricks that you could possibly put in it to make
low-rpm power (roller cam, swirl-port heads, tubular exhaust manifolds,
tuned carb, OD transmission, etc). It's just that you can't get any more
out of it; the factory already did what it could.
1986-88 vin 9 motors are roller lifter engines with swirl port
(dinky) heads. The swirl port was Olds answer to fuel economy. It
was a totally designed intake port combustion area.
The intake ports are small and raised, and the head ports on the intake
side have spiral runners cast into the valve pocket area (sort of like
a spiral staircase). The pistons have a horseshoe looking dish on top.
All designed to promote port velocity at low rpm, and give the intake
charge a "swirl" to promote velocity and atomization of the fuel air
mixture. The exhaust port is smaller also (compared to previous 307 heads),
and round. This did help economy and low end throttle response, but
these cars are sort of pure slugs from the factory!
I bought an 87 442 new and have posted the story about getting dusted
by a 4.3 S-10 pickup the night I drove it off the lot!!! i did "play"
with mine, and got the swirl port to run low 15s, but it wasnt smog
legal (eg. true duals w/no cats). The pre 1986 versions of the 307
have much more performance possabilities.
[ Thanks to Bob Barry for this information. ]
1987 - 1990 307
The VIN code 9 307 was available in full size Caddys. Actually they are
quite common in the '87 to '90 Fleetwood RWD cars.
I have seen a few RWD Cadillacs with the VIN "9" 307, but they are not that
common. Most got the regular "Y" engine. The cars I have seen with the "9"
code engine were either equipped with the 5,000 lb tow package or were the
"commercial chassis / coachbuilder package" sold to limo and hearse
conversion firms.
[ Thanks to Tony Waldner, Frederick Nissen for this information. ]
307 vs other GM Engines
When looking at HP ratings, you should always look at the torque as
well. This is important. Olds cammed the 307 to work with ultra high
gearing. From 2.14 without OD, to 2.41 with OD. That is about
1300-1500 at 60 mph. Chevy engines have cylinder heads that do not flow
well at low lift/low rpm levels. So hence the 2.73 gears on a 305.
Most Chevy's did not get gearing like this. (Granted, a friend of mine
had a 82 Chevy B_Body wagon with 267, 2bbl, OD and 2.56 gears!! Talk
about a SLUG!) The same Cutlass would have 2.14's. Acceleration would
be close to the same once moving.
In 1980 the 301 Pontiac was rated at 140 hp, the 305, 135 hp. The HO 301,
170 hp, the HO 305, 165 hp. The 301 Turbo 210 hp (345 ft lbs torque), while
the 305 needed TPI and a roller cam to get there. And if anyone has ever
seen 301 heads, you understand that the 301 was not a heavy breather! My Turbo
301 layed down at 4500 rpm, poor airflow. Pontiac designed it as a low rpm motor.
The Olds 307 (Y) was rated at 140 hp from 82-90, and the torque was 255
ft lbs. Seems to me it took a 305 to get TPI to get torque like that.
HP is one thing, torque is Olds. Ask any 455 owner!! Can we say Brain
Damaging??
Comparing Chevy's to Olds to Pontiac to ??? is like comparing oranges,
apples and pears. Not at all alike unless you account they are all
around 5.0L.
In GM corporate wisdom, there was a good reason to keep the 307 along as
long as it did. Else it would have made way for the corporate
slo-block, or the slo block would have made way for the Olds 307!
(shared the same bore as the Buick 3.8L, hmm, cost savings on rings and
maybe pistons???? hmmmmmmm). Saved money on tooling!
I always try to remember, GM does everything for a reason, it is not
always sensible, but there is a reason. They want to make money, and
having lots of engines around that are the same size is senseless.
[ Thanks to Thomas Martin for this information. ]
Buildup
There isn't a lot you can do to the 307. There are a few hop-ups, but no
matter what you do you're not going to be able to go out and stomp on
Z-28's. In the end, a bigger engine would be your best
return-on-investment.
307 442 Engine
Your 85 442 is already pretty much maxed out for a 307:
a) You have a respectable cam (.440 lift)
b) 442's came with not-too-shabby 3.73 gears
c) The 1985 still had 5A heads (the better 307 heads)
d) Factory cat-back dual exhaust
e) Dual snorkle air cleaner
Yes you an improve on any of these. Cams are available from lots of sources.
Bigger exhaust might help a little but not major. Gears definitely, but rear
ends aren't cheap. The Edlebrock 3711 intake will fit that motor, about
$200.
What else? Porting & polishing heads? TRW makes 9.5:1 pistons for
it. For the money, swapping a 350 in there is the best overall improvement you
can make. You can even keep the computer controls. People on this list have
done it. After that the sky's the limit. As long as you're willing to part
with your first-born.
[ Thanks to Dave Cullen for this information. ]
VIN 9 Recipe by Olds
To make a 307 VIN Y into a VIN 9 (high performance), just use the following:
| Part | Part Number |
| Long Duration cam shaft | 22519934 |
| High Rate Valve springs | 22510372 |
| Harmonic Balancer | 417142 |
| Rochester 4MV carb | 17083553 |
| Dual Snorkel Air Cleaner Assy. | 25042690 |
| Intermediate Exhaust Pipe | 22516113 |
| Muffler and Tailpipe Right | 22526204 |
| Muffler and Tailpipe Left | 22526205 |
| 2400 RPM locking stall converter | ?? |
[ Thanks to Steve Ochs for this information. ]
Cams
As far as other performance parts, the only thing I've found that would
really make a difference is a cam like in the "9" motor. You can go
bigger, but I'm not sure it would be better.
[ Thanks to Jeff Herndon for this information. ]
Carburetor
Check that carb's secondary opening. A common trick was to
fit the secondary air valve with a longer tang on the RH end, such
that the thing only opens about 60%. First thing I'd change if the
motor was breathing better.
Cooling
[ Thanks to for this information. ]
Differential Gears
The major problem that you have is the launch off the
line, as most 307 cars have something like a 2.14, 2.29 or 2.41
differential gear ratio, even with the 200-4R overdrive transmission.
If you could only go a bit faster out of the hole, the 307 could
hold its own in midrange. The most economic, pain free way to
improve your performance is to get a
set of 3:23, 3:43 or 3:73 grears in the back. You could have a shop do
this at a fair cost (but a lot cheaper then any other mods combined for
three times the price and 1/2 the performance),
you could do it yourself, or the most economic and easiest way would be to
obtain a whole rear end from a 77-85 Delta, Caprice, Cust. Cruiser, etc.
and swap the hole thing.
If you swap in a 3:73
rear end, I think your economy will decrease not more then 10% around town.
When I put a 3.23 in my Delta with a TH-400, the difference in
acceleration was great, while the fuel economy was not that much worse
(and with overdive not bad at all).
[ Thanks to Igor Todorovic for this information. ]
Exhaust
[ Thanks to for this information. ]
Heads
You basically have a choice of two sorts of heads for the 307. Early 307s
used the larger-port #5A heads, as did the 350's of
the era. I don't see much point in hogging out the puny square ports of 6A & 7A
heads or fitting a large-port intake to a small-port head. Brick wall. Make a
funnel's top bigger, the stuff does not go thru faster.
Get #5A or earlier heads, THEN fit a large-port intake- the smogger AL
intakes: 5 is jive (small ports), 4 for more (350 size ports).
A5 has puny ports, A4 has larger intake ports.
Using these large-port heads, fit your big valves in THEM.
The 7A heads, besides having the puny intake port syndrome, have puny exhaust
ports that only fit their exhaust manifolds. So, while you are swapping heads to
earlier than 6A, grab some exhaust manifolds, too. The common #1 LH & #5 RH should
bolt right up to both your large-port heads and the car's pipes.
While changing from a set of 307 heads to a set of 330 or 350 heads
is something that you could do, I'm
not sure that it's something that you'd want to do. Even a
10% power increase would only give
you 165hp, which won't be a world of difference on a 3700lb car. It
certainly won't be cheap to purchase another pair of heads and redo them,
unless you've got to do a valve-job on this car anyway. The chart in
the
head's compression ratio section lists which
heads will give a certain compression ratio, but
they don't account for the effect that the change in port size will have.
So, for example, the small chambers on a 260 head would raise your engine's
compression, but kill the power output due to the straw-like ports and
coin-sized valves.
A more cost effective route might be a cam like the H/O-442 cam, which gave
that engine 180hp. OTOH, if you're planning on getting rid of the motor
anyway, either a head-change or a cam-change is pretty major work, and may
not be worth it; you certainly won't recoup any of the money you spend by
charging more for the motor on account of the modifications you make to it.
The problem with the roller-lifter motor
is that the heads don't flow. Switching from your 7A heads to earlier 5A's
would gain you about 10 hp. After that, aftermarket intakes will fit. There
are bigger cams available for roller blocks too ($$). On the plus side,
that roller motor ranks among the smoothest, quietest, most reliable small
blocks ever made (IMO, of course).
[ Thanks to Dave Cullen, Chris Witt, Bob Barry for this information. ]
Induction
[ Thanks to for this information. ]
Ignition
[ Thanks to for this information. ]
Mechanical Substitution
Keep the 307 Y, but get rid of the carb and distributer and put mechanical ones
on you should really feel the power of the 307 then my 307y out of my 83
cutlass supreme brohagm i had my heads shaved i put a accel coil and gaped
the plugs at .060. After that i peal off the line and kill rustangs 5.slows
Oiling
[ Thanks to for this information. ]
Redline
[ Thanks to for this information. ]
Replacing With Larger Small Block
If you are thinking of replacing a 307 with a 330, 350 or 403, consider the
following.
Everything except the pistons should swap across. Unless
it's an 1985 and up 307 w/7A heads (has the roller lifters),
then you won't want to use the heads, intake, and exhaust manifolds because
they have puny ports.
The 330 will swap right in. The flexplate will stay on the 330 crank.
Everything else is same. Really, all gas SB Olds are very similar
externally: some harmonic balancer diffs over the years, different
bores of course, 403 rods beefier, some engines used roller cams, later
ones had 3/8" pushrod balls. But for a whole-engine swap, the prospects
are really good.
You're better off using as many 350 parts as you can. The only
parts I could see using off of the 307 would be the intake (if the 350
is only a 2bbl) and maybe the heads for higher compression. You probably
need to use the 307 intake if emissions are strict in your area (at least keep
it, just in case). Although
the stock heads from a 307 may not flow as well as stock 1972 heads.
You don't have to dump the 307's computer controlled carb at all.
Doug Roe's Rochester Carb
book has a good chapter on modifying an electronic Q-jet (which, of course,
is computer controlled); highly recommended as a reference for anyone doing
work on a Q-jet. Only part-throttle and idle is controlled by the computer,
which formerly was controlled by vacuum on a non-electronic Q-jet;
everything else (accelerator pump, secondary barrels) is "open loop", so the
same mods for an older Q-jet apply there as well. In fact, as long as your
350's cam isn't too wild, the computer should be able to compensate for the
extra 43 cubic inches. You could use a stock 307 intake, or probably even a
Performer, as long as you have the hookups for the lines and sensors.
Whatever the case, even a mild 350 will be a big improvement. You
should also swap in some better rear gears to complement your engine's
newfound power. If you start looking right now, you might just find a
10-bolt 8.5" 3.73 posi rear from a H/O/442/T-type by the time your motor is
ready to go in.
[ Thanks to for this information. ]
Short Block
[ Thanks to for this information. ]
Transmission, Torque Convertor
[ Thanks to for this information. ]
Valvetrain
[ Thanks to for this information. ]
Buildup Examples
1987 422 307 Vin Code 9
First mod I did was modify the carb, most 307 engines
w\Q-jets have the secondarys modified so that they would not open 100%.
You may have to take a file and remove metal to allow 100% opening,
but do not go to far and let the air valve come open past 90 degrees.
I used a hypertech chip, but now I'm sure someone could burn a superior chip.
This wasnt available back in 1988 and 1989 when i performed these mods.
I also installed a 160° thermostat and drilled
a 1\4" hole on the outside ring. I played with the timing and
finally found out this particular setup ran best with the timing set at
22° when checking with the aldl connector grounded.
Make sure your TPS voltage is 4.8 or better at WOT (a properly adjusted TPS).
I fabricated a ram air setup using dryer
vent etc that got fresh air from underneath the airdam not behind the radiator
as the factory setup was. I played with the secondary rod sizes till i found
the best performer. Remove the hot air tube that runs from the exhaust
manifold to the air cleaner to prevent heating the incoming air. I installed a
B&M shiftkit in the trans (really shifted great). If the car has factory dual
exhaust (two mufflers\tailpipes), take the factory mufflers off and throw them
as far as you can!! If you take one of the factory mufflers off and look
inside, you will see about a 1 or 1 1\4 " hole! This really restricts the
exhaust!
With these mods my 87 ran consistent 15 flats which isn't any
screamer, but for being one of the infamous "swirl port " motors, and having
never ben taken apart, I thought this was respectable. Also helped gas
mileage. I feel with a set of regular 307 heads (non-swirl port), this setup
would have run 3 to 5 tenths quicker.
[ Thanks to for this information. ]
Streetable 307
Here's what I'd recommend for the 307. Assuming you need to remain
streetable, keep the computer, and pass emissions:
The the carb. The Q-jet is good! Besides, if you ditch it you've got
to ditch the computer too. Tune up and calibrate the carb well. Loosen
the secondary tension spring as much as you can 'till it bogs, maybe get
richer secondary rods, adjust your TPS (important!) and idle mixture by the
book.
Ignition hop-ups have not made a noticeable performance improvement on
my 307, nor did I expect them to. Bigger coil; no difference. Good plug
wires; slight difference. MSD 6AL unit; biggest difference; smoother
power, idle, better starting.
Exhaust mods. The only headers that I know of are the Heddman ones.
Marginal quality and fit, and you'll have to get a complete custom dual
system and do something about the trans crossover. There are a few
cat-back systems out there that all fit well and all flow like gangbusters
(Hooker, Dynomax, and factory GM).
Chip and timing! Get a performance chip like the Hypertech
Thermo-master, or better yet, a custom one if you know someone who can burn
them. Advance the base timing by 2 degrees also.
Cam. If you're digging this far into the engine you mightaswell plop in
a 350 or 403, but the VIN 9 cam is worth 20hp over the VIN Y one. Lots of
vendors make cams with similar profiles. If you're got the roller-lifter
equipped 307, Mondello makes cams for that too.
Intake. The performer intake fits and works with 5a heads, but isn't
exactly bolt on. Most of the external accessories need to be moved around
some. The Edelbrock intake helps, but this is probably the lowest
bang-for-the-buck mod here.
[ Thanks to Tom Lentz for this information. ]
13 Second
A short low 13 second recipe would be a stock short
block 307 with #5 1968 350 heads ported with W-31 valves, Mondello
JM-20/22 cam, Performer RPM manifold, Holley #3310-1 780 CFM carb,
4.10 rear gears, M&H street tires or slicks.
I would get some cylinder heads from a 1967 330 and have them drilled to
accept the larger head bolts. The heads would receive a Mondello bracket
porting job, and be fitted with the 1.995" intake valves and 1.62"
exhaust.
The heads would be cc'd and milled for a true 9.5:1 compression ratio
The camshaft would be a Mondello JM-22-25 cam which works out to 274 degree
intake duration and 280 deg exhaust duration, intake lift of .523" and
exhaust lift of .541" and lobe centers of 110 degrees. A full roller
adjustable valve train would be installed.
Complete Mondello oiling system with a full length windage tray and crank
scraper.
The intake manifold will be a slightly modified Edlebrock Performer RPM
with the plenum divider ground away 2" wide and 1" deep.
A 600 CFM Holley double pumper and mechanical pump. Mallory Unilite
distributor and coil. Hooker headers with 1-5/8" primaries, and 3"
collectors.
The short block would receive the traditional hot treatment (ie. prepped
rods, forged pistons, zero gap moly rings), and of course a forged 330 crank.
For the transmission I would use a full manual TH-350 with a 3500 stall
converter, and a Ford 9" differential. Start out with gears ranging from
4.33 to 4.88, depending on the altitude at which I would race.
I think that would be one hot little 307. I would keep the shift points
between 6500 rpm and 7000
Be careful about wanting to use too much cam for a street 307.
Especially with those sad #7A heads. No matter how long you hold those
valves open, it's still sipping through a straw.
Since the computer only controls the primary side of the electronic carb,
as well as the ignition advance, there's no reason to discard it. If the
307's intake manifold is being replaced with one with larger runners,
you'd probably have to change the size of the jetting on the
primary side. You might also want to use a non-computer carb on the car, and
see if this makes a difference.
A high-stall
converter is a good idea, but the real gains would come from swapping in
some 5A heads with a Performer intake. No matter how much you open up the
induction or exhaust system, with the small-port heads you'll really being
held back.
To realize any significant power gain, you'll have to open up the motor.
Try a K&N filter, perhaps an
aftermarket exhaust, and fine-tuning the secondaries on your carb.
The problem is not that
the carb or exhaust is too small; the restrictions lie in the vavle/port
size, the lift and duration of the camshaft, and most significantly, the
highway rear gears that keep your engine revving much lower than any speed
at which you can take advantage of those modifications.
Change gears, add a K&N filter, a turbo muffler, and if you still want more
power, add a cam and port the heads. If you still want more power, install a
350 or 455.
[ Thanks to Bob Barry for this information ]
Rebuilding
Tuning / Power Boost
Clean EGR Tubes
The 307 engine is very sensitive to EGR flow, even a 50%
reduction is enough to cause pinging headaches. Your car should run fine on
87 octane fuel. Mine with 50% blockage still pinged on 93 octane. With the
timing set a 20 degrees as factory specified. Wanna cheap performance
boost? Remove the carb, and run a 3/8 drill bit to
clean out the EGR passages. Mine picked up a lot of power with that,
and I started running 87 oct again. No pinging. The "Y" 307 likes EGR.
Probably in the computer program to run with it, and run well.
If there is a pinging problem on a 307, check the EGR tube extensions.
They commonly get partially plugged. EGR tests pass, (press valve,
stalls engine) but the tubes do not have enough flow. This engine (ECM
Program?) is VERY sensitive to EGR.
Remove carb, run a long 5/16 drill bit down the EGR tubes, drill out the
carbon. If really bad, remove EGR valve and run a piano wire through
the passages. You can remove the EGR tubes and clean them that way as
well. You will see the build up.
My 307 ran MUCH better after I cleared the passages. Of all things, EGR
to help power!
Replace the Worn O2 Sensor
Well, yes, happy days are here again. I've been trying to replace the O2
sensor on my 307 for about the past 3 days. Installed the
new 02 sensor and took it out for a drive. Man, what a difference!
Actually got the tail end sideways...on dry pavement! I've never slid the
rear axle coming out of a dry corner before...just spun the unloaded tire
(yes, it does have a posi). I figured that was an accomplishment,
considering the 150 horse 307 and 200 tranny and 2.29 ring gear. Well,
I'll get off the saddle now.
[ Thanks to Jason Adcock for this information. ]
TPS Adjustment
Make sure your TPS voltage is 4.8 or better at WOT (a properly adjusted TPS).
This adjustment will make a world of difference in how the engine performs!
Timing
Check the timing, low timing will cause run-on. The timing may have
been retarded due to pinging. Check it, set it to spec. Also, a high
idle speed will cause run-on. Read the factory service manual, it is
very comprehensive on this.
[ Thanks to Thomas Martin for this information. ]
Example(s)
I have a 81 Delta 88
I have tried many different
things with the 307 in my Delta, from bolt on ignition, better carb and
even dynomax exaust, no cats. Althought many things made no noticable
difference, overall there was some improvment, but not much. As a result,
I am currantly building a 455 to put in it.
Another very important factor to
consider is the weight. If you reduce the weight a little bit, it will
help a lot. I once had nothing in the trunk, no seats in the car except
the drivers seat, empty tank, and the car accted like a rocket compared to
usual. So, from my experience with the same car, this is what I recomend:
-
Change the rear-end from 2:73 to 3:73 (no less then 3:43) first and
most important.
-
Keep the motor is stock form (no fancy open end cleaners and such
stuff). Just make sure it is in good tune all the time (do a major
tune-up using the best plugs you can afford, avoid champions, a good set
is Bosch Platinum). It will run the best that way.
-
If you want more acceleration at this point(do these things first),
then add a K&N into your stock air box (better fuel economy and little more flow).
-
If you want more, then add a good exaust (from just a turbo muffler to
headers and duals as you wish/are willing to pay for. If you can, by-pass the catalitics with a pipe (less weight, more flow).
-
If you want even more, do as Dr. Barry sugested with a cam and better
heads.
-
Try to reduce as much weight, such as having a clean trunk, don't
necessarly run your car on a full tank of gas. Also, if you are in town a lot, remove your jack and spare and replace it with a can of instant-flat-fix to
get you home. If you really get stuck (how often does that happen), call a
friend or a wife or something.
-
If you then want even more power, get a bigger motor.
I know how you feel about the 307. It is a great motor in everything but
maybe not power. I have spent much money in fancy bolt on mods that did
nothing. 307 in a car that size will just not respond much to better plugs
or ignition coil, carb or flex fan, etc. Sorry for the long posting, but I
just don't want to see you spend time and money into nothing like I did.
[ Thanks to Igor Todorovic for this information. ]