307 CID Engine Detail

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General Information

Note: The information contained in all of the "Engine Detail" sections should be read before proceeding with modifications, etc., because some information that applies to all engines, or all small blocks or all big blocks, might not be duplicated in every section.

The 307 was built from 1980 through 1990, produced from 140hp to 180hp, and was installed in just about every car Olds built in that period at one time or another, including the Cutlass/442, Delta 88's, 98's and Toronados. It was also used in many Buick, Pontiac, Cadillac and Chevy models. You can get a quick estimate of the year of the engine by looking at the 1" high casting number on the lower-left corner of the block and/or head.

The 307 stayed carbureted until the bitter end of production (1990). Every 307 used a 4bbl carb - there were no 2bbl models. The last of the GM 4-bbl engines and the last GM carbureted engine. In fact, it came on the Caprice wagon, Olds Custom Cruiser wagon, Buick Estate wagon, and Cadillac Brougham (5.7L Chevy V-8 was optional on this one).

ESC (Electronic Spark Control) was added to 1988-90 307's. On these engines, the knock sensor is screwed into the driver's side coolant drain hole.

The 5A heads were used on the '80-'84 "conventional" (non roller) 307. The 6A and 7A heads fit the later ('85-'90) roller lifter 307s. The intake gasket sets are different.

There should not have been any factory installed 5A heads on '85 Toros. All should have been roller lifter engines with the 7A heads. The last year for "Y" code 307s with the conventional valvetrain was '84. (The "9" code continued to use the conventional valvetrain for another year or so.)

Some say the 307 H.O. engine has a propensity for detonation, because Oldsmobile always ran high timing (20 degrees advanced). Cracked or rusted A.I.R. tubes create a similar sound.

While a knocking noise probably means a spun bearing, check for loose bellhousing bolts and a cracked flexplate. Both times that this happened to me, the crack in the flexplate would snap back and forth, making a noise that I was convinced was a spun bearing. You may need to pull the converter back to properly see the flexplate.

Sometimes, the main intake-to-heads gasket goes bad, and coolant leaks out at the front of the engine, on the driver's side. The coolant dribbles down by the water pump, and the water pump appears to be bad. This seems to be a problem with the steel heads and intake mating to the aluminum intake.

[ Thanks to Kevin Wong, Frederick Nissen for this information. ]

VIN Y, VIN 9 Comparison
Here is the deal on heads, exhaust manifolds, & camshafts. This information comes from the 1982-1990 Oldsmobile B,C,D,E,G,X parts manual - 1998 version.

Year Part Number
Cylinder Head:
82-84 Y,9 22511238
85 9 Same (22511238)
85-90 Y 22530557
86-87 9 Same (22530557)
82-84 Y 22521997
83-85 9 22519934
85-90 Y 22527149
86-87 9 22531804
Exhaust Manifolds:
83-90 Y 22503678 LH Cast Iron
83-87 9 Same (22503678) LH Cast Iron
85-87 Y 22530287 LH Tubular Welded Stainless
83-90 Y 22521449 RH Cast Iron
83-87 9 Same (22521449) RH Cast Iron
85-87 Y 22530286 RH Tubular Welded Stainless

So, in summary. The 82-85 VIN 9 and 82-84 VIN Y had 5A heads with regular cam, the 85-90 VIN Y and the 86-87 VIN 9 had 7A heads with roller cam. Notice the VIN Y changed to roller cam 1 year before VIN 9 which is causing some confusion.

Also, the tubular stainless exhaust manifolds were used on some 1985-90 VIN Y applications, but there is no set pattern. The stainless manifolds require a gasket, the cast iron do not. Finally, the GM Goodwrench remanufactured engine assembly numbers are different for tubular stainless vs. cast iron manifolds. I do not know what is specifically different, the book just says 1 is to be used with tubular, the other with cast iron.

[ Thanks to Steve Ochs for this information. ]

1985 442 307
The 442 "9" 307 engines, at least for 1985, did NOT have roller lifters. They utilized the standard hydraulic lifters. The "Y" engines used the rollers however. Why, I suppose we'll never know. Maybe it was because they had extra parts left over from the H/O project of 84, I don't know.

I have the 85 book, and it shows completely different procedures to remove pistons from rods, because the "Y" 307 has full floating wrist pins, and the "9" has press fit.

The cam in the 85 "Y" is roller, hence the cam button on the front of the cam to the front cover. Also, the lifters are specific to "Y" only (roller, duh! ). "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. ]


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. ]

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. ]

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.


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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. ]


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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. ]


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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


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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

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Transmission, Torque Convertor

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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 ]


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!

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. ]

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:

  1. Change the rear-end from 2:73 to 3:73 (no less then 3:43) first and most important.
  2. 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.
  3. 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).
  4. 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).
  5. If you want even more, do as Dr. Barry sugested with a cam and better heads.
  6. 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.
  7. 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. ]

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