I’ve been googling this subject for the last 2-3 months and have learned probably just enough to get me in deep dodo unless I post here for some help from all you Olds gurus.


With the exception of some carburetor problems, the 403 engine performs well. Well enough for daily driving and cruising. The problem comes when I hook up to the 4,500 lb Airstream Argosy and start driving around in the northeast Georgia mountains. Soooo, that is what I need help with, getting more HP and TORQUE out of the 403. I had already invested a lot in the car when I learned the 403 inches was 403 smog inches and nothing like the old 396 inches I was more familiar with back in high school in ‘67. Investment to date includes sway bar added to the rear, heavier duty one to the front. New progressive coil springs and coil assist shocks on the rear and gas shocks on front. A set of LT load range 109 Uniroyal tires. I have a 3 core AL radiator and gauges waiting. All in all she hugs the road nicely and with weight distribution hitch tows well except on high grades. Absolutely love the car so hoping you guys can help me out here.



So here is what I have


1979 Buick Estate Wagon. I am the second owner. I have all invoices/receipts of any work ever done to the car.


403 Engine, stock with Quadrajet. First owner purchased it new in California and still has the original California Q-Jet but the emissions pumps is gone, canister still there. Q-jet has typical bog problems. Receipts show no indication of carb rebuild since new .


Car currently has 136,000 garaged miles. Major engine work performed in the past was valve job in 1990 at 78,000 miles then both heads replaced in 2011 at 127,600 miles, ie less than 10,000 miles ago. I strongly suspect that the heads issues were heat related as when I got the car the temperature idiot light wasn’t working. In fact the problem with the light was in the circuit board contacts in the dash so I’m doubting the light had ever worked and was probably the reason for both head jobs, the owner (little ol lady) never knew the engine was running hot.


TH350 transmission. I had it rebuilt 1,500 miles ago with a RV shift kit. Factory converter


Came equipped with factory tow package, which of possible interest here includes:


3.23 geared Limited Slip Differential


Heavy Duty Cooling (High-capacity radiator with internal transmission cooler and a fan clutch)


80 Amp Delcotron Alternator


Heavy Duty Battery


7-wire trailer wiring harness


Tires- LT 235/75R15 109T rating


Vehicle weight – 5,220 lbs. This is per Cat Scales and includes two human and one hound dog passengers


Trailer Weight – 4,500 lbs per Cat scales


Note: Manufacturers maximum recommended towing weight is 6,000 lbs w trailer tongue weight 750 lbs





So as @oddball so nicely and simply put it in another thread, looks like my two options are



a: stock short block with earlier small block heads


-OR-


b: flat top pistons with big block heads




Here are the results of a recent compression test. Retested suspect cylinders with 1 tsp oil squirted in the cylinder




Left bank cylinders

1 - 146, 150 wet

3 – 148

5 – 148

7 – 150

Right bank

2 - 142, 150 wet

4 – 142, 150 wet

6 - 150

8 - 150


The only build shop I can find local is a Custom Performance Engine Build and Balance shop who built my 1957 283 and 1967 396 Chevy engines back in the sixties. His son who seems to be semi retired, now still builds mainly Chevy but was very interested in my project and agreed to take it on and at a good price labor wise. I would be interested in hearing of other Oldsmobile builders within a few hundred miles of Athens, GA


So based on the above what do you all think,


Option # 1 - Stock short block with either earlier short block heads or procomp heads (I've been hunting '68-72 350 heads for a couple months with no luck, so some procomp heads are looking better and better)


Option # 2 – Flat Top Pistons with my reworked heads with bigger valves or big block heads




Realizing this all is a bit overload coming out of the chute, I’ll save the parts take-off list I’ve built for later. I plan to keep this thread running throughout the build. Please know that I am not that mechanically inclined or well versed in a lot of technical terms etc so this may not be easy. But google is my friend and I will research anything I don't readily understand. THANK guys I will really appreciate your help!!!

 

Typical "or equivalent" parts for

Option # 1 Stock short block with either earlier short block heads or procomp heads

Edelbrock 2711 - Edelbrock Performer Intake Manifolds

Edelbrock 60519 - Edelbrock Performer RPM Cylinder Heads

A set of preferably reworked 68-72, 5, 6, or 7a heads

Edelbrock 1906 - Edelbrock AVS2 Series Carburetors

Edelbrock 3712 - Edelbrock Performer-Plus Cam and Lifter Kits

Edelbrock 7813 - Edelbrock Performer-Link True Roller Timing Chain Sets


and with

Option # 2 – Flat Top Pistons with my reworked heads with bigger valves or big block heads


Same intake, carburetor, cam and timing chain as above plus

Keith Black/KB Pistons KB405KTD-024 - Keith Black KB Performance Piston and Ring Kits

Edelbrock 9376 - Edelbrock Stainless Steel Valves

Edelbrock 5812 - Edelbrock Sure Seat Valve Springs

Edelbrock 9724 - Edelbrock Valve Spring Retainers

Again this is all just taken from the Summit web page and is intended to be an "or equivalent" list of possible parts.


I understand the cam will be one of the last things to figure out and inject into the formula as well as likely a new torque converter.

 

So let's step back a moment and discuss this.
What exactly is the problem when towing the trailer in the mountains?
Also, perhaps you should correct the carburetor issue first before going into a full engine rebuild.

 

Nice looking wagon and trailer!

Those tires sound tall/large diameter and would hurt the final gear ratio. Agree to get it dialed in first and reassess. Is the timing chain original/stretched?

 

I made the mistake of stopping at the bottom of a very steep hill and thought for sure either the engine or tranny or both was going to blow before I got to the top. One can never tell when that scenario might be encountered again. I considered rebuilding the carb but although I fully appreciate the good points of the Q-jet, I don't think that with it's huge secondaries kicking in so soon that it is a good carb for towing. On our last trip towing the Argosy I only got at best 5 mpg an there wasn't a lot of hill climbing involved. I will be looking at something else with more equal size primary/secondaries if I do the rebuild.
It may be worth testing a different intake and carb that could be used later if it alone doesn't come through with sufficient power. Good points though, thanks

 

Tires are only one size up from original equipment but agree, may need to get an actual diameter for calculating for the cam. Their stiff sidewall took a LOT of the squirelly side to side motion out of driving especially when towing so am happy with them. I do have a little bit of concern with their impact and the wear and tear on the rear end though. Had not thought about the timing chain, or really wasn't aware that that could pose a problem with power. Hmmmmm....
Thanks Sugar Bear!

 

A stretched timing chain will reduce low RPM torque. How much IDK.

The tip-in rate of the secondaries on a Q-jet is adjustable, There is a spring on the passenger side of the airhorn with adjustable tension to dampen how slow or fast the secondary air flap opens.

IMO, the early heads you are searching for and the right camshaft will help a lot and possibly a higher stall torque converter. There are engine builders on this forum with lots of experience including dyno tests. hopefully they will chime in.

What year is the Argosy? Mostly original?

Good luck!!!

 

I still don't know what EXACTLY was the issue you were experiencing. With not being there, reading what you posted could be attributed to fear instead an actual mechanical dilemma that can be defined scientifically. I hope you understand what I am trying to express here, which is why I said more specific information is needed.

This reminds me of back in the 80s with my Dad towing a 17' Prowler camper behind Mom's '78 Delta 88 through the Ozark Mountains. I commented that he was opening the secondaries on every uphill climb and he said "What are secondaries?" I had to explain to him what that meant, but it appears you are aware. I am unsure how you expect to get sufficient power to pull a heavy trailer uphill without the engine generating the required power. If you had a smaller carb, the engine would not generate as much power, so it would be harder to pull the trailer uphill. Maybe I'm just missing something, though.

Anyway, I do not think that having a poorly tuned / running carburetor on the engine is a good place to be, no matter what. Getting the existing carb running correctly would be the first thing on my list so that you would have a valid starting point for evaluating what needs changing or improvement. You could get an entire new drive train and if the carb is out of whack it could still perform poorly. Again, I'm not there so I can only make suggestions based on the information you provide.

A simple adjustment to get rid of bogging (assuming it's due to secondaries opening at too low RPM) and also restrict tha amount the secondaries open is to tighten up the secondary air valve spring. This adjustment is typically done to ensure an smooth transition from the primaries to the secondaries.

 

To clarify a few things: the Procomp heads are copies of the first generation Edelbrock heads. The current Edelbrock heads have a slightly improved chamber design. Both are big block heads - which means you need flat top pistons to use either Procomp or Edelbrock heads. The Procomp heads are a good casting but have poor QC and sometimes poor components, so you're best buying through and Olds specialist (e.g. Bernard, Remmel, Trovato) that does their own QC. The Edelbrock heads can reasonably be purchased and installed as-is (with your own at-home QC).
In either case, the springs that come with the heads are likely what you should use. The Edelbrock comes in two flavors - one has springs for a flat tappet cam, the other has stiffer springs for a roller cam.

Now, I agree that before going further you should rebuild and tune the carb. I suspect you'll still have poor towing performance though. Keeping that carb will probably make sense with your final build anyway. The common TBI EFI kits are hit and miss - some people love them, some times they're terrible.

As for which option works best, that depends on your budget, final goal, and ability to find parts. I bet lots of folks on here have 350 heads - try posting a parts wanted ad. using big block heads will give you more total performance capability, especially in the top end, but will likely cost more. I somewhat doubt there would be much difference for a towing-oriented build.

In the end, getting a decent modern cam and any heads other than the 4A will completely change the motor. The short block seems like it might be in good shape, so trying to keep this a fairly minimal build - cam, timing chain, 350 heads, RPM intake, assorted gaskets and whatnot - should be reasonable. Regardless of which path you choose, go ahead and use an RPM intake.

Oh, if you have your guy recondition some 350 heads, tell him to set the exhaust valve guide clearance LOOSE. This ain't a chevy. Or reach out to the shops I mentioned above (or some of the others, like J&S, Rocket Racing, Olds Performance Products, etc). Someone's quite likely to have a set ready to go sitting on the shelf.

 

You need low to mid range power. If the Quadrajet is bogging and opening early, you are using more fuel. How much do you want to spend ?

 

I think you need a truck with a diesel.

 

Let me try and get a bit more scientific then. The road was in an older subdivision, grade was maybe between 14-16% or more with a distance from bottom to top of maybe 100 yards. Low gear, pedal to the floor, engine screaming with no backfiring or other bad noises and about half way up forward movement almost ceased, less than a slow walk. And yes, I did become "fearful" to the point that had the grade not started to diminish a bit and forward motion was maintained, I would have let off the accelerator, backed back down the hill and up the opposing hill and gotten a running start to try again. Just not a good feeling hearing the engine in such stress. But there are also times on interstates where extremely long grades pull me back to 35- 40 mph or so. I prefer to maintain at least 50. But maybe that performance is the norm or to be expected from this smog engine and maybe I am spoiled by towing 2 ton plus old Buicks all over the country for years with my fi 6.0 1500HD. I really just want something somewhere in between the 6.0 1500HD and the 6.6 Buick. Sorry I'm no better at explaining things and also for lacking the knowledge and technical expertise to carry out a lot of things most of the true gear heads here are able to.

 

Ancient Iron is correct. What you describe here is not going to be cured by a better-tuned carburetor. You need a tow vehicle that doesn't notice that it's towing anything. The weight of your trailer is too close to the maximum tow weight recommendation for your car. I've been working with my sister in recent years with her horse farm operation where she is needing to tow horse trailers all the time. She uses a Ford F250 to tow her 11,000 lb horse trailer/camper combo, and the truck barely notices the trailer is there. As romantic and as cool as it is to be camping in 1970s style, you need to be practical and consider safety first. Had the road not started to level off on your attempted trip up the hill you describe and you had to come to a halt and then back up, would you have been able to hold the trailer and car on the hill with the brakes? Would you have had to start backing up? What if there had been a car, or worse, a line of cars, behind you and in the way?

Keep the Buick for the weekend trips to the ice cream shop and get a more appropriate tow vehicle.

 

For one, this is a pretty badass wagon and trailer...however.... I saw the other thread, little did I know you were towing unless I just missed it.

3.73 gear
#3 or #4 heads
Erson TQ40 (Mark?? haha)
Headers
Transmission cooler
7111 Intake
Roller rockers
Valvoline VR-1 oil
Wagner Ceramic Brake pads

 

Some great points sir, THANKS

 

Practically speaking, I disagree. I drive an 86 f250 with a 6.9l IDI diesel and while it has heavy duty suspension and brakes the engine it isn't anymore fit for towing than a properly tuned SBO/BBO. In fact, I've commented before on our site that I feel that the 455 in my 71 98 would be better at towing than the 6.9l IDI in my truck. Of course, the diesel engine in my truck is light years behind a modern diesel engine so...

Don't forget that a diesel also has added maintenance costs i.e. 10+ quart oil changes and a water separator, not to mention DEF for newer diesels. Finally, a diesel truck isn't a cheap investment. I spent $6500 on my truck a few years ago and it was about as cheap as you could find for a running diesel.

Ultimately, get the Quadrajet rebuilt and your Buick will do fine pulling your trailer.

 

I can liken that to me riding my bike up a steep hill. Both would need at least one of the following and perhaps all:
a) more torque
b) lower gears
c) go slower

 

For me, add d) Defibrillator pads

 

1. You need the Quadrajet gone through by someone that knows what they are doing. The "Quadrajet bog" you refer to is typical misconception that all Quadrajets bog and stumble. Your secondary air valve needs more tension on the spring. This maladjustment also leads to excessive fuel consumption and poor performance.
2. How much California emissions stuff is on the motor ?
3. You have a low compression, low horsepower engine.
4. You put larger tires on that makes a difference that will require more torque/horsepower to accelerate or maintain speed. This also requires a higher throttle opening which reduces fuel economy.
5. Most trailer towing packages use a lower (higher numerical number) rear axle gears. You will gain power with different rear axle gears.
........Just my two cents worth.

 

I towed a 24 ft Sea Ray with a 78 Olds 98, same size tires and a 3.23 rear end. The 403 was stock. A lower rear gear would probably have been better. The real problem was that I needed a 3/4 ton truck, a gas engine would have been OK. The boat was too much for ANY car. The boat had about the same weight as your trailer as manufactured but was heavier as equipped and loaded.

If you continue with the Buick wagon, be sure to purchase some adult diapers.

 

and what do y'all think towed these '50's, 60's and '70 Airstreams back in their days, before all the big gas and diesel 2500's and 3500's. Big *** Buicks, Oldsmobiles and Pontiacs that's what. My only fault here is that I failed in my search of a Buick as a tow vehicle to recognize the fact that the late 70's engines were such low compression smog engines and THAT is exactly what I am asking for help to try and remedy here. I actually had considered using one of my '54 Roadmasters with a 322 and Dynaflow but would have had to gone with a bit smaller trailer because of the Dynaflow (the torquey 322 Nailhead would handle this trailer no problem coupled with the right running gear) I will get this 403 powered Buick to tow or I'll just shoot it. Well, maybe I'll just shoot the 403 and put a 455 in it's place.


Thanks Olds64. I've hauled cars before with diesels and agree, considering everything I'd just as soon be behind the wheel of my Silverado 1500HD. The Silverado is our primary tow vehicle but it's only because Buick doesn't build trucks.

But this thread isn't about diesels vs gas trucks for towing so hopefully we can get back on subject.

So as you and others have expressed, I may just need to get the quadrajet rebuilt and tuned. Hard for me to believe but may be worth a shot.

 

x2

You're exactly right. Your Buick will do a fine job towing your trailer once you go through the Quadrajet. FWIW, my 71 98 hasn't ran as well since I removed the Quadrajet for a shiny Summit carburetor.

BTW, I love your Buick. I owned a 1990 Buick Estate Wagon with the Olds 307. It was a good car to my wife and I when we first got married.

 

 

Yeah, the edelbrocks can be milled to small block chamber sizes, but it's a hell of a cut ($$$) which throws off everything else - intake fit gets even worse, pushrod length gets even wonkier. So it's possible, but IMO pointless unless there's a very specific, very compelling reason.

Anyway, a basic cam+top end refresh on the 403 will help a great deal.

A 455 is also a very strong contender, but note that you'll be switching to a big block and whatever engine bay fitment issues that may bring. I'm a sucker for the small blocks. That extra inch between the A/C housing and the engine brings me much joy.

 

The reason I said what I said was because you said that the trailer weighs 4500 lbs. And the wagon is 5220 lbs. totaling 9720 lbs. plus people and supplies. That is a lot of weight for a 403 that was a dog from the factory.
Maybe people did pull camping trailers in the '50's with passenger cars. that was 60 years ago, Times changed and their are better and safer ways to tow a trailer that size.

 

I knew and appreciated what you were saying and apologize for the smart alecky response. It's just that I have spent so dang much on this car, time and $$, to make it dependable AND SAFE. (HD suspension, all new brake system, new axles and brakes on trailer, LT tires, fine tuned weight distribution and more) And you're right times have changed, back in the 60's folks were OK and patient (had no choice really) with following behind a 45-50 mph vehicle 'til it was safe to pass, today, not so much. In fact, these days, even without a trailer and going 10 mph over the speed limit folks think I need to get around this old slow poke heap. The 60's and 70's were fun years for my wife and I, we're just trying bring back some of the feel of those days.

and fgi and not that it matters that much, the CAT scale weights were with the truck and trailer loaded for camping, including full water tank. The scales showed that the weight distribution hitch had moved the weight back to the front axle dead on the same weight as without a trailer, very pleased with that.

we cool man

 

No offence taken

 

Yo moderators, I saw after I started this thread that most of the threads here in Major Builds and Projects involve complete restorations. As I plan to continue this thread with more posts related to the rebuilding of the top end of my 403, please feel free to move this to the Engine-Small Block forum if more appropriate. Y'alls call, thanks

 

These symptoms are also consistent with a defective torque converter. A first-class transmission shop should be able to check that for you. Good luck with your diagnoses. Beautiful rig.

 

The invoices from the PO included one showing the converter had been replaced a few thousand miles ago. Additionally, I had the tranny rebuilt just recently so am thinking all that is good. I'll be evaluating the possible need for a RV type converter as I move along with the top end rebuild. Thanks for your thoughts and also the kind comment about the rig.

 

You're welcome.

All the converter problems I've had have been from replacement converters (no problems with factory converters). It only costs you a little time to get an evaluation from a shop that didn't do the original transmission work.

 

I agree.... Sounds like torque converter issue here....

You may likely have "ballooned" the factory replacement torque converter and it was slipping when it wouldn't pull the hill. That or the transmission may have been slipping....


I would strongly recommend a PTC 11 inch torque converter with anti-balloon plates that will stall around 1800-2,000 rpm.

Have you smelled your transmission fluid since the bad hill climb?

As for the engine, the 403 can be a decent engine with enough compression(9:1), the right cam (Isky hydraulic roller with a 215/220 @.050 duration), a decent set of heads (quality built pro-comps or edelbrocks), a good intake (Edelbrock Performer RPM if using aftermarket aluminum or big block iron heads), and the right carburetor (well built1970's quadrajet with a good tune) and a perormance tuned HEI distributor, good wires, etc.

That is the other thing that I haven't noticed any advice on... the distributor timing curve/vacuum advance rate, etc. Is this controlled by an electronic spark control computer or just straight HEI?

By the way, 455 engines fit into these big B Bodies with no problems.... In the contest between a mild 455 vs a mid-level built 403, the 455 will win even with K or J heads. If you can find a decent built 455 with A,B,C heads, that is a good start to a 380-400hp and 450-500ft lb of torque. These numbers are probably 100 above a 403 of a similar build.

You will need a complete 455 with brackets and pulleys and all if you do the swap.


Another option is a 6.0 LY6 or 6.2L L92 LS engine swap. Yes, I said it..... LS swap!

You will spend a good amount on aftermarket brackets, oil pan, cast manifolds, etc., but in the end, it is quite easy to get 400+hp out of a stock engine of these types mentioned above. You can get even more with a mild cam swap.

You also can either switch to carb or convert to EFI at this junction.

 

Thought I'd bring this thread up to date as like I mentioned earlier I'd like to keep it running through out the build. I did post a separate thread asking for help and thoughts on what all might be needed to complete the build and associated costs.https://classicoldsmobile.com/forums...3/#post1201362 During that discussion it was brought up that rebuilding the bottom end should be considered. After seeing the results of an oil pressure test it was felt that while a complete rebuild might be desirable it would not necessarily be needed here. Here are the results of that test.

Castrol GTX High Mileage 20w50

Car in Park

48 at cold crank up and choke on idle of 1400 rpm
38 at warm choke off idle of 685
42 at 2000 hot (operating temperature)
48-50 at 3000
48-50 4000
30 at hot idle of 725

I have done a lot of reading and becoming familiar with this engine including reading the Bob Gerometta's Oldsmobile Engine Modification and Tuning Guide - V8 Engines 1964 - 1978 cover to cover as well as reading pages 1-75 (so far) of the Engine - Small Block of this forum of anything pertaining to the 403 and most 350 subjects. I am really looking forward to this build and have decided to turn it pretty much over to Mark Remmel aka @cutlassefi to determine needs for and sourcing of parts. He has recommended someone in north Florida to do the actual engine work so will be delivering the car there ( about 5.5 hr drive) hopefully in the next few weeks for the work.

Thanks all for your help and comments so far!!!

 

If the plans are to remove the engine to do this work, it is an opportune time to find out if the torque converter has a proper stall speed for the towing application or replace with one that does. Hopefully other members can help with what stall speed would be good. Re-read posts and see others have suggested same, it can make a BIG difference.

Good luck!!!

 

Mark is looking into it but yea I would like to hear opinions as I have learned SOOO much from all the open discussions so far. And thank you for your input on this as well as the numerous other comments you've made.

 

Hello Mr. Earl.

I re-read this thread and am concerned that you have focused on a percieved engine problem. So I'm going to do my best to explain why you should put aside your pre-concieved solution and be open to looking at the facts with a fresh eye.

The problem as you stated it:

An automatic transmission works by coupling the engine to the wheels through a torque converter. At low speeds, the torque converter allows the engine to turn faster than the wheels. Therefore, when the car stops, the engine can keep running. However, as engine speed increases, the torque converter progressively tightens the connection between the engine and the wheels. With a standard converter, the engine could turn perhaps 2500 rpm faster than the wheel motion would usually allow.

This is a key point. Even if the wheels were stopped (or slowly turning), and you had the accelerator floored, the engine could not exceed 2500 rpm.

I doubt that anyone would describe 2500 rpm as "engine screaming."

What this means is that the transmission allowed the engine to turn at a much faster speed than 2500 rpm. This could happen only if the torque converter were not doing its job, or the transmission itself were slipping internally.

Your response to the suggestion was:

Weigh the facts, step back from that first response, and have the transmission evaluated as a first step in solving this problem. This is a near-zero-cost suggestion.

If my explanation doesn't make sense to you, please be the Fun71 of this exchange and keep after me to explain better.

I don't want to see you spend a lot, put in a better engine, and then discover that it didn't solve your problem.

All the best,
Gary

 

Hey Gary, thanks for reiterating your thoughts on the torque converter and I think you and others are probably right. My first thoughts on a possible fix for my problems were to have the Quadrajet rebuilt and swap out the torque converter for a lower/higher stall towing converter. But I did not want to go through that exercise only to find out that I was still lacking in power to handle the trailer in other situations as I mentioned above. And from some things I've experienced on the road where I don't feel the tc was possibly at fault, I fear that would likely be the case. Considering that and the fact that the timing chain has 136K miles on it and that I really don't have the time to be trying one thing then the other I feel my best option is to just go whole hog and do the full top end build including a torque converter swap. Now if you or others think that what I have planned is not going to solve my problem please let me hear it and what other possible options I might have. Thanks again and I truly value and appreciate your input.

 

How would a torque converter be spec'd for towing? Is the optimal stall speed target just below the middle of the torque curve? If it locks up too early the engine won't reach the desired torque band...yes...no?

 

Great question Sugar Bear! Like the cam, the head cc’s, and a correctly tuned carb and distributor, the right torque converter is just another part of the equation that might be needed in order to make this build work. Just another reason I’m so thankful to all the folks here for helping in the challenge to figure it all out. As I mentioned, Mark is looking into it and I look forward to his determination as well as hearing and learning from what others here have to say.

 

Received word last week from Mark @cutlassefi that the #6 heads he is supplying are at the shop being worked.

Since this is a "long distance build", Marks agreed to furnish pictures so before and after pics coming soon I hope.