403 olds motor

OK,I know I stuck my nose into something I know nothing about,but I kinda got hooked into helping someone build a 403 olds out of a firechicken.well,I have a question,so if anyone is an olds expert let me know and I'll expound on my issue.
thanks
gary

 

I'm not an expert but here is a page with a lot of info on the Trans Am 403 engine:
http://www.angelfire.com/fl4/pontiacdude428/PontiacOlds403infl.html

I'm definitely a fan of the firechickens - though if I ever get another one (used to have a '79 with the 403 which I sold) it would be with the Pontiac 400 motor.

 

I can tell you one thing, the 403 has siamesed cylinder bores, so .030 over is all you would want to go if it needs it. And '71-'72 Olds 350 #7 heads will bump the compression up over 9.0:1 but the headbolt holes have to be enlarged to accept the 403 headbolts. The 403 4A heads have huge combustion chambers. They also have 2" intake valves,which could be used on the 350 heads. The 403 is a very under rated engine.

 

Thanks for the link.interesting info,I know the motor was manufactured plenty strong.
my issue is,its all together.but I found a hex shaft ,6" long,in the bottom of the box of parts,its the shaft that turns the oil pump being connected to the distributor.Can it be installed from the top,I can see the pump,or do I have to remove the pan and install from the bottom.?
gary

 

no reputable Olds engine builder would recommend a 403 for high performance use.
they are a time bomb.

they do have a huge bore,but the windowed main block is junk.

it's a big passenger car engine,designed to never be spun over 4 grand

have your buddy get a 350 Olds

350's have a stronger block and are a direct bolt into that T/A.

 

Hey im gonna take a stab at building a 403 olds as well. Was thinking about possibly boosting it.

What you need to know. Windowed main webs (dont know who thought that was a good idea). You cant really rev past 5500 without serious modifications. Halo girdle is probably a good idea.

If you want about 450-500hp, its easy, you can do it with stock parts mostly. If you plan to go over that it gets real expensive for not that much more. The big bores like higher compression, and respond well to it.

This is what i learned after about 3 days of web searching. A freind and I have some olds 455 parts that would normally be crappy for a 455, but will be good on the 403. We plan to put on some E heads, do a home port job, upgrade oiling, and replace bearings and gaskets. Holley dominator intake, and a big carb (750-850 cfm).

 

Also, lots of people will tell you not to build it . But it has alot of potential if you dont go overboard with your expectations.

Mine was free so im ahead no matter what i do with it.

 

When I rebuilt my Olds 350 engines, I believe you can install the hex drive rod from the top.

 

Thanks George,it goes in from the top nicely and fits into the pump and distributor well,I believe the chevron big block powers the oil pump the same way and it needs to be installed from the bottom,thats why my concern and question.
gary

 

Yes, very good info, the 71 #7 heads and the 72 #7A heads are the best to use because they are the earlier heads w/a mid 60's chamber that will have have hardened valve seats, the 403 heads have something like 82 cc chambers.

Boosting a 403 would NOT be recommended at all! If you use the E heads, make sure the intake you are using will have enough meat to cover the ports on the heads as the bbo ports are much taller/higher and some intakes do not have the meat to cover and be ported to match. The Peformer RPM has enough to be ported to match the heads, not sure about the Holley intake.

If you can find a 64-67 330 crank, they are steel cranks, which is obviously stronger and preferred, with the same stroke as a 350 or 403 as the are all the same, 3.385 I believe. You can also offset grind the rod journals to make a stroker and get and extra 20 cubes+/-. 403's are good motors but will not last at higher rpm's for very long at all.

 

the oil pump drives can be installed from the top if the little star type washer is missing from the shaft. it has teeth on the inside of it, i believe it was used for factory assembly only.

 

I used a solid main web 403 along with a olds 330 steal forged crank, as the 330 and the 403 have the same stoke and journals sizes, along with number 5 heads, said to be the best.

I also have the block 3/4 filled,it has seen 7200 not on purpose and no problems, at the bottom is my list of parts and cost, minus the crank and labor. JJJ



"As for the crank, understanding your cost constraints, the best small block Olds crank is the forged unit from the 64-67 330 motors. This will drop into a 403, as main and rod journals are the same size (as is stroke). You will need to rebalance and you'll need to use an early (64-67) flywheel/flexplate due to the crank flange bolt pattern"

Small Block Advantages

The small blocks have a number of design advantages. One, the bore size on a 350 is not much smaller than that on a 455, and the bore size on a 403 is much bigger than a 455's bore. That means these two small blocks can use valves as big or bigger than a 455 can, and with less valve shrouding for the 403 than the 455. Usually, the most restrictive item in the whole intake port of an engine is the valves; this means that a small block Olds engine's heads should be able to flow about as many cfm as a big-block Olds, and ultimately the maximum horsepower you can get from any engine depends only on the airflow. This means that: Gasp! A 350 or 403 Olds should be able to make as much or more horsepower than a 455, albeit at a higher rpm. ​

Want more? Okay, here goes. The 455 has a longer stroke, meaning that more horsepower is wasted in internal friction, rubbing the pistons up and down through that longer stroke; other things being equal, then, the small-blocks should return better gas mileage, even if built to the same peak horsepower as a 455. The rod length/stroke ratio is bigger for a small block than a 455; this means more piston rod angularity for a 455, meaning still more friction with the cylinder walls, and also a lower redline before the connecting rods break from the strain (lower rod/stroke ratios put more strain on the piston rods by accelerating the piston in a more jerky fashion). ​

Still more? Okay. The small block is lighter, so your Olds will be slightly less nose-heavy and will handle better. Also, your Olds is more likely to already have a 350 in it - surely Olds sold more 350 powered cars than 455's! ​

It seems that Chevy 350 engines routinely exceed 350 hp in totally streetable engines, and often get nearer the 400 hp mark with good cylinder heads. I can't see why the same power levels shouldn't be achieved with an Olds 350 or 403! The rpm capability seems to be there, with a shorter stroke and better rod/stroke ratio than the Chevy 350; all it would take is getting the heads to flow well enough, and then getting the rest of the combo right. Unless you're driving a full-size Olds that really needs the extra torque of a 455, or a drag-race oriented car, I would think that 400 honest hp from a small block would be enough for most folks who drive mainly on the street. ​

So how about it, folks? Can we get a few of you to forget your 455 obsession for a little while, and think about what could be done with a 350 or 403? ​

The Big Block rebuttal. [ Thanks to John Carri for this information ] ​

My Parts list............

Parts list for the 403​

1. Heads #5 fully ported and filled by Joe Mondello $1800.00​

2. Rockers SAR-495 380.00​

3. Cam JM 25-28 150.00​

4. lifters 555-HCR 150.00​

5. Timing set TR-499 150.00​

6. Valley Tray VT-580 39.00​

7. Cam Spacer CS-120 15.00​

8. Cam bearings RCB-499 30.00​

9. Pan and Pump SS-820 550.00​

10. Pan Baf PB-300 29.00​

11. Windage Tray CT-850 69.00​

12. Crank Spacer CS-40 13. Restrictors R-105 39.00​

14. Cam Button TB-740 18.00​

15. Harmonic Bal 8080 150.00​

16. Pulleys 2250-5809 300.00​

17. Water Pump Spacer 2250-5810 $ 24.00​

18. Water Restictor WR-499 19.00​

19. Flex Plate OL-1200-FP-E 400.00​

20. Gasket Kit OS-570 115.00​

21. Intake Gasket IG-495 20.00​

22. Intake Bolts IB-350 19.00​

23. Header Bolts HDB-460 15.00​

24. Valve cover Bolts RCS-455 18.00​

25. Oil Pan Studs OPS-455 49.00​

26. Bolts FB-410 12.00​

27. Rod Bolts RB-200 $ 50.00​

28. Head Stud Kit HS-370 300.00​

29. Main Stud and Strap Kit ST-947 89.00​

30. Rod Bearings 4000 50.00​

31. Main Bearings 4020 75.00​

32. EG-530 $ 20.00​

_________​

TOTAL $5158.00​

UPGRADE ADD-ONS​

1. Valve Covers VC-485 $ 300.00​

2. Rockers 7200 $ 600.00​

3. Pan Evac VP-500 $ 50.00​

4. Copper Head Gaskets CG-455 $ 230.00​

5. New Cam JM-25-28 $ 150.00​

6. New Lifters 555-HCR $ 150.00​

7. TS-40 $ 15.00​

_________​

TOTAL $1495.00​

TOTAL SPENT ON THE 403 $6653.00 minus crank and labor​

 

There is an urban myth that some of the very first 403's were solid main web but I have not seen one yet, even early 77 versions. This would be a "Holy Grail" part for many Olds guys out there. There have been a few guys that obsess about proof that they actually exist but they still have not seen one and they have been into Oldsmobiles all their lives. Solid main webs would make a 403 a very nice engine for a high performance build!

 

Yeah I know, I looked for a long time, Joe Mondello gave me a casting number to look for and I found one in a yard in Washinton NJ in 93-94 and then found the olds 330 forged crank in a yard off montana mountain rd near washinton NJ.....

 

I guess Joe Mondello and Cam Benty were just wasting our time telling us how to do it right then...

403 Olds Engine Building
Unsung Hero

Back in the late 80's I had a buddy pulled a 403 from a Trans Am and put it in a Holiday 88. It was built with a lot of what Mondello and Benty considered in this article. With a 4:10 rear end, 2800 stall and Hoosiers it'd pull the left front and pretty much eat any pony car that challenged it.

And only 2500 solid web 403's were produced. Holy Grail, yeah, but urban myth, no.

 

I wondered what that semi fixed washer was for,yep, I'll remove it,thanks to all for the help.

I didn't know I'd cause quite the discussion on performance capabilities of the olds motor.

 

How many blown 403s have you personally seen?

 

Don't use the Mondello name around the Olds crowd. That place has a very bad rep over the past few years. I learned that from my days playing with a 307.

http://classicoldsmobile.com/forums...-mondello-no-longer-mondello-performance.html

 

You were very lucky to find one then because, as I said above, there have been Olds guys that have looked for 20-30 years for one and have yet to find one, even from 77 cars that were built in 76 with some of the very first 403's.

Just because it is written down somewhere, on paper or on the internet, does not mean that there is any truth to the solid main web 403 engines. I have seen this quote many times but nobody has been able to produce an example of one and or been able to provide a even one single picture of one. I have heard stories like Phatteddies's several times but have yet to see any real proof that they exist!

 

Gary,

It's been a while since I've been inside an Olds motor but I believe that the tinnerman type washer is to keep the drive shaft from pulling out of the oil pump when you pull the distributor. I believe the shaft passes through part of the block. The washer should be positioned between the block pass through and the oil pump. So, to answer your question, the shaft should be installed from the bottom up. This would prevent the shaft from pulling out of the pump, falling out of the end of the distrubutor and ultimately into the oil pan. Which wouldn't be fun if the motors back in the car.