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Old 09-05-2005, 07:32 AM
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Recipe for a 403 Olds?

A good friend of mine is going to be tearing down his 403 out of a TransAm soon for a rebuild and he asked me for some buildup recomendations. I've never had a 403 apart and have no idea how the heads flow etc. Does anyone here have suggestions for a good streetable combination of parts for this engine? Does this engine have the poorly designed alluminum oil pump housing like the buick engines? Bob

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Old 09-05-2005, 09:25 AM
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The oil pump is not like the Buick pump at all. Before you start make sure that you have a good block. The 403 olds won't take much of an overbore. .020"-.030" is about the most you want to bore a 403 for any kind of high performance work. Some vendors sell .060" pistons but I wouldn't try them.
Most of the trans-ams in those years had really high rear end gears, some were 2.49's, so keep the cam mild. You should go with something 204-208 degrees on the intake duration @.050" lift. I'd go with a good set of 350 olds heads to get the compression up. The 403 heads do have larger intake valves but they're paired with small exhaust valves. You don't want to try to get radical with this motor. If you're want to go much more than a stock rebuild with mild cam and head mods I'd find a 455 Olds. It will fit without much difficulty.
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Old 09-05-2005, 11:16 AM
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do a search, i posted bot the 403s in the last 2weeks or so in 2 posts.

everything i've read about Mondello in last few yrs has beem bad

Heads Consider swapping a set of earlier 64cc heads onto the engine, small block Olds info here, http://www.442.com/oldsfaq/ofhed.htm#Heads

in my opinion call Mr Olds 1st or post on Olds forum http://www.realoldspower.com

a set of older olds 350 heads and a cam, headers and a big cam will wake the 403 up,
the 403 has a bigger bore than a BBC it has potential. The 403 responds well to a bit more camshaft and compression. an earlier set of 350 heads ('68-'72 will do it, but the '72's are the best) to raise the compression, and an Edelbrock Performer-grind cam (these cams are available from other sources than Edelbrock, who I suspect purchases them from another supplier).

A high compression 403 will not shatter a stock piston, unless you are running nitrous. The "7a" heads only give you about 9.5:1 compression, and the factory high-compression 350's came with 10.5:1 and cast pistons, so you're pretty safe. Just have it balanced, and keep her under 6000rpm.

Any 350 head will raise compression a little to a lot. Depends on combustion chamber size. A set of 1968 to 1972 heads will raise compression, and allow the engine to make more power. Use the 2.00" intakes from the 403. Ream the head bolt holes for the 403's ?" head bolts. and perhaps re-curve the distributor.


all the info is here
http://www.442.com/oldsfaq/ofe403.ht...IDEngineDetail

http://www.442.com/oldsfaq/oldsfaq.htm

Mr Olds will help you build a 403 that will run with the BBC Guys, Call Him.

Contact Mr. Olds A.K.A. Terry he will talk to you on the phone, super nice guy
FCR PERFORMANCE .com 1 877-215-1800 TOLL FREE
OLDSMOBILE PERFORMANCE PARTS AND ENGINES. We sell Kooks headers Ultra Dyne cams and most other performance parts for Olds


Mr Olds is on this site a lot

http://www.realoldspower.com




heres a 79 T/A SetUp

With these not-so-expensive upgrades, my car runs mid 13's.

'79 403
[ Thanks to Ray Costanzo for this information. ]

'79 403 block bored .030 over => 409 CID
403 crank ground .010
stock 403 rods
Arias(?) forged aluminum pistons, 10.5:1
Crane Cam .480/.496; (280-290 adv.? cam card missing!, maybe 292 or was it 272, dual pattern though, both with some high 200's duration (advertised)
Crane lifters, pushrods and springs
'72 350 (7a) heads
Edelbrock 7111 performer RPM intake
Carter 750cfm AFB
Mallory Unilite distibutor w/ Cccel supercoil
TH-350, stock converter, shift kit
3.08 posi

Couple more

1979 H/O
[ Thanks to Todd Evans for this information. ]

1979 Hurst/Olds
Built Racing Head Service 403,
Mondello JM 22-25 cam
W-31 heads
Edelbrock Performer intake,
rebuilt Carb Shop quadrajet
Holley electric fuel pump
less than 100 miles on rebuilt Turbo 350 & B&M 11" converter
3.23 Auburn posi unit
Hellwig swaybars
new dual exhaust
solid body
fiberglass cowl induction hood
Hurst dual gate shifter
original Hurst wheels w/ good BFG tires
Runs VERY strong at 13.1@ 105 mph 1/4 mile


[ Thanks to Samuel Johnson for this information. ]
'80 Cutlass
I had a 1980 Cutlass with a 403 stuffed in it. It ran 13.60s stock with street tires, well semi stock.

Stock rebuild
moly rings
Edlebrock intake 3711
Comp Cam's cam (I believe the one with the 433 lift and 262 duration)
650 dual feed double pumper Holley carb
dual 2.5" Flowmasters
TH-350 trans with shift kit and no stall (with stall I would burn up in the gate)
3.73 rear end
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Old 09-05-2005, 06:57 PM
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ported $5 or #7 castings with larger valves make a world of difference- you'll pass chevy's like they're standing still. Get a higher ration roller rocker installed thoguh- the lift helps a hell of a lot. The RPM is a good manifold, but alittle port work with a hand grinder would help some. HEI helps a lot down low. I like Toatl Seal Gapless rings- they're a little pricy though.
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Old 09-05-2005, 07:51 PM
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A 403 should have a HEI just needs recurved to match cam ect. i bought a set of #5 350 heads for $50 if the motor has been rebuilt with stock aftermarket pistons, i would mill the heads .30ths or .40ths and use a .28 thick cometc head gaskets, to get the quench down. if your rebuilding the 403 i would deck the block to get the quench down. talk to Mr Olds, you will be glad you did.





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Old 09-05-2005, 09:08 PM
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Thanks for the info! The older 350 heads shouldn't be hard for me to find. Any idea what the difference is in chamber size between the 403 heads and the 350's? Bob
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Old 09-06-2005, 10:40 AM
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a stock 403 head is 83cc a #5 to #7 & #7a head is 64cc


everything is on here: http://www.442.com/oldsfaq/oldsfaq.htm



scroll down to head info
http://www.442.com/oldsfaq/ofhed.htm#Heads

Small Block Head ID/Codes, Casting Numbers, VIN Derivative Numbers
The 4 or 6 digit casting number is found around the center exhaust side rocker arm cover bolt or among the rockers on really early heads [pre-68]. Really late heads have #'s like 4417 or such, they might be out closer to the top of the exhaust port. This number is also found on each side of the lower middle valve cover bolt, split into 3-n-3 on each side of that bolt.

If it's an 1, 2, 3, or 4 head, look for the engine unit number/ID code as detailed in the Blocks section under Small Block Unit Numbers. If no such ID is stamped in, then it's either an 1968 and later head, or a 1967 head from the left side of the engine. Check the other end of the other head.

ID/ Use Casting
Code Year(s) CID CCs Number Notes
1 '64 330 385101 Used ROCKER SHAFTS rather than pairs on PEDESTALS.

2 '65 330 ?????? All V-8s now using PEDESTALS.
3 '66 330 60 389394
4 '67 330 60 394497
5 '68 - '69 350 64 397742 Excellent candidate for use today. Good flowing, and high compression.

6 '70 350 64 403859 W-31's had larger 2.000 intakes. '69 W-31's?

7 '71 350 64 409147 W-31's had larger [2.000] valves.

7A '72 350 64 409147 The 'A' is a subscript, like " tall, to lower right of the '7', like | 7A.
8 '73 - '76 350 79 411929 Smog heads. Have huge bb-sized 79cc
chambers yielding poor compression ratios without extremes of compensation.

10 '76, '77? 260? 57 550362

2A '76 - '81 260 554715 Easy way to ID a 260 engine.

3A '77 - '80 350 75 554716 1/2" bolt holes.

4A '77 - '79 403 83 554717 Matches the 4A or 4B block, get it? Easy way to ID a 403. 1/2" bolt holes.

5A '80 - '84 307 64 3317
'85 also???

6A '85 - ?? 307 67 5844 Non-ECM Canadian cars?

7A '85 - '90 307 67 0142 This 'A', and the others from 2A to 6A, is a large capital letter equal in size to, and immediately adjacent to the 7, like | 7A.
D3A 350 3948 Diesel.

it appears that in '71 (when they needed to drop all of the compressions in GM cars - 10.5 to 8.5) that their first method of doing it was to dish the pistons more. In 1973 they increased the chamber sizes on the heads and went back to piston comparable to 1970 and prior.

[ Thanks to Brent Fields for this information.



Details
The 4 or 6 digit casting number is found around the center exhaust side rocker arm cover bolt or among the rockers on really early heads [pre-68]. Really late heads have #'s like 4417 or such, they might be out closer to the top of the exhaust port. This number is also found on each side of the lower middle valve cover bolt, split into 3-n-3 on each side of that bolt.

Be aware that most heads made before 1968 use a pushrod hole that corresponds to a 45&#degree; cam bank angle. What this means is the pushrods will rub the sides of the holes if the heads are used on a block with a 39&#degree; cam bank angle. All blocks 1968 and after use the 39&#degree; cam bank angle. Check the Cam Bank Angle, Lifter Size Considerations section for more information.
ID Casting # Combustion Camber Intake Valve Exhaust Valve
1 385101
The rocker assembly is the same as later non-adjustables, except the aluminum cross pieces are stamped steel, and don't bottom out on the head. The pivots are individual and made of steel; they are linked together by the steel cross piece. These are adjustable rockers.
2

3 389394 60cc


4 394497 60cc 1.875 1.562

5 397742 64cc 1.875, 1.995 1.562, 1.624
All 1969 350s use the #5 head, 2bbl, 4bbl, or W-31, they all use it. The 2bbl and the 4bbl use exactly the same head. Same valves, springs, etc. Only the W-31 got the big valves and springs. Only W-31's were fitted with the larger valves.

6 403859 64cc 1.880, 1.995 1.567, 1.624
All 1970 350s use the #6 head, 2bbl, 4bbl, or W-31, they all use it. The 2bbl and the 4bbl use exactly the same head. Same valves, springs, etc. Only the W-31 got the big valves and springs and were filled with larger valves. Rotator style spring retainers were used on the intake and exhaust springs.

7 409147 64cc 1.880, 1.995 1.567, 1.624
All 1971 350's use #7 heads. Valve springs were different depending on application. Rotator style spring retainers were used on ONLY the exhaust springs. Induction hardened valve seats for use with unleaded fuel.

7A 409147 64cc 1.875 1.622
All 1972 350's use #7A heads. Valve springs were different depending on application. Rotator style spring retainers were used on the intake and exhaust springs.

8 411929 79cc 1.875 1.622
1973 - 1976 350 only. Rotator style spring retainers were used on the intake and exhaust springs.


Mustangsaly
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Old 12-05-2007, 12:11 PM
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403 street hp make over

Heads, intake and cam have to go. early 350 #5, #6, #7 & 7a(hard seats)offer big improvement. all flow similar #'s. the stock 403 heads are worthless. I can not believe the 403 runs as good as it does with stock intake and 4a heads. You can use the 403 intake valves in the 350 heads and get bigger exhaust. anyone who says the Edelbrock performer intake is just a copy of the stock manifold does not know much about intake manifold design. Cam depends on converter and rear end ratio (at least 2.73). With stock, PLEASE keep duration under, I said UNDER NOT AT, 220 degrees at .050 for the STREET, bigger and you go slower. What is a street car, one that spends more than 80% of it's time on the street is a good rule of thumb. As that # changes you can slowly start making changes in favor of top end power and torque. Im not going to bother with the basics such as ignition and carb work except to say keep the qjet, just adjust linkage to open all the way. GM did not set carb linkage (SECONDARY'S) to open fully for many reasons. But lastly one of the first things you want to do is take care of the bottom end. Everyone complains about the windowed mains. Just call Jim at J&S machine and get a halo girdle, studs and ARP rod bolts and forget about the bottom end under 5800 rpm. www.jsmachineoldsmobile.com/. I Would still shift between 5200 to 5500 to maximize use of the power band. Next step would be true duel exhaust, now that you have air in you need to get air out. If anyone is interested someday I could go into a lot more detail. Thanks Gary J.
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Old 12-05-2007, 02:19 PM
How fast is fast enough?
 
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you can go bigger than 220* @.050" as long as you have the gears and compression to match- I hate to see hard and fast BS rules like that.

You can also shove 455 valves into 350 heads... they're just a hair bigger than the 403 valves.

The Edel Performer manifold is damn near an idential copy to the W-31 factory intake manifold... however that manifold is super rare so going with a RPM manifold is the usual route here. You can also use manifolds for the 455 if you want to get them machined.
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Old 12-05-2007, 02:54 PM
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Reply To Ap72

Well Hell, thats just stupid. Of course you can go bigger, you can strap a damn rocket on the back if you want. Maybe you should reread what I wrote and then stop and think about it. I gave a SPECIFIC set of parameters under which a stock 403 could be made to run well on the street. I went bigger for a street cruiser, but it cost more money and a hell of a lot more work. Not everyone can or wants do that, and i'm sure there are other ways to accomplish the same thing, This is just what i consider a nice starting point, that point being that all parts have to match the application. thanks gary j.
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Old 12-05-2007, 07:21 PM
How fast is fast enough?
 
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its not that it won't give good low end response... but for a lot of people- especially ones on this forum- good street manners do not necessitate a 3500 RPM torque peak. If it did few people would run tunnelrams on the street, or solid roller cams, or dual quads, or 4.11 gears, or 12:1 compression... but many people drive those cars several days a week, not because they have to but because its so much more fun that way.
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Old 12-06-2007, 08:18 AM
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Quote:
Originally Posted by ap72
you can go bigger than 220* @.050" as long as you have the gears and compression to match- I hate to see hard and fast BS rules like that.

You can also shove 455 valves into 350 heads... they're just a hair bigger than the 403 valves.
This is what the factory did on the W-31s. The 403 actually has a larger bore than the 455, so valve shrouding is improved.

Quote:
The Edel Performer manifold is damn near an idential copy to the W-31 factory intake manifold... however that manifold is super rare so going with a RPM manifold is the usual route here.
The factory W-31 (and for the big block W-30 as well) is dimensionally and flow wise IDENTICAL to the stock cast iron factory intake. The only difference is the material (aluminum). The Performer is slightly taller and has some runner changes. The performer RPM is taller still.

Quote:
You can also use manifolds for the 455 if you want to get them machined.
The 455 (and all big block Olds motors) uses an intake about 1.5" wider than those on a 403 (and all other small block Olds motors). That seems like a LOT of machining. Of course, the other problem is that the BBO port sizes are larger. Assuming you could even do the machining, you'd need to do significant port matching on the heads. It's not clear that there's enough meat to do that correctly. I'd be very interested in seeing some hard data if someone's actually done this, but I remain skeptical for now.
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Old 12-06-2007, 09:38 AM
How fast is fast enough?
 
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I don't know which factory manifold you are talking about, but I actually have the W-31 manifold and two performer manifolds for the 350 side by side on a shelf. If they are not the exact same they are so damn close it wouldn't make much of a difference. I haven't got a flow bench out, but they are amazingly close.

The RPM is indeed a little taller though.
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Old 12-06-2007, 01:59 PM
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403 street hp make over

Those of us with Firebirds with shaker scoops don't have the option of running the RPM manifold, If I did I would. But, I would run the performer just for the weight reduction alone. Now to stir things up. Had a 70 Nova SS 375 hp 396 (402) bone stock 3.36 gears, th 400 with a very low stall converter. I was the second owner, took it out of a shed myself full of spiders, big spiders, no mice, I think the spiders ate them. This engine came with a rectanguler port sunken aluminum intake that was used on some vettes with hood clearance issues, Chevy was getting generic by the early 70's with some of there parts, the end was near. This was a street car, but I like to run my cars at the strip to set them up properly. First headers gave me 1/2 second, then slicks about 6 tenths, pulled the low, low rise intake and gained nothing, turned exactly the same et to the hundredth of a second. I knew I needed gears and a converter. Car was very capable of high 11's low 12's but thats not what i wanted it for. Now for the Firebird. I'm setting mine up to run low 13's in street trim, closed exhaust, no power adders (NOS) and I hope without slicks and i don't think the performer is going to be my limiting factor but theres a good chance i'll have to modifiy it. I still stand behind my above recomendations for a street 403 firebird and I would probably be better off following my own advise for a street driven 403, but I just need a little more. gary j.
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Old 04-16-2008, 08:40 PM
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[QUOTE=baddbob]A good friend of mine is going to be tearing down his 403 out of a TransAm soon for a rebuild and he asked me for some buildup recomendations. I've never had a 403 apart and have no idea how the heads flow etc. Does anyone here have suggestions for a good streetable combination of parts for this engine? Does this engine have the poorly designed alluminum oil pump housing like the buick engines? Bob[/Q

I have a complete 403 fresh rebuild that i will let go cheap to anyone interested. E-mail me at THISISCHILVIS@YAHOO.COM
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