[CaNNedHeaT]

Hi, I have an Olds 403 in a 79 Trans am. To make a long story short. I bought a set of heads from a guy on a different web site (I know dumb ass) he said they were off a 350 olds. Ok I wanted the smaller combustion chambers. What I got delivered were 4A 403 heads. The same thing I have. They are remanufactured. So I hate to start over. He pretty much fell off the face of the earth. (no return emails or calls) so I'm trying to make the best of this situation. These cost me $275 delivered. I think I read somewhere I can mill these down to raise the compression ratio. Is that true? any one know the specs?

To add to my story - I want to have fun driving this car, up to this point it has been a little disappointing (no balls). So what I bought so far for my winter project. (headers, intake and carb already on the car) Edelbrock Performer RPM intake, Performer RPM cam & lifters (.520 lift) ,1.6 roller rockers, Edelbrock 750 cfm carb, 1 7/8" headers. Still going to buy - double roller timing chain with 4 degree advance and probably an electric cooling fan.

If anyone has any comments or suggestions (not too harsh, lol) please let me know.

Thanks in advance for any help,
Scott

[2manyT/A'S]

Before you start tearing apart your motor,have a look at your diff.,specifically GEAR RATIO.
You've likely got 2.56's if they are originals.
A swap up to 3:08's or 3:23's will feel like you added 50 HP!
With all the engine mods you have planned,your bottom end will be even soggier with the stock gears.

[Grand73Am]

Originally Posted by 2manyT/A'S

Before you start tearing apart your motor,have a look at your diff.,specifically GEAR RATIO.
You've likely got 2.56's if they are originals.

I agree. And actually, the stock rearend gear ratio for a 79 TA 403 is even worse than that. They're 2.41's! I know because I have one .

[1tinindian]

Originally Posted by Grand73Am

I agree. And actually, the stock rearend gear ratio for a 79 TA 403 is even worse than that. They're 2.41's! I know because I have one .

I just wanted to add that I have had 2 different 79 T/As, both WS6 cars with the 403/auto, and they both had 2:73 rear gears.
I'm gonna guess, and say the non-WS6 cars would either have the 2:56s or even the 2:41 rear gear.
Don't need overdrive with those babies!

Leon

[Brian Baker]

Rear gearing needs to be addressed. Install a 3.23 gear, you'll be happier with the acceleration while still being able to cruise the highway.

Don't know about the Oldmobile RPM intake, but the Pontiac RPM intake will not fit under the hood with the factory shaker. There are a couple of systems available from WFO and Blocker to remedy this, but they are geared towards the Pontiac engine.

VALVE SPRINGS !!!

I can't stress this part enough! Make sure you have new springs and that they are correct for the cam, as the OEM springs aren't compatible.

A good flowing dual exhaust will be a must as well.

[Colin]

Brian mentioned the shaker fit with the RPM manifold. I had a '78 with the Olds 403 and I installed a Performer RPM and it wont fit. As a matter of fact it tells you in the catalog that it wont fit............could probably look on their website to be sure.

[2manyT/A'S]

You know,those mid 2 series stock 79 gears are not neccessarily a BAD THING,if you a planning a cross country run @ 100 + MPH.

CANNONBALL,Anyone?

Unfotunately,they are NOT much fun @ the Stop Light Grand Prix.

[olds]

I don't think those 4A heads are of use to you unless are planning to use them with flat top or 6cc pistons. To make the combo you have work you need more compression. Milling the heads 20 or more cc's is not practical. Locate a set of #3, #4, #5, #6, or #7 heads. If you plan on just a head swap. Preferably, a set of #3 or #4. Those are actually 330 heads, but have 62cc chambers. If you don't get the compression up the rest of this combo is mismatched. If the lower end is in good shape then go for the head swap. It will cost you a bit to get these older heads (30yrs+) updated with new valves, guides, springs (that match the cam spec) and a valve job. Keep that in your budget. Don't even think about the alum ebrocks. Those will not help either as they are 77cc.

You can save yourself a bit of headache if you don't use that RPM intake. You really will not benefit much from it. I am using a ported performer and it works fine with #4 heads (67 olds 330) and also fits under the hood as well. I am not a big fan of it for street driven 403's. Too much pain for little gain.

That cam is OK, but not really an oldsmobile grind. It will idle a bit rough and need a lot more fuel at idle and will not have a lot of vacuum. About 10-12 inches at the most. (Fyi, stock is 18-19inches). The 403 does not need a ton of cam to wake up and have some street ball.

Your HEI will need to be tweaked as well. You have too much vacuum advance and not enough mech which will make the combo a dog and run like shyt. Been there. The HEI will need to be recurved. The 403 needs 16-20 intial, 15-20 mech, 10-12 vacuum. This work can only been done on a distributor machine or with a lot of patience with a dial back timing light. Personally, I had Rocky Rotella set mine up he posts here and on tacountry.com Send him a PM or something.

A well thought out combo can easily make 350-400HP.
Get the compression up and the 403 will wake up.

You might give a call to Terry Sr at FCRperformance. He does a lot of work with 403's. Get the right parts before you have future headache. fcrparts.com

I don't post here too often. You can catch me via PM or on tacountry or realoldspower

olds

[CaNNedHeaT]

Wow, thanks for all the repsonses. I have some thinking and possibly some reworking to do before I start tearing apart my engine.

I appreciate everyone taking the time to express their thoughts and ideas.


Thank you,
Scott

[2manyT/A'S]

A friends 79 403 WS6 T/A shows 3:08's on the build sheet,which I felt was pretty uncommon. (it's a non-A/C car)

It's got a stronger bottom end than MOST I have driven.

[Grand73Am]

Yes, I forgot about the WS6 ones getting better ratios. Mine doesn't have WS6, so hence the 2.41's. I do have a pair of WS6 disc brake rearends in the garage, one with 2.73 and the other with 3.08, one of which I plan to swap in to my 79.

[SD73]

The two 403, '79s I had both had 3:23s. One was an SE one was a TATA. The low end was plenty torquey enough to lite 'em up with little effort. About All I ever did to either of those cars was remove that catalyst and smog pump.