Author Topic: Best way to get power from 403? (Read 5868 times)

transamfan · « **on:** November 14, 2006, 11:08:41 AM »

I have a little money saved up and am wanting to do a little work to the 403 in my 79 T/A. I would like to get her up to around 350hp or more. What would be the easiest and most cost efficient things change to get there? I am looking to spend around $1000-1200. How realistic is this? Also, will the upgrades to get the power result in more problems down the road? I plan on having the car for a while, and although I won't be driving it a lot (just cruise around on nice days) I want it to be dependable. I don't know a whole lot about engine work so any advice will be helpful. Thanks a lot.

Tin Indians Rule · « **Reply #1 on:** November 14, 2006, 01:58:27 PM »

Overall what condition is the engine currently? How much wear and tear is there? Have you done a compression check on each cylinder? If you have a great running, non smoking, non oil using, not overheating low milage 403 then you can really crank out some extra ponies with that 1000 bucks.

You didn't mention if that was the original engine for the car or not? You also need to consider the appearance of the engine compartment. If you want to keep it original (pick me, pick me) looking or if you wanna see headers, aluminum intake, etc.

Once you decide if you engine can stand some upgrades decide which route you wanna go for appearance and the post back. I'm sure we'll have a ton of ides on how to spend someone elses money.

transamfan · « **Reply #2 on:** November 14, 2006, 05:20:18 PM »

The engine is the original engine that came with the car, and it is in pretty good shape overall, with 117K on it. It hasn't ran right since I got it about year and a half ago. She runs fine until you get on it and then it bogs down and nearly dies before starting to pull. The carb was rebuilt in attempts to solve the problem but to no avail. I replaced the spark plug wires and vacuum hoses and that didn't do it either. The next thing on the list was distributer but the car went to the paint shop and I haven't gotten it back yet. The car already had headers on it when I bought it so I replaced them with a new set from Hooker. I would like to put a different cam in. I want the car to have a little rock to it when it's idling. I do plan on entering the car in some car shows for fun so I would like to dress the engine compartment up a little, but at the same time I am just getting into the show stuff and I don't know the first thing about what an engine compartment should look like (original vs. custom). Ultimately, I just want to add some hp and do it without spending too much money, so the looks are something that I don't have a real preference on.

Also, I have had some trouble with the oil pressure. Not sure if it's just the gage or what, but I changed the oil in it one day and I bought some synthetic stuff that Auto Zone was having a special on. Ever since the oil pressure will drop once the car gets good and heated up. I replaced the sensor but that wasn't the problem. Should I assume the oil pump?

Again, the car is in the paint shop and not being driven at the moment, but when I get it back I plan to do the engine work and adress the mentioned problems when I get it back.

Starsky · « **Reply #3 on:** November 18, 2006, 12:05:06 AM »

Similar problem turned out to be the gas tank wasnt vented

milly · « **Reply #4 on:** January 06, 2007, 03:21:21 PM »

Concerning the oil pressure drop: What kind of oil and what viscosity (spelling??) was it?? A thinner oil will really thin out once the engine is warmed up. You may need to run a thicker oil. I am currently using Mobil 1 Synthetic 10W30 in my T/A with no loss of pressure.

eroc022 · « **Reply #5 on:** January 06, 2007, 03:33:43 PM »

okay dont use synthetic for one....its designed more for the newer motors.....it can blow by the rings and not hold up between the bearings on older higher mileage engines......now if you want to get power out of you car for the type of cash you have, it might be better to start with a rebuild.....and if you are only wanting about 350 horses it will be fairly easy, if you opt out of the rebuild youll need to at least find a set of heads, preferablly from an older smog free olds motor with smaller combustion chambers, the factory heads are junk, next youll want to get a newer intake, the edelbrock performer is just a factory repro in aluminum so all it does is cut off some weight, the real advantage is in the performer rpm, but with that one youll need to get an adapter kit for the shaker, otherwise it will hit on the hood....next on the list would be your ignition setup, stick with the h.e.i unit they perform good enough for what you are wanting, just upgrade it to a davis ignition or msd, both are great companies....if you dont have headers, that would be a good step too, but look at spending a good penny on your heads cause that is where all your power is.....get the ports gasket matched it will really help.....and it doesnt ever hurt to check out other sites....
www.dickmillerracing.com
www.realoldspower.com
www.mondellotwister.com
those are good sites.....

Joker (§ir£Ðragon) · « **Reply #6 on:** January 06, 2007, 03:42:55 PM »

Best way to get power out of an Olds is head-work. Make it breath easier. Next I'd say is cam (and if you are willing to alter the looks) an intake to go with the cam and headers. Your oil pressure problem could be a number of things. Having over 100k miles I'd say go back to non-synthetic oil. You could look into an oil pump and while you're there maybe look into Mondello's main cap straps (#ST940) to strengthen the weak bottom end. If you plan on rebuilding the engine add oil passage restrictors (also offered by Mondello) to lessen any future oiling issues.

moonrider1 · « **Reply #7 on:** January 13, 2007, 12:13:05 AM »

I had the same goal in mind and was advised to talk to Terry at FCR performance. I was running a stock 403 with TH350 auto and 2.73 gears. I told him I wanted more torque and around 350 hp. I also wanted to keep the engine pretty much stock looking since it was in my 10th anniv T/A.

He recommended 9.1:1 compression flat top hypereutectic pistons with larger adjustable intake and exhaust valves in the stock heads. Also went with a higher lift cam, hydraulic lifters and a 3.23:1 gear set so I can avoid the use of a high rev stall converter. I also plan on changing to a set of ceramic coated headers and a new dual exhaust set up. I'll also rebuild the TH 350 tranny.

I am just now receiving all of my parts and the engine is in the shop right now so I can't comment on the results. I will say this, the parts alone were quite a bit more than the figure you mentioned spending. I'm not sure if its any cheaper to just use some different heads to accomplish the same thing. I'm sure others more knowledgeable than me can comment on that. My engine was matching numbers to the car so I wanted to keep the original heads on it. Changing the valve train won't be so obvious.
Good luck with your build!

transamfan · « **Reply #8 on:** February 05, 2007, 09:38:41 PM »

I have decided to get some heads off of a 1969 Olds 350, the Edelbrock Performer intake, a new cam (don't know what I should go with yet) and I already have the headers. I found the heads at a junkyard and am waiting to get the time to go pick them up and I am still shopping ebay hoping to get a deal on the intake. I saw one on there last week (before I decided what I was going to do) for less than $100. If anyone has a similar set-up and has sudgestions on the cam let me know because I haven't figured out which will be the best. I am not sure what it's gonna cost for the head work, but I believe that I am gonna get everything done for less than $900 (that's doing everything myself except machine work).

Tin Indians Rule · « **Reply #9 on:** February 05, 2007, 10:59:56 PM »

Check with your machine shop because you'll most likely end up needing to put hardened valve seats in your 69 heads. Or else the unleaded gas will beat the seats out.

transamfan · « **Reply #10 on:** February 06, 2007, 10:43:15 AM »

Thanks for the heads up. I have already talked to several machine shops here in town and they all have recommended this. I have found a couple of shops that said it would be no more than $400 to completely go through them, valve job, the works, as well as replace the springs and what not with new parts. The heads are in pretty good shape already so that has cut down on the cost somewhat.

455dave · « **Reply #11 on:** February 06, 2007, 07:57:40 PM »

I'm not sure what compression you are looking at but 9:1 on iron heads should let you run pump gas without worrying about detonation. I'd think that a cam in the 220 to 224 @ 0.050 range would give the car a bit of a rumble, should pull to 5000 rpm, and still have good vacuum. I'm running a 224/224 .510 or so lift cam in my chebby 350 and it works good on the street. The only problem is that the cam has a 112 LSA, not the best choice for an 11.5 to 1 compression engine unless you like changing head gaskets. A 112 LSA would work well with a 9:1 engine though. Lift is pretty much up to you, maybe someone with more Olds experience can give recommendations on lift (I'd guess in the .480 to .500 range) and may a better cam choice.

transamfan · « **Reply #12 on:** February 06, 2007, 08:40:02 PM »

Well, I am thinking about going with a COMP cam 212/218 with .453 lift. Comes with a kit to do up the heads, which I was going to have to get parts for anyway. Think this will work well for me? I am not really looking to have a racing machine, just a muscle car with a little muscle. Also, I want the cam to be compatable with my stock converter and rear end. I am not trying to go too radical and I don't want to spend more money than I have to. I am a poor college student!

455dave · « **Reply #13 on:** February 06, 2007, 08:56:33 PM »

Depends on your compression. Comp seems to cut all their cams on a 110 LSA so the intake and exhaust valves are open together longer which bleeds off compression but it's a low duration cam so the bleed off will probably be marginal. The lift is a plus since the low lift will work with stock rockers and valve covers. It will have a bit of rumble at idle. One thing I don't know is whether the Olds stock rockers are adjustable. You really ought to go to an adjustable rockers.