1979 trans am mod question
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Registered User
Joined: Feb 2005
Posts: 74
From: mn
1979 trans am mod question
My brother has a 1979 trans am with a 403 ci. motor and is looking to spend about 5k on makeing it faster and was wondering what he should do first to make it faster and other things that he can do to his car because the motor is only rated at 180 hp. If you no about how much power each thing will add please list that as well.
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Joined: Oct 1999
Posts: 522
From: CALGARY, ALBERTA, CANADA
Re: 1979 trans am mod question
If he has a four barrel carb, then it should be fine to make a lot of power. Maybe a rebuild might be needed, but no point replacing it, I think they flowed 800CFM back then.
The intake, heads, cam, should be changed for higher performance units if he's looking to make 300hp or so.
The intake, heads, cam, should be changed for higher performance units if he's looking to make 300hp or so.
Registered User
Joined: Dec 2002
Posts: 56
Re: 1979 trans am mod question
What is bad with the olds 403 is that it is a low compression motor ( 8.1 i think ) and the cam is also weak. Also most 403 trans ams came with really crappy gears. So just by adding a better gear will make the car feel totally different. After the gears, Fix the compression issue and get a good cam and exhaust and it will really wake it up. If you like go to these pages they have some good info on the motor.
http://www.442.com/oldsfaq/ofe403.ht...IDEngineDetail
http://www.texastransams.com/article...03_article.htm
http://www.442.com/oldsfaq/ofe403.ht...IDEngineDetail
http://www.texastransams.com/article...03_article.htm
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Joined: Nov 2003
Posts: 1,211
Re: 1979 trans am mod question
Send him HERE.
There is no other group of people more knowledgable on Oldsmobiles than them.
In general, here's the deal:
Those 403 engines all had what are called "windowed" main webs. The windowing was done for piston skirt clearance due to the very large bore, so don't believe anyone who tells you he has or has seen a non-windowed block.
These windows mean the bottom end is unsuitable for high revs, however 5000-5500 is all you need with these engines.
You DEFINITELY need aftermarket pistons, both to get the weight down and to get the compression up. The stock rods are the strongest factory oldsmobile rods you can get, so just recondition them. You can get an aftermarket crank, but frankly the stock steel crank is fine. Just have it reworked and properly balanced.
Oiling is a major issue. You can ask for details at the board I sent you to.
For heads, there are several options, but perhaps the best overall value is to bolt on a set of Edelbrock big block heads. Yes, I said big block. Oldsmobiles are peculiar in the sense that you can bolt big block heads to a small block. And you should, because the big piston bore allows you to use nice big valves.
You'll need to port match an intake manifold to the intake, because nobody to my knowledge makes an intake specific to BB heads on a SB. HOWEVER, the Edelbrock Performer RPM intake, model # 7111 IS cast with material in the right place EXPRESSLY to allow for that sort of port matching.
Offenhauser makes a Dual Quad manifold for both small & big blocks, which would be really cool in that Trans-Am. However, I don't know which is better for port-matching or adaptor plating. That's another question you can ask the guys at that board I sent you to.
In all likelyhood, you'll want to ditch whatever electronics are on the engine, so you'll want an aftermarket distributor. On my last 403 I used a Mallory Unilite, which I liked. Low cost and it worked.
You'll ABSOLUTELY want a custom cam. Try Ultradyne. I think they still have all the profiles that Harold designed. I don't know where Harold works these days, but wherever it is, you can go to them for a custom cam too. Also a question for that board.
You do NOT want to go to Mondello for ANYTHING you can get elsewhere. Too damn much money.
Bulldog makes a head you can use too. I don't know the cost. The Edelbrock I mentioned is still, I think, under $1500 for an assembled pair.
Many people like to use a main girdle on the 403. Some folks think it doesn't matter.
Do NOT use nitrous UNLESS you use a progressive controller, and even the you'll want to stay under 200hp, preferably under 150.
Naturally aspirated and revving to less than 6000rpm, that engine is easily capable of 500+ flywheel HP and Torque.
Gears are a good idea. 3.42 if you have a 3-speed tranny, 3.73 if you have a 4-speed, 4.10(4.11...? I don't recall...) if you have a 5 or 6 speed.
If this was MY car, I'd go with the edelbrock heads, Offenhauser dual quad manifold with twin Carter AFB or Edelbrock 585 or 600 cfm carbs and side pipes, with appropriate gears for the tranny. Top it with a progressive 100 shot, but only if I had a girdle.
ALL your questions can be answered on that board, including stuff you didn't even know to ask about. The worlds foremost experts on 403's are on that board too. Also, be advised that Andy Miller is on that board too. (StrangeMagic)
He's kind of an A-Hole, but NOBODY knows more about building fast Oldsmobiles than he does. Not even Joe Mondello.
Good luck.
There is no other group of people more knowledgable on Oldsmobiles than them.
In general, here's the deal:
Those 403 engines all had what are called "windowed" main webs. The windowing was done for piston skirt clearance due to the very large bore, so don't believe anyone who tells you he has or has seen a non-windowed block.
These windows mean the bottom end is unsuitable for high revs, however 5000-5500 is all you need with these engines.
You DEFINITELY need aftermarket pistons, both to get the weight down and to get the compression up. The stock rods are the strongest factory oldsmobile rods you can get, so just recondition them. You can get an aftermarket crank, but frankly the stock steel crank is fine. Just have it reworked and properly balanced.
Oiling is a major issue. You can ask for details at the board I sent you to.
For heads, there are several options, but perhaps the best overall value is to bolt on a set of Edelbrock big block heads. Yes, I said big block. Oldsmobiles are peculiar in the sense that you can bolt big block heads to a small block. And you should, because the big piston bore allows you to use nice big valves.
You'll need to port match an intake manifold to the intake, because nobody to my knowledge makes an intake specific to BB heads on a SB. HOWEVER, the Edelbrock Performer RPM intake, model # 7111 IS cast with material in the right place EXPRESSLY to allow for that sort of port matching.
Offenhauser makes a Dual Quad manifold for both small & big blocks, which would be really cool in that Trans-Am. However, I don't know which is better for port-matching or adaptor plating. That's another question you can ask the guys at that board I sent you to.
In all likelyhood, you'll want to ditch whatever electronics are on the engine, so you'll want an aftermarket distributor. On my last 403 I used a Mallory Unilite, which I liked. Low cost and it worked.
You'll ABSOLUTELY want a custom cam. Try Ultradyne. I think they still have all the profiles that Harold designed. I don't know where Harold works these days, but wherever it is, you can go to them for a custom cam too. Also a question for that board.
You do NOT want to go to Mondello for ANYTHING you can get elsewhere. Too damn much money.
Bulldog makes a head you can use too. I don't know the cost. The Edelbrock I mentioned is still, I think, under $1500 for an assembled pair.
Many people like to use a main girdle on the 403. Some folks think it doesn't matter.
Do NOT use nitrous UNLESS you use a progressive controller, and even the you'll want to stay under 200hp, preferably under 150.
Naturally aspirated and revving to less than 6000rpm, that engine is easily capable of 500+ flywheel HP and Torque.
Gears are a good idea. 3.42 if you have a 3-speed tranny, 3.73 if you have a 4-speed, 4.10(4.11...? I don't recall...) if you have a 5 or 6 speed.
If this was MY car, I'd go with the edelbrock heads, Offenhauser dual quad manifold with twin Carter AFB or Edelbrock 585 or 600 cfm carbs and side pipes, with appropriate gears for the tranny. Top it with a progressive 100 shot, but only if I had a girdle.
ALL your questions can be answered on that board, including stuff you didn't even know to ask about. The worlds foremost experts on 403's are on that board too. Also, be advised that Andy Miller is on that board too. (StrangeMagic)
He's kind of an A-Hole, but NOBODY knows more about building fast Oldsmobiles than he does. Not even Joe Mondello.
Good luck.
Registered User
Joined: Jun 2001
Posts: 1,209
From: TX
Re: 1979 trans am mod question
Have him yank the 403 and replace it with a 455. I almost did this with my 71, had the engine built on the stand. Changed my mind, sold the 455 and ended up going with a 400 sbc. Not many people know Oldsmobiles, so I was going to put Ram Rod 350 stickers on the air cleaner. 
Banned
Joined: Nov 2003
Posts: 1,211
Re: 1979 trans am mod question
Originally Posted by kacy
I've heard good and bad things about the 403, and [have] only seen them run slowly...
Then you've only seen 403's that were built by people who didn't know what they were doing.
Registered User
Joined: Oct 1999
Posts: 522
From: CALGARY, ALBERTA, CANADA
Re: 1979 trans am mod question
All this info is good, but keep in mind this guy wants to keep up with Lt1's. If the bottom end is fine, that 403 should have no problem doing it with just a few mod's.
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Joined: Nov 2003
Posts: 1,211
Re: 1979 trans am mod question
Originally Posted by OP
All this info is good, but keep in mind this guy wants to keep up with Lt1's. If the bottom end is fine, that 403 should have no problem doing it with just a few mod's.
If I may...
A max effort 403 will never ber able to keep up with a max effort LT1, because the bottom end of the 403 cannot hold the same power as the bottom end of an LT1.
If however the goal is to create a streetable, naturally aspirated 403 that will put out power comparable to a streetable, naturally aspirated LT1, then that is very do-able.
Registered User
Joined: Jan 2001
Posts: 511
From: Newark, DE
Re: 1979 trans am mod question
Originally Posted by LameRandomName
Send him HERE.
There is no other group of people more knowledgable on Oldsmobiles than them.
In general, here's the deal:
Those 403 engines all had what are called "windowed" main webs. The windowing was done for piston skirt clearance due to the very large bore, so don't believe anyone who tells you he has or has seen a non-windowed block.
These windows mean the bottom end is unsuitable for high revs, however 5000-5500 is all you need with these engines.
You DEFINITELY need aftermarket pistons, both to get the weight down and to get the compression up. The stock rods are the strongest factory oldsmobile rods you can get, so just recondition them. You can get an aftermarket crank, but frankly the stock steel crank is fine. Just have it reworked and properly balanced.
Oiling is a major issue. You can ask for details at the board I sent you to.
For heads, there are several options, but perhaps the best overall value is to bolt on a set of Edelbrock big block heads. Yes, I said big block. Oldsmobiles are peculiar in the sense that you can bolt big block heads to a small block. And you should, because the big piston bore allows you to use nice big valves.
You'll need to port match an intake manifold to the intake, because nobody to my knowledge makes an intake specific to BB heads on a SB. HOWEVER, the Edelbrock Performer RPM intake, model # 7111 IS cast with material in the right place EXPRESSLY to allow for that sort of port matching.
Offenhauser makes a Dual Quad manifold for both small & big blocks, which would be really cool in that Trans-Am. However, I don't know which is better for port-matching or adaptor plating. That's another question you can ask the guys at that board I sent you to.
In all likelyhood, you'll want to ditch whatever electronics are on the engine, so you'll want an aftermarket distributor. On my last 403 I used a Mallory Unilite, which I liked. Low cost and it worked.
You'll ABSOLUTELY want a custom cam. Try Ultradyne. I think they still have all the profiles that Harold designed. I don't know where Harold works these days, but wherever it is, you can go to them for a custom cam too. Also a question for that board.
You do NOT want to go to Mondello for ANYTHING you can get elsewhere. Too damn much money.
Bulldog makes a head you can use too. I don't know the cost. The Edelbrock I mentioned is still, I think, under $1500 for an assembled pair.
Many people like to use a main girdle on the 403. Some folks think it doesn't matter.
Do NOT use nitrous UNLESS you use a progressive controller, and even the you'll want to stay under 200hp, preferably under 150.
Naturally aspirated and revving to less than 6000rpm, that engine is easily capable of 500+ flywheel HP and Torque.
Gears are a good idea. 3.42 if you have a 3-speed tranny, 3.73 if you have a 4-speed, 4.10(4.11...? I don't recall...) if you have a 5 or 6 speed.
If this was MY car, I'd go with the edelbrock heads, Offenhauser dual quad manifold with twin Carter AFB or Edelbrock 585 or 600 cfm carbs and side pipes, with appropriate gears for the tranny. Top it with a progressive 100 shot, but only if I had a girdle.
ALL your questions can be answered on that board, including stuff you didn't even know to ask about. The worlds foremost experts on 403's are on that board too. Also, be advised that Andy Miller is on that board too. (StrangeMagic)
He's kind of an A-Hole, but NOBODY knows more about building fast Oldsmobiles than he does. Not even Joe Mondello.
Good luck.
There is no other group of people more knowledgable on Oldsmobiles than them.
In general, here's the deal:
Those 403 engines all had what are called "windowed" main webs. The windowing was done for piston skirt clearance due to the very large bore, so don't believe anyone who tells you he has or has seen a non-windowed block.
These windows mean the bottom end is unsuitable for high revs, however 5000-5500 is all you need with these engines.
You DEFINITELY need aftermarket pistons, both to get the weight down and to get the compression up. The stock rods are the strongest factory oldsmobile rods you can get, so just recondition them. You can get an aftermarket crank, but frankly the stock steel crank is fine. Just have it reworked and properly balanced.
Oiling is a major issue. You can ask for details at the board I sent you to.
For heads, there are several options, but perhaps the best overall value is to bolt on a set of Edelbrock big block heads. Yes, I said big block. Oldsmobiles are peculiar in the sense that you can bolt big block heads to a small block. And you should, because the big piston bore allows you to use nice big valves.
You'll need to port match an intake manifold to the intake, because nobody to my knowledge makes an intake specific to BB heads on a SB. HOWEVER, the Edelbrock Performer RPM intake, model # 7111 IS cast with material in the right place EXPRESSLY to allow for that sort of port matching.
Offenhauser makes a Dual Quad manifold for both small & big blocks, which would be really cool in that Trans-Am. However, I don't know which is better for port-matching or adaptor plating. That's another question you can ask the guys at that board I sent you to.
In all likelyhood, you'll want to ditch whatever electronics are on the engine, so you'll want an aftermarket distributor. On my last 403 I used a Mallory Unilite, which I liked. Low cost and it worked.
You'll ABSOLUTELY want a custom cam. Try Ultradyne. I think they still have all the profiles that Harold designed. I don't know where Harold works these days, but wherever it is, you can go to them for a custom cam too. Also a question for that board.
You do NOT want to go to Mondello for ANYTHING you can get elsewhere. Too damn much money.
Bulldog makes a head you can use too. I don't know the cost. The Edelbrock I mentioned is still, I think, under $1500 for an assembled pair.
Many people like to use a main girdle on the 403. Some folks think it doesn't matter.
Do NOT use nitrous UNLESS you use a progressive controller, and even the you'll want to stay under 200hp, preferably under 150.
Naturally aspirated and revving to less than 6000rpm, that engine is easily capable of 500+ flywheel HP and Torque.
Gears are a good idea. 3.42 if you have a 3-speed tranny, 3.73 if you have a 4-speed, 4.10(4.11...? I don't recall...) if you have a 5 or 6 speed.
If this was MY car, I'd go with the edelbrock heads, Offenhauser dual quad manifold with twin Carter AFB or Edelbrock 585 or 600 cfm carbs and side pipes, with appropriate gears for the tranny. Top it with a progressive 100 shot, but only if I had a girdle.
ALL your questions can be answered on that board, including stuff you didn't even know to ask about. The worlds foremost experts on 403's are on that board too. Also, be advised that Andy Miller is on that board too. (StrangeMagic)
He's kind of an A-Hole, but NOBODY knows more about building fast Oldsmobiles than he does. Not even Joe Mondello.
Good luck.
I would like to add, you can buy a complete SBC crate engine that puts out great #s for under $5k. Many sites around that sell these...check locally and Ebay also.