TAC Spotlight => Projects & Restorations => Topic started by: swims350 on December 12, 2017, 07:40:26 PM

Title: my new 79 trans am project, in wv
Post by: swims350 on December 12, 2017, 07:40:26 PM
I just traded for this a couple weeks back, been wanting one for years. My dad had a 79-81 t-top he did in candy apple red back in the 90's was blue when he got it, don't know much more on it, then his friend had a 78 hardtop t/a it was black they did it in white, first car I ever drove.

Anyways pretty solid car, got an olds403 and th350 that were in it, and got a chevy 350 and chevy th350 not sure what I'll use. The 403 was pulled from a PO to get body work and paint done, got water in it, locked it up, I free'd it and tore it down to rebuild. I got almost every part to rebuild the chevy 350 but nothing for the 403.

Car has solid floors, they had replaced one portion before, trunk looks good, had some patches done on the 1/4's and fenders before paint is ok, was done 4-5 years ago, and never put back together. I got quite a bit of new parts with it, door panels, one white, one been dyed red, I don't like. The seats were dyed red too, wanting to do em in black, I guess re dye in black, i tried to remove what was on them but it wasn't working and I didn't want to risk ruining the vinyl itself.

Anyways the worst part is my roof, it had a sunroof, somebody removed and tried to patch it but they overlapped it and used a good thick coat of bondo which cracked and came off. I can't weld or I'd just weld it up right, and I can't afford to pay for someone to do it right either.

I know my garage sucks, but it's better then out in the open and aint the first one I've built in it before.

now I need to upload pics so I can post so bare with me
Title: Re: my new 79 trans am project, in wv
Post by: swims350 on December 12, 2017, 08:31:58 PM
let me see if this works...























Title: Re: my new 79 trans am project, in wv
Post by: roadking77 on December 12, 2017, 08:41:13 PM
Welcome to TAC. Looks like a nice project. Its a shame they didn't put the roof back together right. I'm sure you will be able to do something with it. I don't think that white door panel is for a 79. You may want to verify before you paint it. You may be able to sell or trade it as is.
Title: Re: my new 79 trans am project, in wv
Post by: FormTA on December 12, 2017, 09:45:54 PM
That's definitely not a 79 door panel. Great looking project. Ya, that roof is a bummer. You just need to make friends with someone with a MIG  welder.. if you were closer I'd help ya out.
Title: Re: my new 79 trans am project, in wv
Post by: swims350 on December 13, 2017, 07:25:19 AM
I've got a flux core wire feed welder I've done some work with, it's just hard.

I first saw those panels and thought, camaro, but I see em online listed as 79 and such standard interior so I guess they are ok. I would love to trade them for some nice originals or some other repops, I like th eolder ones too with the pockets made in the bottom hard plastic piece, basically 2 piece door panels.
Title: Re: my new 79 trans am project, in wv
Post by: swims350 on December 13, 2017, 08:40:17 AM

forgot a pic of the hood, paint cracked bad and came off and let it surface rust on the majority of the panel, I got it cheap so figure why not any hood is better then none and 400 for a new repop is out of the question right now. I plan to strip it down, sand it, use one of those rust removal discs on it and then treat it with rust reformer stuff, then self etch or epoxy the whole hood.
Title: Re: my new 79 trans am project, in wv
Post by: Grand73Am on December 13, 2017, 01:07:45 PM
The white door panel is correct for a "standard" interior 79 TA. That makes sense, since your seats are also standard interior seats. The 79 TA standard interior door panels and seat covers are the same as Camaro.

The "Deluxe" interior for TA's has the fancier door panels with the carpet with pockets on the bottoms, and didn't come on Camaro. The 79 deluxe door panels are better looking than the 77 and older TA door panels to me.

I'd use the 403 Olds engine, if it were me. Need to see if you have all the pulleys and alternator and power steering brackets for it too. If the 403 was pulled from that car, hopefully those parts are still with it.

I suggest not using Rust Reformer or other similar product for "converting" rust, on that hood. They don't really work. The rust will pop back up from underneath. I've tried them many years ago. The best thing is to not paint over rust, but to remove as much of the rust as you can. Sanding and rust removal discs is a good start. Sandblasting is best for rust removal, and you could do some light sandblasting on it with an inexpensive siphon blaster. Don't use a pressure sand blaster, since it would likely warp the panel from the pressure. After cleaning off as much rust as you can, treat the metal with phosphoric acid type of metal cleaner that you can get at an auto body and paint supply store. Using the acid, you can scrub on the metal some more with a wire brush or wire cup brush on a drill, to clean more rust off. Once you rinse and dry it off thoroughly, prime it with epoxy primer, not etch primer. Prepared this way, etch primer is not needed, so don't waste your money. The epoxy will protect the metal, and you can paint over it later when you're ready. 
Title: Re: my new 79 trans am project, in wv
Post by: swims350 on December 13, 2017, 03:02:30 PM
the stuff I got some summit has acid in it might not be phosphric but it's some sort of what it says on the bottle. Anyways yea I was thinking just epoxy, used it on my s10 I finished awhile back. I also did a monte carlo trunk lid that had cracks and rust under it, I stripped it and only sanded, then used self etch primer from the body shp supply place and it never came back thru.

I'lll have to give them a call about some acid, never knew I could buy it from them.

That summit stuff is called rust transformer. I was always kind of skeptical of them actually working lol
Title: Re: my new 79 trans am project, in wv
Post by: TATurbo on December 13, 2017, 09:48:30 PM
Nice project & welcome.
 I have a write up somewhere on how to get the most out of one of those Olds 403's.  I considered building one I had in my '81 (the motor originally came out of a '79).  If  you're interested I'll see if I can't find that write up. I think I filed it away somewhere.

Good luck!
Title: Re: my new 79 trans am project, in wv
Post by: swims350 on December 14, 2017, 06:17:07 AM
Nice project & welcome.
 I have a write up somewhere on how to get the most out of one of those Olds 403's.  I considered building one I had in my '81 (the motor originally came out of a '79).  If  you're interested I'll see if I can't find that write up. I think I filed it away somewhere.

Good luck!

well heck yea I'd be interested in reading it buddy. and thanks for the comment and looking it up for me.
Title: Re: my new 79 trans am project, in wv
Post by: TATurbo on January 03, 2018, 09:43:13 PM
Hey Swims...
I found that write up I was thinking about.  It's not quite what I thought it was. It's pieces of information I pulled together a few years ago from an Olds 442 forum. Hopefully you'll find something useful or interesting here.
A disclaimer...I didn't author or vet this information. At the time I thought I could probably use this info to get the most out of the motor I had. 

Good luck whatever you chose to do!


Olds 403 Build and modification information. From http://www.442.com/oldsfaq/ofe403.htm
403 CID Engine Detail

General Information

The 403 was made from 1977 to 1979 and used across the Buick, Olds, Pontiac and Cadillac vehicle lines. It was also used in other applications like motor homes, boats and some industrial applications. It was sort of meant to replace the previous use of big block engines in the BOP line. Stock specs on a 1977-79 403 are: 185hp@3600 RPM, 320ft/lbs torque @2200 RPM, 4.351 x 3.385 bore/stroke, 8.0:1 compression ratio.

Big pistons and a short stroke are an excellent combination for a high-RPM engine, but here the other inherent 403 weakness comes into play: Windowed main webs, and to a lesser extent, siamesed cylinders. The bottom end of this block is not suitable for extended use at high rpm with very high cylinder pressure.

Sources For 403s
1977   Cutlass, Vista Cruiser, Delta 88, Custom Cruiser, 98, Toronado, Electra 225, Bonneville
1978   Delta 88, Custom Cruiser, 98, Toronado
1979   Custom Cruiser, 98

Main Bearing Webs
The main bearings are supported in/ connected to the block with webs of cast iron. Later motors, after 1976, including the 403's [most, anyhow] had not solid webs but webs with holes. Thus, there were essentially 3 fingers of cast iron holding each main bearing.

Good luck finding a Solid Main Web 403 motor. Rumor has it that some 403 blocks were made w/o holes in the webs- Solid Main Web 403's. Supposedly 403 solid main web blocks are found in the Pontiac Bonneville with the towing package, and in some 1979 Pontiac Trans Ams with a towing package.

Then again, for all but 600HP race motors, it's not necessary; the metallurgy of the 403's is quite well done.

Siamesed Cylinders
The design does have some limitations due to the siamesed cylinders and windowed webs. You must insure the cooling system is large enough and in good order. I would not recommend one for an ultimate dragstrip build up, and I would avoid doing anything that greatly raised the compression especially if the block was overbored. Head gaskets blowing would be the concern here.

The 403 responds well to a bit more camshaft and compression. I used earlier 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 true-dual exhaust really livens up the motor; the factory crossmember from a pre-'75 (year of mandatory catalytic converters) allows true duals without excessive bending, though you'll have to check with emissions laws regarding keeping or discarding your catalytic converter.

The next upgrade on my list is a change from that 2.41 rear axle ratio; while my engine improvements improved bottom-end power (it can roast the tires at will off the line), the real improvements come into play above 3500 rpm, which means my car really starts to take off at about 70mph in second gear. I plan on moving to a 3.23 rear gear, though moving to a beefed 4-spd automatic with Overdrive would allow me to move to a 3.73 rear gear. I don't make enough hp to justify a Gear Vendors overdrive ($2800!).

The 2400rpm stall converter in front of a TH-400 improves the launches of my car.

Block Boring:

An Olds 403 can only be bored out 0.040" before problems with cooling can occur. The siamesed cylinder layout (no cooling jacket between cylinders), and the minimal iron between cylinders is the cause of this limitation.

Well, after a 300+ mile journey with my often-hot running 403, a 403 should not, at least for a car that sees any kind of traffic or distance driving, be bored .060 over.

After watching my temp gauge hover at 250 for over 10 miles of uphill driving at 70MPH, (and the oil pressure fall to 15PSI at that temp, from the normal 30) I am somewhat disheartened, but not really surprised. Going up those hills, I had plenty of opportunity to "play around" by flooring it (to see if richening the mix helped at all..actually got no hotter or colder) and watching the temp, but the temp was pretty constant depending on terrain. 220 on the flats after the hill climbing was about the norm. Very rarely did it drop back down to the 195 the T-stat is rated for. Coasting at high speed (neutral) did drop the temp very quickly, so I know the radiator is working real good.

With a bored 403, or even stock 403, keep the cooling system in A-1 condition. Drain cooling system (radiator, block drain plugs, etc) at least every 3-4 years. Use a cooling system additive that promotes the thermal transfer of heat from the engine to the coolant (Water Wetter, Sy-Cool, etc). I would avoid using any form of stop leak! Use a 6 or 7 blade fan, radiator shroud, 3 row or more radiator, and keep the lower air dam in place. If you can get away with it in your climate, use a 30/70 ratio of coolant to water to enhance the performance of the cooling system additive. A thermostat rated at lower than the stock 195° unit might help as well. But the problem is really with the ability and capacity to transfer heat than overall temp. The ability and capacity to transfer heat directly affects overall temp.

Short Block:
330 forged crank for operation over 5,000 RPM.

A stock 403 Olds engine has tons of torque. Carbs aren't the problem. The problem is the heads. Their combustion chambers are too large, around 83ccs. This results in a compression ratio around 8.0 to 1. Try to find a set of 350 heads from 1973 or before. This will raise compression enough to even think about HP. Before you think about a carb I would think about an intake manifold, if your's is stock.

If you add 72 or earlier 350 cylinder heads, your compression will be abound 9.5:1-10:1. It will increase your HP considerably, though you'll probably want to add a cam that can take advantage of that high compression. If matched with an Edelbrock intake, I'm guessing around 300 hp, though that's a really rought estimate and depends on the parts that you use. Most 350 heads will boost compression, not much boost from the common #8 heads.

My calculations say that unmachined 64 cc heads such as '68 to '72 350 heads would boost the stock 403 to 9.50:1 compression. Mill the heads 0.030" and you have just over 10:1 CRatio. This assumes 0.040" head gasket, and a few other assumptions.

This is my recommendation also. Get '72 350 heads [hard xst seats], install the 403's bigger 2.000 valves or even larger W30 2.072" valves, and limit your expenses. That motor will kick ass w/ the appropriate cam, intake, exhaust. As for those who doubt the ability of the 403 to handle power with its open main webs, you might call a racer who uses one, such as:

The stock 403 heads have 4 additional coolant holes drilled for additional cooling (because of the siamesed bores), compared to 350 heads. Drill these additional holes in any 350 heads you might use for additional cooling potential and additional protection from blowing head gaskets. This advice comes from a number of experienced rebuilders and Oldsmoholics.

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 ½" head bolts. You'll have to use premium gas, and perhaps recurve the distributor.
As far as heads are concerned, my personal choice would be a set of big block heads with big valves. Given that the 403 small block obviously moves as much air as the 400 big block, why strangle it with small block heads? Adapting the big block heads to the 403 requires a couple of things:

You'll need to open up the 7/16" head bolt holes in the heads to fit the 1/2" head bolts used on the 403.
The Performer small block intake has enough meat to allow the runners to be ported to match the larger big block head intake ports. You'll either need to do this yourself or pay someone to do it.
Edelbrock aluminum heads would be great, but that's an additional $1500. Stock big block heads with 2.07/1.625 valves will be more than adequate for this motor, especially if you can do a simple cleanup on the exhaust ports to remove the A.I.R. bumps. Also, have the exhaust flanges milled or welded and milled (as required) to ensure that the divider between the center two exhaust ports goes all the way to the flange surface. You will also need to run the numbers on true compression ratio with your pistons, head gaskets, and head chamber volume. Most stock big block heads run about 80 cc in the combustion chamber, which will be a little large for your 403. Of course, milling the heads will require you to check pushrod height and possibly run a non-stock pushrod length. If you're planning to do some work to the heads (milling and exhaust port cleanup), the smog-motor J heads will be fine. These have hardened valve seats and if the exhausts are ported will flow the same as the harder to find (and priced accordingly) C heads.

When you're done, you should have a small block Olds which will run as well as the vaunted short stroke 400 motor of 66-67.

Head Gaskets
I blew another head gasket in the 403 (other side this time, so it's got all new gaskets) in the same manner as I did the other side last year; I had driven on a hot day, parked it, and revved the motor after it had sat for a little while.

It seems that the 403's need a constant flow of coolant to keep everything nice and square; when you let it sit, the nice cool (relatively speaking) radiator fluid keeps that thin bit of iron between the siamesed bores somewhat straight, but when it's shut down, the heat from the engine evens out, and the cylinder walls perhaps distort. Then, when you give it full-throttle shortly after starting the engine when it's hot, the high cylinder pressure (I've got 175psi static pressure, plus 16' initial timing) can blow out the gasket between the cylinders.

I neglected to pay attention to a rule I made for myself, to not rev the motor for at least five minutes driving time after starting it hot. I might add in a recommendation to O-ring any overbored 403's with small-chambered high-compression heads when you're doing other machine work, unless you don't mind an annual head-gasket change.

Oh, and the fact that I've got properly-torqued ARP head bolts doesn't seem to make any difference in this. Those big pistons are part of the 403's weakness; the large bores leave little room for the head gasket, which limits the amount of cylinder pressure you can develop before blowing a head gasket.

Buildup Examples

'87 Cutlass
I have a 403 in my 87 Cutlass, and it performs very well. The 403, stock, is only about 185 hp, but 320 ft-lbs of torque. This is what it has in it now:

• .030 over bore
• 72 350 heads
• Edelbrock performer RPM intake
• Crane cam (.480"/284 degrees (intake), .496"/292 degrees (exhaust) advertised (at 0 degrees))
• Crane lifters
• Crane valve springs
• Summit True roller timing chain-cast piston 9.5:1
With these not-so-expensive upgrades, my car runs mid 13's.

'79 403
• '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
Recently smoked a 96 Vette (since we fortunately didn't reach the point where he'd be in 6th gear!). 5.0's are effortless, generally, non-blown ones at least.

1979 H/O
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
Runs VERY strong at 13.1@ 105 mph 1/4 mile

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
With that combo I beat almost every Chevy on the west side of Chicago and Ford Mustangs couldn't stay there either. Believe me with a light body and the right gear, you can't lose with a 403. It came stock with 185 horses and 320 lb. of torque.


403 on $500
Well, for that price, you'll have to stick with your stock shortblock, and the stock intake, carb and ignition will have to serve. Under that budget, however, you might be able to address the two main weaknesses of the 403: the cam and the compression.

A set of 7a heads from any '72 350, with your 403's stock 2.00" intake valves, will raise the engine's compression and improve its exhaust flow. The purchase price and machine work will cost you around $400.

A decent cam like the Mondello JM18-20, the Edelbrock Performer or even the '68 Hurst/Olds cam with new lifters (and springs, if you can afford them) and a new timing chain, will make a noticeable difference as well.

In all the above things, the details (such as degreeing the cam, port-matching the heads and manifolds, etc) are the most important thing, and will maximize the gains you realize from these modifications. Needless to say, the above price estimates will not include labor, and neither of these mods are "bolt-ons", but they will be the most effective.

Consider swapping a set of earlier 64cc heads onto the engine.
Title: Re: my new 79 trans am project, in wv
Post by: swims350 on January 13, 2018, 04:24:02 PM
thanks for the read, I had actually already read that alot of good info I want to try or do alot of it mostly the heads.

I did check my crank and it is in good shape it was done before with .010 rods and mains I read it on the bearings and the measurements all came in the same number under the stock numbers of the hayes books .010 So I'm going to move forward with the 403 build for it.

I have not had much chance to work on it since it's been soo cold here in wv but I did get the roof plug cut out and the braces removed the last couple days we had decent temps. I also bought a new in box or NOS sunroof from back in the 80's or whatever by the looks of the box lol but if it works then it'd save me from trying to fix or weld on the roof.

 I really wished I could see good enough or could afford for someone to weld it in place because I'd rather it just be a hardtop and be done no sun roof, or to be t-top.

I'm also wanting to order a window sticker for it so I can find out what options it had and such as far as paint color interior color etc. since the trim tag is MIA
Title: Re: my new 79 trans am project, in wv
Post by: swims350 on January 13, 2018, 04:31:11 PM

I also stripped that hood and treated the rust then used some self etch primer over it for now until the weather gets better then I'll most likely restrip it, and self etch with spray gun primer not rattle cans like it is now, and try to fill in the pits and block it down, maybe epoxy prime it after the self etch before filler, and again after not sure yet, going to have to do the roof the same. The roof has some low spots, dents warpage etc. I may end up getting a stud gun dent puller setup to try and fix it.
Title: Re: my new 79 trans am project, in wv
Post by: swims350 on August 19, 2018, 04:22:16 PM
wow I really need to update this, sorry for not doing so sooner.

I got a hood for it, had alot of surface rust, I stripped it and used some of those rust/paint remover like rock hard sponge looking discs on my grinder on it, then I treated the rust pits and used some self etch primer on them, and did nothing else to it. I had considered using some por15 over it but they say that's not the best. They also say the self etch won't hold up, but for now it's fine, gonna be awhile, maybe I'll find or buy another hood.


I did get a t-top roof cheap and it's got rot in all 4 corners not sure if I'll use that or not.

I tore the front end off so I could clean and paint behind the fenders, the backsides and the inners etc. Doing so led to removing the subframe and found a rotted hole in the bottom of it. I had a good friend come get it and fix it for me. I just got it back a few weeks back. I need to clean and paint it. I found the DS coil spring was broke in 2 spots, one full coil on the bottom one on top of the other broke off twice lol. I bought all new moog parts to rebuild it and got the uppers and lowers, cleaned, painted new shafts and bushings in them as well as ball joints. I also bought red poly boots and need to get the bumpstops.

I also found some floor rot doing this it was covered on the top with caulk so I had to dig into that more. I found some crappy work, they had cut the crossmember when they had installed the rear floor pan between the front and rear seats, never spot welded it to the pan as well. I also found some inner 1/4 rot inside the car not terrible but saw crappy patches on it too. I mean crappy because it appears that they welded it every inch or so then stopped and slapped on bondo. They did not try to make it a continuous weld at all just spot here and there and F it slap some mud over it. So there may end up being new 1/4's for this car as I know the front lower and rear lowers have been patched both sides and I think some wheel arch and I know some wheel arch needs patching too. The trunk drop offs are shot. The rear pan and inner tail pan are shot as well.

I decided to make myself a tip over jig with wood to better work on it. I removed the rear end, found both main leafs broke in two, behind the center pins, and found the sway bar drop link bent, that frame rail had taken a hit on the pass side, and rear floor pan had been hit. I now have it flipped over and currently working on cleaning off the undercoat to find all the rust to get it fixed, cut out and replaced.

I removed all the glass myself without damage with the help of a HF windshield removal kit, the wire and handle type up front and just knives in back.

I also started doing some youtube videos on it but they suck my camera is terrible and sound screwed up, cell phone not much better but it's all I've got for now. I'll try to link those.

first video


second vid.

Title: Re: my new 79 trans am project, in wv
Post by: roadking77 on August 20, 2018, 07:37:38 AM
Glad to see you back at it. Like the video. Nice vette!
Title: Re: my new 79 trans am project, in wv
Post by: swims350 on August 20, 2018, 07:53:33 PM
thanks, my wife claims it. I actually got it last year on trade, I had built a 91 s10 with a 350 v8 and th350 with 4.10's out back did it frame off everything new and did all the paint and body work on the truck, then traded it for that vette. I tore it down to fix the power windows and locks that weren't working and turned into an interior redye to overhaul it a bit.