[Lee]

O.K., I'll try to get graphs to post later, as there are some interesting details...

But for the answers:
15.40 @ 87mph
and 178rwHP (and I believe the rwTQ was right at 265)

[grivera]

That ET is pretty good with that rear gear

['ol Pinion head]

Originally Posted by grivera

That ET is pretty good with that rear gear

Shorter tire height on 15x8's give an effective lower gear ratio vs stock 225 70 height. The extra contact patch of the slightly wider 245's should also has helped. Went through a lot of 255 60's in the early 80's till finally slowed down the problem by running 265-60 NCT's.

[Lee]

Originally Posted by grivera

That ET is pretty good with that rear gear

Agree, it surprised me! I thought it would be about 16.0. I also thought it would be 160's at the wheels.

The owner and I are planning some upgrades, but we both wanted to get a baseline to compare with. I've never seen any truly independent testing on such an original car, and thought that this might be of interest to some people.

[mgarblik]

Those are very good numbers for the car as represented. That is about what I would expect from that car with a carefully blueprinted 100% stock engine and transmission. Everything must have been right on that one when it rolled off the line. I remember having no problem with those cars on the street and track with a 66 4 door Ventura 389 2-bbl. It barely ran 16 seconds flat at the track.

[ta man]

Interesting how the chassis dyno is close the the rated net hp of the 403.

[72projectbird]

Originally Posted by b-man

Back when these cars were new I used to hunt them mercilessly.

I loved it when the girlfriend of the owner was sitting in the passenger seat. Friday and Saturday nights were the best times to find these cars running around with their owners not expecting any real competition from some old Bug.

Note the dial-in on the side window.

Orange County International Raceway 1978, I was 18 at the time.

What the later Trans Ams lacked in power, they more than made up for it in style and comfort.

If you outran me in your bug, I would've shrugged my shoulders and drove off knowing I was driving what I liked, no matter what ET it runs.

[78w72]

Originally Posted by 72projectbird

What the later Trans Ams lacked in power, they more than made up for it in style and comfort.

If you outran me in your bug, I would've shrugged my shoulders and drove off knowing I was driving what I liked, no matter what ET it runs.

dont forget handling... i used to hunt 80s & 90's era corvettes back in those days with my 78 WS6/W72 T/A, the T/A was always faster but could match or beat them on the twisty roads too!

the best part was i was a broke teenager/early 20's kid, whipping up on the rich snobby yuppy types that thought their vette (or 3rd gen camaro/firebird) was fast!

the other best part was i always had prettier girls in the passenger seat!!

[72projectbird]

Originally Posted by 78w72

dont forget handling... i used to hunt 80s & 90's era corvettes back in those days with my 78 WS6/W72 T/A, the T/A was always faster but could match or beat them on the twisty roads too!

the best part was i was a broke teenager/early 20's kid, whipping up on the rich snobby yuppy types that thought their vette (or 3rd gen camaro/firebird) was fast!

the other best part was i always had prettier girls in the passenger seat!!

I'll take the hot chick riding with me in my slow ass Trans Am over a "fast" sleeper any day.

[Lee]

Originally Posted by ta man

Interesting how the chassis dyno is close the the rated net hp of the 403.

As soon as I get the dyno files, I'll make a copy of the graphs that I can share.

Even though the "peak" rwHP was 178, the HP was in the 170-178 range for a rather wide rpm range. It did not look like a normal HP curve. My hypothesis is that the converter and/or sigle exhaust section created a HP bottleneck.

A new exhaust system is planned in the coming weeks, then we will retest.

Edit, we had a photo of the dyno graph on Kevin's phone. Lots of reflections, and the computer screen was cracked, so I ran the pic through some Photoshop filters to make the graph a bit clearer. Bad photo, I know, but it gives an idea of how flat and drawn out the HP curve is. I'll post a good pic of the graph as soon as I have it.

[MarkS57]

Originally Posted by 78w72

dont forget handling... i used to hunt 80s & 90's era corvettes back in those days with my 78 WS6/W72 T/A, the T/A was always faster but could match or beat them on the twisty roads too!

the best part was i was a broke teenager/early 20's kid, whipping up on the rich snobby yuppy types that thought their vette (or 3rd gen camaro/firebird) was fast!

the other best part was i always had prettier girls in the passenger seat!!

I wish I still had the mag but I'm thinking CD had a piece on the 79 w72 vs a 67 400 firebird. The 79 was pretty damn quick & beat the 67. However, the 67 was a 400 auto, if it was best upon best then a 67 RA 4 spd would probably have prevailed. Still the numbers put down by the 79 were impressive as I recall. In the late 70's most all the mag's were gaga over the W72's.

[ta man]

Originally Posted by Lee

As soon as I get the dyno files, I'll make a copy of the graphs that I can share.

Even though the "peak" rwHP was 178, the HP was in the 170-178 range for a rather wide rpm range. It did not look like a normal HP curve. My hypothesis is that the converter and/or sigle exhaust section created a HP bottleneck.

A new exhaust system is planned in the coming weeks, then we will retest.

Edit, we had a photo of the dyno graph on Kevin's phone. Lots of reflections, and the computer screen was cracked, so I ran the pic through some Photoshop filters to make the graph a bit clearer. Bad photo, I know, but it gives an idea of how flat and drawn out the HP curve is. I'll post a good pic of the graph as soon as I have it.

As you know quite well..its amazing how a good exhaust helps these smog era engines..exhaust ,convertor, gear change and maybe a mild cam swap and you can push into the 13's with the 400's and 403's

[Lee]

Originally Posted by ta man

As you know quite well..its amazing how a good exhaust helps these smog era engines..exhaust ,convertor, gear change and maybe a mild cam swap and you can push into the 13's with the 400's and 403's

Yes sir! Near term plans are to replace the stock manifolds with a set of Thornton manifolds (already purchased) along with a high-flow exhaust system. Our 1/4-mile track will be closed before that can happen, but there is an 1/8 track we can use. We will also go back on the dyno, and tweak the AFR as needed.

[Baron Von Zeppelin]

So the 79 403 Olds ran 15.40
and your 73 ran 15.70 ?

What's in your 73 TA ?

Both cars look really sharp !

[Lee]

Originally Posted by Baron Von Zeppelin

So the 79 403 Olds ran 15.40
and your 73 ran 15.70 ?

What's in your 73 TA ?

Both cars look really sharp !

HUH??? The '73 ran a 13.12 @ 103. Details in my signature, for that car.

Glad you like how they look, though!

[Baron Von Zeppelin]

That sounds more like it.
I saw 15.70 on your windshield ... oops

[Lee]

Originally Posted by Baron Von Zeppelin

That sounds more like it.
I saw 15.70 on your windshield ... oops

LOL!!! O.k., that makes sense. That was just the "car i.d." number for the night!

[Mr Anonymous]

If you are not intimately familiar with the 403, its 4.351 x 3,385. The mains are windowed to save weight. HOWEVER, you can swap to a 72 and earlier 350 cylinder head <#5 6 7 or 7a> and go from 8.0:1 to 9.5:1 very easily. Two things to do when you do that, enlarge the bolt holes (350 pre 77 was 7/16 and 403 uses 1/2") and also go up to a 2.00 intake valve. That head swap alone is worth a bunch. Coupled with a 222/230ish cam and its a whole different animal. If you need some #7 heads I have a pair of cores for $150. You arent spending much and its a great runner.

Mark Remmel in FL sells a 4.00 small block olds crank, ,the 403 ends up at 478"!

Even with your friend's car only having 27,,000 miles, its plastic coated cam gear is 44 years old. I'd tear the front cover off and change it regardless of any other work.

[Stan Weiss]

Originally Posted by Lee

LOL!!! O.k., that makes sense. That was just the "car i.d." number for the night!

If you can remember. What was in the other lane? 12.32 @ 130.95 MPH

Stan

[Baron Von Zeppelin]

Sand Bagger
playing cat & mouse.
Looked like he drove it to the 1/8 ,,, then stepped on it