[68bird400HO]

Originally Posted by bird72

Here is a question for you HO guys..... presently in my 72 F400 is an incorrect 71 455, added 4 bolt, with 96 heads, big valve D Port with 9.5 to 1 comp, RAIV cam and headers now.

I have an HO top end, heads, intake and exhaust I will build in a couple of years and use on my 4 bolt 71 bottom end. My first reaction is decam it a notch to a RAIII type pattern.... But I am not sure on that, the 455's seem to like big cams better than 400's and be streetable. So may stay RAIV...

My question: what would you HO guys expect in power change from what I have now? (say I keep RAIV cam) and go to the round port, and factory exhaust, ditch the headers..... Same carb. I wonder what effect the 1 point comp drop will have, but the added round port flow will negate and maybe add a bunch, so this will be an interesting experiment....

I would sell the roundport heads and port/polish the 96s. I think that is the easiest/least expensive way to have the compression and the flow. Then pick up some 2 1/2" RARE reproduction D-port manifolds if you want to lose the headers.

[bird72]

Thanks for replies. My goal will be: at least same power and hopefully more with HO set up, with huge benefit of running mid grade gas and not premium as I do now. It will be interesting and I need to research and put thought into cam selection.

[Super Duty D]

I will apologize first for NOT having this info on the shop reference desk.

Dose anyone have a diagram of the routing of the Vacuum lines from the thermo/Vac switch back? (4-spd car)

The 72 service manual dose not show this routing!!!!
I think this must be in the assembly manual but I can not find one in hard copy and have been looking hard for the last three weeks.

Sorry, I know it can be PITA to find, scan, resize and post this kind of stuff, but I was hoping someone here may have that handy.

The current Thermo/vac switch has like 6 or 7 ports for line hook up and an rubber adapter block that reduces the line input to 4, plus, one barbs on the switch is "open"
or, needs a cover to block it. (this must not be the correct thermo switch for my 72)
IIRC the ports on the switch are numbed 1 thru 7 from top to bottom. Not lettered.

I hope this makes sence, if not I can post some pictures.
The bottom line is, am trying to get this car properly tuned up, and this seem be an area of interest to get things working in harmony.

Thanks for any input.

SDD

[RicksGTO]

your '72 should have a thermo-vac switch with just 2 ports, one on the side that goes to the carb. and one on the top that goes to the carb port of the charcoal canister. Here's a pic of a correct switch I have for mine, it's GM part #3026085, they are discontinued but one comes up on eBay from time to time. I think they were used on several other '72 engines so you might come across one on another car, etc. Also a pic of Lloyd's a/c auto car I have saved that shows the rounting from the switch to the charcoal canister for an a/c car. Your's may or may not have the cad plated bracket to guide it if it's not and a/c car. Maybe someone else will have a pic of the diagram from an assembly manual.

[njsteve]

The vacuum switch can be found on a variety of 72 Pontiacs. In the past, I would search ebay for 1972 Pontiac intake manifolds. I found one switch by buying a 72 intake for $20. I then told the guy to keep the intake and just send me the vacuum switch. He was happy, he got to resell the intake. I was happy, I got my switch and didn't have to pay the $30 extra for shipping that ton of iron!

Anyway, here is a shot of the original switch. You will notice that the original assembly line piece has the two protective arms that shield the nipple.

[bossbirdta]

a few more pics.....

[Super Duty D]

Thanks Rick, Steve and Boss.

The two line routing on the thermo vac switch is as basic as it's gets then......
Top port to the evap can and the side port to the front of the carb.

So..... vacuum from the intake to the TCS, then to the Dist, and the RAM air actuators plug in where? I thought that came off the thermo vac switch as well???

Or dose it go the back barb on the carb?

SDD

[njsteve]

RAM air actuators? Do you mean the Thermactor valves on each snorkel? The vacuum feed line to those goes to the single nipple on the intake runner in front of the carb (red arrow)

[Super Duty D]

Yes, err, I meant, Thermactor valves?????.........You got the gist of it though..
Thanks for the picture showing the intake port barb fitting.
This is all coming together now!
Thanks for all the help!

SDD

[2manyT/A'S]

Here's one to look over.

http://cgi.ebay.com/ebaymotors/Ponti...fCarsQ5fTrucks

Could almost be considered a survivor type car.

The interior looks pretty decent.

Wonder if it has all of the important (engine/trans) original parts?

I see a replacement rad support & alternator.

Some better/clearer pics would help(underneath ones,too)

[Judge273]

Here's my 71 455 HO getting ready to be put back in the GT-37 soon. I think it is missing the rubber boot on accelerator pump? Also should it have the idle solenoid? Anything else missing?

[threefidee]

Hmmm....looking at it, looks like you may have dynoed her ?

[70RAlll]

71 HO Quadrajets DID NOT use the rubber boot. That was discontinued starting 1971 model year. So your carb is correct without it. On Firebirds, seems the manual tranny cars used teh solenoid, and auto didn't.. this is from memory, so could be wrong.. don't have time to look it up..

[bossbirdta]

just found this listing....
http://detroit.craigslist.org/cto/1261803006.html

[Guilty]

The link is not working!!!!!

[aronhk_md]

Go to craigslist....michigan....detroit. Search "trans am" Its an unrestored 72 Luc. blue 4 spd matching numbers car. Needs total resto, but might be solid. Asking price seems a bit high? What do you guys think?

[bossbirdta]

not sure why the link didn't work but aronhk_md's got it right.
car don't look to be all that bad???? of course that all depends on how much of the original stuff is still there.....

[jdeeere]

Just talked to the guy on the phone - he just found the original build sheet.

Seems to be all there, and he is including rust free quarters and door shells!!

Original fenders are in good shape. Only thing not original is the M-22, but he has one that goes with the car out of a '72 TA.

Also, this in a non-unitized car - and the original distributor is there...

This seems like a pretty good deal to me - I may fly out there this week to see it...

I'll let you guys know if it winds up going home with me!

[300 H&H]

Not to change the subject,

But just before a thunderstorm last night, got my H.O. out and ran the grears a couple of times....WOW... after over 30+ years of ownership, it still puts a really big grin on my face to let it rip out here in the corn fields of mid America! For an engine with factory manifolds it is still very much impressive, and is the is the reason we have this little thread. I think I will have to go and check out the "black stripes" I must have left on the pavement. Cliff Ruggles did on outstanding job on my quadrajet, as there is no lag or bog in it. Just mash the throttle and light the rear tires up with no hesitation.

Get those H.O.'s out and enjoy them. It is our reward for keeping them, I figure. Just my
Regards, Kirk

[x-bird2]

http://detroit.craigslist.org/cto/1261803006.html

detroit was spelled wrong in the browser after you click on the link.
weird