[footjoy]

Also I would like to now what gears I can put in my original 65 rearend with 2:56 gears.

Thanks

Greg

[unruhjonny]

ok - thank you for giving more pieces to the puzzle.

As of this latest revelation the only "230hp" part are the heads - which hopefully you have understood to be comparable to other same valve sized 1971-1974 heads.

BUT!! My Pete McArthy book doesn't list a 1971 WX engine;
I see a 1970 WX engine, but it's listed as G-body manual transmission 350.
Can you confirm that it is in fact either a '71-400, or a '70-350?

I have heard of some listi gs that are absent from the "Pontiac Bible", but were I in your shows I would go to great lengths to figure out exactly what you have.

After that please tell us what i take you are running, and what carburetor you are running...

[unruhjonny]

unless this is a soecial situation, a 2.56:1 differential is a two series rear end;
so to put lower gears in it, you will need to swap in a three series differential.

[footjoy]

Originally Posted by unruhjonny

ok - thank you for giving more pieces to the puzzle.

As of this latest revelation the only "230hp" part are the heads - which hopefully you have understood to be comparable to other same valve sized 1971-1974 heads.

BUT!! My Pete McArthy book doesn't list a 1971 WX engine;
I see a 1970 WX engine, but it's listed as G-body manual transmission 350.
Can you confirm that it is in fact either a '71-400, or a '70-350?

I have heard of some listi gs that are absent from the "Pontiac Bible", but were I in your shows I would go to great lengths to figure out exactly what you have.

After that please tell us what i take you are running, and what carburetor you are running...

I think Pete missed this one
400 265 HP WS,WX,XX,YX

[unruhjonny]

so then you have confirmed it as a 400?

the other questions remain.

[footjoy]

To swap to a 3 series rear end is that the whole housing or the internals?

Thanks

Greg

[b-man]

Originally Posted by footjoy

To swap to a 3 series rear end is that the whole housing or the internals?

Thanks

Greg

Your 8.2" 10-bolt rear will accommodate any gear ratio you like, provided that you have the correct carrier (differential unit) for the gear set chosen.

Your current 2-series carrier fits only 2.56 and 2.78 gears.

A 3-series carrier fits 2.93, 3.08 and 3.23 gears.

Finally the 4-series carrier fits 3.36 and higher gears numerically.

[footjoy]

Originally Posted by b-man

Your 8.2" 10-bolt rear will accommodate any gear ratio you like, provided that you have the correct carrier (differential unit) for the gear set chosen.

Your current 2-series carrier fits only 2.56 and 2.78 gears.

A 3-series carrier fits 2.93, 3.08 and 3.23 gears.

Finally the 4-series carrier fits 3.36 and higher gears numerically.

Thank you

Enjoy the Holidays

[SD455DJ]

Footjoy, I have a 1970 Tempest with the factory WX 400 2-bbl motor and, granted it has an actual 8.5 to 1 compression with the small valve #11 heads, with the installation of a good 2-1/4" dual exhaust system with Walker Turbo Mufflers (20" case) or UltraFlo's, a factory cast iron 4-bbl intake and Q-jet, it became a very respectable performer even with the 2.56 peg leg rear. I love that gear for cruising on the highway...60 mph at 1900 rpm, 75 mph at 2400. Ideally, I'd like to add a Summit 2800 cam and 60 lb. oil pump, but it runs great the way it is. I don't rev it over 4500 rpm anyway (where the factory cam runs out of steam). Adding Ram Air exhaust manifolds is simply not worth the expense as mentioned previously and would only add 5-7 hp more than the 20 hp you'll get with a good dual exhaust. You will get 50 hp from the dual exhaust and 4-bbl intake/Q-jet carb alone. Good luck!

Dennis

[footjoy]

Originally Posted by SD455DJ

Footjoy, I have a 1970 Tempest with the factory WX 400 2-bbl motor and, granted it has an actual 8.5 to 1 compression with the small valve #11 heads, with the installation of a good 2-1/4" dual exhaust system with Walker Turbo Mufflers (20" case) or UltraFlo's, a factory cast iron 4-bbl intake and Q-jet, it became a very respectable performer even with the 2.56 peg leg rear. I love that gear for cruising on the highway...60 mph at 1900 rpm, 75 mph at 2400. Ideally, I'd like to add a Summit 2800 cam and 60 lb. oil pump, but it runs great the way it is. I don't rev it over 4500 rpm anyway (where the factory cam runs out of steam). Adding Ram Air exhaust manifolds is simply not worth the expense as mentioned previously and would only add 5-7 hp more than the 20 hp you'll get with a good dual exhaust. You will get 50 hp from the dual exhaust and 4-bbl intake/Q-jet carb alone. Good luck!

Dennis

I think I will put it in and see how it does the way it is. They sound almost identical.

Thanks

[SD455DJ]

Footjoy, I forgot to mention that if you don't have at least a true 8.0:1 compression, it leaves a lot of hp on the table regardless of the valve size and carburation. The '73 big valve 400 heads had big 100 cc chambers and if the pistons aren't at zero deck, you are most likely in the 7.5:1 range. 8.5 and higher will make a world of difference in performance.

Dennis

[FrankieT/A]

Originally Posted by b-man

Your 8.2" 10-bolt rear will accommodate any gear ratio you like, provided that you have the correct carrier (differential unit) for the gear set chosen.

Your current 2-series carrier fits only 2.56 and 2.78 gears.

A 3-series carrier fits 2.93, 3.08 and 3.23 gears.

Finally the 4-series carrier fits 3.36 and higher gears numerically.

There may be spacers available like the 8 1/2" rear end, No?

[footjoy]

Originally Posted by SD455DJ

Footjoy, I forgot to mention that if you don't have at least a true 8.0:1 compression, it leaves a lot of hp on the table regardless of the valve size and carburation. The '73 big valve 400 heads had big 100 cc chambers and if the pistons aren't at zero deck, you are most likely in the 7.5:1 range. 8.5 and higher will make a world of difference in performance.

Dennis

Being new to pontiac engines it seems like they have either 72cc heads or 100cc heads and not a whole lot in between. Which would be best and cheapest to get 85cc heads?
Mill the 100cc heads?
open up the chambers on the 72cc heads.

I know this sounds extreme but I wuld like 300-350 hp on pump gas.

Thanks Greg

[SD455DJ]

Greg, There are more head choices that you can choose from, such as large valve 1970 #64's with 86 cc's from 455 HO motors (d-port), but are getting harder to find and more expensive. There is good small valve heads that have the same port size as the big valve heads, i.e., '69 #46's; '70 #11's and #16's that have 86 cc chambers as well. Check out Wallace Racing's website for there head list that gives casting numbers, chamber size, valve sizes, and other features. The small valve heads are easily converted to large valve shock will match port flow of the factory large valve heads and bump the compression to the upper 8's/low 9's with their 85 cc chambers. The nice thing is these small valve heads are plentiful and cheap.

Dennis

[tom s]

my 15s with a 2.05 valve floed 260!Tom

[FrankieT/A]

Footjoy, you need a head in the 72cc range with a 75cc more on the ideal side. 62's are about 75cc's or so and would be perfect! If you want to deal with 10-10.25:1 compression then 12,13,48's to name a few.

[footjoy]

Ithink I will look for some 1971 #15 heads with 85cc

[b-man]

Originally Posted by FrankieT/A

There may be spacers available like the 8 1/2" rear end, No?

Sure, the 8.2" GM rear ends were around long before the 'corporate' 8.5" hit the scene.

[SD455DJ]

Greg, 1970 #15 heads are off of the 360hp 455 engines found in Bonnevilles (std motor). The 1970 #11 head is off the 400 2-bbl. motors commonly found in Catalinas. Put an ad in the wanted section and you should have minimal problems finding a good set.

Dennis

[SD455DJ]

Originally Posted by tom s

my 15s with a 2.05 valve floed 260!Tom

Tom, Nice numbers! What work did you do to the heads? Dennis