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Canadian Poncho Superstar!

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RE: 2 barrel question


North's test produced a 8% gain and the one I cited was at 11%.



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Ray White, Toronto ON

1973 LeMans 454 "Astro-Jet"

Built March 9, 1973 - Oshawa ON

1993 Corvette Convertible LT 1

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Good info, thanks for sharing. It will be interesting to see if my little 283 will see that kind of gain.

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North wrote:

I actually did a test about 15 years ago with a bonestock pontiac 350 2bbl (in a 71 LeMans I believe). We ran it on a chassis dyno with a factory spec single exhaust (2" head pipe, single stock muffler and 2.25" tailpipe) and it put 145 horse to the wheels. Then we installed a factory correct dual exhaust (2" front to back with stock mufflers and resonators). HP rose to 157 with no other changes made. Btw, flipping the factory air cleaner lid added another 4 horses

I would imagine a 4bbl engine would benefit more than a 2 bbl since peak hp was at higher rpm where increased flow capacity of duals would be more beneficial. Most GM 4 bbl engines in the early 70's were rated as gaining 25 horse net with duals and most 2 bbl's gained 15 net horses. Mine only gaining 12 makes sense since I was measuring hp at the wheel.

Don't forget that net horsepower is still measured at the flywheel.

SAE Gross horsepower (SAE J1995)... stock engine without exhaust pipes, alternator, emission pumps, water pump, air cleaner etc. Some car companies used open headers during test, others used stock manifolds. Power was measured at flywheel

SAE Net Horsepower (SAE J1349)... stock engine with Air cleaner, exhaust system, water pump, alternator, emission pumps. However it does not consider things like power steering pumps or other optional draws. Power also measured at flywheel. The drop from gross to net hp was typically about 15-20% on vintage cars with dual exhaust and 30-35% with single exhaust

Drivewheel horsepower (no specific standard) is typically measured in a car fully equipped as in the net horsepower above but measured at the wheel after transmission, driveshaft and differential losses. Typically this also means things like Power steering and AC (turned off) compressordrag is also lost. typically the drop in vintage cars from SAE net is about 10-15% for manual transmissions and 15-20% with automatics.



The 2BBL vs 4BBL comparison is relatively easy with these, GM did it for you, for a SBC design engine anyway, but the results will be similar with others. In 1969 model year the 2BBL L65 is the same engine as the 4BBL LM1 except for the carb and intake. The LM1 had its peak SAE gross hp fiddled with by GM but not in Australia:

L65: 250hp@4800rpm, 345ftlb@3200rpm.

LM1: 255hp@4800rpm, 365ftlb@3200rpm (GM North American rating).

LM1: 275hp@4800rpm, 365ftlb@3200rpm (GMH Australia rating).

As a comparison both GM and GMH rated the 1968 L48 the same as for most SBC design engines used here: 300hp@4800rpm, 380ftlb@3200rpm

I think it is pretty fair given that most of GMH's SBC engine rating matched the North American rating except for the LM1, that 275hp is probably the true LM1 SAE gross figure. The Australian LM1 was a Tonawanda engine, identical to the US version but with a different bend on one exhaust manifold and a slightly different distributor curve (as most of GMH's engines did) as the fuel here was of slightly different characteristics. They were 388 blocks, 441 heads and 184 intake with a standard Quadrajet.



-- Edited by HK1837 on Saturday 14th of December 2019 05:15:58 PM

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Poncho Master!

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So I thought my problems were over but since I had the car back, it started flooding out at idle.

Not that often but always in a bad spot like a traffic light.

Last night when I was making room in the shop, I had it running with the hood up.

Gas was seeping out of the butterfly pivot holes on both sides of the carb.

Carl's supper nice gestor grommets came today so I decided to tackle the flood problem first.

Off to YouTube,

Not my carb but well explained !

This being a remanufactured carb with less than 200 miles on it, it was hopefully that simple.

I kept my original carb so I pulled it apart first to see what the guy was talking about

(we're not dealing with an expert here! But I used to rebuild snowmobile carbs)

Once I saw the guts and understood what the guy was talking about I pulled off the new one and tore it apart slowly

013aa.jpg

And there it was !

004aa.jpg

Looks like a piece of gas line. I use a in-line filter so the small piece must have came out of the line between the filter and the carb.

Took the (brass ?) part out and blew everything clear.

011aa.jpg

My other carb had a recent rebuild so with the things that this guy said in mind, I decided to use the needle and float from that carb just in case.

But I do think, it my sloppy hose attachment.

Here is the grommet I received today from Carl !

014aa.jpg

It's those little things in life biggrin

I owe you !

Now it wouldn't be my project if something didn't go wrong.

The little tension clip popped as I was re-installing it and quickly became the fabric of my shop.

015a.jpg

Not to be defeated, I took the centre out of a Ford window clip and was back in business 

Got her back together and do you know what ?

It starts, no leaking yet.

Road test tomorrow before it rains.

Darn road tests wink

 



-- Edited by ABC123 on Thursday 21st of May 2020 09:23:18 PM

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Randy(Muttwood)



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ABC123 wrote:
Not to be defeated, I took the centre out of a Ford window clip and was back in business 

 Good for you!thumbsup.gifthumbsup.gif

... but now you have a F**D part on a Pontiac!biggrin



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Prince Edward Island

'64 Parisienne CS "barn find" - last on the road in '86 ... Owner Protection Plan booklet, original paint, original near-mint aqua interior, original aqua GM floor mats, original 283, factory posi, and original rust.



Canadian Poncho Superstar!

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Good catch Randy! One little piece of debris. It probably came out of the in-line filter.



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67' Grande Parisienne. Ex Ottawa USSR Embassy car, 67- 68.
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A Poncho Legend!

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Is that Ford part touching the grommet and bushing I sent you?

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1966 Strato Chief 2 door, 427 4 speed, 44,000 original miles "FAKE_66"



Poncho Master!

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The Ford part is just temporary.

I'm sure that tough OEM GM part can deal with a little contamination wink

And thanks again for that grommet winner.gif



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Randy(Muttwood)



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Haha, no worries, I'm glad it worked!

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1966 Strato Chief 2 door, 427 4 speed, 44,000 original miles "FAKE_66"



Canadian Poncho Superstar!

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ABC123 wrote:

The Ford part is just temporary.

I'm sure that tough OEM GM part can deal with a little contamination wink


 Good, just wipe it down with Lysol!biggrin



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Prince Edward Island

'64 Parisienne CS "barn find" - last on the road in '86 ... Owner Protection Plan booklet, original paint, original near-mint aqua interior, original aqua GM floor mats, original 283, factory posi, and original rust.



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Pontiacanada wrote:

 


 Good, just wipe it down with Lysol!biggrin


 Us real men,

Use Spray-9  whisper.gif

Never was a shortage because women, like my wife, hate the smell.

Spay-9 was invented in Canada !

 



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Randy(Muttwood)

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