hcaliber

455 engine question...

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New owner of a nice 68 Buick Riviera... 

The engine isnt original.. im trying to fiqure out what this engine came out of, and if this is a good combination...its a buick 455 block cast # is 1241735 ..narrowed the year down to a 74 via engine vin on the front under the head ...cant find any other markings

One head has an F stamped in it ...is this good? would this be the infamous"F" head? 

Intake is 1386681-1 (430 4bbl)...

And carb is Quadrajet 7028244 ka 750cfm, all the applications i can find for this carb are for a 350?

Does this stuff match up nicely or was privious owner just smashing parts together to get it out the door..? Runs nice but feels like it has more power hiding in there somwere...

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If it is a 74 block it will have lower compression and not quite a powerful as block from the 60's with the higher compression.   Emission starting to take it's toll on horsepower starting the in the early 70's.      The block my generate 250 hp.  By 1975 the 455 made 205 hp.   

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Except for the 70 model 455, they're pretty much the same. In 73 and 74, the Feds changed the way horsepower was rated and reported.  Quadrajet carbs are pretty much all rated at 750 CFM on all engines.  They're on 9n demand type carb.  A smaller engine has less demand so the carb won't flow to its rated capavity.  If you want more carb, install a Carter Thermo-quad of a Chrysler.  

 

Go to Jon Hargrove's website for his company and read all about carburetors.  www.thecarburetorshop.com

 

Then go to the website for TA Performance and pick and choose your go fast goodies. 

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Please take the following comments with the grain of salt of lack of real world experience:

Your original engine had 10.25-1 compression ratio.  The '74 has 8.5-1.  I tend to doubt more flow will improve the performance enough to justify the expense.  And I tend to doubt more available flow will be advantageous unless you change to a more aggressive camshaft.  Do you know which rear axle ratio your car has?  

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How can we assume the block he has, hasn't been rebuilt to specs other than 74 factory?  This engine has obviously been cobbled together to make it work...what else is in there we can't see?

 

There is a lot that can be done without changing cams or getting deep.  Read this thread about power timing your 455:

 

http://www.v8buick.com/index.php?threads/power-timing-your-buick-v8.63475/

 

71 and later big block quadrajets are rated at 800cfm, not 750.  They also have an idle air bleed that the small block carbs no not have.  Check out Ken at everydayperformance.com or Mark at quadrajetpower.com and they will get you the right carb setup for your Buick.

 

I would start with timing.  Then look at carburetor.  Then exhaust system.  Then you can start digging deeper.  Rear end gearing will wake up the "seat of the pants" power, but these cars have rear ends that don't have any aftermarket support.  You will need to find a rear out of another car if you want to change.  Cam, torque convertor, head porting, compression changes, etc will all be considered fairly major surgery....so start simple.

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And, to add to Adam's post above, the 1970 455 Stage 1, the top dog of performance Buick's, came stock with a 750 CFM Quadrajet.  I do not believe you need "more carb".  You need to get the proper carb for your application, tuned by one of the experts above, AFTER you get your timing sorted out.  You must also define your goals.  If you're looking to run 12 second quarter miles, you have the wrong car.  Only very few people have succeeded in making a late 60's Riv run that fast and, to a degree, they gave up a lot of street manners in the process.  There is no famous "F" head in Buick's, you're thinking of Oldsmobiles.  Buicks had the large valve heads (Stage 1's) but there is no way to identify them externally as they carry the same part number as standard heads. 

 

So, what do you want from your Buick?

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awsome input... thanks guys...i do not know what the rear end is yet...going to look into timing this week. Getting the bugs worked out. 

No plans for racing, is a weekend runner, i just want to get a feel for what is has, and why it may have been assembled the way it was. 

More power is always better so curious about best bang for buck. 

wish i knew what was done during rebuild...but no way of knowing without tearing it apart. 

It does have fancy Kenne Bell Buick tappet covers tho! 

IMG_20190521_180316.jpg

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Nice looking pup!

 

BTW, those rocker covers add 20 hp it is said....  😎

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5 hours ago, Brad Conley said:

Nice looking pup!

 

BTW, those rocker covers add 20 hp it is said....  😎

The same or perhaps just a little more than putting a fart can muffler on a Honda.

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Posted (edited)

A compression test might give some insight as to your compression ratio.

 

Assuming your compression is decent, LOTS of HP can be made using the 7028244 carb. Acquire the book on modifying Q-Jets written by Cliff Ruggles. An 800 CFM would be better, but NOT because it is 800 total CFM. The primary side of the 750 is 150, while the primary side of the 800 is 200. GM found that the transition from primary to secondary was smoother with the 200 primary.

 

Jon.

Edited by carbking (see edit history)

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In 1971 I was around 22 years old and had a '68 Riviera 430. Q-Jets were a fairly modern thing and kind of mystical. I got real excited when Holley came out with a spreadbore, something I could service at the time. A 750 double pumper was, shortly, sitting on top of my engine. Learned that one young, I would prefer a slightly under carburetted car even today. The Riviera stumbled off idle almost every time and then went like hell.

At the time a friend was working in QC at Rochester Products and I learned the Q-Jets quite well, Avoid going bigger or to something else until you ring out what you got.

Bernie

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I got some reading to do!

 

compression is 125hot -135cold... (~8.5-9.2/1??)

cheap gauge and only did one hole, engine supposedly has barely any miles on it and it looks and sounds fresh.

 

Also trying to find timing specs for my distributer 1111964...which i cant find much info on other then someone said it was for a 350

What do u guys think of that? 

 

 

 

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A Buick distributor for a 350 will also fit into any BBB with a simple gear change. My suggestion to you is still get a reputable carb rebuilder to get your carb situation in order and also get a distributor from TA performance that is already a HEI unit and properly curved and install both.  Quit chasing your tail and stop trying to figure out what the other guy did. With those two suggestions above you will have solved 99% of your issues.  

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I am actually not having any issues...it seems to run real well... but i dont have any other 455 to compare it to. I mainly just want to learn more about these old buicks! in the mean time maybe squeeze more power outa what i got without spending alot... for know...my distributer already has the mag pickup upgrade i see...going to check timing...hoping to find how much mechanical advance this 1111964 has, and maybe play with it as suggested by Mr Smartin

 

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