Think I caught the "car bug" - Impala Tech
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post #1 of 9 (permalink) Old 07-04-2017, 11:22 PM Thread Starter
 
 
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Think I caught the "car bug"

Well, I just purchased my 2nd car 5 months. This is addicting......
Bought a 1973 Impala Custom Coupe, which is the 1st car I owned back in 1982. Going to do a few modifications to this car and leave my 1966 SS "mostly" stock. What really attracted me to this car is that it has a factory 454 which is unusual for the Impalas. Typically, if someone wanted the 454, they ordered it in the Caprice since it normally had all the bells & whistles on it. I'm going to have fun "waking up" that 454, which Chevy did an injustice on in 1973. What are some of the best heads/cam/carb combinations I can do with this engine? I'm probably not going to go all out with any bottom end work (although I was toying with the idea of stroking it to a 496). I think sticking with the top end will make it plenty peppy for me and still turn this thing into a torque monster. Anyone here have good results on an early to mid '70s 454?
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post #2 of 9 (permalink) Old 07-05-2017, 03:17 AM
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1973 was the last year the BBC was offered in the passenger car (it was offered up to 1974 in the 'vette).

The heads you have are the best for a 454 as you need almost a 540 cube BBC to utilize the flow rate potential of the bigger HiPerf rectangular port heads on the street.

The PASS heads you have now will support 600 horsepower if you pocket port them and install bigger 2.25" or 2.30" valves on the intake and 1.88" on the exhaust. Those heads are limited more on the exhaust side; so pick a split duration cam with more duration on the exhaust side such as found in a blown application, or a VooDoo or a Thumper cam (can't remember what Crane calls their extended exhaust duration cam).

Upgrade the springs for the larger valves to control the added weight, but only to the maximum pressure on the lifter that the cam grinder recommends as their "Premium" spring. If your guides are worn now is the time to buy lighter 11/64th inch valve stem valves and install bronze valve stem guides in the head. Top it off with a 5 angle valve job.

That will create the "best" head (in cast iron anyway) for your motor. Your cam should be a hydraulic roller for the street. I use a solid roller to obtain more RPM but Not all approve of a solid for street use. A flat tappet cam is not going to work in a big block with today's motor oil.

A cast iron head makes more power than an aluminum head does because it retains more of the heat of combustion within the cylinder that escapes through the aluminum head. Aluminum heads with raised exhaust ports to improve the BBC heads breathing will make more but few of the oval port heads have this feature. Where aluminum heads save you on race day is on the loss of 66 pounds in weight. That 33 pounds lighter is very noticeable when leaning over a fender to remove or install a big block head. At 74 pounds each a cast iron head is a little chunky.

The added quarter inch stoke of a 496 is a noticeable upgrade. You can not easily or safely go longer on the stroke with a Mark IV block because the main oil feed gallery is running along the drivers side frame rail just above the oil pan. That limits grinding for a longer stroke with an I-beam rod that uses a cap screw and retaining nut on the big end. With a H-beam rod you loose the nut and have just a cap screw for more clearance to add more stroke.

Big Dave
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post #3 of 9 (permalink) Old 07-05-2017, 02:49 PM
 
 
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Quote:
Originally Posted by Big Dave View Post
1973 was the last year the BBC was offered in the passenger car (it was offered up to 1974 in the 'vette).
Not true. The 454 was offered through 1976 in both the Corvette and in Impala/Caprice. My dad ordered a new 76 Caprice with 454 when I was 14 years old, and we used it to pull a large RV all over the country for several years. I drove it to school for several years.
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post #4 of 9 (permalink) Old 07-05-2017, 03:15 PM
 
 
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My bad - research shows that 454 was indeed available in Impala/Caprice through 1976 as I posted, but 1974 was the last year for the 454 in a Corvette as noted by Dave.
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post #5 of 9 (permalink) Old 07-05-2017, 05:47 PM Thread Starter
 
 
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Quote:
Originally Posted by MikeN View Post
My bad - research shows that 454 was indeed available in Impala/Caprice through 1976 as I posted, but 1974 was the last year for the 454 in a Corvette as noted by Dave.
I had a friend that drove a 1974 Caprice with a 454 & I had the 1973 Impala with a 350. Needless to say, he always beat me.
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post #6 of 9 (permalink) Old 07-05-2017, 05:52 PM
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Originally Posted by buccaneers37 View Post
I had a friend that drove a 1974 Caprice with a 454 & I had the 1973 Impala with a 350. Needless to say, he always beat me.
Should have come by my shop twenty five years ago. I could have built you a motor and did some suspension mods to beat him at least once. He would have gotten wise after that.

Big Dave
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post #7 of 9 (permalink) Old 07-10-2017, 08:38 AM Thread Starter
 
 
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I think I'm going to take it to a local machine shop (Eisele's) and have the bottom end and transmission done at the same time. Everything is almost 45 years old, so there in no sense in leaving a weak spot that has the potential of failing at any time.
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post #8 of 9 (permalink) Old 07-10-2017, 09:44 AM
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Didn't realize you were local, I used to use Eisele's fifty years ago, but they messed up more than once on my machine work, so I found a couple who where much more careful. Of those only one is still left in business a half century later. I had a full set of inspection tools, snap gauges, micrometers inside and out, calipers to 18 inches and a bore gauge. I checked everything and wrote down the measurements of all of the motors I built.

Of course I think both of the Eisele brothers are dead now, so I can not speak to whoever is running the place today. Just never had a cause to go back once I found a more precise machine shop.

I use A&S Motor Sports located at 7824 Causeway Blvd., Suite B, Tampa, FL 33619 located behind the VFW Lodge on US 301. Give Gil a call (if he is still alive, and has not yet retired) at (813) 677-3981. I haven't seen him in seventeen years or so, but I used to build a lot of motors relying upon his machine work, flow bench and engine dyno.


Gil from twenty years five ago before cell phone cameras.



Used to have four or five Wally trophies in his lobby and a slew of local track trophies from local short tracks and Daytona. Across the street a block over was a shop that tuned mechanical fuel injected engines and did magneto and distributor work.

Big Dave
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post #9 of 9 (permalink) Old 07-13-2017, 05:57 PM Thread Starter
 
 
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My business is just east of Ybor & I live in south Brandon.
I think they have talked me into only going .030 over in case I ever have a future problem, so I can still rebuild that block. I'm not building a racing motor, just something to move that 4,400# beast down the road & sound "throaty".
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