1978 454 compression test|454 compression test : agency got a few things going on with the motor so I thought I'd run a quickie compression . webNewsletters. Beyond Blue. The Bush Telegraph. Your quarterly news from The Homestead Hub. FEB 2021. MAY 2021. NOV 2021. FEB 2022. OCT 2022.
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Opinions on a compression test. Mystery 454 unknown internals, been sitting for years in the shed. Compression test with a push in type tester 100-110 psi. No carb or intake .got a few things going on with the motor so I thought I'd run a quickie compression .
Compression Numbers for 454s
got a few things going on with the motor so I thought I'd run a quickie compression test on all 8 cylinders. Here's what I got. #1 180 psi. #3 180 psi. #5 180 psi. #7 . The stock compression for a 454 with 781 heads and flattops is around 7.75:1 cr. Then the bigger cam with the later intake valve closing point will reduce cylinder pressure even . The most accurate way to do a compression test is with the engine at operating temp, throttle held open and a fully charged battery. Don't forget about having a good battery & . got a few things going on with the motor so I thought I'd run a quickie compression test on all 8 cylinders. Here's what I got. #1 180 psi. #3 180 psi. #5 180 psi. #7 .
For the test to be relevant you must pump the exact same numer of revolutions for each cylinder. A cylinder that gets 180 with 4 puffs and one that gets 170 with 10 is not within .
When a manifold leaks coolant, it can be an external leak, or an internal leak, in which case you need to flush any water out and fog the cylinders to prevent rust, then run a . The spec for 454 compression is lower than for small block 6 and cylinder engines. Around 130-140 for a healthy 454 would be very good. Small blocks spec around 170 . I just did a calculation based on the info I gave you and the CR came out to 7.548. I used the KB Pistons calculator. That was a -10 cc dish. With a flat top it was 8.04, but most of . I have a 454 with flat top pistons. The machinist told me this combination is only going to produce 8 to 1 compression ratio and the engine won't make much power. Is this .
Pick a cam in the 224 to 230 duration at .050 range and have fun burning the tires off. Although, Mr. 4speed has a buddy with a 8 to 1 454 that has the 238/248 summit cam in it and it runs real strong as well. Do a search on TC for 454 and find a combo similar to yours that you like. If you copy it pretty close, you most likely won't be . Chevy produced the 1978 454 blocks with both two- and four-bolt main caps. Displacement occurred via a 4-inch crankshaft stroke and a 4.25-inch-diameter cylinder bore. . mid to late 1970s saw some of the lowest-rated engines in history due to tightening emissions requirements and lower compression ratios. The 454 engine produced about 230 .
Our stock 11-1 L78 runs fine on Ultra 94 and ok on 91. You certainly don't run 38-40 degrees any more on any pump gas. Also, these factory stock engines are often as much as a full point and even more below what is . I performed a compression test, cold engine throttle closed all plugs out and the numbers seem low, all cylinders are at 120 except for number 7 is 105. . 71 camaro. (owned since 1978!) 454-th400 3.07 12 bolt 66 chevelle 350 4 . I didnt realize that Im supposed to test the rings using regular motor oil when doing a compression, I used WD40 instead, Cyl 4 jumped to 110 and 3 went to 110 also, none of the other changed when using WD40. I will have to re-check with an oil squirter. Its a '90 stock 454bbc by Hardin Marine 4-bolt.
The 1979 Chevrolet 454 V8 had a four-barrel carburetor, a compression ratio of 7.6-to-1, and a bore and stroke of 4.25 by 4 inches. Click to expand. My `79 GMC C2500 454 wooden longbed with manual SM465 has plenty of torque too. feels like I could dump the clutch in 4th and it would go through a mobile home with no throttle. At the Dyno. Smog-era big-blocks get a bad rap. Their sub-8.0:1 compression ratios, tiny cylinder head ports, and anemic camshaft grinds are the main culprits.But what would our 31-year-old engine . The 1978 Chevy 454 engine was a powerful V8 engine with a displacement of 454 cubic inches (7.4 liters). It had a compression ratio of 8.2:1 and produced 230 horsepower and 360 lb-ft of torque. The engine was equipped with a 4-barrel carburetor and an electronic ignition system, ensuring efficient fuel delivery and reliable ignition. Cam selection plays a key role on what static compression ratio will run on "pump gas". Dynamic compression ratio is a better indicator which takes cam timing into account. With iron heads you need to have a dynamic compression ratio of 8:1 or less and with aluminum heads you need to have a dynamic compression ratio of 8.5:1 or less.
Chevy 454 Big Block Variants. Chevrolet 454 engines never really disappeared since 1970. It’s certainly best known for its stretch in muscle cars of the early 70’s. However, it was also used in Chevy and GMC trucks from 1973-1991. In ’79, GM got rid of the 454 option in the half-ton trucks but continued using it for heavy-duty truck . A narrower LSA cam will close the intake valve sooner than a wider LSA cam. And you can see this even on a compression test. For example, my 540 BBC motor with 10.75 to 1 static compression ratio ( 7.43 to 1 dynamic compression ratio) and a 266*/272* at .050 cam, with a 108* LSA has a cold cranking compression of 175 psi. This tutorial will teach you everything you need to know to do a compression test on any engine. I cover the process from start to finish including what comp. Doing a compression test, is a good way to measure the condition of, the rings, cylinders, and valves. So, if your engine is running rough or is lacking power, consider doing a compression test. Also, it is important to perform a compression test every time a tune-up is done, as part of preventative maintenance.
The 454 that is in my friend Mark's gold 69 SS came out over the winter for a little freshening up. Car ran a best of 13.30 @98 MPH with a 1.81 60 ft. Combo is a rebuilt 454 from chain parts store, nothing special. When Mark bought the motor, it was never fired, still in the shipping crate from the parts store Typical 8 to 1 compression, 781 heads.
Cooley shows you how to do the king of all engine tests.Subscribe to Roadshow: http://bit.ly/1Z3Ff7GVisit us online at http://www.TheRoadshow.comTwitter @Roa. Tonight I did a compression test and the results varied from 97 to 122 PSI. This was a dry test and none of the cylinders seem to rapidly lose pressure or anything along those lines. . 1973 C-20, 3+3 454 4BBL TH400 Water Injection 1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs 1980 C-10 under construction. Print; Pages: [1] Go Up .
question for all the pontiac guys: I have a pontiac 400 (406) KRE 74cc alum heads, mild crower cam Pistons are not the best just TRW stock replacement with 4 valve reliefs The compression ratio is around 9.6:1 I have about 6000 miles and never had the need to check the compressions yet. I autocross a lot and I started to get blue smoke on deceleration so I . 454 rebuild, showing no compression. . hydrolic, springs are stock, rockers are stock, valves were within spec for play at the guides. The engine is a 1978 peanut port. I backed off the rockers so there was plenty of play but still opened the valve, but still no compression. . did the compression test after all else failed and wouldn't .
Abnormal compression test, Chevy 454
Im going to be working with stock 4 bolt main 454 Gen IV bottom end.. ( in vehicle) I have a set of stock 781 heads.. I'm ready to send the heads off to a machine shop for work ( if needed/recommended) for new parts to match cam and for port&polish job. . Dynamic compression ratio with this cam is 8.53:1.. Or, if you want a little more . The 454 cubic-inch LS4 would serve as one of General Motors’ final big-block powerplants for the Corvette. Read on to learn about this engine, its specs, features, and more. . 1978 MY Story & Guide; 1979 MY Story & Guide; 1980 MY Story & Guide; . Compression Ratio: 8.25:1; Displacement: 454 cubic-inches (7.4 L) Cylinder Bore: 4.251 inches . Attach the compression test adapter into the cylinder nearest the front of the engine, then connect the gauge to the other end of the adapter hose. To perform the test, crank the engine 4 times by turning the key in your car’s ignition, then check the compression gauge for the result. After you get a result for the first cylinder, repeat the .
The most accurate way to do a compression test is with the engine at operating temp, throttle held open and a fully charged battery. Don't forget about having a good battery & starter when testing compression as that can affect your readings too. . 71 camaro. (owned since 1978!) 454-th400 3.07 12 bolt 66 chevelle 350 4 speed 3.55 12 bolt and .The Performer High-Compression 454-O has been rolled 11⁄2 degrees to produce a 100-cc chamber that gives a compression ratio of 9.2:1 with 454 flat-top pistons. Performer RPM 454-R heads have rectangular 315/300-cc (long/short) intake ports and 118-cc open chambers. A revised spark plug location promotes better combustion, but they do not .
A cranking compression test is also an excellent way of determining the health of the engine in a car you're thinking about buying. Its non-intrusive nature means you won't be taking any risks. Mind you the crate engine had at least a full point less compression, which might be worth 15-20 hp tops. But same heads, and arguably a better intake manifold. It was dynoed with headers The AFR's were really good on the tune, but we didn't test if the engine wanted more fuel or less, but it was 12.5-12.6:1 and stable with the EFI. The 1979 four-bolt-main iron block (PN 361959) has GM forged high-dome TRW pistons (PN 3963551) as well as GM 6.135-inch 4340 forged-steel I-beam rods, and an externally balanced GM forged-steel . The low-compression, hydraulic-lifter 454 is still the hot set-up. Whether you choose a 4-speed transmission or an automatic, the quarter-mile times come out to about 14.7 seconds at 97 mph in .
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454 compression test low?
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1978 454 compression test|454 compression test