What cam to put in this 1976 454 for increase in performance

[HeavyHauler]

I just purchased a 1976 454 with block casting number 361959. It has 781 oval port heads on it with stock size valves. It is .060 with some type of domed piston that are brand new and is close to zero deck height. The pistons do not have a part number on the top but only .060 with a arrow cast into them pointing forward.

The engine had been rebuilt and is very clean with a very good cross hatch in the bores. It came with a Edelbrock RPM intake.

The engine will be going into my 1968 Chevy C10 shortbed fleetside that was originally a 396 with 400 turbo.

What cam and carb would you guys use in order to get some more performance out of the engine? What about headers or exhaust manifolds?

[68 P.O.S.]

You're gonna get a lot of different answers on this one. To narrow it down some, what is your intended use for this engine?

[sick472]

In General...Headers are a cheap way to gain horspower, maybe even up to a 15% gain when compared to stock run-of-the-mill exhaust manifolds. Headers get the most bang for the buck when used with the proper intake and carb, but even the average header produces gains. The real question is...Do you need or really want that added power and sacrifice the lack of noise and heat benefits from mainiflods. Headers vs mani's can be argued all day long, but in the end it's your opinion that counts.

I find that 1 hp per cubic inch builds can be done without headers so long as there are high performance manifolds available. Then I port match them to maximize the flow. This keeps the heat, leaks, and noise levels down while producing a good streetable engine.

If your after the "sound"...you can't beat headers.

[Sheepdip]

Be nice if you could come up with the compression ratio of those domed pistons also. If unknown I'd stick with a mild performance cam with not a lot of valve overlap.

Quadrajet would be my choice for a carb but I don't think those Air Gaps take a spread bore so I'd go with a well tuned Holley or Quik Fuel in the 650 range, Holley platforms are not exactly known for mileage they are a performance carb so don't be disappointed at 8-9 mpg.

[jimijam00]

You want to know about increased mpg "performance", right?

[68Gold/white]

Need a part number for the pistons or the volume of the dome, then the combustion chamber volume. to calculate the comp ratio.
Have the domes been clearanced to fit the chambers? (dome edges can't get too close to chamber surface, it will block flame travel...)

Picking a cam without knowing the comp ratio is not a good thing...

Pictures of pistons might help...

[weim55]

Since the engine has already been rebuilt there’s a pretty good chance somebody already added a hotter camshaft. Simple to remove the cam plug at the rear of the engine and check for an aftermarket part number. If you have a dial indicator and a degree wheel you could also map the cam yourself and determine the specs.

Steve weim55 Colorado

[custom10nut]

Let’s say you want to just replace the Carb/Cam to improve performance.
You can contact any/all the different Cam makers, and tell them what you have, and what your desired outcome is. They’re happy to give you all the Pros and Cons, of each of the Cams they build. If they don’t want to give it to you, move on, but I don’t think you’ll find that.
Do your homework

[JMac11]

I built a similar 454, went with a Lunati Bracket Master II. 544 Lift 292 Duration. Ran a 750 Holley, engine pulled excellent vacuum and ran a 3400# car 7.00 in the 1/8 mile. Those heads have enormous combustion chambers so you might get by with regular gas. The one difference I upgraded the valve size to 2.19/1.88. I found the combo very tunable and an excellent torque producer.

[HeavyHauler]

Originally Posted by 68Gold/white

Need a part number for the pistons or the volume of the dome, then the combustion chamber volume. to calculate the comp ratio.
Have the domes been clearanced to fit the chambers? (dome edges can't get too close to chamber surface, it will block flame travel...)

Picking a cam without knowing the comp ratio is not a good thing...

Pictures of pistons might help...

1976 454 that is 4.31 bore and 4.0 stroke

It has stock 781 oval port heads that are 118cc with 2.06 / 1.72 valves

The pistons are KB Silvolite 1434-060 with compression height of 1.75 Dome Height of .140 and i think the Crown is -8cc ??

The pistons are approximately .015 down in the bore at TDC.

I pulled the flat tappet hydraulic cam and it has what looks like Z001 stamped on the back of it. I have done a search of this number and found absolutely nothing. I took a digital caliper and measured the first 4 lobes 1.602in /1.608/1.618/1.605 and the last 4 lobes 1.602in/1.609/1.614/1.602
but I am not sure what to make of those numbers in terms of lift?

I am just looking to make as much horsepower and torque with this 454 as I can without swapping out the pistons and essentially building a new shortblock. Please no nitrous or turbo comments as I just want to run all motor.

[Mike C]

What sort of performance do you want? Wide, smooth power band? ie, high torque or wide narrow, peaky power band with high HP. You can't get both. What is your planned usage for the vehicle/motor. What's the weight, gear ratio, transmission choice.

So assuming best case scenario 9:1 compression with the small dome piston and the 120cc 781 heads I would choose a cam with no more than 230 degrees on the intake.

I have a similar motor with 20 cubic inches less for my Corvette. 427 steel crank with L2300f small dome pistons and a mildly worked set of 781 heads with stock size valves. Really needs more compression, but it's what I am working with like yourself. I am running a Comp XM284HR marine hydraulic roller that is 230/236 @ .050 112 lsa which my hope makes for a good street performance in a light car with 3.70 gears and a 5 speed manual trans.

This motor ran 10 mph faster than a 330 hp Mercruiser 7.4L so I am guess-timating 440-460 hp at 5500 rpm and 500 lb/ft. at 3500 rpm.

This is not a package I would have spec'd because of the large, open chamber heads, but it was cheap because PO had damaged bearings because of mis-marked dipstick on large marine oil pan that was overfilled and aerated the oil.

[SCOTI]

Originally Posted by 68Gold/white

Need a part number for the pistons or the volume of the dome, then the combustion chamber volume. to calculate the comp ratio.
Have the domes been clearanced to fit the chambers? (dome edges can't get too close to chamber surface, it will block flame travel...)

Picking a cam without knowing the comp ratio is not a good thing...

Pictures of pistons might help...

This.... x2.

[CST10]

I have a 454 that I put a comp cam XM270HR cam in along with an eldebrock RPM manifold with a 770CFM Holley carb. Otherwise stock short block, flat top stock pistons with stock cast iron exhaust manifold. On the Dyno, once carb tuned it put out 480ft torque and 448HP. All between 1200-5000 RPMs. Torque came up fast and flat lined at 3100 RPM. Running a T350 with a 3.08 rear gear, at the tire it put down 379 torque and 345HP. Roasts the tires all day long in a truck. Very streetable and still has a little lope idle.

[Mike C]

Originally Posted by CST10

I have a 454 that I put a comp cam XM270HR cam in along with an eldebrock RPM manifold with a 770CFM Holley carb. Otherwise stock short block, flat top stock pistons with stock cast iron exhaust manifold. On the Dyno, once carb tuned it put out 480ft torque and 448HP. All between 1200-5000 RPMs. Torque came up fast and flat lined at 3100 RPM. Running a T350 with a 3.08 rear gear, at the tire it put down 379 torque and 345HP. Roasts the tires all day long in a truck. Very streetable and still has a little lope idle.

Those are some great numbers for a pretty small cam! Hope mine pulls a little higher than that but would be happy with those numbers.

What heads are on that motor?

I have an L36 from a '69 'vette that I am planning on putting in my short step. It has the 290 closed chamber heads and should be 10:1 compression with the Comp Nitrous hydraulic roller with 224/236 @ .050 and 113 LSA. Plan was 350 hp and your numbers suggest that is quite doable.

[CST10]

the cam is a 218/224 @ .050 with a 112 LSA, duration is 270. I have the factory 049 heads. They were reworked a the ports smoothed out while in the shop and roller 1.72 rockers installed. My compressor ratio static measurements was estimates at 8.3:1. The bores are .040 over, so really the engine is a 462CI. I was pleased with the out come. I didn’t expect it to reach that level of power.