I need to select cam and heads for a big block going in my 76. I want a weekend driver for local cruising, but be able to run under 12 sec at the drag strip. Looking for recommendations.

Here are the engine parts I already have.

454 Block bored 0.030 over, 4-bolt main
Stock forged crank
990 rectangular port heads, stock, not ported (considering replacing)
1.7 roller rocker arms
Hooker headers with side pipes
850 Holley carb, dual feed, w/ mech secondaries
GM Dual Plane Aluminum Intake
Reed solid roller cam (don't know secs)

I need to select forged pistons for 9.5 compression ratio.

Want help selecting piston-head-cam-intake to make 550hp.

Leaning towards Rpm Air Gap Intake and hydraulic roller cam

Budget 3 to 4k.

Let me know what you think.

Thanks

Roger

 

Its the 3'4K budget parameter that makes this interesting, but depending on how resourceful you are, it could be done. The rest of your drivetrain will impact whether or not you tickle the 11 sec barrier though.

Personally I dont like rect port heads, not unless there is a supercharger or 7K rpm shifts. 049's with a big valve and a polish will make for excellent useable power where you need it.

Many books will tell you that the 049 and 781 are 114cc...my last set ccd at 120.

Hydraulic roller is definitely the hot ticket, however it is going to kill your budget. A solid cam will deliver the goods, and keep the budget in line...dont let people tell you all the nonsense about constant adjustment, its not true. I'd be looking at cams with over 600" lift.

Outside of this, your rear end gear and whether its a 4spd or auto is going to play a big role...make sure your converter can play nice with the cam of your choice.

I also prefer dual plane manifolds like the RPM, but your hood is going to be the limiting factor...dont know if the RPM fits under a stock 74-79 hood, but Im sure someone will say it doesnt.

 

the rectangular heads flow best at higher rpm..6k or above
your compression will not support the cam that would be ideal for those heads
suggest edelbrock oval ports with a solid cam with duration #'s between 220-230 at 50 off

you could go hyd roller but call a cam manufacturer for a pick, especially with that compression ratio. many are a lot different from others and the duration and lift #'s are not the same as a solid lifter item....good luck

 

Dave,

I have a th350 auto transmission with 3.36 rear end, and drag radial tires.

I also have a high rise hood that will fit RPM air gap intake.

Ill take a look at some solid lifter cams on desktop dyno. Do you recommend roller or flat tappet?

Roger

 

Go solid flat tappet...the roller setup is a budget eater (well worth the money, but not viable for your budget)

Pretty much any cam that is going to make the power that you need to get into the 11's is going to need a serious converter, and that serious converter is also going to want more gear than 3.36's.

This car is going to be largely street driven yes? Personally I would tone down the expectations of what you want the car to be able to run, for the sake if keeping the car more streetable. I would select a cam that can make big broad power, but doesnt need anything more than a 2800 stall converter....this way you get to keep those 3.36's and maintain the integrity of this car as a well mannered street driven car.

Realistically you could have a nice mid 12 sec car that will still function like a car, or you could have a car that runs high 11's, and you may not be happy with its manners.

 

Bump the compression to just over 10:1 and run a solid roller that'll let you get into the rpm range where those heads will shine.

 

Midyearvette,

I agree with your comments about the 990 heads. I'll look into the edelbrocks. I have desktop dyno and am trying a different setups.

Dave,
I made 1 pass with my old big block. I ran 12.73 with and accidentally shifted from 2nd to neutral, then went to 3rd gear. The engine dynoed at 470hp and 550ftlbs. Didn't get a chance to run it again it had a cracked block. I do have a 2800 stall.

I was thinking increasing the hp to 550hp would get into high 11's. Thought better heads for low end would give reasonable idle too. It will mostly be street driven.

Roger

 

dont even consider a cam thats not a roller the best investment you can buy.

 

L88,

Solid or hydraulic?

 

If the 3.36's are staying, then the rectangulars need to go. A nice set of Brodix oval ports would be killer. AFR makes a sweet set also..but pricier. The Edelbrock heads would do well too. In fact I just saw a guy on the Chevelle Forum looking to upgrade his 502 and was going to sell his GM aluminum oval ports which are the same essentially as the Edelbrocks. The 3.36's aren't going to allow super high revs really...so a hyd roller makes sense. I love solid flat tappets..but if you can swing the price increase the roller will be great and less trouble.

RPM or Air Gap intake will do fine and you can easily run 11's. I'd put compression in the 10'ish range. Ck out some of Isky's hyd rollers...they work well.

JIM

 

Another vote for a good oval, little more reasonable cam.
It will be so much more fun to drive.

Leav ethe square ports for the race only and resto guys.
Technology has caught up

 

Another vote for dumping the 990's. Sell them to help out your budget. A friend of mine just did so and netted $800. That's half way to a good set of AL heads. For your combo, shoot for 10:1 with around a 220* duration cam.

 

I am running Brodix ovals, Air Gap & 950 DP with a mildish hyd flat tappet cam but 489 cu in. and 3.08 rear end + 4 speed. Develops useful power from 1500 rpm & maxes out at an easy 528 hp 5800rpm & 565 ft/lbs at 3800 rpm. and gives mileage slightly better than stock L36!

 

Is there something that you don't like in how it runs now? IMO. You can make better decisions when you know what you have and know what direction you want to go.

Since you don't know you cam specs. Start there. Degree wheel, pointer, and dial indicator can give you very close to the cam specs

Why guess, when you can make informed decisions.

 

That must have been quite an ugly discovery ...how did it let you know?

As far as combos go, I wish I had taken my last one to the track, it was pretty much what you are looking for, except that I think your gear and converter wouldnt like the cam.

JE Pistons with polished 049's [and 2.19 intake valve] yielding 9.86:1. GM steel crank and truck rods, performer RPM, BG850 carb. The cam was a Comp 306s... .629 solid.

Mind you, this was coupled with 4k stall and 4.10s in a 67 Chevelle. My other area of concern for a cam like this in a corvette is that it only made about 6" of vacuum at idle.

While I dont know what this setup ran numbers wise, it was a helluva lot faster than the 396 it replaced, that used to run 12.45 @ 107. This was a deep 11 sec combo, but the car is also part of the combo. The car had no sway bar, drag shocks all around, worn out body mounts...the 396 would 60 ft at 1.72 in this car.

 

Roger,
You'll find that pistons, unless they are custom order, will be a problem on a budget build. Select your heads and cam based on dynamic compression, not static. Start with LS6 pistons as your baseline.
Mike

 

Here's a brief engine background.

I wanted a big block for my car and found one last year. The guy I bought it from said it made 550hp and was a good daily driver. He said it was pretty much an old LS6 build. Once I got it home it sat in my shop for a few months before I had it dynoed. The engine only made 470hp, not 550hp as promised. I got it home and it sat for a few more months before I got it in the car. Once I got it in the car and drove it on a few short trips (1mile or less per trip) I found water in the in oil. I replaced the intake and head gaskets, sealed the head bolts, etc. Drove it on several short trips, 1 to 2 miles per trip, no problems. Put it on my trailer, took it to the track, just before making my 1st pass, checked fluids and found water in oil again. Changed the oil at the track and made one pass. Ran a 12.73 (after accidentally shifting from second to neutral, then back to 3rd), 1.9 sec 60ft. Called the guy I bought the motor from we agreed to take the engine to a shop and have it taken apart to find the source of the water leak, turned out have a crack, below the lifter valley, in the cam tunnel. The guy I bought the engine from wouldn't refund the money, he was suspicious it took me nearly a year to find this problem, but he is supplying me with another block and forged pistons. We spoke last week to discuss the compression ratio I want. I told him between 9.5-1 and 10-1.

Since the motor is apart, I want to make changes while I have the oppurtunity. I see lots and lots of articles where people say they can easily make 550hp with 454, unfortunately, they don't usually give their engine combination, hence this thread. They also don't usually mention how it performs around town, in traffic, etc.

Gkull,
My only complaint with the existing setup is that it didn't idle well below 1000-rpm and I would like a little more horsepower for lower ET. Hate to lose at the track to kids borrowing his mother's new Camaro.

The existing cam is a Reed's Solid Roller. The end of the cam has these numbers on it:
L6552 T284-292 108-2. I haven't found the actual specs for it online.

Big Block Dave,
Yep, water in the oil ruined my day, week, and month. Chalk it up to bad decision on my part to buy an engine from someone without getting a written warranty, and didn't get any references or discrepancies.

I have a copy of desktop dyno and have tried several different cams but can't seem to find anything that seems like it would have good street manners to make above 500hp with the 990heads.

Mike,
I agree with the cost of pistions being high. Luckily the engine seller is going to replace them. I need to decide which heads I want to use to select the pistons. Good to hear from you Mike, my rear end works perfectly and looks great.



Here's what I had in mind for my combo:

454 + 0.030 Bore
9:5 to 10.0 Compression Ratio
Head Choides
Either GM 049 from Mark Jones at Vector Pro, Ported and Polished, Ready to go $1600/pair
or
Edelbrock Oval Port Heads Assembled 290CC $2000/pair
or
Brodix Race Rite Aluminum Heads 270cc $2300/pair
or
ProComp 320cc $1700/pair (these have a bad rep on some older posts but I see several recent posts where people are saying good things about them, so still undecided)

Intake - RPM Air Gap (Already have taller hood so clearance won't be a problem)

Cams - Totally undecided, looking for suggestions.

I see that Edelbrock offers a BBC top end kit (heads, intake, cam) that makes 540hp for $2700. I am going to look for reviews to see what users think about it.

Thanks,

Roger

 

Let me offer up another head option for you.
Take a look at the Trick Flow PowerOvals. http://www.summitracing.com/parts/TFS-41310001/
For $1850 a pair they are a great value.
They have published flow numbers similar to the Brodix heads, but were flowed on a smaller bore. (4.250 vs 4.50")

 

Engine Update

Desktop Dyno showed that with the parts I already have (minus pistons) my motor should make 470hp. When I dynoed it before my water leak problems it make 468. Just by upgrading the intake from a GM aluminum dual plane, to the RPM Air Gap, Desktop Dyno showed 535hp.

I decided to go back with my original combo, with the Air Gap intake. It was the best bang for the buck. Adding a decent set of heads would cost about $2k, a hydraulic roller cam with lifters would be around $800. I tried a couple dozen hydraulic roller cams in desktop dyno and couldn't find any of them that performed better, or even close to the solid roller I have.

So here's my final combo:

Probe Forged Pistons 0.030" Over
Rectangular Port 990 Heads (unported)
RPM Air Gap Intake
Reeds Cam Solid Roller Cam 251 Duration at 0.050", 0.624 Lift
1.7 Roller Rockers
Final Compression Ratio 9.8
Holley 850 Carb
MSD Street Fire Ignition
Timing 34-deg

Peak Horspower was 539 at 5800rpm
Peak Torque was 555 at 4300rpm
Engine Idles good at 900rpm

First few pulls were with my GM stock mechanical fuel pump. At 3900rpm, fuel pressure was down to 2.1psi. We switched to an electric fuel pump so fuel pressure was at constant 6.2psi.

Most pulls were without air filter. Last 2 pulls included the air filter. I lost 1.2 max hp with the air filter.

Got it home today. Hopefully I will get it installed over the holidays and be ready to run it in the next couple weeks. Can't wait to get it to the track.

Roger