Simple Mods to a 454

Performance modifications, tips & tricks

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stroker97k1500
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Simple Mods to a 454

I know another guy named taprunner asked a similar question to this but he didn't get any replies.

On the 454 what is the biggest power robbing issue? The tune, camshaft, valve springs or something else? I know this engine does not seem peppy at all with the stock tune especially at 3500 and up rpms.... torque seems to fall off pretty fast pretty quick..
any input would be greatly appreciated.
Thanks
Robby

Speeder
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Post by Speeder »

Depends on the engine year. I know that on the 454SS engines the heads are pitifully small. Decent heads and a decent cam will really wake those engines up. 454s in trucks aren't really set up for speed, they are set up to tow.

stroker97k1500
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Post by stroker97k1500 »

Speeder wrote:Depends on the engine year. I know that on the 454SS engines the heads are pitifully small. Decent heads and a decent cam will really wake those engines up. 454s in trucks aren't really set up for speed, they are set up to tow.

The 454 I have is a 2000 yr model, but was hoping to keep the heads but wake it up some also

ThunderTT
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Post by ThunderTT »

a lot is in the tune. maybe James will jump in here and share a bit.

also, the springs are weak, so not much you can do there with a cam - but a cam package may help.

4 Speed Dave
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Post by 4 Speed Dave »

I have a 98 454 dually and I have the following modifications: Flowmaster cat back, Doug Thorley Full length Tri-Y headers, a Wati for Me tune that I have modified to suit my driving, gapped the AC plugs to .045 and a K&N drop in flat filter and no cats at the moment.

The PCM tune is very, very conservative as far as ignition timing goes as you will see if you do your own tuning. The camshaft is quite small on these engines and also the valve springs are not the best. So if a camshaft swap is in the works also plan on changing the valve springs.

These are set up to be tow motors not high rpm motors. I tow my enclosed trailer and race car with this truck and it works very well.

James B.
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Post by James B. »

As has been said, the valve springs, cam, and tuning all conspire to hold back the 454.
The stock tune on these engines is intentionally setup up for them to be run at wide open throttle continuously without melting pistons, plugs, manifolds, or catalytic converters.
The valve springs are so weak you can open them manually.

This is the stock L29 timing map:
Image

This is the current timing map I use with Brodix Race-Rite oval port heads and 226/235,114LSA cam:
Image

stroker97k1500
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Post by stroker97k1500 »

Are the heads on this motor really that bad? What cam and valve springs would you recommend using if I were to go with the stock heads?
Maybe I should look into those heads you have?, but might be over my budget for a little while.

James B.
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Post by James B. »

Here's a side-by-side comparison between the stock heads and the Brodix heads - everything else the same including cam and exhaust:

Image Image

All bigblocks are under-valved, that's why you'll see such huge cam profiles specified for "mild" builds.
The stock L29 heads have plenty of potential for porting to improve flow. It's a lot of work since they're cast iron. They will need valvesprings for anything over 4500RPM.

stroker97k1500
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Post by stroker97k1500 »

here is a little more info i found on these GEN VI heads..... but havent really found any "camshafts" or valve springs that are a upgrade for a stock replacement spring.
http://www.chevelles.com/forums/showthr ... 642&page=2

I was looking at a comparable upgraded camshaft like the zz4 cam is to the L31 but for the 454. anyone have any ideas?

Last edited by stroker97k1500 on Sun Jul 19, 2009 5:54 pm, edited 1 time in total.

stroker97k1500
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Post by stroker97k1500 »

thanks James... That is a pretty big difference. Where did you buy those heads and cam from?

James B.
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Post by James B. »

Summit Racing has everything. Bigblock stuff is not generally in-stock, so expect lead time. The heads I got were the CNC-machined version. Also, with big block heads you have to make sure you're getting the right valve springs. Brodix has springs for solid flat tappet, solid roller, and hydraulic roller. The hydraulic roller springs are the "weakest" of them, they are required so the lifters don't collapse.

James B.
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Post by James B. »

Hey look, "70 chevelle" is the same Lee we have here as "Blown 4x4"! That Chevelle he's talking about is the nicest shade of blue I've ever seen too...

blown4x4
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Post by blown4x4 »

That's me, I spent a ton of time on those heads. I wanted to see if they were really that bad. When it was all said and done I think they flowed OK. The cost was minimul but I think a set of aftermarket aluminum heads would be a far better deal.

I havent driven the car too much but it has far more power then expected. The old gears were 2.73 and I was able to smoke them at will up to 35MPH, never tried at faster speeds. I am in the middle of replacing the rear end that has 3.73 and is much stronger then stock so next week I'll be able to really get on it.

The engine is out of a 98 truck but I replaced the cam with a ZZ502 cam and the intake with an Edelbrock and a Holley throttle body, it had to look traditional! I used the stock wiring harness and just cleaned it up along with the 0411 computer with the express van OS. I had to really modify the heack out of the tune to make the car drivable.

James, this setup is in my firebird, the chevelle I sold a few years back. The chevelle was HOK Kandy Cobalt Blue, the Firebird is HOK Kandy Majestic Blue, far more blue the the chevelle!!

Image

Image

Image

Image

Sorry about the shameless promotion of the firebird...

blown4x4
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Post by blown4x4 »

The problem is the rockers are not adjustable, there's a kit you can buy that fixes it but when I saw it "there was no way" I was going to use it so I just bought new rocker studs and rockers.

I can get you the part numbers I used for the studs, rockers and pushrods if you like. The cam you mentioned is a little smaller then the ZZ502 I put in mine which is good because the lift will cause an issue. Mine was .527/.544 and I had to trim the guides for proper clearence. I "think" the cam you mentioned will work without clearence issues.

Lee

stroker97k1500
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Post by stroker97k1500 »

blown4x4 wrote:The problem is the rockers are not adjustable, there's a kit you can buy that fixes it but when I saw it "there was no way" I was going to use it so I just bought new rocker studs and rockers.

I can get you the part numbers I used for the studs, rockers and pushrods if you like. The cam you mentioned is a little smaller then the ZZ502 I put in mine which is good because the lift will cause an issue. Mine was .527/.544 and I had to trim the guides for proper clearence. I "think" the cam you mentioned will work without clearence issues.

Lee

Thanks Lee. I Would like to have those if you don't mind. I am new to the bbc's and have a lot to learn yet. What is the reason for changing to adjustable rockers?

James B.
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Post by James B. »

It would be possible to use the non-adjustable rockers with a bigger cam. Both sizes of pushrods would have to be perfect, just like with roller rockers. Custom lengths for stock rockers, probably. The stock L29 hydraulic lifters can take up a lot of lash. Stock L29 rockers are just stamped steel and non-roller. With stiffer springs better rockers would be favorable.
I've found that the stainless roller rockers fit under the stock covers with modification to make room for the polylocks. It turns out the locks are the highest points with the cam I've got. Maybe one with more lift would cause clearance problems between the rocker covers and lifter bodies.

blown4x4
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Post by blown4x4 »

These are the parts I used, they worked for me but you should check everything out first:

cca-1411-16 rocker arms
arp-135-3601 head bolts
cca-924-16 valve springs
cca-7815-16 push rods
cca-4779-8 need two sets, spring spacers, replaces the rotator cups
cca-4501-16 rocker studs

I didn't replace the lifters. You have no choice but to run the umbrella valve seals, the guides would need to be cut for the positive seals and would require removing the heads.

stroker97k1500
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Post by stroker97k1500 »

I hope this doesn't come across a stupid ?, but what is the biggest lift and duration camshaft that I cam put in this stock Gen 6 motor without having to take off and modifying the heads. I would like to replace the valve springs, valve cover gaket, timing chain, and camshaft..... and pushrods if necessary. Where can I find this information out at? I have been doing a huge amount of reading on this motor, but haven't found any DEFINITE answers of whats the largest "stock" replacement.
Any one have any ideas?

blown4x4
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Post by blown4x4 »

Well, with the cam I used, 527/.544 I had to grind down the guides .040 to get proper clearence. So the cam you picked would most likely be OK.