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96-99 7.4 performance mods
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James B. wrote:
I never did, no. I was throwing a lot of parts at the problem trying to solve the issue before figuring out it was the pump. It was months old by that time. If you do swap in a BBC radiator you'll need a pair of the upper support brackets. Also, the BBC water pump has no provision for a heater core return like your SBC water pump does, instead the big block truck rely on a coolant return port in the passenger side radiator tank. Some of the aftermarket companies, like Murray (sold through O'Reiley's) are now putting this heater core return on even their smallbock radiators too and shipping them with a rubber cap on them. You're going to need some solution for that.
One more thing, you talked about long tube headers. I used to run Hooker Super Comps in mine. There are a few issues. First, they are so tight you have to lift the motor to get them in. Them, the drive side will need clearanced with a BFH to clear the steering shaft. Then you have the issue of the rear A/C lines on the passenger side occupying real estate wanted by a primary, they had no EGR and no O2 bungs. So, after resolving all those issues I still became so annoyed with them that I cut them out one day with a sawzall and went back to manifolds. Not that you would, but if you do decide to run the stock manifolds temporarily, the rear upper a-arm frame mount interferes. You will need to cut down the back of it by about a half inch and then heat shield it to protect the rubber bushing from being melted by the exhaust manifold radiant heat.


Yeah, ive been there before thinking you have a good part and try everything else only to still come back to the original part. Sucks, but such is life.

On the headers, i already have a set of Hedman 69450 LT's, 1 3/4 primarys with 3" collectors, and will be replacing the 3 bolt std collector flange with some flowmaster ball and socket flanges to keeps leaks and blown gaskets a non issue, and will be welding in some O2 bungs as well. I havent read about any clearance issues with them, and they are designed for the 88-95 trucks and i am delteing the EGR so not a big deal there.

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I'm guessing the edelbrock water pump you have and had issues with is this one?

http://www.summitracing.com/parts/edl-8853/overview/make/chevrolet


was doing some research into other options, and came across this Stewart Components Stage 2 pump that looks pretty good for less money. Ive always heard good things about there pumps.

http://www.summitracing.com/parts/emp-21123/overview/make/chevrolet


I also found this one that says high volume, and listed as a Heavy Duty upgrade replacement on some other websites for a decent price along with a lifetime warranty.

http://www.summitracing.com/parts/gmb-130-1700p/overview/make/chevrolet


Thoughts, comments? Thanks

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That is the Edelbrock one, yes.

I don't have personal experience with the next one. The last one is just the auto parts store equivalent. Volume is always the problem with the knockoffs. There's no way to know for sure unless you want to be a guinea pig.

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James B. wrote:
That is the Edelbrock one, yes.

I don't have personal experience with the next one. The last one is just the auto parts store equivalent. Volume is always the problem with the knockoffs. There's no way to know for sure unless you want to be a guinea pig.


Yeah thats true. Ive read alot of good stuff on the Stewart pumps, so i may give that one a shot and if it doesnt work out then ill just go with a stock pump and call it a day.

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The OEM cast iron was is so heavy, an aluminum alternative that actually works would be great. Looking forward to hearing how it goes.

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James B. wrote:
The OEM cast iron was is so heavy, an aluminum alternative that actually works would be great. Looking forward to hearing how it goes.


Yeah thst's why i was looking for an aluminum replacement and also using my L31 aluminum accessory brackets. The 454/4L80e is gonna be heavy enough as it is. If i had the cash id upgrade the heads to some nice aluminum ones too, but that will have to wait.

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Forget about the ball and socket flanges for your headers. Guys tell me they warp and leak. I never messed with em when I got my headers I cut the collector off and welded a v band flange on. No leaks, no gaskets just happiness

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Whipped383 wrote:
Forget about the ball and socket flanges for your headers. Guys tell me they warp and leak. I never messed with em when I got my headers I cut the collector off and welded a v band flange on. No leaks, no gaskets just happiness


Yeah i was thinking about that route as well, and have actually done that in the past, and your right they do work pretty well.

Decisions, Decisions...

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I have stainless works headers. The collectors on them where designed for the pipe to slide over and clamp on. Never really had any type of a flange. I just figured it'd suck a lot to have to try and get that apart to have to work on something. My left hand primary tubes actually curve under the transmission to the passenger side to connect to factory pipes.

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Whipped383 wrote:
I have stainless works headers. The collectors on them where designed for the pipe to slide over and clamp on. Never really had any type of a flange. I just figured it'd suck a lot to have to try and get that apart to have to work on something. My left hand primary tubes actually curve under the transmission to the passenger side to connect to factory pipes.


Yeah Ive seen those 8.1 headers and the pacesetters i had on my 03 Silverado 5.3 were the same way, once clamped down you weren't getting them apart, so i did the v-band clamps too and never had any leaks. I was thinking the ball and socket flange would be easier, but maybe ill just stick with the tried and true v-bands.

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Does anybody have any experience with these valve covers?

http://www.ebay.com/itm/GM-Performance-Die-Cast-Aluminum-Valve-Covers-12495488-Chevy-BBC-396-427-454-/391039855951?hash=item5b0bcaad4f&vxp=mtr


They seem like a nice upgrade over the plain stock covers, and was looking at adding these emblems to give them a factory look.

http://www.ebay.com/itm/390934300743?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

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I love those covers but the breather ports are on the wrong side for the L29.

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James B. wrote:
I love those covers but the breather ports are on the wrong side for the L29.


OK, so ill have to fab up some new hoses for the ports? Or not worth messing with?

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The driver side is just the PCV, I think there will be room for it in the front. On the other side there is a rubber elbow that connects from the port to the throttle body. You can make up something for that too.

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L21 valve covers. Run distributor less

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Whipped383 wrote:
L21 valve covers. Run distributor less


Those are not easy to find. But id love to do the L21 COP setup.

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On those brackets, I would still wait until you have your setup working before selling them. You are going into uncharted territory building adapters to run them. Not saying they won't work, just that you want to make sure your new setup works before dumping a setup guaranteed to work. You can always sell them after you get it going.

I might also add, you can use the factory iron accessory brackets to make sure the small block brackets work by using them as a template of sorts. You know they work, and fit perfectly so you can use them to help make measurements to fit the adapter for the small block brackets. If your adapter and small block brackets put the accessories the same distance in front of the block as the big block brackets do, then they should put the belt in the correct place. You may wind up having to shave some material off the small block brackets to make them work with the adapter you plan to build, and it'll be a lot easier to measure the brackets against each other on the work bench than by having to keep fitting them to the engine over and over. It'll be safer for the engine too, with you not putting bolts in and out over and over.

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My 2c

http://www.superchevy.com/how-to/engines-drivetrain/sucp-1006-454-big-block-budget-engine-build/viewall.html

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CrazyHoe wrote:
My 2c

http://www.superchevy.com/how-to/engines-drivetrain/sucp-1006-454-big-block-budget-engine-build/viewall.html


In the BBC world, that is an awesome build for the money. And mine won't be to far off i don't think. I don't have the cash for the aluminum heads right now, but i don't think the stock vortec oval port heads are that bad and ill be running the zz502 cam which is similar to the flat tsppet cam they ran and with a solid tune and the 1 3/4 headers and full 3" exhaust ill be running im hoping to see 375-400 at the wheels.

On a side note, i have sold the 80e trans i got with the engine for 400, and sold the stock serpentine belt setup for 350, so minus 200 for the adapters needed to run my stock L31 serpentine setup and im only into this engine build for 50 bucks so far! The cam and upgraded valvetrain will be about 550, then 180 for the stage 2 water pump from Stewart, and new ignition tune up parts i think im doing pretty good.

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Here's some simple mods I found for the other 454 tread:

James B. wrote:
There are plenty of choices for oval-port aluminum heads for the L29. GM Performance Parts sells aluminum 110cc heads, part number 12363390. They have dual valve springs and will support more RPM with a different cam. GM heads will take a standard length set of head bolts but you mighr try the aftermarket for heads. Edelbrock's BBC heads need four different sized head bolts because they've designed the runners differently to make them flow more like rectangular port heads.
Be sure that the cam you are buying has a stepped nose for a factory roller Mark-VI block. You need this for compatibility with the thrust plate and the single-roller timing chain that leaves room for the reluctor wheel. That brings up another point - don't bother trying to replace the timing set.
Unfortunately roller rockers do not fit underneath the factory low-profile valve covers. The placement of the throttle body over the passenger side valve cover restricts the use of taller covers. In order to install roller rockers and taller covers you'd need to fabricate some plenum spacers to go between the upper and lower manifolds. I'm going to eventually be doing this myself, but it's a ways off. Keep in mind swapping the cam that the factory rockers are not adjustable. New pushrods will be required because the new cam is likely to have a different base circle diameter than the stock one. Big block have two different length pushrods, about 1" difference between the two, and are sold in custom lengths in sets of 8 for that reason.
If the new cam can better get the exhaust out you'll find it will accept a lot more timing advance in the top end. Have you ever looked at the stock timing curve on an L29? It falls off past 2400RPM and never gets past 13 degrees at WOT. Pretty pathetic.
If you're willing to run a 180 degree thermostat and Premium Unleaded fuel, I can tell you that completely stock, it will take an additional SIX DEGREES of timing in the upper kPA with absolutely no knock retard. (That's a huge increase.)


James B. wrote:
I found some pretty interresting information on the stock L29 heads. I don't know if this is accurate but apparently the L29 heads are the only factory heads ever to actually flow better on the exhaust than the intake. This has to do with shrounding of the intake valve I guess, the exhaust valve being smaller isn't as bad.
With that rotating assembly you'll want more RPM out of it. I think the factory rev limiter is 4800RPM and OEM shift points are at about 4500. I bumped my limiter to 5100 on a totally stock longblock but you'll want to put yours up to the maximum that the PCM supports, which is 5800, if the rotating assembly is rated for it. (The 96-2000 "black-box" PCMs do not support more than 5800RPM.) Of course in order to do that you're going to have to do something about the valve springs. They are so weak you can literally press them open with your thumbs. Valves start floating on the stock heads at about 4800RPM. Personally I'd rather just spend the $2K on a pair of aluminum heads that already have the right springs and valves in them.
The fuel injector flow rate in the PCM for a L29 is 2.804 gm/sec or 22.3 lbs/hr. They will support 415HP but you'll be at almost 100% duty cycle doing it. If you can get more RPM out of it I think you'll find 415 is a very conservative number. I think you'll be looking at more like 500HP. Luckily the injectors are standard EV1-type and easy to replace after lifting off the upper plenum. (Clean the oil out while you're in there too, it tends to pool int he bottom of the intake plenum.) You can put any injectors you want to in here. I used a few different injector types on the Whippled 383 and found that the 62# Siemens ceramic disc units support shorter duty cycles than conventional pintle-type injectors. The Siemens units even idle better. 62# is kind of overkill for this but I can tell you they work so much better than pintle injectors it's worth using them. In fact, the set from my 383 will be going on the 454 before it gets boost.
Keep in mind the OEM fuel pressure regulator is a 4-BAR unit and most injectors are rated at 3-BAR.
The intake manifold gaskets are GM part #12534412. I think Fel-Pro FPP-1071 will work for the head gaskets.
This might be just nitpicking but it seems like the general concensus on multi-electrode plugs is that they don't work well in high-swirl combustion chambers. You might be better off with a set of NGK TR-55's if you have problems with misfires.
Aftermarket billet distributors for L29, L30, and L31 are available now. This is a nice upgrade over the plastic POS OEM distributor.
What do these exhaust manifolds you have look like? I have seen a set of long-tube headers add 35HP on a stock 454. It's almost hard to believe.
Edit:
I can't find if that cam you're looking at has the smaller bolt circle and stepped nose for the factory roller block and thrust plate. If it does, cool. I've found that Crower uses "LM" at the end of their part numbers to indicate factory roller block and stepped nose. Here's a slightly larger Mark-VI cam from them: http://www.crower.com/misc/cam_spec/...rt_num=01401LM


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Ok, so now you got me on my soap box Smile So sorry in advance for my rambling .... and long post.

I am a veteran of 5 big block duallies from a Q-jet, BG/Holley, TBI™™ and two Vortecs. I still have a '76 GMC with a purpose built internally balanced 454 tow motor with a comp hyd roller, ported 049 oval ports, and a custom exhaust with x-pipe, backed up with HD NV4500 5 speed. This is my "reference vehicle." Forget that it gets 7-8mpg, it will tow anything any speed. With that said, I compare the performance of my other 454's to that truck.

I had a '94 454 ... horrible ... wouldn't out pull a fat kid on a bicycle .... next subject. I then had a '96 Vortec 454, 5 speed that was a good performer with only a programmer & cat-back dual exhaust. Then I traded it in on a '99 spec'd the same way. Well, my '99 was a dog from the factory, and lost about 2 mpg straight across the board. I have been told GM started a "torque management" program in '97-'98 that reduced the power output in certain situations to protect their parts from idiots (and reduce their warranty claims). I would have to agree there is some type of this reduction programmed into our Vortecs as the performance and mileage was significantly reduced between my 96 and 99 models. From the factory, the 99 just wouldn't go. It pulled better with 3/4 throttle in 5th (OD) than if you dropped a gear and put it on the mat which is not typical of a 454.

Now on to your question. No, they aren't dogs that can't be fixed ...it's more like they were fixed (neutered) at the factory, but they can be unfixed. First, upgrade your intake to atleast a high flow filter or intake system. Make sure you get cool air, don't buy any intake that will suck in air that has come through the radiator, its a costly mistake. And save your money, a brand name MAS is a waste. Next, upgrade your ignition with a MSD 6a box (or equivalent), a good coil and some iriduim plugs. Don't run Bosch platinums in this motor, it doesn't like them. Next and very importantly, spend the bucks on a good exhaust. Headers (Gale banks makes a nice set), high flow cats and a good cat back with a tru x-pipe is what you need. Finally, you need to have your PCM reprogrammed. Forget the handheld units, go with a custom tune (somebody like Nelson) or even a dyno-tune after you do your ignition, intake and exhaust mods, and make sure they take out all the factory limiters and torque management. It's not cheap, as what I've outlined is about $2,500, but it is well worth the results. Your 454 will run like it should when you get all this done. My 99 now runs pretty good.


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I have done mods to my two vortec 454's in stages, so I've felt the incremental increases. So here goes:

1) Yes, If you only reprogram your PCM, you will notice an improvement, especially when you stick your foot all the way down.

2) Yes, the factory exhaust system is good for factory; however, it can definately be greatly improved. For exhaust manifolds, the vortec 454's do well, but compared to headers, they are costing you about 30-35hp right were you need it most in the 2500-4,000rpm range. The dual cats do flow well, don't mess with them, but the muffler is holding you back. On my '96, the first thing I did was cut off the exhaust behind the cats & dual it out. There was a noticable improvement. As for the noise level, I now have dual 3" turbos & a Dr. Gas true x-pipe with dual 3" exhaust (no big tips or "echo chambers") out the rear sides. It is not loud at all, infact, everybody give me a hard time about it sounding stock. Yes a good cat back will work well.

3) Yes the factory intake is ok, just add a K&N filter or the like.

4) The factory heads flow plenty well for the application. You'll never see the high side of 5,000rpm. The aluminum heads will definately outflow the factory ones with a big cam, but with the stock cam or close to it, the aftermarket aluminum heads won't benefit you at all.

5) I have never changed out a cam in a Vortec. With my exhaust, intake, ignition and PCM mods, my factory cam long block will buz to 5,000 rpms like a small block. And you don't need to go much past that with an external non balanced big block ... bad things can happen.

If I had a totally stock vortec 454, the mods I would do first are:
Cat back exhaust
PCM reprogram
K&N Filter
MSD ignition & coil
Iridium plugs

These are all easy mods. Later you can add the headers, they are a pain, but worth it when the budget allows.

Hope this helps.


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