96-99 7.4 performance mods

Performance modifications, tips & tricks

Moderators: flyingpolarbear, Eric@PPE, VicC, James B.

HotRodV6
Posts: 207
Joined: Fri Jan 05, 2007 11:11 pm
Location: Conroe Tx 77304

Post by HotRodV6 »

OK, well i have secured a deal on a complete, used 00 454 that was pulled with 113K miles from a 2000 Suburban 2500 to do a duramax swap. Got the engine for 600 bucks which i feel is an awesome deal, gonna go pick it up this weekend.

Ive also been thinking about ways to make this swap as easy as possible, and came across some adapter brackets that would allow me to reuse my stock 5.7 aluminum accessory drive brackets on the 454, and since the 454 brackets are cast iron, i figured it would be a great way to save some weight, plus i know all my stock accessories work great with no issues.

http://www.ebay.com/itm/Big-Block-Chevy ... 32&vxp=mtr

I can then sell off the 454 setup and recoup some of my money. Just wanted to see if anybody thinks it would be better to stick with the stock 454 setup for some reason?


Also, i was doing some more research on the wiring harness, and have read several threads that say i can reused the stock 5.7 harness and just get the 454 injector harness and splice it into the stock harness, pretty much the same way you would when doing the marine intake swap on the 5.7. I already know its not a big deal to convert the stock 60e wiring to work on the 80e, just re-pin the plug and add in the front vss sensor, and then of course i know ill have to have the PCM retuned for the 454/4L80e setup which isn't a big deal either, just money...lol

Reusing the harness seems to be the easiest way, and alot less labor, but im not sure how it will fit the bigger 454. i do plan to remove the egr wiring and the post cat O2 wiring as i wont be running either one of them, so again, just looking for some advice on which way would be the easiest way to go. Both engines have all the same sensors and plug ins, and just about in all the same places, so im really thinking this may be the most cost effective way.

James B.
Moderator
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Joined: Thu Apr 03, 1997 4:00 pm
Location: '98GMT400, '98GMT410, '99GMT420, '00GMT420

Post by James B. »

I wasn't aware there were GMT400 2500 Suburbans available in 2000. That is interesting. By 2000 the GMT800 2500 Suburbans were on the market, but smallblock only.

CrazyHoe
Posts: 6228
Joined: Tue Feb 19, 2008 8:30 am
Location: Mtl; '98 2dr4x4 Tahoe, L31,Hookers Long T, 0411,EFIlive, 4L80-E,dual 3",marine int+inj

Post by CrazyHoe »

Ask Robby, he got his 454 from a GMT400 2000 IIRC

stroker97k1500
Posts: 2702
Joined: Thu Apr 12, 2007 6:13 pm
Location: Macon Ga., 94Toyota truck with LSX stuff

Post by stroker97k1500 »

Mine was a GMT400 2000 yr model but from a 3500 dually not suburban

HotRodV6
Posts: 207
Joined: Fri Jan 05, 2007 11:11 pm
Location: Conroe Tx 77304

Post by HotRodV6 »

Well the engine i was supposed to be getting was from a 2K 3500 and pulled for a duramax swap. But i got bit by another CL flake as the guy never showed up. So i was out a tank of gas and 16 bucks for the uhual trailer rental. Plus the drive time. Talked to the guy the night before but never heard from him the day of.

But i have found another deal that works out better hopefully. Its a 96 engine removed from a 1.5 ton 4500 type truck thay was wrecked at 90K miles complete with the harness and computer for 600 bucks. The harness I'm going to dissect it and it will make it much easier to redo my stock 5.7 harness for the swap and ill be doing the 0411 swap as well.

CrazyHoe
Posts: 6228
Joined: Tue Feb 19, 2008 8:30 am
Location: Mtl; '98 2dr4x4 Tahoe, L31,Hookers Long T, 0411,EFIlive, 4L80-E,dual 3",marine int+inj

Post by CrazyHoe »

HotRodV6 wrote:Well the engine i was supposed to be getting was from a 2K 3500 and pulled for a duramax swap. But i got bit by another CL flake as the guy never showed up. So i was out a tank of gas and 16 bucks for the uhual trailer rental. Plus the drive time. Talked to the guy the night before but never heard from him the day of.
WTF !

HotRodV6
Posts: 207
Joined: Fri Jan 05, 2007 11:11 pm
Location: Conroe Tx 77304

Post by HotRodV6 »

CrazyHoe wrote:
HotRodV6 wrote:Well the engine i was supposed to be getting was from a 2K 3500 and pulled for a duramax swap. But i got bit by another CL flake as the guy never showed up. So i was out a tank of gas and 16 bucks for the uhual trailer rental. Plus the drive time. Talked to the guy the night before but never heard from him the day of.
WTF !

Exactly!! Have no clue what happen. Still haven't heard anything but at this point Ive moved on.

Chevy 97
Posts: 1076
Joined: Tue Jan 24, 2012 1:19 pm
Location: 97 ECSB K1500 6.3L 4L80E 14 bolt SF Hydro Boost, Headman Ellite Headers, 140 amp alt.

Post by Chevy 97 »

That really sucks. I hope you find another one. When my engine went out, I wished I would have been set up to put the 454 in my truck. I settled for a 383.

HotRodV6
Posts: 207
Joined: Fri Jan 05, 2007 11:11 pm
Location: Conroe Tx 77304

Post by HotRodV6 »

Chevy 97 wrote:That really sucks. I hope you find another one. When my engine went out, I wished I would have been set up to put the 454 in my truck. I settled for a 383.

Yes it really did. but i have found another one that turns out to be a much better deal on a lower mileage engine. I just wish i had seen this other one the other day when i was less than an hour drive from the guy.

HotRodV6
Posts: 207
Joined: Fri Jan 05, 2007 11:11 pm
Location: Conroe Tx 77304

Post by HotRodV6 »

Ok well even though i got screwed over on the other deal my patience has been rewarded with an outstanding deal and i have the engine/transmission on the trailer and headed home with it!!

Scored a deal on a 96' 7.4 L29 out of a chevy 1.5 ton and was originally only getting the engine with harness and computer for 600 bucks but the guy didn't want to mess with removing the trans so i got the 4L80e for free!! Its one of the ones that has the drum brake parking brake setup on the tail end of of. I think just a tail housing swap for a reg 2wd one is all you have to do right? Or is the output shaft different? I already have a 2017Know mile GM SERTA remaned trans I'm gonna use so this one is for sale if anyone is interested. Engine and transmission have 90K miles.

CrazyHoe
Posts: 6228
Joined: Tue Feb 19, 2008 8:30 am
Location: Mtl; '98 2dr4x4 Tahoe, L31,Hookers Long T, 0411,EFIlive, 4L80-E,dual 3",marine int+inj

Post by CrazyHoe »

Good news!

Chevy 97
Posts: 1076
Joined: Tue Jan 24, 2012 1:19 pm
Location: 97 ECSB K1500 6.3L 4L80E 14 bolt SF Hydro Boost, Headman Ellite Headers, 140 amp alt.

Post by Chevy 97 »

Nice.

HotRodV6
Posts: 207
Joined: Fri Jan 05, 2007 11:11 pm
Location: Conroe Tx 77304

Post by HotRodV6 »

Thanks, got it home and unloaded. Now the fun begins!!

I posted up and thread int he classifieds for the transmission, accessory drive and exhaust manifolds if case anybody is interested, i wont be using these parts for my swap.

James B.
Moderator
Posts: 2823
Joined: Thu Apr 03, 1997 4:00 pm
Location: '98GMT400, '98GMT410, '99GMT420, '00GMT420

Post by James B. »

I wouldn't dump those accessory brackets just yet. You may still need them.

HotRodV6
Posts: 207
Joined: Fri Jan 05, 2007 11:11 pm
Location: Conroe Tx 77304

Post by HotRodV6 »

James B. wrote:I wouldn't dump those accessory brackets just yet. You may still need them.
Well my plan is to run some adapters that will allow me to run my stock L31 aluminum brackets and accessory's.

http://www.ebay.com/itm/331578342631?_t ... EBIDX%3AIT

http://www.ebay.com/itm/331578343731?_t ... EBIDX%3AIT


I figured since the 7.4 brackets are cast iron, i can save a good amount of weight, and Ive already for a 43% underdrive crank pulley on my L31 and an overdrive alternator pulley plus i know all my accessories are good.

Do you think the aluminum brackets wont hold up to the big block? I thought about that too, cause why would GM have used cast iron other than making sure there would be no problems with breakage.

The other concern i had with running the adapters was how far forward they would push everything, i know the engine bay is gonna be alot fuller with the big block, but from what the company says that sell the brackets they wont stick out any further than the stock iron big block brackets do, so i don't foresee any issues there, and will be running a set of 07+ dual efans on my stock 34" radiator.

James B.
Moderator
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Joined: Thu Apr 03, 1997 4:00 pm
Location: '98GMT400, '98GMT410, '99GMT420, '00GMT420

Post by James B. »

Interesting, I see. The accessories have no additional load on them with a big block than they do with a small block, as for as holding up the aluminum ones will be fine - it even uses the same part number tensioner.
Might have a problem with the crank pulley adapter if it's not the smaller diameter bore of the later model BBC. Early BBC have a step up in the balancer to a larger bore for the pulley where the newer (1-piece seal blocks) have a balancer that retains the crank snout diameter all the way to the front.

In terms of clearance, I can tell you the water pump is where it's tight. I had Electric fans on my Tahoe with an L29 and had to change the water pump pulley studs to bolts just to gain 3/8" clearance I needed. Flex-A-Lite fans are thicker than OEM type fans, so most likely it will be fine.

HotRodV6
Posts: 207
Joined: Fri Jan 05, 2007 11:11 pm
Location: Conroe Tx 77304

Post by HotRodV6 »

James B. wrote:Interesting, I see. The accessories have no additional load on them with a big block than they do with a small block, as for as holding up the aluminum ones will be fine - it even uses the same part number tensioner.
Might have a problem with the crank pulley adapter if it's not the smaller diameter bore of the later model BBC. Early BBC have a step up in the balancer to a larger bore for the pulley where the newer (1-piece seal blocks) have a balancer that retains the crank snout diameter all the way to the front.

In terms of clearance, I can tell you the water pump is where it's tight. I had Electric fans on my Tahoe with an L29 and had to change the water pump pulley studs to bolts just to gain 3/8" clearance I needed. Flex-A-Lite fans are thicker than OEM type fans, so most likely it will be fine.

Yeah i had those same thoughts and with engine swaps its usually the water pump where you have the most issues. I was planing on running bolts already and going to be upgrading to an edelbrock water pump as well. On the crank pulley, i was originally thinking about getting a 51% underdrive pulley from ASP that is made for the BBC, but since i have the 43% one already im just gonna reuse it for now.

My L31/4L60e is going to go into my 97 S10 SS using the original V6 accessory drive, and the V6 already had underdrive pulleys that will go on the L31, along with an LT4 hot cam and 1.6 rockers.

James B.
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Post by James B. »

I tried that exact aluminum edelbrock pump you're referring to and can say without hesitation that this is a piece of shit. It flows less than half what the OEM pump does, had severe cavitation issues to the point where temps would spike coming down from anything over 3k RPM. It was light weight and pretty but functionally junk. I still have the POS somewhere, I meant to take it apart to see if it has the wrong rotation rotor installed - because it works THAT terribly.

HotRodV6
Posts: 207
Joined: Fri Jan 05, 2007 11:11 pm
Location: Conroe Tx 77304

Post by HotRodV6 »

James B. wrote:I tried that exact aluminum edelbrock pump you're referring to and can say without hesitation that this is a piece of shit. It flows less than half what the OEM pump does, had severe cavitation issues to the point where temps would spike coming down from anything over 3k RPM. It was light weight and pretty but functionally junk. I still have the POS somewhere, I meant to take it apart to see if it has the wrong rotation rotor installed - because it works THAT terribly.

Wow, i would not have expected that kind of performance from a $200 water pump. Maybe ill just stick with the OEM one and call it a day, i was trying to look at upgrades to avoid any cooling issues a head of time. I was gonna upgrade to the thicker 3/4 ton radiator but since there is nothing wrong with my stock one ill give it a shot first.

Did you ever try and contact edelbrock about the pump?

James B.
Moderator
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Post by James B. »

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.

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