Well, the intake manifold gasket virus attacked me this weekend in my '93 GMC Sierra with 87K on it. Seems like you could safely say...."if you have a GM, you WILL BE REPLACING the manifold gaskets at some time." My question, I need a little more oomph out of the engine. Was wondering if any of ya'll had replaced the original intake manifold with an Edlebrock or other performance minded aftermarket intake? They got one that is a direct replacement, and uses the same TBI. Would I notice some increase in power? Or take the plunge and get the manifold for a 4 barrel, swap all that out? Would that be a better improvement? I bet there will be a bunch of changes....i.e. fuel line, air filter, etc. etc. Has any one done this yet? Is it worth the extra bucks? Or since I'll have the intake off, should I swap out the cam? Like I said, I'd like more power, but I know I can't expect a V8 out of a V6, but closer would be nicer. Thanks.
4.3L, GM intake manifold
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The crank is the weak link in the even fire 4.3s.
If you were planning a re-build with a high volume oil pump and .0025" rod and main clearances, go for the power mods, or easier yet, stick a SBC in the truck and put the 4.3 in a Toyota 4X4.
Right now, your intake ports and small valves are one of the limiting factors.
Try "Ultra Blue" on your gaskets and bolt threads.
[ November 12, 2003, 02:51 PM: Message edited by: userfriendly ]
If you were planning a re-build with a high volume oil pump and .0025" rod and main clearances, go for the power mods, or easier yet, stick a SBC in the truck and put the 4.3 in a Toyota 4X4.
Right now, your intake ports and small valves are one of the limiting factors.
Try "Ultra Blue" on your gaskets and bolt threads.
[ November 12, 2003, 02:51 PM: Message edited by: userfriendly ]
I'd think you'd for sure get more power out of a properly tuned carb setup. However, it wouldn't be as stedfast reliable as EFI, well, maybe if you got a good edelbrock carb with electirc choke etc. I doubt you'd see that much improvement with just replacing the EFI intake manifold. Getting a new cam would make a noticeable improvement, but would probably require taking out the radiator etc. to access it and facilitate removal and replacement. Anything you do in this regard will broden the power band and lenghten it past where it currently falls off. I know my Dad's 98 4.3L is dead past 4,000 rpm and up. Good luck with what ever you decide. We've already had two 4.3L manifold gasket failures in our home
Most of the intake gasket problems with the 4.3, were only on the vortec models. Luckily, an intake swap on a TBI 4.3 is cake.
An edelbrock intake will help on the top end a little. A larger cam (compucams 2000, etc) will help, but may require a custom chip and larger throttle body and/or injectors, to be completely effective. I think that the 4.3 uses a different stock TB than the 305 and 350. If so, you can find a 305 or 350 TB from a junkyard and swap out the injectors and try that. Vortec heads will also give you more power if you are up to the swap. I would recommend a larger exhaust, for whatever route you take. UF is right, a 350 swap is better for power production and is perfectly legal as well. I don't know if the light duty 5-speed that came with the 4.3 will handle the torque of a 350, but that may not pertain to you.
[ November 12, 2003, 04:44 PM: Message edited by: sbc350gearhead ]
[ November 12, 2003, 04:44 PM: Message edited by: sbc350gearhead ]
Thanks for the info. Kind of what I was learning doing research on the net. Don't expect a lot of difference with a simple intake change. Even those power graphs from Edlebrock showed about a 10 horse difference, but that was with catbacks and cam in addition to the intakes. Think I'll just swap out the intake gaskets. Any specific kind? Like FelPro or others? I'm a little leary on going with a GM gasket after what has happened. Anybody got the torque spec's on the intakes handy?
Did you see the recent article in Hot Rod and High Perf Chev magazine (same article) on the build up of a 4.3 Chev V6? There may be some answers to your questions. They went all out to get the most HP out of the V6. They say it is much harder to build up a 4.3 V6 than a V8 like the 350. Definitely stay with the TBI fuel injection. IOW dont go with the carb.
Well, I found it. The Hot Rod issue with the article on the 4.3L V6 build up. See page 72 in the August 2002 Tech section. Did I say 'recent' issue? They got a max of 301 HP and 312 ft lbs of torque out of it. With an Edelbrock Performer intake manifold and an Edelbrock 500 cfm carb, they got 288 HP. To get the 301 HP, they went to a Demon carb. Comp cam.
I like both Fel-pro and mister gasket sets. I only use embossed intake gaskets, but for a iron intake, they are probably not necessary. Chuck the end rails and use a 1/4 inch bead of rtv. The right stuff rtv is supposed to be excellent, but it sets up in 5 minutes so you have to work quickly. I have not used it yet so I can't endorse it. Make sure you don't use too much RTV, and make sure you set the intake straight down onto the engine, and do not slide it into place.
P.S. I like to put a thin layer of RTV around the water jackets to prevent leakage. I like to give the RTV 24 hours to cure.
[ November 20, 2003, 11:45 PM: Message edited by: sbc350gearhead ]
P.S. I like to put a thin layer of RTV around the water jackets to prevent leakage. I like to give the RTV 24 hours to cure.
[ November 20, 2003, 11:45 PM: Message edited by: sbc350gearhead ]
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