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Old 08-02-2009, 09:35 AM
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LT1 Block

I have a 94 LT1 Corvett block 4 bolt main, and a 2 bolt 93 LT1 out of a Z28 what would be stronger build 2 bolt with splayed caps or the stock 4 bolt?. was thinking of building a 396 CID (4.030 bore and 3.875 Stroke) but thinking a 383 (3.75 stroke)may be a safer build as clearance may be an issue. I also looking for info about the water pump I would like to use a belt driven Water pump instead of the OEM pump due to the leaking issues the Gear driven pump on the LT1 has I know there is a electric one but was wondering if the may be a aftermarket timing set cover and water pump I can use due plan to use a coil pack instead of Optispark and if I can get a belt driven water pump it would make things easier and less problematic.

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Old 08-02-2009, 08:47 PM
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Quote:
Originally Posted by rwc112
I have a 94 LT1 Corvett block 4 bolt main, and a 2 bolt 93 LT1 out of a Z28 what would be stronger build 2 bolt with splayed caps or the stock 4 bolt?. was thinking of building a 396 CID (4.030 bore and 3.875 Stroke) but thinking a 383 (3.75 stroke)may be a safer build as clearance may be an issue. I also looking for info about the water pump I would like to use a belt driven Water pump instead of the OEM pump due to the leaking issues the Gear driven pump on the LT1 has I know there is a electric one but was wondering if the may be a aftermarket timing set cover and water pump I can use due plan to use a coil pack instead of Optispark and if I can get a belt driven water pump it would make things easier and less problematic.

The order of strength goes something like this: 2 bolt, 4-bolt, then 2-bolt block modified for splayed 4's. Unless you are going north of 500 hp, don't worry about anything more than a 2-bolt. 3.75 should not require clearancing if you use rod bolts that are designed for stroker applications. 3.875 and even 4" cranks aren't out of the question with a little careful grinding.

The water pump is not an issue at all. It is a beacon of reliability. Its the Dexcool that was the problem. A shaft driven pump puts no stress on the belt drive, and the belt yanking on the bearings is a thing of the past. I had to replace my LT1 water pump three times in the first 30,000 miles using Dexcool. After that I switched to green coolant and I'm now at 130k. That's 100k on this current pump. I have the pump off now to replace the optispark and I'm going to replace it because I have another one sitting around, but the bearings and packing around the seals looks A+. There is an electric option, but it won't help you. First of all, the electric options for LT1s (CS and Meziere) are terrible. They are billet bling that posers put on their LT1s to get that last 1/10 hp and it always ends up letting them sit at Burger King some night on the way to the cruise-in. Secondly, they don't replace the pump, they simply bolt on in place of the front plate and you remove the driveshaft from behind the pump. Its the same pump, housing, etc, just driven from a front electric motor instead of the driveshaft in the back. There is no belt-driven option. The water passages are LT1-only. There is no belt-driven water pump that you can put on that car. There is an optional heavy duty cooling setup that puts an idler pulley on a bracket in front of the water pump to drive a clutch fan, but the pump is the same.

Coil packs are a nice upgrade, but again... the Optispark is NOT an issue as long as you get a 96-97 version with the vents. Mine finally died at 130k (rotor broke). The "opti" part is an optical trigger that is incredibly accurate and very robust. The "spark" part is like any cap and rotor and can be replaced/upgraded. The bad press that the Opti gets is from (again) Dexcool. The Dexcool make the packing around the bearings fail, and the weep hole on the pump drips right on the optispark. I solved that issue by switching to green coolant, but some guys have epoxied in a little nipple in the weep hole and used some vacuum line or something to route any drips away from the Opti.
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Old 08-02-2009, 08:48 PM
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generally the 2 bolt blocks have more webbing than the 4 bolt blocks, however they are both really strong to about 600 hp. it also shouldnt b an isue it clear the 3.875 stroke crank just give yourself .060 clearance on the rod to block. Also the water flow system on the lt1 is reversed from you reg sbc the coolant goes tothe heads first rather than the block. the cam driven water pumps are very reliable just change the bushings and seals for the intermediate shaft between the cam and water pump. this style produces less drag and more hp.
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Old 08-02-2009, 11:36 PM
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LT1 block

well the 94 4 bolt has the caps and the 93 Ill need to have an engine shop fit a set of mains all the mains front back and center will cost plenty but can trade the 93 in and two rolling assemblies for a 3.875 crank and rods and what ever else I can get. thanks for the info on the coolant I would never have guessed changing the coolant would solve some of the issues I still like the idea of coil pack or coils right on the spark plug have that setup on a JAG and really liked it I plan to build a GMC or Chevy pickup street rod with the 4 bolt and use a supercharger that bolts on the front and just compresses the air this setup as a 396 CID should be around 500 to 525 HP the cam I have is only got 27k and will clear better if I send out for regrind.should use the single roller 100.00 timing set as the cam is first the type out of the Z28 block and will have a smaller circle for better clearance. the guy at the engine shop recomended to use a crank with a Big Block snout if I want to supercharge but will I get a timing set crank gear to fit?
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Old 08-03-2009, 06:20 PM
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LT1 block

also I read in a forum the replacing the water pump drive shaft with a aftermarket part helped prevent the seal from wearing a grove in the shaft where can I find one only found the stock LT1 water pump shaft at the dealer the one on the block is worn and would like to find the best replacment
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Old 08-03-2009, 07:24 PM
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One of the things to look for when your stroking that thing is your rod to cam clearance. 1-2 and 5-6 are normally extremely close even with capscrews, watch those as you may have to clearance your rods a little. Also, my 96 LT1 block needed clearanced at the pan rail when I put together my 383.......

I guess the water pump question just depends on your intentions with the car, if you plan on using it as a DD then I would just run the stock pump. I don't really understand how someone is a "poser" for running an EWP, however if your intentions are to street race(SCCA) or taking it to the strip an EWP would be a nice addition. IMHO
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Old 08-03-2009, 08:24 PM
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LT1 block

No just planing on building a 1955 Chevy short bed pickup street rod and like the coil pack for simplicity and will cost about the same as buying a new optispark setup
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Old 08-03-2009, 09:42 PM
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Originally Posted by Steel
I don't really understand how someone is a "poser" for running an EWP, however if your intentions are to street race(SCCA) or taking it to the strip an EWP would be a nice addition. IMHO
Agreed. I get so tired of street cars chasing down hp with little expensive and ineffective bolt-ons. I fully understand chasing down the last 1/2 hp for the strip, but on a street car it just adds headaches that you don't need. We've had Impala meetings where as many as three cars out of 70 show up on a flatbed because their Meziere or CS pump died on the way. A couple of those cars only see the light of day during Impala meetings, so that's not a good average

I just changed brake pads on a Honda Odessey Minivan the other day for a customer. You know what pads were on it? Hawk B9012. They are a very aggressive autocrossing-type pad.... and they wondered why their brand new parts-store rotors had been destroyed by the pads. I just get so tired of people thinking that "race" means better for everything.

The other thing about LT1s having the cam-driven water pump, there is almost nothing to be gained with an EWP. It already doesn't have the friction of the belts or the side-loading of bearings. Any gains you get by going EWP are mostly lost by the additional load on the alternator since the LT1's shaft-driven WP is highly efficient to start with. I know guys in Impalas running low 10s with the shaft driven pump because the electric doesn't really offer any advantage, but does add some headache.

Last edited by curtis73; 08-03-2009 at 09:51 PM.
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Old 08-04-2009, 03:47 AM
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LOL, that's a hard lesson to learn with the EWP, I've heard many similar stories. The only gains I can see from an EWP would be the flow rate would be higher than stock and if used with a manual fan control you have the ability to cool your car in the staging lanes without it running......I got a chuckle out of the Hawk pads, that's right up there with race stickers and noisy ricer exhaust systems. LOL, need some more power? Put a couple more stickers on your window and for a definite HP gain you just can't lose by adding an aluminum spoiler on the rear of your car, 100 horse minimum........

Last edited by Steel; 08-04-2009 at 03:55 AM.
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