BradNaylor Posted March 16, 2012 Report Share Posted March 16, 2012 I have an 89 chevy with the tbi system. the engine is seized up, so I acquired a 93 corvette lt1 tpi shortblock today and plan to put it in the truck. the corvette block is a roller cam block with a mechanical cam driven water pump which i'd like to remove. Anyone familiar with these blocks knows that the water pump from this engine is way different in design to where it mounts on the block then the conventional sbc water pump. in the timing cover is a hole where the lt1 "optispark" distributor used to go. does anyone know of a belt driven water pump i can find to put on here, or of a "plug" i can insert where the old distributor went in this lt1 timing cover to switch to this style water pump setup? Basically I'm wondering if anyone on here has ever done what I'm trying to do? it seems like trying to fit an egg shaped peg into a round hole. Link to comment Share on other sites More sharing options...
Bobby Posted March 16, 2012 Report Share Posted March 16, 2012 Just to get you started - Have you Googled "LT1 Water pump Conversion"? I saw several posts that might be helpful. One mentioned a timing cover from a 4.3, another mentioned reverse water flow through the different engines, another mentioned issues with mechanical vs electrical fans. That was just a quick look, not trying to actually think through the issues, nor see if anyone had a perfect solution.... Link to comment Share on other sites More sharing options...
jwmbishop Posted March 16, 2012 Report Share Posted March 16, 2012 GMPP 12367600 LT1/LT4 Front Cover Plug • Covers hole on front cover of engine when original distributor is removed and replaced with rear mounted distributor. Link to a good write up of just the kind of conversion you are dealing with. Not sure there is a simple solution on the WP - may have to stay with the lt style and just move the dist. As you are using an LT short block make sure the heads are correct - I don't think the 89 Gen III will work! Link to comment Share on other sites More sharing options...
JamesHigdon Posted March 16, 2012 Report Share Posted March 16, 2012 The '89 head isn't a GenIII to my understanding, its a late GenI. The generations are GenI is everything up to the LT-1, the LT-1/4 are the GenII and the GenIII is all LS and on motors (the LT-5 shares not much with anything else and isn't a "Gen" of the motor). The TBI head (a GenI style head as is the Vortec truck head from '96-'99) will bolt to all GenI blocks and while it will bolt to GenII blocks the coolant passages/intake manifold coolant flow won't work together. A GenII motor has a much different coolant flow path then a GenI motor (much more like the GenIII then the GenI it shares engine block dimensions and architecture with). You're GenI TBI intake and heads MAY bolt up to the LT-1 block but the coolant system will not work the same IIRC. You have three choices with you're current parts. A mix-up of LT-1 and first gen components as possible (to include LT-1 block, heads, and water pump with a modified TBI intake) using the TBI electronics which will require a different radiator (to match the LT-1's reverse coolant flow) amoung other things and some electrical work; a full TBI to LT-1 conversion which a few companies offer kits for or rebuilding your old TBI engine. Keep in mind the LT-1 camshaft doesn't have provisions for a camshaft driven distributor so you will have to buy an aftermarket camshaft with a gear. If it was MY truck and I didn't want to re-use the old TBI block and heads I would use an L31 Vortec shortblock ('96-99 Chevys/GMCs as well as some other year Vans and such) which SHOULD take the TBI intake and distributor as we have used Patriot's Vortec heads on TBI motors with success in the past. L31 short blocks can be had for $300 or so. You could also convert the entire truck over to L31 style injection and electronics which are head and shoulders above the TBI setup, you can actually go as far as fitting the entire wiring harness and dash from the later Vortec trucks into the TBI trucks! Link to comment Share on other sites More sharing options...
BradNaylor Posted March 16, 2012 Author Report Share Posted March 16, 2012 Looks like I'll just sell this tpi shortblock. my old tbi block is cracked, so i'm screwed on that. know anyone interested in the shortblock? its got low miles only like 30K.. pretty sweet looking setup Link to comment Share on other sites More sharing options...
BradNaylor Posted March 16, 2012 Author Report Share Posted March 16, 2012 pic Link to comment Share on other sites More sharing options...
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