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Old 10-22-2007, 06:24 PM
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Vortec heads on LT1

i heard a roumer that you cant put regular SBC heads on an LT1 block, i have a set of vortecs off my old motor and im getting a LT1 long block and was going to rebuild it and put the vortecs on it, can it be done?

also can LT1 heads go on a regualr SBC? is there any performance gain? thought if it was true id give them to my buddy

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Old 10-22-2007, 06:53 PM
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LT1 heads will not work on other small blocks and Vortec heads will not work on a LT1.

However, I do believe the Vortec heads will bolt up to the LT1 block but they won't work on a running engine. The LT1 uses reverse flow cooling and the coolant ports in the heads are routed a little bit differently than those found the more typical Gen I/II small blocks.
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Old 10-22-2007, 07:19 PM
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Quote:
Originally Posted by the dan
i heard a roumer that you cant put regular SBC heads on an LT1 block, i have a set of vortecs off my old motor and im getting a LT1 long block and was going to rebuild it and put the vortecs on it, can it be done?

also can LT1 heads go on a regualr SBC? is there any performance gain? thought if it was true id give them to my buddy
If you're talking the early-mid 1990s LT-1 the answer is no for the block and maybe for the heads. These LT-1s and 4s use reverse cooling like the early Pontiac OHV V8s. The block and heads are very different from other SBCs to accommodate coolant being pumped to the head first then into the block and back thru a combination valve to the radiator. The block is radically different from other SBCs where the coolant discharge from the pump is immediately directed up into the heads where it flows down into the block is brought forward to discharge below the inlets. The entire front end is different from regular SBC's and will not accept a standard water pump.

LT-1 and 4 heads can be adapted to a regular block, bit it's a SP of work. The coolant vents on the ends of the heads have to be enlarged to take 1/2 inch NTP fittings. The return coolant is routed outside in hoses from those fittings to a collector return (MOROSO part) which has to be mounted to an LT-1 or 4 carbed intake, then to the radiator. you could probably do this return with OEM EFI, but it's tough enough with a carb, you're really space constrained with the EFI installation. PLUS, there are 4 large holes 2 on each end, one being coolant in to the head from the block the other oil drainback from the head. Both (well all 4 when counting each end of the head) need to be welded shut. Then with an L-98 aluminum headed engines, head gasket, one small coolant hole (1/4 inch) and a oil drain back hole needs to be located into the head using the L-98 gasket as a template.

The Vortec heads are cast iron version of the LT-1/4 head having features of both while not quite being either. The Aluminum Fastburn head is the LT-4 head with a regular coolant return.

Bogie

Last edited by oldbogie; 10-27-2007 at 01:28 PM.
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Old 10-22-2007, 08:23 PM
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Yep, I agree. Can't mix n match LTx with non LTx
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Old 10-23-2007, 03:26 PM
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I heard the vortec heads are patterned after lt1 heads and should be about the same?
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Old 10-23-2007, 04:58 PM
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The iron LT1 head introduced in late 93 used a new intake port that ended up being unexpectedly wonderful. They copied the PORT design in the vortec heads in 96, but that is it. The LT1 has the same basic SBC design, but the water passages between the block and head are completely different. It just won't work.

I have known of someone who welded up the LT1 passages and drilled traditional SBC water passages to get LT1 heads to work on his SBC, but that is insane money and work to accomplish for getting heads that are only as good as vortecs.

http://www.automotiverebuilder.com/ar/ar99928.htm
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Old 10-26-2007, 10:13 AM
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so lt1 heads are generally vortec heads with reverse flow cooling?

what i was getting at is i have a set of 2001 vortec heads all machined and done up for roller rockers and high lift that i did last year, i guess they wont work in an lt1 because of reverse cooling? if so then i will not be getting an LT1 because i cant spend another 20 hours in a machine shop.

or did i take that information wrong?
i got that lt1 heads wont work on a general SBC
but vortecs wont work on a LT1?
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Old 10-26-2007, 10:14 AM
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and sorry if i just didnt read something right in advance
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Old 10-26-2007, 11:47 AM
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Well, according to oldbogie, it CAN be done but sounds like a lot more work than it's worth. Remember that people adapt Ford Cleveland heads to Windsor blocks. There was also a short article in (either Car Craft or Hot Rod) about a guy that was adapting such things as Subaru and Porsche heads to big and small block Chevys. The nice thing about metal is that you can make just about anything fit just about anything if you've got the time, dedication and money to do it.

I personally would go with a Vortec Gen I or build the LT1 in its entirety instead of mix and match the parts.
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Old 10-26-2007, 03:22 PM
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Quote:
Originally Posted by the dan
so lt1 heads are generally vortec heads with reverse flow cooling?

what i was getting at is i have a set of 2001 vortec heads all machined and done up for roller rockers and high lift that i did last year, i guess they wont work in an lt1 because of reverse cooling? if so then i will not be getting an LT1 because i cant spend another 20 hours in a machine shop.
Yes, the water passages are in different places on LT1 heads. They'll actually bolt up, but the gaskets won't seal at all because the water passages won't line up at all.

LT1 iron heads have the same ports as vortec heads, yes. BUT>>> You mentioned that you have 2001 vortec heads... which are not vortec heads They're LS1 heads. Confusing, huh?

Traditional small block is early 50s up through 1999. They're still actually produced for commercial applications, but I won't get into those. Here's the general breakdown. Up through 1986, they are a 2-piece rear main with a flat tappet cam. 87 and later were 1-piece rear main and roller cam blocks (for the most part). Starting in 96 and ending in 99 they were Vortecs. I know the vortec name existed prior to and after those years, but its just a name. True vortec heads carry the casting numbers that end in either 906 or 062. In 99 all trucks went to the LS1 style engine. In corvettes, the traditional small block stopped being used in 92 when they switched to the LT1. Other GM cars switched to the LT1 in 94. Then all cars switched to the LS1 in 1998 when the big cars stopped being produced.

With some extra parts being involved, all heads, intakes, and other things can be used on any traditional small block provided you use the right parts to fit the right heads. LT1s can share a few things, but not heads, intakes, or much else. LS1s are a complete clean slate design and I don't think anything (except maybe lifters) will interchange.

So, unless your heads came off a commercial truck like a cube van, bus, or rare export commercial truck, those heads are LS1 style

Traditional small block heads (regardless of vortec, LT1, or not) look very similar on the outside and look like this:
http://www.jegs.com/images/photos/80912464298.jpg

LS1 style heads all look very similar with their tall skinny intake ports and look like this:
http://www.jegs.com/images/photos/350-61969.jpg

How about some casting numbers?
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Old 10-27-2007, 01:35 AM
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lol yeah they are off of a cube van actually, and i know ls1 heads are completely different, i did build this engine, i just have too much time blueprinting the spring seats, machining valve guides and milling the rocker stud bosses for screw ins, i know i wont be able to get a bridgeport for a week again so looks like ill be building another normal small block
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Old 10-27-2007, 01:45 AM
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yeah they are 906 vortecs made in 5/2001

this is the engine that had a bad break in (4 thermostats found out the 4th one the hard way - seized after overheadting)
yes the carbs on backwards

these are the heads

and this is me machining them (17 at time) first time on a bridgeport the owner of the shop wanted to hire me because somehow i knew almost exactly what i was doing (and my hands there just for vibration it was out of the way)

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Old 10-27-2007, 04:46 AM
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Nice looking engine. Keep us posted.
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Old 10-27-2007, 09:14 AM
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never mind it wasnt even an LT1, and it was full of water, yippee

Last edited by the dan; 10-28-2007 at 12:53 AM.
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Old 12-29-2007, 05:24 PM
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L31 Vortec heads were used in commercial trucks into 2005, in the Express vans through 2002 and in the fullsize trucks through 1999 and in the Tahoe Limiteds in 2000.

peace
Hog
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