[kiwiroger]

Hi everyone.
I have a chance to get some early vortec heads off a 350 truck motor. I think the truck is around a 1990. Will those heads work on my 87 305. They have the smaller valves in them 1.90 intake and i think 1.50 exhaust. Or do i have to go and fork out for a set of EQ lightning heads, Cam and intake.:dontknow:

 

[87next2last1]

You will need to get a vortec intake also !!

 

[kiwiroger]

Hi Steve

So the later model heads will fit the earlier model block without to much drama

 

[87next2last1]

I will let the experts chime in & let you know !! I've have not worked on vortec heads !! Hope to soon !!

 

[speedy86]

If they are off a 90 those are NOT vortec heads, just TBI swirlport heads. Those are not good for performance.
Both the TBI heads and true Vortec heads will bolt to earlier blocks.

 

[kiwiroger]

thanks Jeff:beer:

 

[JJLT1]

check the numbers vortec are 906 and 062 ?? IIRC.
they didnt come out till 95-96 trucks?? and have the strait up bolts,,with the 8 bolt pattern..:texas:

 

[xcookpac]

Another route you could go is to get some L89 corvette aluminum heads from a late 1980s TPI Corvette. These heads are the first vortecs and have D shaped exhaust ports, 58cc combustion chambers, 1.94/1.5 valves, angle plugs, center bolt valve covers and pre-86 intake bolt pattern. I believe Chevy uses a modified version of these heads on the ZZ4. These heads will require at a minimum that you do the following: i.) get exhaust manifolds (such as the LT1 exhaust manifolds 1992-1996) or headers that match up to D ports and angle plug heads; ii.) get new valve covers for center bolts; iii.) drill/mill/grind the four ("4") center bolts on your intake manifold and fabricate/buy washers (should take about an hour) so that the intake bolts can get a good "crush" on the gasket. I have found "hillside washers" to be more time effective than fabbing up such washers. See fastenal catalog for hillside washers - http://www.fastenal.com/catalog_pages/2005/0159.pdf

Please note, what you are in essence doing is putting a post86 intake on a pre86 bolt pattern (even though the L89 heads are typically from 86, 87, 88, 89 corvettes - yes I know its a little confusing). This is the opposite of what most people are doing (namely most people are putting a pre86 intake on a post86 bolt pattern). Holley makes a kit for such a situation. See http://www.holley.com/90748.asp I am unsure whether this holley kit will fix the angle problem (as it is intended for the opposite configuration) but it seems awful pricey at $85. Finally, depending on what cam and rocker arm ratio you are running, you may need to inspect/clearance the valve as the bore on the 305 is substantially smaller than the 350. I have heard that as long as stated lift does not exceed 450 with 1.5 rockers than you should be OK. Additionally, I have heard that you can go to 500 lift with a little checking, clearance work and maybe new valve springs.

There are a set of these heads rebuilt for sale on ebay for $600. See
http://www.ebay.com/itm/tpi-corvett...ies&hash=item2c643846c3&vxp=mtr#ht_500wt_1202 the auction is entitled "tpi corvette 350 aluminum heads 10088113 sbc chevy zz4 z28 gta trans am"

These heads will give you better flow, more power, better mpg and more low end torque.

 

[leogexx]

Hi everyone.
I have a chance to get some early vortec heads off a 350 truck motor. I think the truck is around a 1990. Will those heads work on my 87 305. They have the smaller valves in them 1.90 intake and i think 1.50 exhaust. Or do i have to go and fork out for a set of EQ lightning heads, Cam and intake.:dontknow:

As stated before these are swirlies and not vortecs , 96 was the first year of the true vortecs . If you do ever buy a set of vortec heads make sure they have the self aligning rocker arms as these can be expensive to buy aftermarket . You also have to buy the right intake to match the heads, these have come down in price substantially over the last 5 years. .
What I am curious about is why you would spend money on a 305 for performance ? Doing the same thing (heads cam ,intake) to a 350 or 400 will net you more horsepower gain then if you installed these parts on a 305 .The 305s that were installed in 78-87 el caminos were more fuel efficiency orientated then horse power orientated. If you want a better performing engine you could swap the 305 for the right 350 already rebuilt for a decent price . just my 2 cents

 

[spencersr]

Vortec heads on a 305 with the right intake will get you better mpg

 

[JJLT1]

L89s are big block.:texas:
L98 are the tpi vett head.
vortec heads are copys of lt1 heads without reverse cooling..

x2 Leo,, Roger if you need more power i'd grab the 350 and start a build or
check out the new gm crate vortec motors for about 2000$,, cant beat it for new..:smileyb:

vortec links
http://www.nastyz28.com/forum/showthread.php?t=56505
http://www.chevymania.com/tech/vortec.htm
http://www.onedirt.com/tech-stories/engine/a-guide-to-vortec-vs-oe-small-block-chevy-heads/
http://www.chevymania.com/tech/vortec.htm

 

[Kerno]

If you are subject to emissions inspection, you need to make sure that the heads you decide to use have the exhaust crossover or you'll have a problem with the EGR valve.

 

[xcookpac]

L89 corvette aluminum heads do not have exhaust crossover. however, LT1 exhaust manifolds have a port on passenger rear which bolts to factory tube which can then be plumbed to intake for operational EGR.

 

[ccc]

chevy called all of thier truch engines vortec , thier trade name .the heads prior to 96 were very restrictive truck heads and were done at 4500. the real vortec heads are a great head,usually around a 40 hp gain just in the head swap.as stated above you will need a vortec specific intake. i have a set on the temp motor i just pulled from my 86 and it pulled good well past 6000 in every gear,they all have the old six bolt exhaust flanges,you will need to change to headers or early exhaust manifolds as your last bolt on the pass side has no place to screw into. gm put a set of these on a 190 hp target motor and made 404 hp with a 600 holley and slight performance cam. check the casting no. befor you buy them and look for no center exhaust crossover at the intake mounting flange. if it has an exhaust port thier not true vortecs.

 

[ccc]

i think he means l98

 

[xcookpac]

Made Typo: Should Be L98 (not L89)

i think he means l98

Yes, I was meaning to say L98 (NOT to say L89). Thanks for catching that.