DuronClocker

Okay, I'm going to be modifying a pair of LT1 aluminum heads I have here for use on a rebuilt '70s 350, and I have a few questions about some things.

I'll be using a 222/232 duration cam with .479/.501 lift on a 114LSA. Heads will be mildly ported as will intake, and it will be run with headers.

As for the valvetrain, I need to buy some hardened chrome moly pushrods, some new rockers, and probably some guide plates, seeing as NSA rockers are a lot cheaper.

#1. Guideplates...do I need any modifications to my heads, or do I just un-torque the studs, slip them in, and torque them down? Also, I've read that only the GMPP ones should be used on LT1 heads. Is this true still with my older SBC, or should I use standard guideplates?

#2. Rockers. How big of a difference will there be going to 1.6 rockers over the 1.5 rockers on my above listed setup? Assume about 250-260 intake flow and 180-190 exhaust flow through the heads. I'm trying to decide on this because then that will allow me to choose between LT4 springs and EX-612 springs.

#3. Pushrods. What size pushrods do these motors use stock, what width, what length? Can I run the same on my motor? Should I get different length pushrods with the 1.6 rockers?

#4. Valves. I know they use 1.94/1.5 valves. How much of a gain should I expect going to 1.6 exh valves? Would it hurt performance because my cam is such a split-pattern grind? Also, what size are the valveguides, and what size are the valvestems? Are they the same as the late 80's SBCs? I already have some valve seals sitting here for an 80's SBC, so I'd use those if possible.

If I come up with any more questions, I'll be sure to ask..

amean94ta

why? you can get sbc heads to outflow any lt1 head out

WS Sick

The Guideplates for traditional SBCs will work, but they are slightly off.I ran a set and my only problem is the stud spacing holes were slightly narrow if I remember right.

KevinVandevenne

Its hard to find alum. gen 1 sbc heads for under $200 a set. A lot of folks here seem to be running pretty decent times on stock and ported LT1 heads. Plus, the amount of work require to convert the heads is minimal, provided you use an LT1 intake.

Good luck with the project Duron, I'm doing the exact same conversion as well on my 91 GTA. I've been following the thread over on thirdgen.org and it motivated me to do the swap.

amean94ta

bull get a set of steel (882) castings extreme port with some 208 and 160's they will outflow any lt1 head

KevinVandevenne

Why spend the money though? I have no doubts that someone who was willing to take the time, and spend the cash, could make any head flow better than what stock or mild ported LT1 heads flow. Put that same investment into a set of LT1 heads, and you will still have a better head than 882's. 882's would need new seats for a 2.08 valve, and that work alone would put you over the price tag of what stock LT1's would cost. Not only that, but the 882's weight 60~80lbs more (not sure of exact weight), have a poor chamber design, and most, if not all, are thin wall castings which are prone to cracks and warping.

96capricemgr

A pair of Vortec heads has the same chamber and ports as iron LT1 heads, which if you remember flow a bit more than most of the aluminums and as well as the rest, but come with a standard coolant flow. I know everyone likes to say the irons are 50lbs. heavier but a knowledgable person I respect actually weighted them and said 35lbs.difference, can't see the Vortecs or any other SBC head weighting that much more than the iron LT1s.

DuronClocker

I'm going to be using the LT1 intake anyways, so this will actually save a lot of work. Its also something different that not everyone has. They are lighter (everyone I've heard has said 50lbs+, but even 35lbs is 35lbs). They have screw-in studs, they have 1.94/1.5 valves, etc. Small things, yes, but when I got a pair of LT1 heads, an LT1 intake, and 24# injectors for $250 shipped, I couldn't pass that up.

882 castings suck. The compression with those things would be horrible, and the chamber designs suck as well. Sure I could port them (and thus lower compression even further), but that would take a LOT of porting.

I suppose aluminum vette L98 heads would be the best of both worlds, but those are rarely found for under $500 a set. I got mine for next to nothing (give the intake a value of $80, and the injectors a value of $60, and I spent $110 on heads, including shipping).

DuronClocker

^bump^

jonnyi

I have a set of New zz4 heads with crane gold race 1.6 rockers used for 32.6 miles before replacing with Edelbrock perfromer rpm heads. I can sell the shole set up for $600.00. The rockers alone were $300.00. let me know

N20Dave

#1 Weight savings.

#2 Low lift velocity and flow on the LT1 kill the old designs.

#3 The chamber design on todays heads is far superior in terms of burn rate and flame control.

#3 Paying someone to port them.

I don't think I would do this conversion myself but I give him credit for being different. Besides if he has the heads laying around and the can do most of the work himself it becomes cost effective.

WS Sick

I was wondering why you chose to use the 882s as an example, they are a huge handicap starting off, Now if you had said some nice 041s or somthing along that lines I could see a partial argument, but you still have iron heads that will need well over 600$ to get them up to par. (that not even the cost of the head)

Out of the box the LT1 has a port size advantage over the 882 (170 cc vs 160cc) then you throw in the port shape and combustion chamber and youre really leaving the 882s behind.The exhaust side isnt even close LT1 advantage all the way there.

But I do tend to agree with the Vortech head thinking on a traditional SBC. The heads are absolutely awesome compared to the older irons. (they flow better than an alum LT1 head). But since you already have the heads and intake I guess youre already halfway there.

chrism400

I agree with above. Just get a set of Vortecs. What are they like 400 a set complete? Do you realize that the LT1 head is a reverse cool head, and that the intake has absolutely no water running through it? Are you running a carb? How are you going to do that? You are causing a lot of problems for yourself. You could always run L98 heads I guess. HOT ROD had a 9 to 1 406 with vortecs out of the box, Edelbrock Air Gap, 750 carb, 230/230 Lunati 292 hydraulic cam running 428 hp with gobbs of torque.

DuronClocker

Yes, and that just means two ports on each head to get welded. Already have that figured out. The intake, as you mentioned, is a "dry" intake, and I already have all of the coolant hose stuff figured out because I was originally just going to run the LT1 intake on my stock setup.

If I was running a carb, why would I be using an LT1 intake? I'm using multipoint fuel injection using the TPI computer.

L98 heads? For what benefit? Lower compression? L98 heads have bigger chambers, and use 1.94/1.5 valves and have NO better flow than my current LB9 "081" castings (which are very good candidates for porting). These LT1 heads, stock, will flow as much as my heads with "stage 2 porting". Even then, I'd lose quite a bit of compression, whereas with the LT1 heads, I'll have higher compression, lighter weight, and the ability to use a bit more timing if I'd like to.

Can anyone answer my LT1-related questions above? I'm not going with any other heads. I just need to get the stuff above figured out. To get these heads on my block, I'll weld in some aluminum plugs and get the heads milled as little as possible. That is ALL I have to do for the actual head modification. The rest is with the intake, which was going to be done in the first place anyways. I just need some info on the rockers, pushrods, and guide plates.

WS Sick

Ok, I addressed to my knowledge the guideplates. 1.6 rockers on that cam would help alot, the faster you open a valve to full lift the more air you get in.
LT1s use stock factory hydraulic roller block pushrods. I wouldnt go that big on the exhaust , I like the 2.00 intake and 1.56 exh valves in the LT1 heads. blend the bowls after the valvejob.