When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I own a 1984 4plus3. I have low compression in number seven cylinder and the plugs are fouled and backfiring. I think that the exhaust valve is NFG.
So next Sunday after this Sundays High performance driving experience Englishtown Nj. I will be pulling the heads. I have a question. If the L83 heads are so bad how did they with a restrictive manifold propel the car to 140 mph? Not bad for 205 HP car, IMHO. I have ported the intake and I was thinking of porting the heads, going to 1.5 roller rockers and installing 2.0 and 1.6 valves in the existing head. I am thinking the porting and valves would give me air in and out. Keeping the stock cam would keep the idle characteristics. Maybe I will change the ECM to an EBL ECM.
guess my basic question is how bad are those heads. Can I/should I use vortecs i.e, 87 truck heads.
Thank you.
I own a 1984 4plus3. I have low compression in number seven cylinder and the plugs are fouled and backfiring. I think that the exhaust valve is NFG.
So next Sunday after this Sundays High performance driving experience Englishtown Nj. I will be pulling the heads. I have a question. If the L83 heads are so bad how did they with a restrictive manifold propel the car to 140 mph? Not bad for 205 HP car, IMHO. I have ported the intake and I was thinking of porting the heads, going to 1.5 roller rockers and installing 2.0 and 1.6 valves in the existing head. I am thinking the porting and valves would give me air in and out. Keeping the stock cam would keep the idle characteristics. Maybe I will change the ECM to an EBL ECM.
guess my basic question is how bad are those heads. Can I/should I use vortecs i.e, 87 truck heads.
Thank you.
You probably wouldn't even be able to hit 350 hp with the stock heads. And yes, I have heard very good things about Vortec heads. I actually almost bought a pair for myself.
If u want go for it Here is an article of an 86 with a good stock bottom end and whats considered the worst heads the 85/86 With bigger valves/porting manifold changes and a 2000 rpm stall auto and 354's in the pig and a real mild cam
Ran low to mid 12's
Dont bother trying to port those heads and adding larger valves
They are crack prone and thin
Youll have set of expensive heads that still make mediocre power
it went 140....with time.
Why not its a start for ya. Maybe get a 50 dollar dremal kit do some port matching Intake and Exhaust a little bowl prep and chamber polishing have a good valve job done and new springs save the dough and don't do the bigger valves unless they are really cheep and get TPIS Intake parts and a cam latter and do everything like in this article and maybe down the line go for some AFR 195 heads
Intake upgrades will get ya up there but ur heads will be ur choke off point and later u can remove them if ur bottom end hasnt exploded by then and open her up and install some new heads and all the Intake mods will work perfect with better heads. Mid 12's is flying with those torque monster set-ups
If you are planning on modifying a stock set of heads, use 89-91 heads, they were the best years for the L98 head castings.
I believe our performance goals are different, but I will not waste my time with stock casting anymore.. If your goals are mild then by all means use the stock castings. The D port heads are good. I put so many hours in porting and money spent flow testing them and then all the goodies to go on them that I could have bought a set of really good flowing heads. Now all I have is an expensive set of ok flowing stock castings. My heads rock for stock castings but no where near aftermarket designs that are available now.
Why not its a start for ya. Maybe get a 50 dollar dremal kit do some port matching Intake and Exhaust a little bowl prep and chamber polishing have a good valve job done and new springs save the dough and don't do the bigger valves unless they are really cheep and get TPIS Intake parts and a cam latter and do everything like in this article and maybe down the line go for some AFR 195 heads
Intake upgrades will get ya up there but ur heads will be ur choke off point and later u can remove them if ur bottom end hasnt exploded by then and open her up and install some new heads and all the Intake mods will work perfect with better heads. Mid 12's is flying with those torque monster set-ups
funny but I was thinking about doing just that. Going to larger valves may be too expensive and too little return. I will most probably replace the burnt valve, dremel the ports clean up the bowls and call it a day.
I may upgrade in the future with a little more research. Looking at the articles on the vortec swap. It is not just take off one set and slap on the others. Thank you all
Sure man 1 last thing with the vortech u have to lose ur Stock intake and use one that matches the vortech heads and didn't think u wanted to go that route. Thats whats soo kool about the older c4's, The long runner Bosch TPI and even the newer LS motors are kinda going that way. Im keeping mine on my 85 but going with upgraded TPIS intake/base/runners/tb with the higer lift low duration cams fully ported up and later going with the afr 195 and a 383 short block kit that will get me up to the 500 lbs of Torque I want. Don't get all upset or chase the HP numbers. Like u said its still doing 140 mph and its got seat of the paints pull with its torque already.Just Image Twice that. Torque is what those motors are all about and the 500 to 525 lbs possible, that gets in the slightly modded LS C5 class Around 410-425 lbs to the wheels for that Torque Monster
To me thats Amazing that's maybe more than the 70's stock big blocks.
Heads
but fun after !! 
Damn some Head ****
