Engine Guru's: I need your knowledge on heads

[Dweano]

Hey guys, first off here is what I am talking about:

Clicky Here

I have always kinda wanted ported stuff as I think that increased airflow will increase power and mileage a bit (correct me if I am wrong) so I have been emailing the guy back and forth and here is what he says:

"Yes the heads have been ported also. They have been port matched to the intake. These heads have less than 1000 klm on them and the bearing went out on 2 rods.
All they need is to be washed and installed"

"They are 93tm castings, yes they were planed 10thou each, and there are spacers under the springs to bump the pressures a little (to handle bigger cam but I never bought the cam) Intakes were ported to straighten out the shot from the intake manifold. Intake manifold ported lots cause that’s were the power is gained. "

"One head was a brand NEW head cause one of my cores was cracked (so all new valves and seats) , the other valves and seats were checked and reground, springs are just originals reused. Heads were rebuilt, and planed at Economy Cylinder Head on Ogden rd. These are ready to install. Just wash and bolt on."


What do you guys think? Good buy? Sounds not too bad. The spacers under spring thing in a bit confusing to me.

I have a 1996 4.0L OHV. Would these A) bolt on? and B) Raise or lower compression? I would like to keep running 87 octane. So what do you guys think overall...good price? Good quality? Stay away? Haha. I really don't know much about this stuff so any help would be appreciated

 

[rusty70f100]

In 1996 they were small chamber heads / large dish pistons. In 1993 it was large chamber. They'd lower compression a lot, negating most of the airflow benefits.

 

[Big Jim M]

HA!

In almost any event I wouldn't purchase someone elses reworked heads.. There is no tellig what you'll get.. Positively you will NOT get the true reason he is selling them.
As far as porting, polishing, port matching and shaving goes.. Them things WILL NOT be of help at normal driving uses. In the event that seven grand is the target rpm they WILL be of help.
In their stock form the heads supply the combustion areas with as much fuel as they would after being altered. That is a fact until the upper limits of the engine are reached. If you do not intend to add rpm to the engine, head altering is a complete waste of time and money.
However if the engine is being built with a radical camshaft, improved intake and exhaust system then by all means do the head work.
Big JIm

 

[Dweano]

Alright sounds good. I will stay away then haha

 

[RacinNdrummin]

In almost any event I wouldn't purchase someone elses reworked heads.. There is no tellig what you'll get.. Positively you will NOT get the true reason he is selling them.
As far as porting, polishing, port matching and shaving goes.. Them things WILL NOT be of help at normal driving uses. In the event that seven grand is the target rpm they WILL be of help.
In their stock form the heads supply the combustion areas with as much fuel as they would after being altered. That is a fact until the upper limits of the engine are reached. If you do not intend to add rpm to the engine, head altering is a complete waste of time and money.
However if the engine is being built with a radical camshaft, improved intake and exhaust system then by all means do the head work.
Big JIm

While I agree with the "buying someone elses reworked heads" statement, I dont agree with the following statement. The only time porting heads is detrimental to "normal driving" is when you hog out the heads to the point where velocity is effected in a negative manner. You can do a port job on heads that just cleans up the casting and fixes flaws in the port, combined with a good valve job, and you will gain everywhere in the RPM range. Also, decking heads will gain you power everytime no matter what, its just the trade off with the possiblity of having to run a higher grade fuel, and whether thats worth it or not.

 

[Big Jim M]

Ha!

While I agree with the "buying someone elses reworked heads" statement, I dont agree with the following statement. The only time porting heads is detrimental to "normal driving" is when you hog out the heads to the point where velocity is effected in a negative manner. You can do a port job on heads that just cleans up the casting and fixes flaws in the port, combined with a good valve job, and you will gain everywhere in the RPM range. Also, decking heads will gain you power everytime no matter what, its just the trade off with the possiblity of having to run a higher grade fuel, and whether thats worth it or not.

If you will reread my post I did NOT use the word "detrimental"! What I said was it doesn't HELP! That MUST be the true fact.. If in fact at normal driving MORE fuel was introduced into the chamber, there would be things happen that would confuse the computer.. then the timing would be retarded by it and the rig wouldn't run as good as it would with the stock head profiles..
This doesn't happen with mild porting as MILD PORTING doesn't help anything until max rpm is reached..
YES shaving the heads results in more compression.. More compression in a computerized engine is a BAD thing! Again lots of bad things happen..

Before doing head work the owner should know in advance what to expect from that work..
Big JIm