Port n Polish junkyard heads

[Dirmaid]

Port n Polish junkyard heads (And other head questions)

I'm considering running to the junkyard nearby and pulling a set of 4.0l SOHC heads/upper/lower intake so I can port n polish in my free time and still have a running vehicle if I screw up

Have y'all ever heard of junkyards takings major parts off of motors or do you think i'll end up with the whole engine (assuming I could find one). Also, if I end up having to pull them myself, what kind of tools should I bring with me to pull these parts?

I may also increase the valve sizes, but Ill cross that bridge when I can find some that would fit

 

[disciplerocks]

Every junkyard is different. And it will depend on whether its a salvage yard or a u-pull.

But if you are asking what kind of tools to bring, I'd be worried about you doing internal motor work. But its your truck. Good luck.

 

[DFracing]

yea, you have to get a special tool to hold the gear in place on the head so it doesn't rotate out of proper timing the second you remove the timing chain

 

[Dirmaid]

Tool wise, i was just asking about specialized tools for this engine. I usually just bring the truck to my buddy's shop and we have everything we need, just didn't know what i'd need to borrow from them. I'm not a mechanic, never claimed to be one, so excuse me for not knowing everything about the tools needed. Not getting pissy, just coulda went without that comment. It strikes people as condescending, but i appreciate your concern

@DF alright i'll see if theres one at the shop. but it seems like if i'm swapping heads they would be out of timing anyways once they get put onto the other engine. but this project is still in the early stages so i may end up having the stock ones professionally port n polished. all depends, ya knw?

 

[disciplerocks]

Sorry. I was a little rude all around this morning. The timing tool you will only need when installing the timing chain after all the work is done. As far as pulling a motor. Set of basic tools. Good sockets, small and large ratchet, wire cutters, impact would be nice, pry bar, and a BFH.

 

[chazz79]

Look into core engines. Usually junk yards will leave them out for awhile for before scrapping them. I'm sure you'll find one that has a skipped or broken timing chain and the boneyard will let you have them for scrap weight, around here you'd take a whole engine like that home for @75.00. You're tearing it apart so what do you care if it's got a few bent valves?

 

[Dirmaid]

@disciple no problem man. everyone has those kind of days. ill round up all that and worry about that timing tool come install

chazz, good point ill see if i cant round up one of those on the cheap. shouldnt be too hard to find something with the amount of wrecks here lately

 

[Destroyer000]

ive got a set of 04 ones..... shooot me a pm if you want.

 

[Dirmaid]

pm sent

on another note, have any of you guys found larger valves for these heads? I just keep coming up with either the stock valves or valves that are wayyyy too long/short

 

[Dirmaid]

ok guys, new question! Do the SOHC cams use bucket style followers? I am pretty sure that they do but I'm looking for confirmation from some guys that have actually worked on these heads

 

[woodyedmiston]

Hmmmm. I just ported a set of heads for an OHV. Made a mell of a hess in my shop. It remains to be seen just what they will do – it’s been a while and I’ll through in the benefit of my recent experience. (1) Before you insist on going to all the trouble of grinding away on the heads, first read the tech article in TRS. (2) Then go to the Eastwood Welding site and buy a set of their 6” carbide burrs. Don’t make the mistake of thinking you can make do with a 3” burr from Lowe’s or rotary files. You can get your sanding rolls there too, but there are available all over. (3) Just polish the ports.

If you insist on removing or reshaping, the ports find a cracked head like mine and cut it up through the middle of the ports with a cutoff saw. (another mess) but it will give you an understanding about where you can take out material and how much. Use a large flat washer on a 4” bolt as a template. Shape the washer or washers to match the first port area you are working on . . . then match the others to it. Do at least one of each ports on what’s left of the busted head before you start on the real deal. The big shops use CNC milling machines etc. but this works too. Keep in mind, you don’t have a sponsor paying you to win races with this stuff, you can get close and still have a pretty good flowing set of heads. It’s another story about how you check your flow. (Google: DIY Flow Bench if you are a real glutton for punishment) Stay the heck out of the combustion chamber unless you really understand what you are doing – and can measure the results. You can imbalance the compression from on cylinder to the other and have the same basic result as having low compression on one or more cylinders as if you had bad rings.
And there's my two cents . . .

 

[Dirmaid]

Thanks for the info, i had read the article but i wanted to hear from guys that have actually done it. My buddy (who runs a local performance shop) is gonna give me a hand with the porting job. I've actually been talking with a regrind company to get a set of performance cams custom made. They quoted me 99 per cam so hopefully i can get us a new source for sohc and make prices competitive...

 

[Gotta_gofast]

I have never personally had the opportunity to massage some SOHC heads, but I have looked closely at one to get an idea (in case I have the engine apart in the future! lol). Here's what I noticed and what I would do about it.

The good!
The intake runner does not suffer from a "bulge" that pushrod heads have.
There are plenty of cooling passages in the head. Better for eliminating hot spots (deto) and allows higher compression/timing
Nice uniform ports. The one I seen had no large casting slag or any major flaws
Exhaust port easy to access from either side (great for blending the short side radii, working the roof into the valve guide, and valve guide work)

The bad
The valves themselves I thought were garbage. Lots of texture and "pitting". I'd opt for some higher quality valves (stock size) and a good shop that can give you a 5 angle valve job for good seal/heat transfer
The intake runner is wild. Its long and has one turn "up" into the manifold and then the other "turn" that feeds the valve. Most of your access will be through the bowl. Blending back the short turn radii will be almost impossible without access through the runner.
In the combustion chamber, the intake valve is shrouded. If you look at the "V" across from the spark plug you will notice that the intake valve sits very close. I would roll that back a touch (but any material you remove in the combustion chamber will reduce compression)
And lastly, remember all those coolant passages that kept our heads consistantly cool? Watch out for them. haha, I've gone too far on a head and had to repair it. It involved me baking it for 24 hours. Start at 100 degrees and increase the temp 50 degrees every two hours. When it reaches 750 hold it. Have your tig torch ready, remove from oven and fill in where you broke through. Return back to oven, and step down 50 degrees every two hours. When cool, you can go back and remove excess weld.
If a junkyard has access to a "bad" head, pick it up for dirt cheap and cut it open. This will tell you how thick material is in certain areas and how thin it is in others.

For a first time port, I would not get too aggressive. Take that "bad" head and practice a little. A 60 grit sanding roll on a die grinder will remove aluminum very fast. You want a steady hand and to take your time. (For a set of V8 heads it takes me about 70 hours). For spots you cannot see well, use your finger to "feel" for imperfections. The SOHC head I seen had the valves intact so I didn't get an opportunity to see what could be done underneath. And lastly, its obvious that hogging out material won't give a better flow. Concentrate on casting flaws, smoothing out sharp bends, and working out "bulges" in the bowl. The short turn radii is most important on the intake runner, and the roof/bowl is most likely the most important on the exhaust side.

Good luck!

 

[Dirmaid]

Thanks ggf, thats more info than i could whip up after days of googling. First hand experience often equates to better understanding i reckon!

In my searches i noticed that these heads use roller rockers and hydraulic lash adjusters to control valve motion. The regrind company warned me that .05" would be removed from the base circle. Do you guys reckon that the .05" would cause any issues with valve train motion? I'm slightly worried that some parts may not be in contact at the closed position of the valves. is this a reasonable concern?

 

[woodyedmiston]

Is this from Deltacams? They can supply you with longer pushrods if that is necessary. The question should be directed back to your cam grinder and he should help you figure that out.