Head Porting

[Locobob]

Thought I'd share my latest project with you guys: porting or rather reporting my cylinder heads. The motor is a 368 put together by LPE back in the mid 90's. The heads are pretty gummed up, likely do in part to the car having an open loop only chip when I bought it. When we burned a new chip for it we had to be very conservative on the timing do to knock sensor activity, I suspect all the gunk in the heads may have something to do with that. Anyhow I did some measuring prior to getting started so here are the numbers:
Primary intake runners at narrowest point (just above the valve guide) 33mm high, 33.8mm wide
Secondary intake runners at same spot 33.3mm high, 35.6mm wide
Intake bowls just above the valve seat 34.8mm
Exhaust bowls just above the valve seat 33.8mm
Exhaust port at narrowest point (near union) 33mm
Exhaust port at header gasket surface 36.3mm high, 53.8mm wide

I found a few things about the prior head work suprising, one being the combustion chamber surface was pretty much left as cast - very porous. I was expecting to see a nice smooth surface below all the carbon build up. Thought smoothing and polishing the combustion chamber was standard fare for head porting. Here are a few pics of the combustion chambers before (with just a little clean-up) and after a bunch of very tedious hand work.

http://i418.photobucket.com/albums/pp270/locobob68/P2280001.jpg

http://i418.photobucket.com/albums/pp270/locobob68/P2280002.jpg

http://i418.photobucket.com/albums/pp270/locobob68/P2280009.jpg

Here is a primary intake runner after a bit of work with a sanding drum

http://i418.photobucket.com/albums/pp270/locobob68/P2280016.jpg

[Polo-1]

only 31 more holes to go Rob:wink:

how the cam cover repair looking any luck.

[tf95ZR1]

Wow, lots of work!
I'd be interested in the dyno # changes when its all back together.

[lbszr]

I went with a lot of your posts a year ago and ported upper with match porting heads, but didn't do heads even though they were off with great results, so thanks, guess it's a year late.


But if you post this kind of good info you'll have me pulling the heads again, not complaining though.

[jonszr1]

wow i have never seen heads that were ported that didnt have some combustion chambers smoothed out at least . bowl work is a very important part of head work . i will bet that bob really improves his power with his mods to the heads . thanx for sharing, sure opens ones eyes

[Zr1 Destroyer]

Holy valve guides batman......don't forget to nip those babies off!)

[Pete]

Great work Bob :thumbsup:

I think all Zr-1's should have/get ported heads & top end.

Pete

[Locobob]

Holy valve guides batman......don't forget to nip those babies off!)

I've been giving the valve guides some serious thought. I've seen pics of some that have been ground right to the floor. I have also had a few knowledgable people opine that this is a bad idea and that I should just shape what's there and not reduce the length of the guides. A shorter guide would possibly be subject to increased wear from friction/heat. On the other hand the engine being an overhead cam design one would think the valve guides would be less critical than a pushrod design in respect to side loading. Hmmm

[blackjack]

in harley heads,we streamline the intake guide,but leave the exhaust guide ''chubby'',otherwise they become very hot at the end if too thin
bj
91/1735

[Locobob]

in harley heads,we streamline the intake guide,but leave the exhaust guide ''chubby'',otherwise they become very hot at the end if too thin
bj
91/1735

That would seem to make sense, thanks for the input.

Any other opinions on this?
What did you do with yours Pete? How bout you Flyin Ryan, any thoughts on this?

I'm currently favoring trimming them back some and then contouring - on the intake side at least. The exhaust side is a bit shorter already so I'll probably just do some shaping on it.

[Zr1 Destroyer]

I've been giving the valve guides some serious thought. I've seen pics of some that have been ground right to the floor. I have also had a few knowledgable people opine that this is a bad idea and that I should just shape what's there and not reduce the length of the guides. A shorter guide would possibly be subject to increased wear from friction/heat. On the other hand the engine being an overhead cam design one would think the valve guides would be less critical than a pushrod design in respect to side loading. HmmmHasn't hurt either of my zr1 engines......funny how these knowledgeable people have never tried this in an lt5 before...hmmm!:rolleyes:

Anyways....lookin good. Wish the heads came from the factory looking more like yours....a lot of power hidden in there!


Originally Posted by blackjack http://www.zr1netregistry.com/forum/images/buttons/viewpost.gif (http://www.zr1netregistry.com/forum/showthread.php?p=55793#post55793)
in harley heads,we streamline the intake guide,but leave the exhaust guide ''chubby'',otherwise they become very hot at the end if too thin
bj
91/1735
That's an aircooled head vs. a liquid cooled head.......bad comparison!

[Pete]

I didn't wanna take a chance so all i do is taper the guides,basicly like the IH's injector boss.
Left the length alone.

I think our guides are short enough from the factory.
Just be careful grinding on them make sure the grinder/carbide doesn't jump on the guide,they are made something like pot matel.

Use a steel cutting carbide.
Had a guide break/drop on me,it wasn't pretty.

Also wanna add, don't do much if at all just polish and blend in the guide for the exhaust ports.

From the stock flow #'s that i have after your done with the intakes you will be at about 75-80% Intake/Exhaust Ratio

Pete

[blackjack]

Hasn't hurt either of my zr1 engines......funny how these knowledgeable people have never tried this in an lt5 before...hmmm!:rolleyes:

Anyways....lookin good. Wish the heads came from the factory looking more like yours....a lot of power hidden in there!


That's an aircooled head vs. a liquid cooled head.......bad comparison!

it doesnt matter if your heads are air or liquid cooled....the exhaust guides will run a lot hotter than the intake ones,as they are exposed to direct combustion,and hot exhaust gases..i should add that the harley guides stick out in the ports a lot more than the lt5 guides
bj

[Locobob]

Getting pretty close to done with this project, mainly just some fine tuning left. Here are some more pics of the work coming along:

Port matching the injector housings to the heads.
http://i418.photobucket.com/albums/pp270/locobob68/P3120002.jpg

Alignment dowel pin for port matching injector housing to head.
http://i418.photobucket.com/albums/pp270/locobob68/P3120008.jpg

Intake ports almost done.
http://i418.photobucket.com/albums/pp270/locobob68/P3120010.jpg
http://i418.photobucket.com/albums/pp270/locobob68/P3120012.jpg

[FU]

You do good work Bob :thumbsup:

[4DSZR1]

Looks outstanding Rob!

[1990 415]

beautiful!

[Paul Workman]

Getting pretty close to done with this project, mainly just some fine tuning left. Here are some more pics of the work coming along:

Port matching the injector housings to the heads.
http://i418.photobucket.com/albums/pp270/locobob68/P3120002.jpg



In this picture the top of the runners are siamesed, no? I'm curious about that: Is it a result of opening up the ports and the "septum" being narrow at the top and the ports simply merge, or was that portion of the septum removed (siamesed) in a deliberate way?

Very interesting thread, BTW. Oh! I took your advice on the porting process - grind a bit, sand a bit and measure, then grind a bit, etc... It's working out very nice so far:thumbsup: This my first LT5 porting attempt (plenum and IHs only, for now), and I really appreciate you, Pete, Marc H, Lee, and Dom and others willing to show me where the "bread crumbs" are through the woods. Maybe next winter I'll fuss with the heads. Between now and then (if then) I'll be soaking up all I can about it. Your pix go a loooong way to explaining at least some of the mysteries! Thanks so much for sharing, Bob!:thumbsup:

P.

[Jim Nolan]

Locobob,

When you did my injector housings and plenum I finally had it dynoed, 349hp at the wheels. Not bad for a 375 motor. Aaron Scott has the car now and he's porting the heads, adding headers and changing the rear end to a 3:90. That should be for a good gain.

Question; In conversation with him I thought he mentioned burning the chip to open loop what's the down side to this?

[Nick]

Looks great Rob! :thumbsup:

[Locobob]

Paul: The siamesed plenum/injector housings were done on purpose. You can read up on the process in this old post from the other forum http://forums.*************.com/c4-zr-1-discussion/1085144-368-porting-project-more-power.html

Jim: Sounds like the HP bug bit you pretty hard, should see a big difference with the new mods. I'm not a big fan of open loop only chips. Running rich in part throttle driving conditions is going to dirty up the motor. Emissions testing will also be a problem if you are in an area that requires it. I'm not an expert on the subject though. I'd suggest starting a thread on the topic, we have some folks here who are quite knowledgeable in regards to tuning.

[Pete]

Rob,killer work.:thumbsup:

Pete

[Locobob]

All done, here is the finished product:

Gasket trimming, note the primary on the right hasn't been trimmed yet so you can see the increase in size.
http://i418.photobucket.com/albums/pp270/locobob68/Head%20porting/P3190001.jpg

http://i418.photobucket.com/albums/pp270/locobob68/Head%20porting/P3270009.jpg

http://i418.photobucket.com/albums/pp270/locobob68/Head%20porting/P3270024.jpg

http://i418.photobucket.com/albums/pp270/locobob68/Head%20porting/P3270032.jpg

http://i418.photobucket.com/albums/pp270/locobob68/Head%20porting/P3270038.jpg

[Pete]

Nice,very nice.

Good work Bob :thumbsup:

The exhaust ports WOW

Pete

[4DSZR1]

The craftsmanship is second to none Rob, VERY WELL DONE!

[1990 415]

the Sistine chapel of porting!

[jonszr1]

i to agree that this is some of the finest work i have ever seen .i really like the dowling the the assemblys to ensure allignment

[-=Jeff=-]

WOW BOB!!!

that looks awesome

[DDSLT5]

Dem's shiney AND purdy!:wave:

[Locobob]

Kind of a shame they're going back on the motor just to get all dirty again. Maybe I'll just hang-um on the wall to stare at.... nah.

[tomtom72]

Kind of a shame they're going back on the motor just to get all dirty again. Maybe I'll just hang-um on the wall to stare at.... nah.

Your work looks sooooo goooood that it is almost a shame that they need to go back on the motor, but all things considered I'd have to say....NOT!:mrgreen:

Bob I hope you enjoy the fruits of your labor for a long time! Kudos man!

:cheers:

[jonszr1]

i would be willing to bet you now have 25-30 more hp to your allready nice 368.i would have to go to the strip and see what she would do . enjoy:thumbsup:

[Polo-1]

All done, here is the finished product:

http://i418.photobucket.com/albums/pp270/locobob68/Head%20porting/P3270038.jpg

Way too much Aluminum in there and whats that stick in the middle for:p

Should look like this Rob



http://i7.photobucket.com/albums/y292/kpie/KP2.jpg

[Locobob]

Way too much Aluminum in there and whats that stick in the middle for:p

Should look like this Rob



http://i7.photobucket.com/albums/y292/kpie/KP2.jpg

Kevin you need to hurry up and get that monster running so we can see if bigger turns out to be better.

[Locobob]

Finally got a chance to do some work on my car. Decided to CC the chambers to see how close they are. My budget method involves a clear piece of plexi in which I drilled a few holes, a large syringe and some trial and error to come up with consistent readings. All of them came in between 39 and 40cc except for one which was about 38.5cc. I did some clean-up work on the low chamber and brought it up above 39cc.

http://i418.photobucket.com/albums/pp270/locobob68/Head%20porting/P1010012.jpg

[Locobob]

Also after waffling over the idea for what seems like eternity I have decided to yank the secondarys out. For those that have done this procedure.... how in the hell do you pull the throttle shafts out??? Tried yanking on them with vice grips to no avail.

[Polo-1]

Put the nut with washer back on and use 2 flat blades. You have get the alum steak spots cleaned out. 2 or 4 punches per throttle blade/bearing.

Mine cc'd 39.7

Looks good Rob:thumbsup:

[Paul Workman]

Also after waffling over the idea for what seems like eternity I have decided to yank the secondarys out. For those that have done this procedure.... how in the hell do you pull the throttle shafts out??? Tried yanking on them with vice grips to no avail.

Per Pete, I placed a socket over the shaft, and put a washer over the end of the socket, and used the nut from the throttle shaft and cranked it down on the shaft against the washer. The shaft and bearing pull right out!!

I recommend pulling the breather box, or you'll have trouble getting the throttle shafts out. Just loosen the AC pump (two bolts, if I recall) and move it out of the way. Then the box top comes off and removing the remaining throttle shafts is a "snap". And, another reason for removing the air breather box is so you can drive the freeze plugs into the bearing well!:rolleyes:

Speaking of freeze plugs, the next thing your gonna need is the right freeze plug. Pete suggested the Dorman 555-108, but they didn't fit, for some reason - too big. I went with the Dorman 555-110s, but had to splay them a bit (with a socket and a hammer) to make them fit snug. (I also sealed them with JB Weld, after degreasing the holes w/ brake cleaner.). (Marc H jotted down a note for me indicating the Dorman 555-011(?) would also work, but the dealer would have had to order them, so I went with the -110s on hand.)



Piece o' cake, buddy!

P.

[Pete]

Per Pete, I placed a socket over the shaft, and put a washer over the end of the socket, and used the nut from the throttle shaft and cranked it down on the shaft against the washer. The shaft and bearing pull right out!!

I recommend pulling the breather box, or you'll have trouble getting the throttle shafts out. Just loosen the AC pump (two bolts, if I recall) and move it out of the way. Then the box top comes off and removing the remaining throttle shafts is a "snap". And, another reason for removing the air breather box is so you can drive the freeze plugs into the bearing well!:rolleyes:

Speaking of freeze plugs, the next thing your gonna need is the right freeze plug. Pete suggested the Dorman 555-108, but they didn't fit, for some reason - too big. I went with the Dorman 555-110s, but had to splay them a bit (with a socket and a hammer) to make them fit snug. (I also sealed them with JB Weld, after degreasing the holes w/ brake cleaner.). (Marc H jotted down a note for me indicating the Dorman 555-011(?) would also work, but the dealer would have had to order them, so I went with the -110s on hand.)



Piece o' cake, buddy!

P.

Paul the 555-108's work they are on Al's,Bob's (2 motors),Kevin's and my LT5's you need to use a smaller socket to hammer them in you can not use a socket that fits too tight in the freeze plug it won't let the freeze plug crush, been there done that.:thumbsup:

Pete

[Locobob]

Thanks for the input guys. I've been trying the socket method but don't seem to have the right combination of stuff to get the job done, looks like a trip to the hardware store is in order.

Oh and thanks for the freeze plug info too, that was gonna be my next question.

[Paul Workman]

Paul the 555-108's work they are on Al's,Bob's (2 motors),Kevin's and my LT5's you need to use a smaller socket to hammer them in you can not use a socket that fits too tight in the freeze plug it won't let the freeze plug crush, been there done that.:thumbsup:

Pete

Ah! The socket I used just fit inside the cup with a little slop, but prolly not enough to allow the plug to squeeze into the hole...(story of my life!:mrgreen:)

P.

[Paul Workman]

Paul the 555-108's work they are on Al's,Bob's (2 motors),Kevin's and my LT5's you need to use a smaller socket to hammer them in you can not use a socket that fits too tight in the freeze plug it won't let the freeze plug crush, been there done that.:thumbsup:

Pete

Ah! The socket I used just fit inside the cup with a little slop, but prolly not enough to allow the plug to squeeze into the hole...(story of my life!:mrgreen:)

PS: Bob...I know someone that has a buncha 555-108s you're welcome too!!;) I'll put 'em in the mail tomorrow if you need them!

P.