Bo White

iTrader: (59)

Hey, new here as an actual member. I have read a few threads on this subject here and was wondering who does or did their own. I will do my own and have done some for others already. Any good stories, horror stories? I do not have a LS1 powered car or truck but working on it, LS1 swap in '92 S10. I also see a forum here for swaps so I will be spending some time there as well doing research. I had my first set I did over a year ago flowed by Bennett Racing and they flowed 272/210 at .650 and they were 2.00/1.55 valved 5.3 heads and the last set I did were 2.00/1.55 valved 5.7 heads that flowed 272/205 @ .600, do not know what they did at .650. I think I lost a little flow on the last set because I heard that the truck exhaust valve flows a little better than the car valve, is this true? I asked Terry @ Racetech about it while he was still at PP and he said they do and I trust his judgement. All of my ports flow with in 3% of each other, I try very hard to match every port to the nth degree.

Hysteria

Ported my own here too. I think there are a hand full of people here that have done their own that have posted on threads that era along the same lines as this one. I see that your heads flow almost the same as mine, what kind of shaping do you do to the ports? The truck valve is usually good for 5-10 cfm depending on porting style. I flowed mine before and after the truck valve swap in my sig.

ROCNDAV

iTrader: (100)

Hysteria, do you have any pics of the work at different stages of the port job? I know there are several areas where one must becareful not to go too deep, it would be nice if someone could post pics of these places as well.

Dave

Hysteria

I have only before and after pictures. I wish I had taken some as I went to try to document progress. The main thing you have to keep an eye on is two areas: The ramp in the intake port and the bump in the exhaust port just behind the valve. The ramp is just there for low speed stability and swirl IMO, and is alot thicker than most would suspect. Mainly cut the ramp out and blend it into the existing port roofwith no dips or high spots. When you put your bit into the port to start cutting start at the very peak of the ramp and shave it down a little at a time and you will start seeing it take shape. Continue doing so until it is completely blended into the stock surroundings. On the exhaust side shape the valve guide boss into a wing/tulip shape and the blend the rest of the bump that was behind the stock boss into the port roof.the bump that is in the intake port that covers the intake rocker arm bolt, cut it out and when it starts to get close to being gone start blending it into the port wall. Other than that just blend and smooth. BTW, my pictures are by a traditional camera and my scanner is on the frits.

FASTONE

Hey ROCNDAV,the only place you have to watch on a 241 casting is the intake swirl ramp,you will go thru if you try to take it out completely.I would take about 75% of it off.On the rockerboss you probably will go thru to get it completely out.
Did any of you guys do any special seat work?Thats a good place to gain on a ls1 head.A local guy that did the valve work on my SB Chevy said he got 300 cfm on the first set off ls1 heads he did.

Hysteria

I have not done a set of 241s. They must have altered the casting a little. I know that the seat is super sensative to how it is done but 300, I do not know. Maybe that is were I am loosing my flow, but what do I know, I am just a novice. I see that the way you talk you have went through on a set FASTONE.

FASTONE

Yes I have I also went thru on a set of iron Vortec heads(on the intake where the pushrods go by)and I brazed them back together,it was the most nervracking thing I ever done!!!These heads had been extensivly ported had bigger valves and studs and had been flow tested 2 times plus the combustion chambers were opened to match the 4.165 bore on my 408 SB.Every time the torch would POP I just knew I had cracked the head!! Not funny!!

Hysteria

No doubt. I have never welded before so I probably would have crapped on myself if it had of popped with me! The 241s should have been easy to fix though unless you could not get to it with the TIG. I have been lucky that I have not been visiting a weld shop with mine. I wonder how often profesional porters run into core shift problems. Maybe one can chime in.

z-ya

iTrader: (1)

They use a sonic tester to check wall thickness .

xfactor_pitbulls

iTrader: (16)

I am still practicing different ways to port, on a set of '98 heads. There seem to be a few ways to approach what you are looking for. As a point of reference I got out the compound saw and cut one of the heads in 3 pieces. One cut right through the center of an intake port, and the other down the center of the exhaust port. I do have to say that what see in the cross section is invaluable. There are parts you would think that are thicker than they are. Some places are thicker than you would imagine they would be. I would put the pictures up, but I took them with the cell camera and cant convert to a usable file type for here. I am going to get some with the digital at home and post them up. It might be a far cry, but I think that home porting for Heads, intakes, TB's, etc, could use its own section on the website..........

Brandon

DAPSUPRSLO

iTrader: (14)

I am getting ready to undertake the job of porting a set of 5.3s. These pictures would be greatly appreciated.

Arigom

iTrader: (3)

Make the exhaust D-shaped. Pay particular attention to the area around the valve seat. Smooth it as best as possible. The valve seat will need to be trimmed. Only smooth the short side radius - do not remove much - it should be a nice transition straight into the valve. The valve guide in the port is not needed for the most part and a lot of it can be removed for smoothing purposes.
The tools Summit sells is not the best. You need many shapes and sizes of bits to really do a good job. Some put wax on the bits to limit the chatter. A variable air pressure helps untill you know what you like. Always wear safety glasses, and headphones for tunes. You should really have one head to practice on - and when you get done, cut it up to look at cross sections.

FYI, I've done several sets and enjoyed the gains. Eventually bought a set of Patriot heads and had better results. After I bought valves, had a valve job, milled .030, bought springs and retainers it wasn't worth the effort. Between the overhead and time - I'll just pick up a CNC set where every port flows the same. Although, I am glad I did it, and at the time heads were $2,500 a set, not $1,200.
Good luck, have fun.

ROCNDAV

iTrader: (100)

Are there very many differences between a 241, 853 and 317 heads? I mean, they "are" different castings, right?

Bo White

iTrader: (59)

I have done a set of 5.3s, '00 5.7s, and a set of '98s and there was not enough difference to speak of. The area just behind the seat is terrible from the factory so really do it up blending that like Arigom said. Another thing is do not gasket match the exhaust port, some of the gaskets availible for the LS1 are humongiloid! Header tube match is the way to go anyway.

xfactor_pitbulls

iTrader: (16)

Arigom, I can understand what you are saying about just buying a pair outright rather than doing it yourself. Like me, many people dont have the $1000+ to shell out at a whim. The machine shop is going to do a valve job and mill the heads for me for $200. I paid $100 for low mileage '01 heads. The rolls and buffs are $50. Already have springs and retainers. So basically end up getting heads that should be noticably better than stock heads for around $400, plus my time. I enjoy learning and getting better at new skills, so no worries with the time. I guess the final verdict will come in when it gets back on the dyno in a few weeks. Plus if I hadnt started this project I wouldnt have had the pleasure of mangling some LS1 heads

Brandon