Jack's Information on Head Porting

[Bewarethemoon]

I would get with Jay760 and build the motor around his combination as it seems to run real strong. You'll need to install bronze guides to prevent seizing or galling of the valves stems,iron guides are a no no in this type of racing and i would'nt use a guide seal on the exhaust guide either,you'll want all the oiling that guide can receive for lubrication,but thats my opinion. As for the port work the intake is fine but me personally I would work the exhaust port differently in getting the E to I flow ratio down to around 70 to 75% to prevent over scavenging but again that's my opinion cuz if you get that port right it'll flow big time right with the intake at certain lifts. Anyway I hope it all comes together with that 250-30 for you.

I’ll contact Jay760 and ask his advice, cheers Jack!

Where can I source bronze guides???

So the usual port work on the intakes but different work on the exhausts to what you’ve re-posted so far?

I have a bare cylinder head arriving this week, shall I take photos of the ports as they look?

Thank you for your continued help, I’m really beginning my journey with making my motor ‘racey’ and I want to absorb as much info’ as I can from everywhere I can!

Daniel.

 

[Jack]

Hoos racing has the guides. Yes on the exhaust port and take photos of ports as they are. I'll try and take some images of that exhaust port,it was trail and error head with the E/P epoxied up. If you'll look at the exhaust port floor at the outer section,you need to work the corner of the floor down and work if up and out exposing more of the valve seat. This stabilizes the flow in the upper lifts for a more ideal flow ratio with single pattern cam.

 

[Jack]

Heres the port with the outer corner worked down. Once you establish a good flow pattern and don't see a flow lose with different port shapes theres no incorrect way of porting the exhaust port ,it's all about the combination and it's attended usage.

 

[Jack]

Heres another exhaust port with floor welded, slightly canted and upper left roof portion by the guide was opened up and turned out to the gasket flange. The flow on this port
shot the flow ratio off the charts, 90% + in some lifts.
Working the turns in the roof section for me has giving me good results as long as there's good casting.

 

[Bewarethemoon]

The head I sourced arrived today.

I’ll clean up and little and take some photos of the ports in the workshop tomorrow evening.

 

[Bewarethemoon]

Photos as promised.

The first two are of the left intake ports (as if looking from the rear) and the second two are of the right .

(ignore the attached photo, not sure why it did that)

 

[Bewarethemoon]

Now for the exhaust ports The first two photos are of the right (as if looking from the front) and the second two from the left.

 

[5twins]

Seems those ports have been "worked" a bit already, guides cut down too.

 

[Bewarethemoon]

I hope these photos suffice Jack?

Am I correct in thinking someone has been at the intake ports previously? They don’t look anywhere near as bad as I expected and I think I see tooling marks???

That said I’m a complete novice here so more than likely it’s an incorrect assumption?

I hope I am wrong because I want to do the work myself.

Thanks to all for any feedback!

Daniel.

 

[Bewarethemoon]

Seems those ports have been "worked" a bit already, guides cut down too.

My thoughts exactly and I was just posting that!

Where does that leave me?

Any opinions on the workmanship?

 

[5twins]

The intakes don't look too bad. As I mentioned, you want a textured finish on them to keep the fuel/air mix agitated as it flows through. You might touch them up a bit around the valve seats if they need more blending there. I can't tell much about the exhausts, they're too dirty to see. You can use paint stripper to clean all that carbon out of them. It won't get them 100% clean and shiny, but clean enough so you can see what's been done to them already.

 

[Bewarethemoon]

The intakes don't look too bad. As I mentioned, you want a textured finish on them to keep the fuel/air mix agitated as it flows through. You might touch them up a bit around the valve seats if they need more blending there. I can't tell much about the exhausts, they're too dirty to see. You can use paint stripper to clean all that carbon out of them. It won't get them 100% clean and shiny, but clean enough so you can see what's been done to them already.

Thanks 5twins, that’s encouraging! I was concerned I’d bought a head that had been ‘opened up’ too much and would be unusable!

Still shame it’s been touched at all as I wanted to do this myself.

I’ll get some paint stripper ASAP and take some more photos.

 

[Jack]

yes someone has attempted in porting the ports and half assed it in doing so particularly the guides real poor workmanship. There's still work to be done for you to educate yourself porting these heads. Clean the head up real good,the exhaust port still needs some work. If you're planning on replacing the guide and oversized valves,now is the time to do it before working the ports.

 

[Jack]

Here are some areas in the intake that need addressing ,the guide boss and the ridge behind guide when you're ready

 

[Jack]

The frontal view of the intake guide boss should look simular to this guide when worked.

 

[Bewarethemoon]

yes someone has attempted in porting the ports and half assed it in doing so particularly the guides real poor workmanship. There's still work to be done for you to educate yourself porting these heads. Clean the head up real good,the exhaust port still needs some work. If you're planning on replacing the guide and oversized valves,now is the time to do it before working the ports.

Cheers for the reply and continued advice Jack!

I’m stoked to hear that there’s still work I can do and they’re not a throw away!

By “clean up the head real nice” are we talking a more thorough degrease and clear as much carbon as I can on the Exhausts???

I plan to vapour/soda blast eventually, should this be done after porting work as a final cleaning cycle?

I do plan on installing bronze guides, do all these need to be installed before any porting work?

Sorry for all the questions, I’m a true novice but eager to learn all I can.

Daniel.

 

[Jack]

Soda blast thoroughly first,heat head to 200 degrees for 30 to 40 minutes and drive out the guides,"DO NOT DRIVE OUT GUIDES WITH HEAD COLD"
Then you can proceed working the ports and work the guide bosses after new guides are installed. When installing new bronze guides you want to pull or press them in and not drive them in,the guide ends can mushroom out.

 

[Bewarethemoon]

Soda blast thoroughly first,heat head to 200 degrees for 30 to 40 minutes and drive out the guides,"DO NOT DRIVE OUT GUIDES WITH HEAD COLD"
Then you can proceed working the ports and work the guide bosses after new guides are installed.

Brilliant, cheers Jack.

I’ll get on that and report back.

Hopefully get a copy of your head stand built soon.

 

[Jack]

I just noticed one thing before soda blasting, radius the outer guide the best you can where that idiot butchered the guide ends to prevent gouging guide holes

 

[Bewarethemoon]

I just noticed one thing before soda blasting, radius the outer guide the best you can where that idiot butchered the guide ends to prevent gouging guide holes

Sorry to be a pain but could you possibly illustrate this for me Jack?