P&P question

[Forced_Firebird]

Re: P&P question

I do porting, polishing and combustion chamber modifications (and build headers, turbo kits etc etc)...









^^^These are some 3500 60* heads.

You can try to port them, but without a flowbench it's like running through the woods with a blindfold on.

I would suggest what some of the others have said and gasket match, then blend the entrance back into the port, and finishing it up by sanding to remove casting marks/seems. Anything before the injectors can be a mirror finish, after don't go any higher then 180-220 grit. Match the intake manifolds to the same gaskets (and mark everything because gaskets can be slightly different from one another). The exhaust ports can also be a mirror finish.

Helps to remove the valves, and try to use some junk ones while grinding to avoid hitting the seats/guides.

Please post results/progress.

[Camarodragcar2002]

Re: P&P question

ZZP isnt the only place for valves. We sell port polished heads, with no core charge.

[Forced_Firebird]

Re: P&P question

ZZP isnt the only place for valves. We sell port polished heads, with no core charge.

What flow bench do you use (sorry a little off topic)?

We do mostly 60* and SBC stuff. The 3500 (3.5l) heads flow about 218cfm @ .500 lift on the intake side - untouched after the factory makes them.


If a valve grind is in the plans, I would suggest a 5 angle valve job (look closely at the last pic in post #16) ;).

[bullit70]

Re: P&P question

forced firebird has jsut the idea i was going for. i am not looking for a full 100% port job but at the same time i don't have the money to buy them 1000 for me is alot of money. but i would just like to get it polished and everything to match up like it should. i know i am not going to get alot if any horse power off the job but i think it is a great suporting mod for FI or NOS. and it would more than likely help with breathing for a cam. i have never done anything like this and i do think your average joe can do somthing thing like this. it might take me 2 weeks to get both heads done but i think if i take my time with it i think i can do it. like you said gaskit match and just make everything even and smoth. now i have two question, the 5 angle valve job were can you get the kit or stones to do that and is there anyone that is selling a used set of heads cheep?

[camaroman1181]

Re: P&P question

forced firebird has jsut the idea i was going for. i am not looking for a full 100% port job but at the same time i don't have the money to buy them 1000 for me is alot of money. but i would just like to get it polished and everything to match up like it should. i know i am not going to get alot if any horse power off the job but i think it is a great suporting mod for FI or NOS. and it would more than likely help with breathing for a cam. i have never done anything like this and i do think your average joe can do somthing thing like this. it might take me 2 weeks to get both heads done but i think if i take my time with it i think i can do it. like you said gaskit match and just make everything even and smoth. now i have two question, the 5 angle valve job were can you get the kit or stones to do that and is there anyone that is selling a used set of heads cheep?

you do not do a valve job yourself. that must be done by a shop that has the proper equipment to do the job right. Check around at local machine shops and performance shops to see who they use and you might be able to find someone who'll do that for a decent price. A lot of heads use a 3 angle valve job, but the 5 angle really helps flow...

[Forced_Firebird]

Re: P&P question

A valve job takes a very specific (and expensive) machines, stones, and craftsman to do. It's not something you can do at home. I have seen used quality valve/valve seat grinding machines go for more than $5k.

[bullit70]

Re: P&P question

good god ya that is really expensive. ooo well i guess i will have to find a shop around here that does that kind of things. i think the biggest thing i am worried about is geting to close to the valve when i do the polish job. but o well a few set of used heads i should get something right. thanks guys.

[crysmatic]

Re: P&P question

i'm working with my engine builder to develop a cnc port for the 3800. we're using 1.84" x 1.52" valves. we actually do outflow abbott. here are a few things i learned:

stick with stock valves. the stock intake valve is 95 g. the 1.84" is 105 g - 10 g heavier. to get the valvetrain weight back down, i'd need titanium retainers. 1.84" is the largest valve you can use - and still make gains. however, you can get quite close with stock valves. SI valves aren't made for FI, so plan ahead.

this is from superflo documentation:
wall friction: 3-4%
contraction at pushrod: 2%
bend at valve guide: 11%
expansion behind guide: 4%
expansion 25°: 12%
expansion 30°: 19%
bend to exit valve: 17%
expansion exiting valve: 31%

forget port matching and polishing - they're worth 4%.
however, 79% is the bowl down!!

get a really good valve job (~$250), then blend the bowl into the seats. have your valves back cut. keep the die grinder and sanding roll moving very quickly back and forth so you won't flat spot. for your purposes, i wouldn't worry about flow testing.

do you really want to learn how to port heads, or do you want a faster car? it'd take my engine builder 6 hrs to fully port a set of heads properly...and cost ~$750. i have a bsme, but my hands can't reproduce what's in my head, like my engine builder can.

hth

firebird...great job on the intake! imo you really shouldn't have port matched the exhaust port...how's the air speed? what do you get on fully ported 3500 heads?

[Forced_Firebird]

Re: P&P question

I'm building a flow bench using fFlowQuik, so I haven't flowed these heads yet, but stock they flow about 218cfm on the intake with the manifold on :D, all I did was smooth the casting marks in the heads because these heads are so well designed from the factory. They are close cousins to the LSx heads on a v6. The exhaust ports got matched to the older 3400 heads (3500 gaskets are huge) and the header flanges are d-shaped and are gettiing matched as well. The port wasn't mached to the gasket, only the entrance, and then blended back to make a smooth transition. Velocity shouldn't be lost because the narrowest part of the port wasn't increased.

Must be nice to have that SuperFlo.

This same method made 270whp 291wtq in SuperDave's Cavalier, and is running a 13.6x 1/4 on top of a 3500 (3.5 litre, 10:1SCR). Now I'm doing the same on top of a 3.4 in a 3rd gen Firebird (more traction, and 1.5 more SCR points). Should be pretty quick for an N/A 3.4 :D

[crysmatic]

Re: P&P question

this thread has pretty much been answered. excuse me for the slight highjacking.

They are close cousins to the LSx heads on a v6.

from the looks of it, the port are WAY taller, and more direct than L92/LS3 heads. is the intake a good match for the heads?

what are the valves sizes? i'm sure a 99 mm bore, and canted valves allows for some monster valves!:eek: i can't wait for the 3.5L 2010 camaro:naughty:

Must be nice to have that SuperFlo.

yes. yes it is. and friends with laser cutters, cmm, and 5-axis cnc;)

[bullit70]

Re: P&P question

ok i just got done reading the posts. now with matching the head to the lower intake manfold on a 3.8 what gaskit would i want to use to match the the two up just like what forced firbird was talking about? and that is what i wanted to do must match the entrence not the whole port so the velocity will stay the same.

[Forced_Firebird]

Re: P&P question

I usually get FelPro, they are generally a little bigger then stock. Someone might know of better ones for the 3.8, though.

[Bonemaro]

Re: P&P question

Ahh... I wish I understood cams and the like. Can changing the cam when everything else is relatively stock make a big difference or is it one of those things that require 5 million supporting mods?

[bullit70]

Re: P&P question

I usually get FelPro, they are generally a little bigger then stock. Someone might know of better ones for the 3.8, though.

is there anyone out there that knows of any other gaskits that are bigger than the felpro? also to you Forced Firebird, is the felpro big enuff to make a difference?

[Forced_Firebird]

Re: P&P question

is there anyone out there that knows of any other gaskits that are bigger than the felpro? also to you Forced Firebird, is the felpro big enuff to make a difference?

You can use an exacto knife to trim the gaskets bigger, but the 60* motors have a metal LIM gasket available that is quite a bit larger then the stock (or standard FelPro's). I haven't done a whole lot of research on the 90* v6's to be able to answer that.