Reworking C heads

[CJK440]

I have a pair of 99 C heads that I tore down and am bringing to the machine shop soon. I think I will need new exhaust guides and of course seats re cut and valves ground.

I planned to blend the cast port and the bowl machining myself. Only goal is to smooth the transition and round the sharp edge on the short side radius. I do not plan to "port" the heads nor do I want to pay for a full port job.

This is not a max effort build but I'd like to take advantage of any cost effective modifications while I have the heads off and apart.

I read about cutting the seat ID's larger but that seemed to be geared toward B heads. Do 99 tumble ports suffer from a small seat ID?

Any other ideas?

 

[na svt]

all 4v seats need to be opened up.

 

[CJK440]

all 4v seats need to be opened up.

OK, considering that these heads will only get a little cleanup in the bowl area and not a full port job, do you think the cost/work to bore out the seats worth the gain in my application as a healthy street/autox car? I'm planning on a stock 4V bottom end, these heads of course, 106100's and long tubes.

If so, what is the target diameters for each? I think I saw 90% of the valve diameter?

 

[na svt]

90% of the iv dia and 85%/of the ev id.

Yes, it will be worth the gain.

 

[CJK440]

I have my guy looking into cutting the seat ID now. I'm wondering if the cost of opening them up, installing new guides and a proper valve job will get close to the cost of a set of already reworked heads from any of the players out there.

 

[na svt]

The shop that does my valve jobs will enlarge the seats for free when doing a valve job ($350).