Sharpe

iTrader: (7)

I just purchased a 225/229 .580"/.590" on a 114+4 cam and spring kit from Patriot. I have a set of stock 241's that I'm going to disassemble, inspect, clean, and put new valve guide seals in at the same time that I'm installing the springs.

While they're off, should I mill them? IF SO, BY HOW MUCH? <-- Very important part of the question.

Or, should I run a thinner-than-stock head gasket? IF SO, WHICH HEAD GASKET? Part number?

This is my first big foray into performance building. I'm doing all the work myself in my garage.

Thanks a lot, guys and wish me luck!

tilly

iTrader: (5)

I am quite curious about this too. I would like to do something similar with my 853 LS1 heads. Would like to achieve 11.2:1 to 11.5:1 compression ratio on a stock bottom end.

And where could I send the BARE heads off to to have some one else port, mill and do a valve job possibly.

Sharpe

iTrader: (7)

Bump for mill/gasket and compression ratio info. There is already a thread (which Tilly posted in) about porting heads so no thread hijack on that.

BigKap94z

iTrader: (47)

I would probably mill the heads, you can have them milled with the money you save by running GM MLS gaskets instead of thinner cometics. I would mill them .030", you should still have safe piston to valve clearance as well with this setup.

BTW is there any advance ground into that cam? I'm unsure of the info on that cam, whats the advertised duration for that cam as well?

Sharpe

iTrader: (7)

No, no advance ground in. Other than 225/229 durations, I'm not sure what you're asking about.

What would my compression be milling them .030"? I want to run it on 93 octane 95% of the time, with very rare quarter tanks of 91...

EDIT: I was wrong. There is 4* of advance ground into the cam.

will69camaro

iTrader: (19)

Well I ran my old setup (230/236 cam and 243 heads) with .015 off the heads and a cometic .040 gasket (.015 thinner than stock) which in total is .030 off setup. I hear for every .007 off the head its ~1cc off stock. Since 241's are 66cc heads if i'm not mistaken id say you could take them down to 62-63cc without a problem. I ran the cometic gasket because it would be easier to change out the gasket if i had a poor calculation or had PTV clearance. I could just pull the gasket throw a stock one in and be on my way. Mill the heads too much and you have to run a thick head gasket or get a new set of heads.

Kinda hard to tell someone how much is "safe" to mill their heads or what would work best with their combo. Look up the DCR calculator in the advanced tech section and play with it some with your cam/heads and see what you can get the dynamic compression ratio too. Old motor was 8.6:1 and this one should be closer to 8.7:1. Static on both those was around 11.5:1 and 11.25:1 respectively.

William

BigKap94z

iTrader: (47)

I am asking about advertised duration, your giving duration at .050". I am asking just to determine lobe choice thats all. Your compression ratio would be right around 11:1 depending on gasket thickness.

1CAMWNDR

iTrader: (21)

There is also a pushrod calculator somewhere on here so you can put in the basecircle of the curent cam, base circle of the new cam, new gasket thickness, and new head mill and it will tell you what length pushrods you need.
I used that to try several combos untill I got what I needed to keep my 7.4" pushrods.

seawolf18

iTrader: (18)

LSA: 114+4, according to the patriot web sight.

Sharpe

iTrader: (7)

Thanks for all the replies and the specific info. This gives me some good info to work with when talking with sponsors.

I was talking to a local head porter who does Gen 1 stuff. He said the stock compression was as high as he would want to go on the street and that "If you go to taking too much off the bottom, you're gunna have to take some off the exhaust side too."

I don't even know what that means.

BigKap94z

iTrader: (47)

WOW. I wouldn't walk to the door of that guys shop, I Would RUN.

To be very generic in my answer; You can easily run 8.5DCR on pump gas. I don't know alot about what lobes are used to find an exact answer but with Comps lobes in the 224-226/228-230 size You would need the chamber size of 63cc to get to 8.4-8.5 DCR. Milling of the heads 0.006 or 0.007 will remove 1cc of chamber size. So average the 2, 0.0065 would be 1cc off the chamber size, you would need to mill approx. .024" off your heads. I would call Gunner and take consider his suggestion on how much you can mill and still have safe piston to valve clearance with that cam.

Sharpe

iTrader: (7)

Thanks. I'm calling Big G after lunch.

EDIT: Called Patriot. They said they would have Gunnar look at this thread...

Sharpe

iTrader: (7)

BUMPS for Gunnar.

Gunnar@Patriot

iTrader: (20)

We would suggest going with a new set of 243 heads. We can mill them to 63cc to give the compression you are looking for, they will flow around 20 cfm better than the stock heads, you can use your parts, and for $395.00 per pair bare, would probably be close to the same price as having your heads cleaned, milled, etc. If you have any questions, please let us know.

Sharpe

iTrader: (7)

Well, yeah, that would be wonderful, but I don't have an extra $400 laying around. You already got me for $550+. I selected my cam from you because I plant to add your heads later.

Got my cam and springs from you today after ordering them Monday. Fast shipping!

The shop knows me real well and is going to inspect, clean, assemble (with springs) and mill them for $40. So, that's the route I'm going to have to go.

So, you're saying that 63cc is what I'm after? Are stock heads 66cc? If so on both counts, would that mean I need to mill them .021"? Is that good for 93 octane?

I also need to know what hieght to set your springs up at. Some people say 1.81-1.82, others 1.74-1.78... I mean, I have no idea. Stock 241's, your cam and your springs.

Please advise. Thanks.

BigKap94z

iTrader: (47)

The stock heads are 66-67cc. If you can have them milled and assembled for the price you quoted thats wonderful. You will be fine with a 93 octane, afterall your only picking around a 1/2-3/4 point of compression with reducing chamber size by that small of an amount.

Alot of people don't even shim those springs with much larger more aggresive cams. When installing i would probably just install them at 1.80", they should install that way out of the box i believe.

Sharpe

iTrader: (7)

Just got off the phone with Gunnar. Wow. That guy knows his stuff, and he is helpful! Glad I went with Patriot!

With some quick calculations and without me checking the piston to valve clearance first, Gunnar recommended a safe .010" off with a .040" or .041" graphite gasket (he said Felpros are .041" gaskets). He said that would take me to a safe, streetable 10.4 or 10.5:1 compression ratio. That's what I told him I was looking for; not on-the-edge performance. My engine has 113,000-miles after all.

He said I would still have to check my PtVC, but it sounded like a "don't blame me if you blow your car up" disclaimer.

Also, he recommended installing my springs at 1.800.

Thanks a lot for the info, Big G!