CrawlerXJ

Ok, the cam thread is done. I ordered the "231" Comp cam. Now, need to find some bigger valves for the head. New topic

I see 1.94, 1.97, and 2.02 (factory is 1.92) I would like to get the 1.97 Mopar performance ones.

http://www.summitracing.com/parts/dcc-5249877

Can I use the Mopar performance springs without head work added?
http://www.summitracing.com/parts/dcc-5249464

fedx95

Bump for a really interesting and original Question!!!
Hopefully someone can reply, i will be doing the same in the future (who knows when, but definitely an engine mod i want to pursue)

CobraMarty

So from Summit-
$126 Intake valves ($21eax6)
$132 Springs ($11eax12)
$168 Exhaust valves 1.56" ($28eax6)
$426 Total -But still need keepers and locks and ?valve seats and Labor.

How much was that complete new head?

CrawlerXJ

Agreed.

Here is my thought and some of what I read. The bigger valves only come into play after 4000 rpm. I am $426 + $400 to have machine shop do it. That's $826. VS, 505 has a head for $775 + shipping. I heard people sueing 505 and not sure I want part of that.

Or, I can do (drum roll) roller rockers. Ya, ya. I did order/receive my "231" cam and lifters. So, if I go with roller rockers (which I get power out of the gate) do I go with 1.6 (since I have a cam)?

3/8 or 5/16 stud?

http://www.summitracing.com/search/y...ller%20rockers

CobraMarty

Neither. get one of these and they fit under the stock valve cover and gasket (no spacer or taller valve cover needed).
http://www.ebay.com/itm/Yella-Terra-...ae7ad3&vxp=mtr
http://www.ebay.com/itm/Yella-Terra-...ae7e8b&vxp=mtr

What is the lift specs of the 231 cam again?

CobraMarty

I am almost positive that they are 5/16".
Actually the second set of the Harlands look good, they have the bar tying 2 rockers together. That is what you need. But only 1.6. That might not be an issue depending on the cam and springs used.

CrawlerXJ

I'll use Mopar performance springs you posted for springs.

1.6 or 1.7? Is 1.7 not needed since I have a cam. Confused there.

231 specs

Cam Style:Hydraulic flat tappet

Basic Operating RPM Range:800-5,000

Intake Duration at 050 inch Lift:206

Exhaust Duration at 050 inch Lift:214

Duration at 050 inch Lift:206 int./214 exh.

Advertised Intake Duration:250

Advertised Exhaust Duration:258

Advertised Duration:250 int./258 exh.

Intake Valve Lift with Factory Rocker Arm Ratio:0.462 in.

Exhaust Valve Lift with Factory Rocker Arm Ratio:0.485 in.

Valve Lift with Factory Rocker Arm Ratio:0.462 int./0.485 exh.

Lobe Separation (degrees):111

Computer-Controlled Compatible:No

Grind Number:A6 X4 250H-11

Valve Springs Required:Yes

CobraMarty

Intake Valve Lift with Factory Rocker Arm Ratio(1.6) :0.462 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio(1.6) :0.485 in.

Valve Lift with Factory Rocker Arm Ratio(1.6) = 0.462 int./0.485 exh.
Valve lift with Aftermarket Rocker arm ratio(1.7) = 0.491" int./0.515"

IDK if that extra 0.030" lift at that point will make much difference. On a stock lift cam, that 0.030" extra difference will make a difference.

CrawlerXJ

Mopar springs only handle .500 or .525?

Ok, I re-read. I follow. So, 1.6 factory or roller is the same. To gain, I need to go 1.7. But, your thinking maybe not worth it? Also, not sure the Mopar performance springs can handle .515?

CrawlerXJ

Also, do I have pressed in studs or screw in studs? Not sure what the article said. But, it recommended over .500 to go with srewed in studs.

CobraMarty

The factory rockers are stamped steel and not very precise and are 'supposed' to be on average 1.6 ratio. The 'rollers' are exactly 1.6 and with the roller surfaces, have less friction than stock and that is why they can make ?3-5hp, quieter, better mileage. The 1.7 should make 10-15+hp.
The stock head doesn't have rocker studs, it uses bolts to fasten the rockers to the head and I think 5/16" at that and 5/16 might be at or near it's limit at 0.500" lift. IDK, low reving 4.0 engine might be OK.

CrawlerXJ

You sound like roller rockers aren't a good idea? Or am I miss reading? Sounds like their real close and maybe not a good.

CobraMarty

Just the opposite.

CrawlerXJ

So, its not close? You says it's ok to get the 1.7?

CobraMarty

With your cam, 231, Mopar Performance springs, I would use the 1.6 ratio rollers.

The head won't flow much more with the additional lift of the 1.7 and the the additional lift will bring higher spring pressures at max lift and potentially more risk to flatten the cam and lifters.

With a stock cam, stock springs, 1.7.
With a Mopar 28 cam, stock springs, 1.6.
With a Mopar 28 cam, Mopar Performance springs, 1.7.
With a Comp 231 or 232 cam, Mopar Performance springs, 1.6.