randy442

I have a 66 442 that came with the stock Quadrajet set up. Many years ago I got a Olds tri carb setup, so I want to run a W-30 cam in it. My research says that the profile for that cam is .474 lift for both intake and ex. 308 duration for both intake and ex. and 82 on the overlap. Well, with the lifter bank angles and all that taken in to account, I should be able to use the W-31 cam that Mondellos sells. So I got one, but the cam card says: 474 lift for both, good, then it says "running duration" 329 intake and 328 ex. , whitch makes it sound more like a 1968-1970 W-30 cam.

It also list the "Gross cam lift" at 296 for both, and "Duration at .050" at 232 for both and "lobe centers" at 113.

What am I missing here?

Nufo

I think if you take the "Gross Cam Lift" as stated on the cam card and multiply it by the "rocker ratio" in this case I believe 1.6 to 1 it will come out to the valve lift of .473... don't understand the difference in the other numbers though.... somebody jump in here....

Nufo

are both the specs for duration you researched 308 and the duration quoted on the cam card 273 both measured at the base circle? As noted in your posting the duration for the cam card cam is measured at .050 lift. Is the duration for the "Stock" cam measured likewise? If NOT then there is possibly the difference in duration figures. Again, anybody else want to jump in here. I could be off base, it's been awhile since I researched cams and how different manufacturers like to play with numbers....

Nufo

sorry you quoted the card as 232 not the number I gave... you get the idea though...

randy442

The 308 number is from the tech info on the 442.com website and also from the mondellos technical reference manual. I double checked this again and it does state the 308 number @ 0". So that would explain the 232 @ .050". BUT what does "running duration" at 329 mean. If its 308 at zero lift then how can it be more than that?

Nufo

I'm gonna go out here on a limb probably but as I recall through the cobwebs I have in my head after such a long time, that as the rocker ratio changes, so does the duration. Perhaps not linear but it does change. Also a simple adjustment in your valve adjustment can affect duration. Check the two different cam specs to see if you can determine what rocker ratio they are talking about. Still waiting for a professional to jump in here.... good luck

Nufo

perhaps Joe P. will take an interest and provide his insite....

cutlassefi

I have a fair amount of cam experience.

Here you go;

.296 lobe lift equates to about .473 lift. It may have .29625 then they would round up.
Actual lift at the valve will be somewhere around .460, you have pushrod deflection and lifter dynamics to contend with.

Increasing rocker ratio does not increase actual duration. Duration figures are taken at tappet lift not valve lift so the ratio doesn't impact that part. However what it does do is make it act like a bigger cam because it will increase effective duration, pushing the valve open higher sooner and you're now holding the valves open farther at overlap as well, just like if you were to increase duration and/or decrease/tighten lobe sep.

A valve lash change really only impacts the duration on a solid lift cam. Tighter lash makes the valve open sooner, effectively increasing duration.
That's a good way to tell if you have the right cam, if it runs better with tighter lash then your cam is too small, if it runs better with it looser then the opposite is true.

Hope this helps. And never heard of running duration, I'd ask them to explain that. I'd be interested in their answer.

Nufo

sounds like you got your answers ...

randy442

THanks for the responses and yes I will call those guys to see if they can splain that s%#t.

ah64pilot

Your best bet is to call Engle, they used to grind most of the Mondello cams...now Mondello is selling the lowest bidder stuff unless you get a specialty grind which still comes from Engle.

If anyone is going to be able to explain it to you, it will be Lynn...but even then I have my doubts. If you talk to Jr. you're wasting your time.

randy442

Called Mondellos today and asked what "Running Duration" was. Long pause on the other end, then he said that was advertised duration. Asked why the original cam was advertised at 308 and this one was 328? Said call back later and talk to Lynn.

Called later and Lynn said the difference was in the base circle size. Ok, so this cam has a larger base circle size of .020, right?

I later thought....so will this cause a problem with push rod length?

I will try and call Engle tomorrow and get another opinion.

1969w3155

Ask for Doug, I believe that he is still there...he was bought out, but I understand that he is still with the company.

randy442

The 1966 442 400 cid engines were all 39 degree lifter bank angle. At least mine has the proper drill spot that says that it is. Tried to call Engle cams today but they close early on fridays.

cutlassefi

I'm not sure why anyone would want that, there are much better grinds out there today.

Jmo.

costpenn

PM sent to the OP.

Like I said, I've got several of the ones made by EPC (Engine Power Components) for Olds OE & service back in the early 70's. It was pretty cool getting to see the prints with the customer denoted as Oldsmobile/GM.

67442nut

Not sure about '66, but, as I recall, '67-'69 W-30's had a 308 duration with automatic transmission
and 328 with standard shift.

randy442

Here is a link to camshaft use thru the years at 442.com. Mondellos list also agrees with this.

http://442.com/oldsfaq/ofcam.htm#Cams

sorry, I dont know how to make it a click on link.