3800 I have a lot of cam swap questions

[v6buicks]

don't you have 1.9 rockers though? That is why you check clearances.

Yeah, but I'm not using them with the cam.

Those are for sale on marketplace by the way. Shameless plug.

 

[sktchy]

So, what your saying is make sure the rockers arent shoving the retainers into the seals then?

I guess I'm not quite sure how much added lift the 1.9s give without doing some research but this could be probably be valuable information to someone looking at cam swaps.

 

[GTPpower]

You need to have a certain amount of clearance between the retainer and seal. Exactly how much, I can't remember offhand. For some reason .040" rings a bell.

I don't think there are any cams that can run 1.9's without head work.

 

[Mr_Roboto]

Get the clearance do both lol.

So, what your saying is make sure the rockers arent shoving the retainers into the seals then?

I guess I'm not quite sure how much added lift the 1.9s give without doing some research but this could be probably be valuable information to someone looking at cam swaps.

stock rated lift/stock ratio*new ratio. These heads seem to stall flow wise at .5 looking quickly but you really want lift to be near peak flow lift/.85 due to the cam not spending a lot of time at peak lift.

1.9 is a lotta ratio though so I am not sure how that would play out. The thing to do would be machine the guides down for smaller seals. if possible.

 

[v6buicks]

Get the clearance do both lol.


sotock rated lift/stock ratio*new ratio. These heads seem to stall at .5 looking quickly but you really want lift to be near peak flow lift/.85 due to the cam not spending a lot of time at peak lift.

Lol I like the attitude, but I don't think there's much point without putting bigger valves in. I might be wrong about that though. Maybe Yates will come out with his "max effort" aluminum heads soon. $$$$

 

[sktchy]

I mean that's kinda what I was getting at I guess. Like stock cam lift to be able to figure out how far the 1.9s would push the valves compared to say somethin with like a .560 lift

 

[Mr_Roboto]

Go read how to build horsepower by Vizard. you will probably question your cam choice after though

 

[sktchy]

I wouldn't particularly say I'm dead set on the idea but ill check it out. Surely more lift/duration is going to drop cylinder pressures reducing potential for knock and therefore allowing for more power but it's more a matter of how far you can push things before you have to take the heads in?

 

[Mr_Roboto]

You would be taking the heads in for sure at .6 if convention is .54ish is max.

 

[sktchy]

The st5 looks to be .544 .536 so that's probably on the hairy edge of things? So if you tried to run somethin like the intense nitrous/blower cam at .539 .562 you'd smash the valve seals out of it?

Also why would one prefer the intake valve to open more than the exhaust valve or vice versa when it comes to choosing a cam?

I'm just kinda trying to figure out what a guy could get away with and adding a little content to this thread for anyone that may come across it. Weird for me to be asking actual questions instead of just slappin somethin together til it blows I know

 

[sktchy]

Also after looking up stock cam specs both intake and exhaust lobe are .413. Divide that by the stock ratio of 6 you get .0688, multiply by 9 and your at .6194

So, either my maths way off or we should be machining valve guides for 1.9s?

 

[SleeperLS]

If this reference helps at all…. I had an S1X cam and 1.8YT rockers in my Monte. I had to get stage 3 heads for clearance. Similar spec heads to the ZZP stage 3 heads.

 

[sktchy]

I guess my thoughts are if the 1.9s are pushing out to .619 and they're fine then why do we have to machine the guides over .540? Something isn't adding up here but it's probably just my math ?

 

[Turbocharged400sbc]

Missh it's really easy if you use an old valve in each guide as you go along you can use the old valve and the head spaced off of your workbench as a guide for stopping you at the correct depth but then you just Chuck a half inch drill bit in your drill and you drill away the top of the guide tell it stops on the end of the old valve repeat for the rest of them and then clean up with a small little 3-inch roloc die grinder read redo the chamfer around the outside for the seal install and walleye you have .1 inch more cam lift clearance

 

[Mr_Roboto]

should be lift w/stock ratio*1.9/1.7 or lobe lift*rocker ratio.

p2v clearance may be an issue too and I didn't think of that. you guys are probably right simplicity is better vs wringing out every last hp.

 

[Mr_Roboto]

Shit like this is where I miss having desktop dyno or engine analyzer pro.

 

[GTPpower]

Also after looking up stock cam specs both intake and exhaust lobe are .413. Divide that by the stock ratio of 6 you get .0688, multiply by 9 and your at .6194

So, either my maths way off or we should be machining valve guides for 1.9s?

.413÷1.6= .258

.258×1.9=.490

So, .490" lift with a stock cam on 1.9's.

 

[sktchy]

Isn't stock ratio at 1.6 tho? That would make more sense and would put it at .490 with 1.7 it'd be at .461. So my math was definitely off

 

[GTPpower]

Lol I like the attitude, but I don't think there's much point without putting bigger valves in. I might be wrong about that though. Maybe Yates will come out with his "max effort" aluminum heads soon. $$$$

Get on the list! We need 19 more people for it to happen!

 

[GTPpower]

Isn't stock ratio at 1.6 tho? That would make more sense and would put it at .490 with 1.7 it'd be at .461. So my math was definitely off

Stock ratio is 1.6 - 1.66 depending on the year according to gm.

 

[GTPpower]

Missh it's really easy if you use an old valve in each guide as you go along you can use the old valve and the head spaced off of your workbench as a guide for stopping you at the correct depth but then you just Chuck a half inch drill bit in your drill and you drill away the top of the guide tell it stops on the end of the old valve repeat for the rest of them and then clean up with a small little 3-inch roloc die grinder read redo the chamfer around the outside for the seal install and walleye you have .1 inch more cam lift clearance

Lol. I've even see people take an angle grinder to them.

 

[sktchy]

Missh it's really easy if you use an old valve in each guide as you go along you can use the old valve and the head spaced off of your workbench as a guide for stopping you at the correct depth but then you just Chuck a half inch drill bit in your drill and you drill away the top of the guide tell it stops on the end of the old valve repeat for the rest of them and then clean up with a small little 3-inch roloc die grinder read redo the chamfer around the outside for the seal install and walleye you have .1 inch more cam lift clearance

So, pull the springs, space the old valve .1 under the top of the guide and drill down til you hit the valve then clean it up with the die grinder? That seems fairly simple but you'd have to be fairly precision when finding a way to space the head off your bench to make it work. But say you left the head on the bench with the valves off and used your calipers to measure distance to your bench and took .1 off that? You'd accomplish the same?

 

[sktchy]

Lol. I've even see people take an angle grinder to them.

This seems sketch even for me ?

 

[GTPpower]

I just take it to a machine shop. Last time I did it, it was like $30 for both heads.

 

[Mr_Roboto]

Whoops, 1.6 would be even higher lift difference. May be thinking Ferd or something.

You'd be at .646 and 0.6365 with 1.9s and that cam. If you multiply those #s times .85 you'd end up with .5491 and .541 as the desired peak flow lift. Yeah, you're not gonna get even close with these heads based off ported #s I've seen. Definitely doesn't seem worth the headache. If you had heads that flowed near .55 I'd give it consideration but these just aren't those heads.