Interesting Maybe I should get them ofr a total lift of :

Intake = .578
Exhaust = .591

hmmm.....Thanks for getting me thinking! What was the price? Was it more expensive then the list price for the BB's?

 

if you want that kind of lift just get the more agressive 224/230 cam it comes close to that with 1.6 i'm fairly sure. and you can modify your heads to work with bbc 1.7's i'm pretty sure. you either have to move the studs or the pushrods or maybe valves (cant remember at the moment) then theres the thing where you have to use offset ones and move just one thing dunno i never looked into that too deep usually not worth the money when you could just buy a cam for 100 less than the rockers. you'd have gaskets to pay for but thats like 85 dollars and you still come out ahead.

 

Will 1.7 even fit under the valve cover?

 

i think it might require talls.

 

Id say if you could get roller 1.7s to fit an SBC for even $400 it would be worth it if you already have the cam in. That install was such a bitch that just how easy it would be to drop the rockers on there for an extra .3 lift (if it would even help, assuming it does and doesnt screw up velocity and swirl) it would be worth it. You have $20 oil pan, $20 timing/seals, plus about 10-15 hours of labor doing it yourself, and lots of frustration taking the radiator out and putting it back in. And if you dont already have the rockers, but have the cam you are coming out ahead. Assuming they fit under the covers, anybody know how stable they would be at higher rpms?

 

maybe im missing something but how do you move any of these esspecially the valves.

 

maybe lloyd will answer that question. he knows more about it than i do. i had thrown the idea around and decided against it. if i was going to do it i'd just buy ones that were made for sbc and not have to mess with it. but you have to more the stuff to restore proper geometry.

 

Maybe somebody knows the answer to this tech question. What is the highest lift on a stock bottom end. Say the heads are not decked at all, say with stock head gaskets at .49 or whatever it is, stock pistons, stock valves. It would have to be more than .600 I would guess since lots of guys run that high of lift.

Looks like this would be a really good test, doesnt sound like anyones ever tried it before. Hey, anybody with a dyno like to sponsor this, run it before the rockers, run it after, no other mods?????

 

Thought you guys might like to know this. I emailed compcams about a 1.7 rocker and he sent me this reply:"

Jon
We do have some 1.7 rockers that will fit. How ever you will have to have a
7/16" studs and guide plates, Hardend pushrods, And a .600 lift spring.
Hope this helps.

Thanks
Shane

springs 26918-16
ret. 787-16
rockers 1117-16


On racenet.net the rockers are $339.00, which yeah is kinda high, but 1.6 promags are $280ish, for an extra $80 you get almost .4" of lift extra.

I wish I could get a dyno to do this test on, there is a dyno in the area, but its $100 an hour, and they probably wouldnt let me take the car off to put the rockers on and do it again (its actually a rice shop, so it is fun to run the car on the dyno there).

 

TTT, I want to know the same thing.

 

Both Comp and Crower make a 1.7:1 stud-type rocker. I know guys who've went with a 1.7 and picked up a little power.
You need to know the limitations of your springs though..... ie, check them for coil bind.
I'd also ask the cam manufacturer their opinion on going to a 1.7. Some of the guys I've talked to say that the manufacturers don't recommend it with some of their cams because it "is more acceleration at the lobe than they had designed it for". That may run you into some valvetrain issues. I've used the 1.7's on some older cam grinds with good results but alot of the newer profiles are pretty much maxed-out as they are. I'd check with the cam grinder just to get their opinion. Either that or do the swap and see what happens. You might just decide to go to a better faster lobe before its all over though.

-Mindgame

 

It's not just the lift. The max lift won't be seen until the piston is quite a ways down in the bore. Check it out some time... use a dial indicator and take the spark plug out.... peer in there with a flashlight and you'll see.

The thing is the amount of overlap, combined with the lift. That's where you run into problems as t both valves are open at and about TDC. I'll find an article I have on a solid-roller cam swap on the LT4 shortblock.... I believe they were running tight with that swap so that'll give you an idea. More later.

-Mindgame

 

Thats what I would be worried about, my car wont rev very high, 6500 if I get really heavy footed, but I will normally be shifting at around 6200. I dont think it would be so much the amount of lift, but how fast it will get there, even with 1.7s on my cam .6 springs would be more than enough, but its an XE so the lobes are steep. Im afraid that the rockers wont stay on the valve on the way down, I guess a hydra rev kit might help this, but that becomes very expensive if Id have to get one of those.

Im gonna call around to CC, Crane, Jesel, see what they think. I also emailed Jesel to see if they make a 1.7 for our cars, I dont think they even make 1.6s, but they might just not advertise well.

 

jon,

Jesel doesn't make a stud-type rocker... just the shaft-mounts. If you're running the XE lobe then I'd just talk to Comp... they put a good deal of work into those lobes and will know what they're capable of better than anyone else. Comp does make a more agressive lobe on that same duration.... the 3100 series.

For instance, a 224 on the 3300 series lobe has .503 lift with a 1.5 rocker, .567 with the 3100 series lobe.

Just throwing some stuff at you.

-Mindgame

 

canyou tell me how you get .4" from 1.5 to 1.7. from if you had a cam that had a .520 lift with 1.5. if you put 1.7s you would have a .589 lift that only a .069 gain in lift. not .4