I have searched the threads and not really found an answer to my question so thought I would ask. I have seen in summit and other catalogs that they sell 1.7 for 7/16 studs but none for 3/8. Is this for strength issue? Also if I did the switch so I could run the 1.7, will they clear stock valve covers? I am thinking not but thought I would ask. Last question is I know the hot cam at 1.5's is at 495/495, the 1.6's that come with make it 525/525. So with 1.7 it would be 555/555 or is that not a fair assumption?

 

If everything is done correctly, I dont see an issue witha 3/8th stud. The 1.7 will not fit under a stock cover, I personally had to move to lt4 covers to get 1.6 to fit.

As for the numbers, I would have to let someone else chime in.

 

I had to modify my LT4 Composite VC to make my ProMags to fit

 

When I did my 1.7 install, I did not come across any 3/8" 1.7 rockers, or any self aligning. The 7/16" studs are cheap enough, and I would recommend upgrading, as you'll need to remove the stock studs to install guideplates anyway.

They will not clear stock valve covers, at least not unmodified ones. I ended up going with the LT4 covers as well, and they clear the scorpion 1.7 rockers without modification.

Check out this thread for lots of info on the 1.7 conversion. If you are thinking of doing it as a cheap way to gain some lift, don't bother; as it was not cheap to do. If you are planning to do a cam, just stick with 1.5 or 1.6 rockers and get a cam with the amount of lift you are looking for.

Regards,
Thomas.

EDIT: Just read your sig and see you already have the hotcam installed. Something's wrong with the #'s you posted though, and I don't think they're right. A '96 - '97 stock cam is .447 .459 with 1.5 rockers. So 1.7 would be:
[(.447 / 1.5) * 1.7] = .5066 Intake
[(.459 / 1.5) * 1.7] = .5202 Exhaust

Not sure what the lift numbers are for the hotcam, but you can see how to perform the calculation.

 

I appreaciate the advise and help, but allready did my cam swap when we rebuilt and did not want to tear it all apart again. I didn't think it would be cheap, just less tear down. Something I could get done in a day

 

A guy on the Corvette Forum switched from 1.6 RR's to 1.7's on his Hotcam, and gained 14 rwhp.

 

Ya, completely understand. Are you running guideplates with your current setup? and what springs are you using right now?

Thomas.

 

The LT4 HOT cam with 1.6's is 0.525/0.525. With 1.5's its 0.492/0.492.

With a 1.7:

(1.7 / 1.6) X 0.525 = 0.558"

 

No guide plates and am using the springs that came with the lt4 kit.Hardend pushords. That's about it.Is it probable that I would need to upgrade the srings as well?

Injuneer, thanks for the math, I was curious.

With the exception of having to change the springs, 10-14 rwhp would be nice for a few hours work.

 

Yes, you will need to upgrade your valvesprings when running 1.7 rockers. The LT4 springs you are running are marginal with 1.6 rockers.

 

In addition to upgrading the springs (The LT4 springs you have now will most likely bind with the added lift of the 1.7s), you'll also need to install guideplates and 7/16" studs; unless you can find 1.7 self aligning 3/8" rockers. I used the GMPP guideplates, and had to modify them to work with the added throw of the 1.7 rockers. The pushrods were bottoming out on the plate, so I extended the notches in each plate about 1/8".

Also, consider the added stress on your lifters. Did you replace the lifters when you did the cam? When I swapped out the stock springs for the Comp 26918 beehives, I lost a lifter and ended up replacing all 16 with stock LT1 lifters.

Thomas.

 

No I didn't change out the lifters, they have 140k on them. I have had one other OEM roller engine with lifter with closer to 200k on them and thought that they would be fine. So I should also consider changing lifters too then or will I be ok with mine?

 

who knows ..... it's a gamble I suppose. Mine had 118k miles on them, and I thought the same thing. when I got it all back together, #2 wouldn't adjust properly.

You can read the thread I linked to in the above post for a full account of my experience.

Thomas.

 

Another thought I had is again with the springs, if I increase spring size, is it possible to reach bind too early due to the valve stems not being long enough? Would beehive springs like the LSx type cure this. What about going nuts and going to 1.8? I have been adding up the parts cost and seems to be about the same and with a set of really tall valve covers(custom fab) shouldn't be an issue right?

 

I am running Harland Sharp 1.65rr's 3/8" under unmodded valve covers. Mods in sig. Been running great.