So does anyone have any before/after dyno numbers with these rockers?

 

Maybe a more knowledgable guy like Bret will chime in but i'd personally go with the 918's that way when you decide to add a cam you'll have some springs you can really work with.

 

I am using the 987 springs with my 1.7 stock cam install. Been going strong for over a year. Lift is right at .510 .521 I believe with my stock 96 Lt1 cam.
IMO the 918's is way to much spring with the stock cam and 1.7 setup, Now if you were to add a cam then the 918's would be perfect then.

 

exactly why he should do the 918's now in my opinion. I hate changing springs so i'd only want to do them once. Thats why i suggest going with the 918's.

 

I did end up going with the 918s due to reported issues of the 987 inner spring contacting the valve seal; and because the 918s have less open spring pressure than the 987s. The 918s have more seat pressure, but less open pressure due to the spring rate.

I'm now waiting for my new lifters to arrive before testing out the new setup. The car is parked until the new lifters go in.

It seems changing spring pressure from ~86 lbs/in seat and ~250 lbs/in open (new stock spring pressures) to ~145 lbs seat and ~300 lbs/in open (918 pressures) was just enough to send a 118k mile lifter over the edge.

Thomas.

 

I finally got some time to upload pics of the install to cardomain.
Check them out here: http://www.cardomain.com/ride/491988

Thomas.

 

Well, the new GM lifters are in place, and I changed the pushrods to Comp chromoly 7.150" one piece rods. The wear pattern is now centered, so I'm glad I did that. The noise problem with the intake rocker on cyl#2 is now resolved, but these things are still very noisy.

I set valve lash 3 times, with the motor running, and I cannot get rid of the clatter. I ran a search and found others who said their Scorpion 1.7s were also loud, but got quieter over time.

I've put about 20-25 miles on the car now, and pulled it back into the garage to have another look at the setup. Here is what I found:



The pushrod is definitely making contact with the GM guideplate. This is why others report the noise getting better over time; the pushrod wears the guideplate away.

I am now in process of taking the guideplates off to open them up further. I just don't like the idea of the pushrod doing the clearencing on the guideplate

Thomas.

 

Why would you spend all that money to still have a stock cam? If your on a budget an LT4 Hotcam Kit is cheap. What gains are to be seen with this vs 1.6's?

Don't get me wrong, I understand in a SI class this would be a good idea and I think this is a great compilation thread for the subject, sure makes it easier for somebody to find everything needed in one post.

What are you guys going to do when you go with a larger cam? The lift is going to be high and will probably have to change out your valvesprings again after all that hassle and money spent.

 

If I started adding up what each project costs me when I'm done, I'd never begin any of them! I also have an '84 Blazer (which is my actual project vehicle -- the Z28 is my daily driver), and I don't even want to start thinking about how much that beast has cost me over the years.

I see this setup as being able to last the life of my car, no matter what future upgrades it may get. If I do decide to go with a cam later on, I can always get a custom grind for this setup.

But, you are definitely correct; I could have spent the same amount and installed the Hotcam kit; but then I wouldn't have 1.7 RR

Thomas.

 

Good job on the thread!! Let us all know the gains! Not sure if it says in your sig or not, but what do you plan on doing with the Blazer? A co-worker of mine had a mid 80's that was all ragged out, when we went on our lunch break it would squeak and get alot of attention.

 

Yee Ha! The install is done, and it's quiet!. I took all of the guideplates and ground down aprox 1/8", extending the pushrod guide hole. Reinstalled everything and the valvetrain is now very quiet.

Everyone who is complaining of valvetrain noise with the scorpion 1.7 RRs is most likely hearing the pushrods hitting the guideplates. I actually expected this setup to make more noise than it is making!

Now to break it all in. I plan to change the oil after 50 miles or so, then wait a good 300 miles, reset valve lash, and head to the dyno. I am very interested to see what kind of numbers I'll get with stock manifolds and a stock catback. (I will definitely do one run with cutout open for comparison). Then next year, when the SLP shorties go on, I'll go dyno again to compare.

Thomas.

 

Any news pics of the ground down guideplates? A before and after compasion? Congrats on finishing and most of all, being satisfied with the end product

 

I thought about taking pics of the guideplates after the grinding, but I didn't have an unmodified one to compare to anymore. I just used a bench grinder to extend the notches about 1/8".

Thanks for the congrats! It's a very satisfying feeling to have it all done with no unknowns. I really did not want to run it with the clacking, even after reading other's posts that it would get quieter over time.

Thomas.

 

grinding won't mess up the geometry of the pushrod? Or does the guide plate just hold the pushrod in place from moving from left and right. Sorry if this doesnt make sense.

 

Makes perfect sense, and you are correct. The guideplate keeps the pushrod from moving right/left, which in turn keeps the rocker from rotating around on the stud, which in turn keeps the rocker's roller tip centered over the valve stem.

What was happening, is on full valve seat, the pushrod was bottoming out on the guideplate. when I spoke to a guy at Scorpion (beofre I purchased everything), he cautioned me to check for this if I was going to install his 1.7s on a stock LT-1 head. I guess his comment is what made me open it back up and check; and I'm glad I did!

Thomas.