Sweet.. Im excited to see your dyno numbers. This might be a project for me to do later this summer.

Rob

 

Any updates on this? Was it a well worth it to go 1.7 over 1.6? If it gives you a good gain, I know exactly what I am doing this summer

 

Awesome write-up on a subject that many LT1 owners have been patiently waiting for results. So, would you say if someone was doing this install that you should get the 7.150 " pushrod for sure ???

 

Well worth it? I guess that depends on your goal. This was not a cheap mod to do. The price of the mod was really driven up by the cost of replacement lifters and swapping over to LT4 valve covers. These 2 pieces of the install alone added up to about $500 ($200 for lifter package, ~$300 for LT4 covers and hardware).

Personally, I think it was well worth it becaue I really learned a LOT on how the valvetrain works. I've been working on vehicles for over 15 years, but never really set up a valvetrain before. So this was a great experience for me. I took my time, choose parts carefully, and did ample research to make sure I installed a solid setup. I like having the LT4 covers (I think they look a lot better than stockers) and didn't have to bend or cut anything for clearence.

I don't know about the gains yet, but I do have a Dyno run scheduled for March 11th. I'll post the results afterwards. I did recently hook up a laptop with Datamaster, just to check everything out. I made several full throttle, redline runs and everything is looking good. No knock and mixture looks fine.

As far as 'how it feels'? I normally don't like guessing on performance by 'feeling' it; but it does feel good. It seems to pull harder in the upper RPMs than before the swap; but this could just be my brain wanting to see gains after 2 weeks of installing everything! Remember, I don't have headers yet; so the gains might not be as high as they would if I did have headers installed (SLP shorties are planned for the future).

After checking valve stem geometry, I definitely needed the 7.150" pushrod. I would recommend you check your geometry if you want to do this install. There are too many variables in play to just say 'Yes, use the 7.150" rods'.

I have a stock cam, new GM lifters, stock block, original head gasket, stock heads & valves, and Scorpion rockers. With this combo, the 7.150" seems just about right.

Thomas.

 

You said you had to change the lifters as well. I read through the thread and didn't notice anywhere as to why you had to change those out. Maybe I missed it, but is that a necessity to replace? I could imagine so with the extra stress in the valve train now.

 

I thought somewhere in this thread I had it documented? Maybe I forgot to. You can read about it here.

To sum it up, I believe the added spring pressure of the 918 springs was enough to cause a 118k mile lifter to fail. I ended up replacing all 16 lifters with stock GM ones from Jason Crower.

Thomas.

 

Dyno results are in! I went down to Colvin Automotive in Austin today, and ran 3 pulls. 1st pull with cutout closed, 2nd with cutout open, and 3rd with it closed again.

Environmental Conditions were:
91'F | 29.0-0.49in.Hg. | CF=1.04





I only wish I had dynoed the car before the 1.7 install. Oh well, I think this thread is finally done

Thomas.

 

Now get some decent headers and hit 300rwhp

 

Congrats... every bit helps! I did see one thing that really looks good to me though, that your cutout helped out. My car is with the mechanic right now getting some valvetrain "issues" fixed and the cutout installed. If I can pull the same gains you showed (which backs up what people are saying about cutouts), my HP and torque will be up noticeably (crossing fingers ).

When my valvetrain issues showed up, this thread on 1.7's was the first thing I thought about. It's ashamed you don't have a "before" graph though to make some comparisons against.

 

TTT for this thread! This is an excellent read!

 

Question: How does one modify stock LT1 Valve Covers so that there is enough room for the 1.7's? Dremel? Hammer?


btw, fantastic thread, I will be using this thread over the summer when I do my 1.7 install

 

Thanks guys, I appreciate the comments on the thread. I wanted this to contain all the information someone would need to run 1.7 RRs on a stock cam; and on more of a selfish note, it really helped me having all my thoughts and calculations documented in one location on a public forum

I'm not sure how the stock covers could be modified to clear the Scorpion 1.7RRs? I decided on the LT4 covers early on, so I didn't do much reasearch on modding the stock covers. There are a few members who did though; A search should turn something up to answer your question.

Thomas.