I am trying to find a set of replacement pushrods to install with the new 1.6 RRs (have not bought these yet either - still shopping around for the right deal).

Normally I would go with Crane or Comp chromemoly type pushrods however last year I read about some pushrods made of exotic light-weight and super strong materials which, due to their construction, caused a dramatic loss of mass in the valvetrain (vs. stock).

Apparently this made for some interesting improvements in the operating characteristics of the testcase SBC valvetrain (when combined with roller cam and roller rockers). Faster revving, etc. Now that I am shopping around for these light-weight pushrods I can't seem to find any information on the subject.

If you have seen these or have any information on light-weight pushrods I'd appreciate hearing from you.

I'd also like to hear comments/feedback from anyone who has actually installed 1.6 RRs in the 305.

thx, RP.

 

Do you think the added cost of something like that would justify the gains in performance?!? I don't know any thing about them, but my first question I'm asking myself is "Is it really worth the extra cost? And how much gain should I be expecting?"

You're already gonna notice a change when you upgrade your rockers.

Of course just my two cents.

 

Good point -- I am not sure if it is worth the extra cost ? More important -- would they be reliable for a daily driver ? I'll probably let it die and just go with the chromemoly rods.

RP.

 

I'm sure they would be reliable...but so are the chromemoly ones too. If you find an article on the exotic ones, make sure to post it though. I'm curious.

 

What kind of HP/Torque gains are you hoping for with the 1.6 rockers?

 

Well I read in a magazine that I can get about 105hp gain with a set of 1.6 roller rockers... JUST KIDDING !!! No really, I expect about 8-12 hp and about 10-12lbs torque at the rear wheel. Pretty modest gains.

The way I see it this is one of those mods that is more than just the sum of the hp gains. I am interested putting together a fully roller valvetrain first, and while I am at it, picking up abit more power by upgrading to 1.6s. I did this mod back in '93 with my '88 Formula using Comp Cams 1.65 roller tip rockers. Pretty good product too that worked really well -- I would do it again except I am looking for fully rollerized this time. I figure rollers are alot stronger than stamped steel rockers so it is a system upgrade as well.

RP.

 

I can recommend 2 things.....CompCams Pro Mags and get new valve springs. The lift won't be maxed out on the stock springs but they are garbage to begin with.

 

That's the advise I didn't want to hear -- new springs. Now let me ask you -- what will new springs do for me with the setup being so near to stock ? Don't get me wrong, I don't mind finishing the job properly by installing new springs... but only if it is neccessary.

Previous experience:
I installed a pretty radical cam in my '88 Formula 305 TBI (217/225 .480/.485) and I used 1.6 Comp roller tip rockers. (Man did that 305 TBI rev ! Of course it wouldn't idle worth beans but went like a bat-out-of-H**L ! Well that is another story). At the same time, I replaced the springs on that engine with Comp Cams conical style springs because of the excessive lift (over .500).

I found replacing the springs to be a ROTTEN job. Wouldn't want to do it again unless I had too. (Pretty funny story actually, I used rope in the combustion chamber to prevent the valves from collapsing and on the number 2 cylinder the rope somehow got a knot INSIDE the combustion chamber. I spent hours trying to get the rope out of the engine. Live and learn next time I'll rent an air compressor).

My point is this -- I did not expect to have to upgrade springs given the minimal lift from 1.6 rockers ? Are the factory springs really that bad ? My motor has 70,351kms on it. As far as I am aware they are factory original.

thx, RP.





[B]

 

The stock springs are barely adequate on a stock engine. Frankly, they are junk if you plan on regularly running the engine hard. I've heard of TPI engines floating the valves as low as 4500rpm. If you have ever buzzed the engine, it can happen at even lower rpms. When you increase the rocker arm ratio you increase lift, duration (barely) and you also increase the speed at which the valve opens and closes. The OE GM roller setup is great but it's also very heavy and that weight combined with the added ratio could allow for valve float. I know how nasty a job replacing the springs with the engine in the car is but in my opinion it's worth it. That is a ton of cam for a TBI engine. How did it run? Oh and for the pushrods......... I used the LPE part# LN0280H chromemoly pushrods. They are light, strong, and the price is great.

http://secure.techservices.net/fwist...ID=111&CATID=3

They can be used without guideplates. Either way, I hope this helps you in your decision.

 

Ok, I get the message. Fact is although my current springs have only 70k on them, they are over 10 years old now and I do hit 4500rpm+ from time to time <grin>. I am 10 out of 10 NOT looking forward to changing the springs and retainers though. I'll be sure to order the LPE parts too.

The cam that I installed in my '88 305 TBI was an Isky roller (217/225 .480/.485). At that time (1993) not many people could tell you what effect a cam like that would have on a 305 TBI. In fact NOBODY even knew HOW to hop up a TBI ? I was cutting ground as-it-were and was told on numerous occasions to sell the car and buy something carbureted instead.

The cam was outrageous from about 1800-6400rpm (no kidding). It wouldn't idle, MAP was always down to around 11-12 inches so the ECM went crazy trying to find a setting that worked. Consequently the car loped at idle QUITE abit and it ran VERY rich on the low end (wouldn't pass emissions). I got a chip from Ed Wright (he was just starting out way back then) that helped somewhat but the bottom line was I was not making enough vacuum at idle for any chip (available at that time) to deal with. The car broke into the 13s once and would have done ALOT better with 3.73s. As it was the 3.23s were just the wrong gear for the setup.

I had a Weiand 7525 manifold with a Holley 650cfm TBI (replaced the factory 550cfm unit) plus headers and complete custom built 3 inch mandrell bend exhaust from the header to the tailpipe, hi-flo cat, Flowmaster, etc. I used a Jacobs ignition package as well and a custom built cold-air setup. I played alot with that car's setup. It was the best handling car I've ever owned (did suspension work too), the best braking car I've ever owned (modified the brakes) and the best engine setup I've ever driven (and I've driven a number of exotics). I used to get a REAL charge out of blowing away 5.0 Mustangs with that low output 305 TBI (sleeper).

One day I'd like to build up another TBI f-body except this time I'll go hunting for LT1s <grin>.

RP.

 

What happened to your old Formula? Those LPE pushrods are made by a certain cam company that has it's name on just about everything. They cost about $90 if you get them straight from the manufacturer.