new with a pushrod, piston, and timing question.

[z24door]

hello, this is my 1st post so please be nice.

I am going to be fixing my 3400 in my 1992 cavalier very soon here, and I am going to be rebuilding and porting the heads and plenums, at our local machine shop to the felpro gaskit kit with updated LIM and head gaskets, now my question is thus.

I have researched a little bit and found out that corvette LS6 springs are usable in our motors, with the help of stock valves, 3.1L mpfi valve stem seals ( I have the 1996 - 1999 LA1 ), corvette LS1 valve guides,and the stock 1.6 Roller rockers, . I plan on going with the Manley steel retainers and keepers on wot-tech.com because of the better clearance,

however will it require me to have a different set of pushrods, now due to having this valve setup?

I will also be replacing a piston, due to lean fuel conditions in the motor (didn't swap out the 3.1L injectors like i should have) so being that I have never removed a crank from a vehicle in my life, are there any other precautionary steps i should take, other than the basic idea that I need to remember what parts belong to which cylander and to remember to put the rings on the piston before install. (i have made this mistake once, so I laugh at it). I also plan on purchasing the Ishihara - johnson crank scraper from wot-tech.com, just because crank scrapers worked wonders on my old motorcycle.

Also, what is a good tip so that I don't lose my timing marks. (it's probably different from doing an old carburated motor I can imagine.)

[MidnightriderZ24]

no, for changing just springs, it isnt really required to have different pushrods, stock is strong enough. for assurance i used ls6 springs, on stock pushrods and 12psi, no problem. As for keepers and locks its up to you, stockers are fine as well.. for clearance, proper machining to the seats will need to be done for the correct spring install height (lots of people break ls6 springs due to this factor!!!). as for the piston, unbolt the rod, and take the cap off, and just tap it out through the top! timing marks use this picture: small round hole on cam sprocket facing down, and arrow on crank drive gear must be facing up. #1 cylinder sound be at TDC.

[MidnightriderZ24]

here is a picture of the head machined for the correct ls6 install height. - note this is a 3500 head, but still the same thing will be needed for a 3400 head.

[z24door]

how far down are those bad boys machined. I have a booklet I am making up for my machinist of everything he will need to do, so far i ahve him refacing both heads, retapping the plug holes on both heads, porting polishing and installing the springs and hardware to go with it, what is the measurement I will need to tell him, and will that number apply to both the intake and exhaust ports?

[MidnightriderZ24]

yes both seats will need to be machined. stock height on a 3400 is 1.700'', ls6 install height is 1.800''. so 0.100'' machined off the seats.

[z24door]

thank you very much for the quick responces, I have this bookmarked and on ms word for the instructions for the work order.

[z24door]

hey i have been reading some information on wikipedia.com, and it got me thinking, will the pistons from a 3.4L RWd fit into our LA1 motors, the reason I wanty to do this is because the pistons have coated skirts where as our 3400 ones do not.

[bszopi]

Where did you hear that 3.4L pistons have coated skirts? You can get aftermarket hypereutic (sp?) pistons for the 3x00 engines from several manufacturers. And, you won't have to worry about such a high CR that you would get by installing the 3.4L pistons (~11.5 IIRC).

[Joseph Upson]

Where did you hear that 3.4L pistons have coated skirts? You can get aftermarket hypereutic (sp?) pistons for the 3x00 engines from several manufacturers. And, you won't have to worry about such a high CR that you would get by installing the 3.4L pistons (~11.5 IIRC).

I don't think we're giving these engines enough credit, I don't believe 11.5:1 is to much to run on midgrade fuel as long as the engine temps are kept below normal max like around 190 deg. It would certainly be worth the increase in efficiency and power.

How on earth did you and everyone else pass up the chance to poke fun at him for putting pistons in an engine without rings! I put my first clutch disc on backwards, but that doesn't compare to pistons without rings :-)

[IsaacHayes]

3400 with RWD pistons is more than 11.5:1. Somewhere in the 12's. It's in the 11's with 3500 heads IIRC.

[bszopi]

I never said that high of compression is bad. In fact, I think it is great. But there is a lot more to it than just building an engine with high compression and running mid-grade gas. Tuning is the key, and not everyone has the know-how on how to do it properly, or is willing to take the time to learn.