3.4 hybrid into a fiero questions

[dimerunner88]

i'm building a LA1 from a venture to swap into an 85 fiero,i'm planning on running the fiero heads,intake and front cover. i'm using 3.4 dohc pistons and an edelbrock 2.8 cam. i have everything needed except the piston rings which i can't find anywhere and after having to wait 5 months on my pistons to be made(ordered from summit) i don't want to have to wait on rings. i'm also wondering if i can run some 1.6 rockers from a 3.1 in it with the cam i have without bending valves. the cam i have is
Duration Advertised 253° Intake/263° Exhaust
Duration @ .050'' 204° Intake/214° Exhaust
Lift @ Valve .420'' Intake/.442'' Exhaust
Lift @ Cam .280'' Intake/.295'' Exhaust
Lobe Separation Angle 112°
Intake Centerline 107°
Intake Timing @ .050" Open 5° ATDC
Close 29° ABDC
Exhaust Timing @ .050" Open 44° BBDC
Close 10° BTDC

so basically i'm asking if anyone can point me in the right direction for the correct rings for the 3.4 dohc pistons for cheap and if i can run 1.6 rockers with those cam specs i posted.

any help is appreciated.

[3XTurboAgain]

just run the whole venture motor w/aluminum heads and convert your computer to distributorless ignition and it will outrun the fiero heads/intakes by far. its a little more work but just my opinion. Or you could just completely ignore this post... BTW any machine shop should be able to get you a set of moly rings for a decent price. Good luck!

[FallenZ24]

I agree with 3XTurbo....

The 3400 (LA1) already has 1.6:1 roller rockers, much better heads and intakes, a roller camshaft, and 9.5:1 scr. The gen3 motors also use a much better accessory drive setup with a tensioner (means no more "Fiero belt squeal"). The Fiero parts are junk! The heads flow shitty even ported and the intakes are a choking point past 4500 rpms.

You should save your money and install the entire 3400. You can buy a cam that is actually designed for a gen3 engine from the wot-tech store.

Why revert back to shitty parts? Are you afraid of the extra work? The biggest part of the swap is wiring for the 7730 ecm. That isnt even all the bad though.

-Joseph

[dimerunner88]

i only have the shortblock,thats the reason for the need to use the old fiero parts. the motor was pulled from the van cause of a broken camshaft,then the mechanic sold the heads,then years later i bought the short block.

[FallenZ24]

IMO you should toss that short-block and just buy a known, running 3400. If the 3400 "broke" a camshaft it is probably junk. The cams don't usually break for no good reason. Usually it involves oil starvation and/or spun bearing. As cheap as 3400s are you can buy and install the engine for less than rebuilding that short-block.

Good luck with whatever you do. I just hope you don't use that block...

-Joseph

[dimerunner88]

theres nothing wrong with the block,all the main/rod bearings were in great shape. the cam bearings had some scoring,but since everything is being cleaned and new bearings installed i highly doubt i'll have any trouble. the local yards all want over 1k for a 3.4 with less than 100k and i'm just a lowly independent mechanic. so i don't have money to spare and i can do all the work myself. everythings ready to go i just have to get the pistons and rods pressed together,and get some piston rings. which napa wants $115 for a set of stock dohc 3.4 rings and i would like to see if they can be had for cheaper.

[3XTurboAgain]

check craigslist for parts cars... i found a 3400 over here in NY for 500 bucks w/ 17k on it off criagslist... car got T boned.

[mikewzman]

I am doing the same swap in my Fiero. Federal Mogal now makes flat top pistons for the 3.4L. The DOHC pistons have the valve clearance cutouts which will problably drop the compression ratio back down to close to what the stock dished postions are. I think you can use the standard 3.4L rings with the flat top pistons, which should be a stock item. With the flat tops you should be getting close to 10:1 on the compression ration. With your cam it should be a pretty good set up. Better on the low end torque with the shorter duration cam, especially in the light Fiero. I am using the 1.6 roller tipped rocker from Comp Cams. Make sure to do a good port & polish on the heads, as you will need the best flow you can get out of the cast iron heads. Good Luck!

[Superdave]

$1K for a 3400 with less than 100K miles? where do you live??

I've picked up 3400's with 30K for $300, and even a 3500 with 700 miles for $600.. you've got some shady yards around there..

but like the others said, junk that block. The 3400 uses priority main oiling which means that since the LIM gasket probably went in it, oil & coolant hit the mains first, then the cam. When cam bearings spin (and i'm sure they did when the cam broke) it causes damage to the cam bearing journals in the block. Simply replacing the bearings is a gamble. I bet there is some damage to the mains and rod bearings as well.


your cam choice is pretty much the same as the stock 3400 cam, piston to valve clearance will have to be checked by you upon assembly (the tootsie roll method works well) but 1.6 rockers shouldn't be a problem.

I hate to ask but what kind of power are you expecting out of this combo?

[dimerunner88]

the cam broke due to poor manufacturing,it broke right behind the 2nd bearing race.

this whole rebuild thing started with a 2.8 that had a spun rod bearing(doing doughnuts while low on oil) the crank was trashed along with two rods,so i looked around for 2.8 stock parts and they were all wayoverpriced IMO so i came across this short block for $100 and the way i figure it with the set-up i have is that its basically a bored/stroked 2.8. i tried to go mild on most stuff so its able to be a daily. its all ready to go besides the fact i need piston rings still and the cheapest place i found with good parts is $115 for stock 3.4 dohc rings.
as for power,i'm expecting around 180ish not sure. i'll just be happy if it runs,lol