thought it was a 2.8 when purchased, its a 3.4!

[dgsmooth]

howdy all, awsome site/forum here. well i'm a new fiero owner, just picked up a 86 gt for next to nothing as it had a bad engine knock/tick, which turned out to be a rod bearing. interesting part is that as i tore this engine apart and started measuring things to order parts, i found out its not a 2.8, but a 3.4. had the red 'fiero' upper intake plunum and everything so i never even asked. anyways my question is when a 3.4 has been put in place of a 2.8, where does the 2.8 end and the 3.4 begin? i know every conversion can be done differently, but typically speaking, would the computer and harness be fom the 2.8 still? what would need to be changed to put a 3.4 in place of the 2.8....would the intake have to be changed (ths one had the red 2.8 upper part at least)... would injectors ahve been changed, or would the 2.8 ones work? the cam had 4 failed lobed and that metal debris got into all bearings. luckily crank and pistons still in good shape, so i'm putting in all new bearings, a hone with new rings, new cam and lifters. i've ordered all that based on 3.4 an by size so thats all fine, but what led me down this question is the oil pressure sensor was broken off, so that got me asking wether i'd order the stock 2.8 fiero oil pressure sensor or order one from a 3.4? (or they might be the same). my guess would be the block, crank, pistons and rods, and heads would all be 3.4, then intake and everything else 2.8....i'm a heavy duty mechanic by trade so automotive/gas type intake systems not really my field of expertise. anybody who's savy with that stuff or has done a 3.4 conversion, i'd really appreciate a little advice or whatver insight anybody could throw at me. thanks to all and cheers for now.

[Fierofool]

Your thread got bumped to the 2nd page real quick, so I didn't see it.  Welcome.  Good to see you posting. 

To answer some of your questions, the 3.4 is the same block as the 2.8.  Basically.  They used the 2.8, 3.1 blocks and did some upgrades.  Better oiling system, part of that being just a bolt-on high efficiency pump.  Larger oil galleries, too.  They made provisions for a crankshaft sensor which wasn't used with the 2.8.  This may be because the 2.8 used a distributor and the 3.4 used a Distributorless Ignition System (DIS).  The pan also had a low oil sensor.  A feature not offered on the Fiero. 

While the oil pans of the 87 and 88 2.8 are shaped like the 3.4 pan, the changes to the 3.4 were the low oil sensor and a change in the design of the baffles inside the pan.  This was to accommodate the higher volume oil pump.  The 87 and 88 pans can be utilized by notching the baffle for clearance of the pickup and tube. 

You can quickly identify a 3.4 by looking at the bell housing flange on the right side of the engine.  If it has holes to bolt a starter, then it's a 3.4.  It has to be drilled and tapped on the left side in order to accept the Fiero starter setup. 

Bore and stroke changed and that gives it good low-end torque.  After driving a 2.8 then a 3.4, you can feel the set-me-back-in-the-seat difference.  It will also cruise right on up many hills that you'd need to downshift with a 2.8.  I know from experience. 

The 2.8 also had a stud on the lower front of the engine for the purpose of mounting the AC bracket and torque shock.  The 3.4 didn't have it, so a stud has to be welded to the block.  Some just bolt the shock and AC bracket together with a bolt. 

The 93 and 94 Camaro/Firebird 3.4 used a flat tapped cam.  The 95 version upgraded to the roller lifter camshaft.  The heads are identical to the 85-88 Fiero.  Everything from the Fiero 2.8 bolts directly to the 3.4, except that the starter has to be relocated to the left and if you're hooking to an automatic, part of the old starter boss on the right must be ground away for clearance of the Fiero TH125 transmission output housing. 

The 3.4 gives you about 20 more HP and you can get a little more out of it by going with the 7730 ECM and original DIS system and converting the vacuum EGR system to a Digital EGR system utilizing the Georgia Fieros Digital EGR adapter plate kit, available in the club merchandise section of the home page. The kit also works with the distributor setup when used with the 7730 ECM.   

Sign in on the General Discussion forum and tell us a little about you and your car and where you live.

[Fierofool]

All the Fiero external parts will bolt directly to the 3.4 block.  One thing I forgot to mention is that the 2.8 used 15# pintle style injectors.  The 3.4 in its stock form used 17# multec injectors.  The multecs tend to run rich with the stock Fiero ECM setup.  You can get 17# pintle injectors or have your stock Fiero injectors resized and rebuilt at www.fuelinjectorconnection.com  They also have a 17# injector in stock that will do the job.  It should be a pintle style unless you plan to convert to the 7730 ECM.  That would involve some modification to your engine and ECM harness. 

[dgsmooth]

wow thanks for the info, you are clearly familiar with a situation like mine.....I think I must have a 2.8 and 3.4 combination. I still have a distributor, and I dont have low oil sensor. but when I tore engine apart and measured I found all 3.4 numbers....92 mm pistons, and block casting number matches for a 3.4. also starter bolts to block not clutch housing. also found cam is a comp 16-233-4. so somebody has done some fiddleing with this thing, but I really dont know the exent to such.

I think next I'm going to see if I can find some head casting numbers, is there a way to tell 15 and 17 injectors apart? I also found a broken sensor on the right side (rearward side I guess), couple inches up from pan, goes into cooling system. but cant find it on any 2.8 diagrams...I also am pretty sure I dont have the temp sensor on the top corner of the rearward head.....would that indicate I have somehing other than the stock 2.8 harness? the broken sensor had nothing plugged into it, and I'll look at my harness again but didnt see any loose end that would go to it.

anywho thanks for all the info and help. I've always wanted a fiero, just didnt really want such a mystery to start with. I gues when yoh buy a car with an engine knock yoh know youre in for some fun. I have got the bug though, already got my eye on a couple more.....thanks again and cheers for now

[Roger]

 
Welcome to the madness!

[Fierofool]

Sometimes when people drop in a 3.4, they leave the heads on the car.  The gauge sending unit as used on the 3.4 is in the corner of the head above the # 2 cylinder.  Right front as installed in the Fiero.  The plug must be removed from the other head and the sending unit must be relocated to the left of the rear head above the # 5 cylinder in order to connect with the Fiero engine harness.  The head casting numbers of the 2.8 and 3.4 are the same.  They have the larger valves.  Other 2.8 applications like the S10 and S15 and Camaro's, and FWD applications all had small valves.  The larger valves was how Pontiac got the extra HP.

The numbers on the injectors are extremely difficult to see with the upper intake in place.  It may be possible to see a number using a flashlight and a small mirror like a good quality dental mirror. If you get the car going and have no issues with it running rich, I wouldn't worry about it.  It would seem, though that if you have the engine torn down, you have the top end off the engine.

I believe the broken sensor you found, if it's on the trunk side of the engine, is the crankshaft sensor.  It doesn't go into the cooling system.  It 's located just underneath the # 3 cylinder? 

Check out the link for the 3.4 conversion on our website.   Tons of valuable information there.  I'll also PM my phone number.  I was looking for some other information, but can't find the link at the moment.  Here's the 3.4 conversion page.

http://www.gafiero.org/tips2.shtml

[Fierofool]

Dennis, the email I sent you last night just before midnight and the one I sent this morning around 8:30 have bounced back as undeliverable. 

[Fierofool]

Here are copies of the emails I sent you in case the private messages also failed.

Good morning.  First, here's the message I sent last night.  It was returned as undeliverable.  After this, I'll try to answer your questions from this morning.



If you're in the US, it costs me nothing to call.

For the sensor, there was no provision in the Fiero wiring harness for a
sensor on that side of the block.  You can probably just put a brass plug
into it and be just fine.  I'd keep the sensor you take out of it, though.
For future reference.

I think you probably have the stock Fiero ECM.  If you have the standard
EGR valve on the crossover pipe, nothing has been changed. The heads are
interchangeable from one side to the other.  It's easier just to swap sides
than to try to get the pipe plug out of the head.

You will need a complete gasket set for a 2.8 engine plus head gaskets for
a 3.4 engine.  If your timing cover and oil pan slopes down at the
crankshaft pulley end, you will need the gasket sets for the 85-86 2.8.  If
the top flange of the pan is flat, you will need the 87-88 gasket sets.

Look at your flywheel.  If it has weights on the back side of it, you will
need to have them ground off, or purchase a new flywheel for an 88 engine
or for the later model 3.1 engine.  If the flywheel has weights on the
back, you will experience premature failure of your crankshaft bearings due
to vibration.  The 3.4 is internally balanced and uses no counterweights on
the flywheel.

Get the casting numbers from the side of the block.  That will help me find
out what block you have.  It's possible it may be a 3.1 block that has been
bored to the 3.4 displacement.  Or, you may be able to ask your local parts
supplier.

It just occurred to me that the sensor might be a knock sensor.  If it's
parallel to the freeze plug, that's what it would be.  The crankshaft
sensor is located just above the oil pan mounting flange.  I'm basing this
on a later version of the same block that was used with aluminum head FWD
engines that I have in the garage.


Now, for this morning's questions.  I can't really tell you anything about the listed order without a description of each, however, some of the parts numbers give an idea of what they are.

CLE-MS2037P
MAIN BEARING SET
I believe this would be Clevite brand bearings.  Generally, they are good bearings.

FEL-CS9471
CONVERSION SET
This is a FelPro gasket set.  FelPro is a very good product, but I don't know what a conversion set is.  See my email above about the gaskets you will need.  I've been looking for my list of what's needed, but I can't locate it.  If I do, I'll email it to you right away.

FEL-HS9105PT
HEAD SET
This should be FelPro head gaskets.  If it is anything more than head gaskets, you will have to discard the rest of the gaskets.

As for the other items, I don't know anything about them.

[TopNotch]

Picture of a counter-weighted flywheel:

To use this with a 3.4, it would need the weight ground off, and then professionally balanced.
Picture from the GM 60-Degree V6 Power Manual.

[Fierofool]

I replied to your last email around 6pm but it bounced back, too. 

I found my list of gaskets for the 3.4 as used in the Fiero.  Only thing I don't have is the head gasket numbers for the 3.4.  This is based on using the 3.4 or 87-88 Fiero oil pan and timing cover and are all Fel-Pro numbers.

TCS 45828 Timing Cover Set Includes Water Pump Gasket.
MS 93045 Exhaust Manifold Gasket Set
VS 50077 R Valve Cover Set--Rubber Gaskets.  Cork Valve Cover Gaskets also comes in the Intake Manifold Set, but aren't used with the Fiero Valve Covers.
MKS 93020 Intake Manifold Set, includes lower, intermediate and upper manifold gaskets.
OS 34501 R Oil Pan Set.
BS 40625 Rear Main Bearing Seal. 
Distributor O-ring seal can be bought for the 3.4 oil pump drive at auto parts stores.  It fits the Fiero distributor.
Since you've done a full tear-down, you'll need to order a set of 3.4 head gaskets.  I don't know the number but that's an easy order.
When installing the rear main bearing, be aware that there's a tiny O-ring that goes underneath one of the bearing halves.  Also, the thermostat housing doesn't use a flat gasket.  There's a very thin O-ring seal between the housing and manifold.  There is also no gasket at either end of the lower intake manifold.  The space is sealed by use of RTV gasket sealer. 

It's advisable to replace your exhaust manifold studs with studs from a Saturn.  Not sure which Saturn, so someone else will need answer that question. 

[dgsmooth]

okay i think i have my email/pm issue fixed, i definelty dont want to miss out on any advice coming my way....

i've checked the block and casting is # 10118608, my best google-ing shows its a 3.4

heads casting is 14054884, and like the fool stated that is the stock head for 2.8 and 3.4 (and 3.1?)

i checked the timing cover, and i couldnt quite see what was meant by it slanting inward as it meets the block.... the pan flange is 90 degree/flat all the way around, timing cover look the same idea, no slant, just straight down, 90 degree corner and then straight towards block. if i'm interpreting that right, its a 2.8 cover?

also checked ecm, is part number 1227170, so that is stock ecm, not the upgraded one to go with bigger injectors.

i was out of town today (looking at two other fiero's  , and on way home stopped at shop i work at to get all that info off of parts but forgot to check flywheel for weights and injector #'s, but i'll do that tomorrow)

i am going to get more/better info on the parts i have coming, just so a foolish expert can take a look at tell me how i messed it up and why i'm going to be choked when i don't have the proper gaskets to re-assemble later.....

thanks again to fierofool and the other guys in the know who have helped me so far - would already be lost without that kind of guideance

[dgsmooth]

okay this is what i've got coming:

cam and lifter set:

http://www.summitracing.com/int/parts/cca-cl16-233-4/overview/

main bearings:

http://www.summitracing.com/int/parts/cle-ms2037p/overview/

rod bearings:

http://www.summitracing.com/int/parts/slp-6-4020a/overview/

timing set:

http://www.summitracing.com/int/parts/slp-kt3-368s/overview/

bottom end gasket set:

http://www.summitracing.com/int/parts/fel-cs9471/overview/

top end gasket set:

http://www.summitracing.com/int/parts/fel-hs9105pt/overview/

12 of these push tubes:

http://www.summitracing.com/int/parts/slp-rp-3207/overview/

2 sets of these rings....enough for 8 cylinders cause thats all they had in stock. they 1.5 x 1.5 x 4.0 and 92mm bore so what difference from 4 cyl to 6 cyl? 2 sets for 4 cyl cheaper than sme set for 6 cyl anyway.... not sure why that is, unless i'm missing smething there.....

http://www.summitracing.com/int/parts/slp-e-510k/overview/

so hopefully this stuff will work based on the engine/intake combination i have. i can see in the head/upper set an o-ring, hopefully thats the one for the themostat housing, although i havent actaully seperated it there anyway. as well the bottom end set shows a couple small o-rings, hopefully one of those is for the under the one main bearing as fierofool infofmed me - i actaully didn't notice an o-ring there when dis-assembling, but will check that tomorrow along with flywheel weights and injector part #'s. i'm 95% sure injectors are stock 2.8, but very curious to see (or hopefully not see) flywheel weights. can't believe i forgot that - tempted to drive down to shop now to look but too much drink for that - will have to dream about it till tomorrow.

thanks again people. i've joined all the fiero forums i could find, other great ones as well but definelty warm (est) feeling from this group of fiero-addicts

[Fierofool]

I can only address the bottom end gasket set and the timing set with certainty.  They will work. 

The top end gasket set should be for the 2.8 Fiero.  That will have the thermostat housing neck gasket.  The one you have doesn't have the proper gaskets for the Fiero intake. 

If you specify gasket sets for the 87 or 88 Fiero 2.8, you will have everything you need except the 3.4 head gaskets.  There will be some leftover gaskets, but that's because they incorporate some of the gaskets for the 3.1 and 3.4.  Ordering gaskets for the 3.4 won't give you all of the gaskets you need.  Remember, you are actually building a bored and stroked Fiero 2.8.

Referencing the taper or slope of the oil pan and timing cover, the bottom of the timing cover where it meets the oil pan flange should be flat. 

[dgsmooth]

okay everybody forgive me, im sure its me but i'm just not getting this gasket issue; when i look up gasket kit for 2.8, the water pump gasket isn't right, the opening to the right of the main impeller opening is sort off oval shaped, 1" by 2" type size, but on my engine its perfectly rectangular.....also the 2.8 oil pan isn't right. it shows it much more 'pointed' on the front end, with four bolt holes going up into the timing cover. mine has no bolts there, the front of the gasket is the same as the back end more or less. does a normal 2.8 pan look like this one:



or like mine, which is like this one:



you can also see in the second licture the two different water pump gaskets....mine is the one on the right, the one you get with a 2.8 kit is the one on the left.

i'm realizing as i write this that as i don't know what this engine is made of etc etc i'm just going to have to order something and see how it goes when i get it.

on a good note the flywheel has already had the balanceing weight removed.

and i found my injectors are #'s 5235210

[Fierofool]

This is the gasket set you will need.  It's the one designated for the 87 and 88 Fierio 2.8 rebuild.  The FelPro number is 953416VR   


Now, compare to the gasket set for the 93-95 3.4 V6 engines.  FelPro part number 953554VR.


The 3.4 gasket set doesn't have intermediate manifold gaskets because the upper intake is bolted directly to the lower intake.  Also, if you look very closely at the 2 water pump gaskets, you will see a difference in the shape of the main impeller chamber.  Though you can bolt the 3.4 timing cover and pump to the engine, the rotation is backward to what the Fiero requires, and the engine will quickly overheat.

The pan gasket is a one piece gasket and is made of rubber. The profile of the pan should look like this:


The injector you have is the stock Fiero 15 lb/hr pintle injector.  It should look like this except it will be solid black.