Hello,

car specs: 1987 Trans Am LG-4 700-R4

I have removed the 305 from my t/a and have a 355 (3970010) on the stand rdy to drop in but i have run into a few snags, and probably have a few more snags i havent seen yet

1. i am using a pre 80 block (left hand dipstick) and old style smog heads (882's) so my manifolds no longer work for me. i am going to change to proper manifolds for that engine but i need ideas on what i should look for to avoid any pipe hookup problems with the frame etc. example will centerdump style work fine?

2. a minor thought but someone here has the answer, will t-handle style valve cover bolts clear heater box etc etc? and i noticed something about oil pans while browsing, the pan i am using is a stocker off another 4 bolt block, should be fine aye?

those are the only 2 things that have popped up so far but after looking at other posts i will prob have other things to change, pls post anything you feel i may have a problem with so i can address any issues before the engine is in the air.


Thank You,
Dave

 

Ditch the manifolds, and get headers. You will thank yourself later. As far as anything else, you need to work out the flywheel-starter setup. You are going from 1pc rms to a 2 pc rms.

 

Your current exhaust manifolds will bolt to those (really, really bad) heads. But, like said, just get some headers made for 3rd gen V8. Just don't get LG4 or TBI headers.

Your current intake manifold will bolt to those (really, really bad) heads if you elongate the center two bolt holes on each side of the intake ('87-up have a different angle for those 4 bolts than the other bolts, unlike '86-earlier).

 

five7- the engine has all new parts (edelbrock cam, intake, carb, sealed power rings, clevite 77 bearings, all on/in freshly machined block and crank) except for the heads, the lg4 decided to start knocking half way through my 355 build up so i have no heads rdy yet, the 882's came off a demo derby motor with nothing done to help them, and hopefully they wont be on the engine over a month i have a pair of 265 heads from a 56 belair i am having 194/150 valves dropped in, the engine just picked bad time to die hehe. I plan to go to headers as well just down on the green and need the car up and moving. after staring and manipulating the items around some, i do believe i can massage the dipstick tube enough to clear the left exhaust dump.

ljnowell- Aye headers rule, just low on the green stuff and have to make do to get car moving then i can upgrade more, could you explain the flywheel problem i will have? i was hopin to use the same flywheel/starter combo the lg4 used. i do alot of auto work, but this is the first time i have replaced a post 80 engine with a pre 80 engine and it has its share of snags i am finding.

as a side note i see we all feel the same about those crack prone 882 heads, thanks for the warning but as i said i hope to change em out very soon.

any other thoughts or ideas?? i love reading about problems before i get into them

Thank You,
Dave

 

The 265 heads won't have the holes on the ends needed to mount accessories. Most likely, the 1.94/1.50's won't help them, either.

 

The problems lie with the difference in flexplates (or flywheels). Depending on the year of your carit could originally have a 1 pc rms flexplate, and you are going to need a two piece flexplate. YOu need to make sure that you match the starter to the flexplate (make sure they are made for each other), or else it wont work.

As far as the headers, make sure that you find manifolds that will fit the car, and the oil pan.

Watch out for those old heads you were talking about using. If they are from that old of a car, they arent going to have accessory holes, and that pretty much makes them useless to you.

 

five7- you know i knew that......grr, perfect example of trying to move to fast on the project. ok well i dont own any 5.0 HO heads so i guess i can have my LG4 heads reworked. I am looking for that 58cc chamber the 305 heads have for compression. not going to be turning more than 6k rpm so i am building for torque more than mid - upper rpm power. am hoping the 194/150 combo will flow enough for mild street performance.

ljnowell- good call on the acc bolt holes, i knew that but havent looed at the heads in a bit and totally forgot. The original lg4 was a 1 pc rms and the 355 is a 2 pc rms, is this where the 168 tooth / 186? tooth dfference is in sbc engines? if so i learn something everyday.

also out of curiosity do we have a forum on the board i can post my engine specs to and get a desktop dyno number or guesstimate on tq/hp?


Thank You,
Dave

 

305 HO heads are the same as the LG4 heads. The fact that an engine is HO (L69 versus the LG4) comes in the cam and compression, not the heads. Both heads are the 416 castings, or should be. So it doesnt really matter. Don't hold back either. Port the heck out of them. Install 1.94/1.6 valves.

its a 153 or 168 tooth. The difference is in the actual diameter. the 153 is ~12.75" across while the 168 is 14". If your block is either or, your starter motor will be either or. Thus, either the starter will fit just fine, won't fit because it's too close, or won't engage the fly at at all. Also, bolt patterns are not interchangable, either.

My suggestion would be the appropriate flywheel and a mini starter. I have a CVR one and it has like 12 different bolting patterns. Most good aftermarket ones can be fitted to either 153 or 168 tooth plates/wheels.

Essentially, you have a 153 tooth now (1 pc rear seal, smaller 'wheel). You will need a larger 168 tooth and incidentally, a new starter, unless you have plans for this.

IIRC, accessory bolt holes didn't come until the 68 heads. Yes, the T-handles will clear.

You could post here, you could make a new post in general engine / tech. Desktop Dyno is a bit "generous" you could say on the predictions, tending to suggest more power than actually produced. Give or take 25-50 hp more or less. It is a great tool, however, when it comes to seeing how a different camshaft or heads or whatnot, will effect the overall powerband and curve.

 

is it possible to use a flywheel from a 305 on a 350 or will that not work cause it is balanced differently?

also, will the stock torque converter on a 700r4 with a 305 tbi be able to handle a 355?

(in process of swap-- info gladly appreciated)

 

It will work, unless it's for a 400 crank.

Yes.

 

'82-'85 3rd gen V8's had 153 tooth, 2-piece rear main seal flexplates/flywheels. Buying one for that application will allow you to use the 3rd gen starter on an earlier 350.

 

five7- my 1985 grand prix went through a starter phase that was WAY too tight , took few trips to parts store to get a proper starter, now this makes me think i have the larger diameter flywheel on the prix, (its the original LG4 engine not a clue on 1 or 2pc rms, bottom was done before i got car 5 yrs ago and i have only messed with top end from there) does it sound like the starter on this car would be the proper match for my 355 with a large flywheel?

For the record guys i have close to 4,000 bucks in my prix engine it was my project car until i ran across this t/a in a trade for a riding mower... now it is the project car but i havent funds to build it yet (i usually spend most cash during winter season) so even though i am grabbing the cheapest ideas tossed to get car moving, i do have plans to upgrade later, headers, duals, better heads, better ignition system, etc. but i have wanted this t/a since i was 17 and sat in one just like it new on showroom floor, so all my other vehicles dont exist at present except as parts cars as long as the t/a needs something. i just cant help the feelin i get driving my 3rd gen.....

Thank You,
Dave

 

sounds like someone who has fallen in love with thirdgens. I feel the same way about my car. I have had a few chances to get rid of it, get something newer. I just cant bring myself to do it though.

 

882s are crap, are some good ones out ther ebut you just dont know which are gonna crack on oyu, ive throw away bilions of 882's over the years,

LG4 heads and L69 heads are same yes

14014416 is one of the LG4 L69 305 head casting codes,
fnd them on '80-up 305 engines 4bbl aluminum intake with EST or ESC system and the two stud outlet car exh manifolds,


58cc


and 67 older heads had accessory holes all cept for a coupel or few castings,

63-72 trucks used the head bolt holes to mount the alternator brackets to, they used two of the holes, cars had em too i have seen alot of 60s caprices with 307 or 327 and they use the same exact brackets driver side high alternator mount on the cylinder head end, but alternator wasnt until 1965, 64 and older GM were generator



68 is when temp sender unit moved from intake down to the driver side head and 68 was last year of the filler neck style intake
and was when block mains were strengthened

307 and 327 shared alot of same heads and crank and such 68-up especially, large journal

302 350 and 327 blocks were the same 4" bore blocks for a given year- 69-up or 68 down(camaro only for the 67 and 68 350 and 67-69 302 engines)



oil pans same from 55-79 and changed in 80 through 85 and then new pan again for 86-up

cranks and RMS changed for 86 too,

exhaust manifolds, the 79 older ones after the 72 older ram horns will fit and bolt in an 82-uyp F body engine compartment, bt the passenger side youll have to have a pipe custom bent because stock bent ones from other cars and trucks wont clear the trans crossmember and the firewall si in the way anyways you would probably end up with burnt firewall and or carpeting, etc if gets too hot

i know this cuz i have a set of the big commmon 70s manifolds on the 76 350 engine in the 82 and i have no way to put a pipe on the pass side,, just is no room for it, and i cant remember why but a 72 older ram horn wont work either, it hits the engine crossmember somewhere i believe its the bottom most stud that hits the cradle before you can even mount the manifold to the head


so you are stuck with 80-up car 305 manifolds, or headers

i wish my car was 80-up LG4 or L69 with the stock Y pipe and manifolds and p/s pump setup and all still, but the original LG4 blew up and i cant find an LG4 donor car anywhere now,

i have yet to find 80s p/s setup and manifolds and y pipe so i can at least stick it all on this 76 350 in the t/a so it can all work, for now til i find another LG4 or an L69

350 into especially the older third gens is no fun, exhaust is a killer,

the dipstick 55-79 does have issues with the 80-up manifolds, yep, that wil be fun too,, another reason why i wish i had a 305 to put back in the 82,...



good luck

 

i just made the same 355 block swap a month ago. 3rd gen headers and y pipe cleared the dipstick and the t-handle valve covers work just fine

 

im doing an engine swap on my 84 camaro going from a 80-85 305 carb'd to a 79 350 carb'd. im wondering if i will be able to just pull the 305 out and drop the 350 in without any changes, like motor mounts and flywheel, basically just unbolt and unscrew everything for the 350 and drop it in hook everything up and be set to go? i dont have an air box, heat, its just a 305 with stock exhaust manifold power steering and power brakes meaning lots of room under the hood. im tryng to get a 2 piece rear main seal 350 but will i be better of with a one?

 

1. the t-handle style valve cover bolts will work but you will regret ever putting them on i have done this a couple times and all that ends up happening is the little t's that slide onto the top of the hold down bolts keep vibrating off and you end up loosing them .

2. the pan should be fine