Need New Engine
Thread Starter
Member
Joined: Dec 2011
Posts: 188
Likes: 1
Car: Transam, 85
Engine: 305 HO, 4bbl Carb, G Engine
Transmission: 5 Speed
Axle/Gears: 3.73
Need New Engine
85 Transam. I have a G engine 305 4br HO with T5 trans. Engine has 140k miles, runs tired, leaks, smokes, coolant never remains clean as block sheds iron. Typical tune up hadn't help. I believe being 36 years and multiple sittings of years, engine ran its time. Rebuild can be option but a quality rebuilt is hard to find, and I will not do it.
Can any one suggest a 'brand new (or semi new) engine' (less then 300 HP) that fits with T5 and rest of the system without much changes. I am still learning on engine types, but definitely want a sport car engine (hot camshaft) not a regular engine type.
Can any one suggest a 'brand new (or semi new) engine' (less then 300 HP) that fits with T5 and rest of the system without much changes. I am still learning on engine types, but definitely want a sport car engine (hot camshaft) not a regular engine type.
Joined: Nov 2008
Posts: 2,093
Likes: 175
From: Milwaukee
Car: 92 Firebird, 77 Trans Am SE, 86 Z28
Engine: 5.7 HSR, T/A 6.6, empty
Transmission: T-5, TH350, T-5
Axle/Gears: 3.08 posi, 3.23 posi, 3.23
Re: Need New Engine
I'm not really sure where to go with this answer. You aren't asking for much but asking for a lot at the same time. How much of the original do you need to keep, emissions etc? How much are you capable of doing yourself? Hopefully you're not expecting to pay a shop because that rarely works out when it comes to antique cars like these at this point. Not to mention you didn't mention a budget. Sub 300 is an easy goal but then you really don't need a "hot" camshaft. The simplest thing is to rebuild the 305 (if that's really what it needs) which I normally don't suggest, it's not very cost effective but it could do what you want. That all said, I don't know of a good direct replacement that'll do what you're looking to do. You could probably put a comp cam's 'thumpr' cam to get the choppy idle and low performance you want and put it in a rebuilt 305 but I'm not sure that'll play well with the computer controlled carb. Could build a simple 350 to get the performance goal but it won't need a big cam. Plus, a big enough cammed engine will have plenty of power to shred that early T5.
I realize this was all over the place but I think you need to research and really decide what you want to do, currently what you want is a strange order. It's kinda like asking for a turkey burger with beef in it.
I realize this was all over the place but I think you need to research and really decide what you want to do, currently what you want is a strange order. It's kinda like asking for a turkey burger with beef in it.
Thread Starter
Member
Joined: Dec 2011
Posts: 188
Likes: 1
Car: Transam, 85
Engine: 305 HO, 4bbl Carb, G Engine
Transmission: 5 Speed
Axle/Gears: 3.73
Re: Need New Engine
No rebuilding current engine. I will do the install (with help). $5k or less fully dressed if possible. What I actually meant on cam is I do not want a 'slow engine' as long it is enough for T5 to spin fast. I do not want to shred T5, nor want any more then a T5 can handle. Yes I was looking for a direct new replacement similar kind within 300 HP. that I can install. As long the new engine can fit in and connect to T5 I am willing do some install adjustment as needed. If some mod is needed I am willing to do, but as long I do not have to do any changes in dashboard meters. As for emission, preferred to be street legal.
I have looked into Chevy, jasper website and kind of willing to go something they offer (fully dressed). Hope through thirdgen, I can learn pros and cons and finally pick a right one.
I have looked into Chevy, jasper website and kind of willing to go something they offer (fully dressed). Hope through thirdgen, I can learn pros and cons and finally pick a right one.
Joined: Jul 2011
Posts: 695
Likes: 73
From: New York
Car: 86 Sport Coupe
Engine: 5.3 LM7
Transmission: T56
Axle/Gears: 4th gen 3.42 posi
Re: Need New Engine
Easiest thing that comes to mind would be a goodwrench 350 from gm. Yea its a rebuild, but you’re looking at the same thing from Jasper anyway. I think the warranty is pretty good, and they rate it at 308hp, but that would depend on what intake and header you put on it as well. I’m assuming the cam would get along fine with the factory carb, but I don’t know how much it will affect power. I also know nothing about t5’s aside from the fact that they were apparently built with glass internals, which is why they weren’t offered with 350 cars. 350+ ft lbs of torque may be an issue..
Heres a link to random variation of the goodwrench 350 I found online:
https://www.jegs.com/i/Chevrolet+Per...xoCUi0QAvD_BwE
Heres a link to random variation of the goodwrench 350 I found online:
https://www.jegs.com/i/Chevrolet+Per...xoCUi0QAvD_BwE
Thread Starter
Member
Joined: Dec 2011
Posts: 188
Likes: 1
Car: Transam, 85
Engine: 305 HO, 4bbl Carb, G Engine
Transmission: 5 Speed
Axle/Gears: 3.73
Re: Need New Engine
LSXMatt, thanks for the info.
It looks like a right fit. Few questions if you know it
1. I do not have to do any mod in in my dash board. Correct?
2. Any fuel pump mod/change?
3. What do I put on top? 308 HP is OK, if little less is OK too. do not want too much power.
4. Is this emission legal.
5. Rebuild means what? re bored, new piston, ring ???
6. Will it marry with T5
7. Any other info that can be helpful
It looks like a right fit. Few questions if you know it
1. I do not have to do any mod in in my dash board. Correct?
2. Any fuel pump mod/change?
3. What do I put on top? 308 HP is OK, if little less is OK too. do not want too much power.
4. Is this emission legal.
5. Rebuild means what? re bored, new piston, ring ???
6. Will it marry with T5
7. Any other info that can be helpful
Supreme Member
Joined: Jan 2009
Posts: 2,313
Likes: 115
From: belle fourche,s.d.
Car: '82 z28
Engine: L83 5.7
Transmission: 700r4-1985
Axle/Gears: 3.42 posi
Re: Need New Engine
# 1: no mods
2:no,unless an upgrade is found to be needed
3:the whole original setup will work great-just rejet the carb for the larger engine
4:doubt anyone will be checking #s on an old '85 firebird,engine will look stock
5:rebuild will be freshly machined bore,journals,new parts as needed.
6:yes,except if the replacement engine is 1 piece rear main(1986-later style)a new flywheel will be needed to match the later crankshaft flange
7:will be easy swap/uprade
2:no,unless an upgrade is found to be needed
3:the whole original setup will work great-just rejet the carb for the larger engine
4:doubt anyone will be checking #s on an old '85 firebird,engine will look stock
5:rebuild will be freshly machined bore,journals,new parts as needed.
6:yes,except if the replacement engine is 1 piece rear main(1986-later style)a new flywheel will be needed to match the later crankshaft flange
7:will be easy swap/uprade
Joined: Apr 2000
Posts: 1,533
Likes: 322
From: South Windsor, CT
Car: '89 GTA
Engine: ZZ6TPI
Transmission: T56
Axle/Gears: Borg Warner 3.70:1
Re: Need New Engine
I agree. The Goodwrench 350 is a great choice for this. Even if you stay with the stock exhaust manifolds and just re-jet the carb, should be in the 250-270hp range. Would be a nice upgrade over the 305ho.
Trending Topics
Thread Starter
Member
Joined: Dec 2011
Posts: 188
Likes: 1
Car: Transam, 85
Engine: 305 HO, 4bbl Carb, G Engine
Transmission: 5 Speed
Axle/Gears: 3.73
Re: Need New Engine
A new fly wheel is manageable.
What is 're-jet'.
Actually I was thinking to put an entire new intake with all new new stuff.
What is 're-jet'.
Actually I was thinking to put an entire new intake with all new new stuff.
Joined: Apr 2000
Posts: 1,533
Likes: 322
From: South Windsor, CT
Car: '89 GTA
Engine: ZZ6TPI
Transmission: T56
Axle/Gears: Borg Warner 3.70:1
Re: Need New Engine
You can run the original aluminum 4 barrel intake manifold, or change it to something like an Edelbrock Performer with EGR.
Junior Member
Joined: Dec 2020
Posts: 2
Likes: 0
Re: Need New Engine
Hello,
brand new member, was reading your post. I am also looking for an engine replacement for a 305, although mine is actually an 87 GMC. I’ve run across this, would it suit your needs? Brand new not rebuild.
https://www.ebay.com/itm/GM-OEM-NEW-....m46890.l49292
brand new member, was reading your post. I am also looking for an engine replacement for a 305, although mine is actually an 87 GMC. I’ve run across this, would it suit your needs? Brand new not rebuild.
https://www.ebay.com/itm/GM-OEM-NEW-....m46890.l49292
Junior Member
Joined: Feb 2020
Posts: 57
Likes: 21
From: Twin Cities Mn
Car: 1983 Z28
Engine: L69
Transmission: T5
Axle/Gears: 3.73
Re: Need New Engine
I would ask one question to myself. What do I want out of the car??? Third gens are a vehicle that will be increasing in value as time goes on. How nice is yours and what are your long term plans for it?? How much modification are you willing/able to do?? Is this car ever going to the strip or is just a weekend cruiser? You will need to reinforce the body with at least subframe connectors.
My impression of what you asking is the biggest bang for the least amount of time, money and effort. Members here can give great advice but YOU need to decide and clarify for everyone your goals for this car. Pictures might be helpful for everyone here.
To give you an idea of what "plans" are for a vehicle I will share my goal for my 83 Z28. I have the same motor/transmission as you.
I will rebuild my 5.0 and convert the flat tappet camshaft to hydraulic roller and stamped steel rocker arms to full roller to pick up HP. I am also going to port the heads for the same reason and do pollution controlled headers and run a 3" cat and single pipe exhaust. I am looking for a T56 for sale in my area and will upgrade from the T5. The NWC T5 will not even handle a stout 305 so I will not even consider a 350 in front of a T5. I will tweak my carb after the rebuild is done. I already have a steering box brace, pan hard arm and rear control arms. TBA is a rear axle upgrade with a rear disc brake conversion.
My goal is to keep my Z28 stock looking and keep the numbers matching but improve the weaknesses of the early 3rd gen F body. Mine will be a weekend car and maybe a car for the once a year car show. If I wanted a truly fast car I would buy something new and take advantage of the improved technology.
My impression of what you asking is the biggest bang for the least amount of time, money and effort. Members here can give great advice but YOU need to decide and clarify for everyone your goals for this car. Pictures might be helpful for everyone here.
To give you an idea of what "plans" are for a vehicle I will share my goal for my 83 Z28. I have the same motor/transmission as you.
I will rebuild my 5.0 and convert the flat tappet camshaft to hydraulic roller and stamped steel rocker arms to full roller to pick up HP. I am also going to port the heads for the same reason and do pollution controlled headers and run a 3" cat and single pipe exhaust. I am looking for a T56 for sale in my area and will upgrade from the T5. The NWC T5 will not even handle a stout 305 so I will not even consider a 350 in front of a T5. I will tweak my carb after the rebuild is done. I already have a steering box brace, pan hard arm and rear control arms. TBA is a rear axle upgrade with a rear disc brake conversion.
My goal is to keep my Z28 stock looking and keep the numbers matching but improve the weaknesses of the early 3rd gen F body. Mine will be a weekend car and maybe a car for the once a year car show. If I wanted a truly fast car I would buy something new and take advantage of the improved technology.
Last edited by Scott's 83' Z; Dec 26, 2020 at 01:41 PM.
Joined: Apr 2000
Posts: 1,533
Likes: 322
From: South Windsor, CT
Car: '89 GTA
Engine: ZZ6TPI
Transmission: T56
Axle/Gears: Borg Warner 3.70:1
Re: Need New Engine
Hello,
brand new member, was reading your post. I am also looking for an engine replacement for a 305, although mine is actually an 87 GMC. I’ve run across this, would it suit your needs? Brand new not rebuild.
https://www.ebay.com/itm/GM-OEM-NEW-....m46890.l49292
brand new member, was reading your post. I am also looking for an engine replacement for a 305, although mine is actually an 87 GMC. I’ve run across this, would it suit your needs? Brand new not rebuild.
https://www.ebay.com/itm/GM-OEM-NEW-....m46890.l49292
Re: Need New Engine
.
Hi Matt , sofakingdom explains it best in this post I quoted from a different thread . The major weakness does not come from the internals themselves , it comes from the fact that under high torque the case actually stretches allowing the gears to become misaligned , resulting in the quick destruction of the gears
Hi Matt , sofakingdom explains it best in this post I quoted from a different thread . The major weakness does not come from the internals themselves , it comes from the fact that under high torque the case actually stretches allowing the gears to become misaligned , resulting in the quick destruction of the gears
Very easy to identify which revision of transmission you have. Even in the car, a clearly identifying part is visible
BTW, I REFUSE to use that W s*** to name the 2 revisions of that product. I'm guessing they let the Marketing Dept's summer intern pick the "trendiest", "hippest", most "fashionable" term s/he could think of; and the best they could do was to copy that disgusting TQM 6-sigma "lean" BUZZWORD that was SO STUPIDLY POPULAR in the late 80s. Fortunately, like other corporate BUZZWORDS like "run it up the flagpole", "synergy", "take it offline", and other clichés that just make me PUKE will eventually do, it faded into well-deserved oblivion.
If it's the 1st design T-5, it will have the straight roller bearings on the countergear. Front countergear bearing looks like an upside-down freeze plug.
2nd design got tapered rollers with preload. The front countergear bearing looks like it was a depressed center, and has a sort of dull or matte finish.
1st design on top, 2nd below.
You cannot turn one into the other. ABSOLTUTELY NOTHING WHATSOEVER interchanges between them, except for the bolts, the spring on the reverse/5th shift rail and MAYBE the rail itself (not sure), the extension housing bushing, the shifter detent parts (block, ball, spring, cup), the clutch gear bearing retainer, the clutch gear bearing, and the main bearing.
Or maybe I should say, you can; but only by using Sofa's Magic Patented Exclusive 2-Step Method:
.
If the transmission "leaks heavily", it's probably the 1st design, and the reason it leaks, is because the case is destroyed. The metal is weak around the front countergear bearing, and it stretches across the front right there, which makes the hole oval instead of round. You can see in that photo above, the stain below and to the left of the bearing; that's the fluid that leaked out of that one. Worse even than the leeeeeeek, the stretching allows the clutch gear and countergear to misalign, which causes them to EAT each other as though for lunch. If that's what it is, and that's what's wrong with it, DO NOT spend even ONE EURO on it. Throw it in the trash and move on to something halfway decent.
BTW, I REFUSE to use that W s*** to name the 2 revisions of that product. I'm guessing they let the Marketing Dept's summer intern pick the "trendiest", "hippest", most "fashionable" term s/he could think of; and the best they could do was to copy that disgusting TQM 6-sigma "lean" BUZZWORD that was SO STUPIDLY POPULAR in the late 80s. Fortunately, like other corporate BUZZWORDS like "run it up the flagpole", "synergy", "take it offline", and other clichés that just make me PUKE will eventually do, it faded into well-deserved oblivion.
If it's the 1st design T-5, it will have the straight roller bearings on the countergear. Front countergear bearing looks like an upside-down freeze plug.
2nd design got tapered rollers with preload. The front countergear bearing looks like it was a depressed center, and has a sort of dull or matte finish.
1st design on top, 2nd below.
You cannot turn one into the other. ABSOLTUTELY NOTHING WHATSOEVER interchanges between them, except for the bolts, the spring on the reverse/5th shift rail and MAYBE the rail itself (not sure), the extension housing bushing, the shifter detent parts (block, ball, spring, cup), the clutch gear bearing retainer, the clutch gear bearing, and the main bearing.
Or maybe I should say, you can; but only by using Sofa's Magic Patented Exclusive 2-Step Method:
.
- Sell 1st design transmission
- Apply (the very little) cash you get toward buying 2nd design one
If the transmission "leaks heavily", it's probably the 1st design, and the reason it leaks, is because the case is destroyed. The metal is weak around the front countergear bearing, and it stretches across the front right there, which makes the hole oval instead of round. You can see in that photo above, the stain below and to the left of the bearing; that's the fluid that leaked out of that one. Worse even than the leeeeeeek, the stretching allows the clutch gear and countergear to misalign, which causes them to EAT each other as though for lunch. If that's what it is, and that's what's wrong with it, DO NOT spend even ONE EURO on it. Throw it in the trash and move on to something halfway decent.
Thread Starter
Member
Joined: Dec 2011
Posts: 188
Likes: 1
Car: Transam, 85
Engine: 305 HO, 4bbl Carb, G Engine
Transmission: 5 Speed
Axle/Gears: 3.73
Re: Need New Engine
Learned a bit more today.
My T5 can only handle max of 305 Ft/lb, and recommendation is engine should not go beyond 250 Ft/Lb say at 3500 rpm. In summary any engine above 250HP will definitely provide more torque and can bust T5 if not careful in driving.
That means engine has to be 250 HP or less, or I must have right engine and T combo. I rebuild diff and I know it can handle 400 ft/Lb.
Objective is not to go crazy with HPs but have the right combination to have a regular drive.
Current engine is tired, but T5 is good, did not wanted to spent money or hours on trans.
Back to drawing board and I have been circling in it for quiet some time. LS1 +T56, to new engine +T5, to new engine + T56, back to LS1 T56................
My T5 can only handle max of 305 Ft/lb, and recommendation is engine should not go beyond 250 Ft/Lb say at 3500 rpm. In summary any engine above 250HP will definitely provide more torque and can bust T5 if not careful in driving.
That means engine has to be 250 HP or less, or I must have right engine and T combo. I rebuild diff and I know it can handle 400 ft/Lb.
Objective is not to go crazy with HPs but have the right combination to have a regular drive.
Current engine is tired, but T5 is good, did not wanted to spent money or hours on trans.
Back to drawing board and I have been circling in it for quiet some time. LS1 +T56, to new engine +T5, to new engine + T56, back to LS1 T56................
Junior Member
Joined: May 2020
Posts: 14
Likes: 1
Re: Need New Engine
1996=2003 L31 5700 5.7 / 350 truck / van vortec; cheap, plentiful, and have room to grow and you can find them wth 4 bolt mains. They drop in without too much out of the box rated at 255 horsepower (190 kW) and 330 ft·lbf (450 N·m) of torque. The pair up nice with a Qjet. Even the stock cast heads flow and perform nicely. Keep it fuel injected the torque line is almost flat and consistent up to almost 5K RPM, carbed you gain about 5-10 lbs and then tapers down around 4500 rpm.
Re: Need New Engine
Learned a bit more today.
My T5 can only handle max of 305 Ft/lb, and recommendation is engine should not go beyond 250 Ft/Lb say at 3500 rpm. In summary any engine above 250HP will definitely provide more torque and can bust T5 if not careful in driving.
That means engine has to be 250 HP or less, or I must have right engine and T combo. I rebuild diff and I know it can handle 400 ft/Lb.
Objective is not to go crazy with HPs but have the right combination to have a regular drive.
Current engine is tired, but T5 is good, did not wanted to spent money or hours on trans.
Back to drawing board and I have been circling in it for quiet some time. LS1 +T56, to new engine +T5, to new engine + T56, back to LS1 T56................
My T5 can only handle max of 305 Ft/lb, and recommendation is engine should not go beyond 250 Ft/Lb say at 3500 rpm. In summary any engine above 250HP will definitely provide more torque and can bust T5 if not careful in driving.
That means engine has to be 250 HP or less, or I must have right engine and T combo. I rebuild diff and I know it can handle 400 ft/Lb.
Objective is not to go crazy with HPs but have the right combination to have a regular drive.
Current engine is tired, but T5 is good, did not wanted to spent money or hours on trans.
Back to drawing board and I have been circling in it for quiet some time. LS1 +T56, to new engine +T5, to new engine + T56, back to LS1 T56................
I know it's all too easy to spend someone else's money , but if it were my money , and I had the power upgrade jones goin on , I'd be SERIOUSLY considering the LS1-T56 option . First ya $pend on rebuilding the tired 305 , and then the NWC T5 blows up . Now ya $pend on rebuilding the T5 , and STILL have the weak T5 link in the drivetrain .
OR
$pend some $$$$ upfront and get parts far better suited for the 300 ish HP it sounds like it's gonna take for you to be satisfied with the car .
Joined: Nov 2008
Posts: 2,093
Likes: 175
From: Milwaukee
Car: 92 Firebird, 77 Trans Am SE, 86 Z28
Engine: 5.7 HSR, T/A 6.6, empty
Transmission: T-5, TH350, T-5
Axle/Gears: 3.08 posi, 3.23 posi, 3.23
Re: Need New Engine
Wait wait...do you need to pass emissions or not? So far this has been all over the place and the OP sounds a bit over their head in mechanicals. Even a mild upgrade to a 350 can be a pain if you can't tune an engine with at least rejetting a carb. An LS1 and t56 will be lightyears better but the fact that it's a lot more to sort out and mechanically know to swap in an LSx. Barring if you need to pass emissions or a visual inspection then it's not going to fly easily.
I feel the OP can learn these things and I know plenty on here willing to help but the OP needs to grip goals first, see if those goals are doable and reassess goals before going much further.
Emissions?
Budget still $5k? Note, LSx is more expensive typically to swap.
How much can you and your help feasibly do?
How fast do you really want it to be? Almost every one ends up wanting a 'little' more. And any upgrades in engine begs for more brake, better axle, suspension upgrades. Gotta explore that all when you go above the factory expected power levels.
And by all means you still don't explain why that 305 needs replacing, what says it doesn't just need repair?
I feel the OP can learn these things and I know plenty on here willing to help but the OP needs to grip goals first, see if those goals are doable and reassess goals before going much further.
Emissions?
Budget still $5k? Note, LSx is more expensive typically to swap.
How much can you and your help feasibly do?
How fast do you really want it to be? Almost every one ends up wanting a 'little' more. And any upgrades in engine begs for more brake, better axle, suspension upgrades. Gotta explore that all when you go above the factory expected power levels.
And by all means you still don't explain why that 305 needs replacing, what says it doesn't just need repair?
Thread Starter
Member
Joined: Dec 2011
Posts: 188
Likes: 1
Car: Transam, 85
Engine: 305 HO, 4bbl Carb, G Engine
Transmission: 5 Speed
Axle/Gears: 3.73
Re: Need New Engine
Orange Bird: Agreed.
As learning, T5 is only good with old similar HP engine. Any typical good new engine and thirdgen T5 is defiantly not the way. Unless old engine gets rebuild, one must find a new combo of engine and Trans.
As for buying at junkyard and rebuild has 100s combination and definitely not for me . LS1 T56 is good, but spending 7 to 8 k of 20 years old engine seems not a great idea. My budget of 5k simply will not do.. New combo I searched saying 13k & up of bare minimum.
Any one else has a better price of a new combo.
As learning, T5 is only good with old similar HP engine. Any typical good new engine and thirdgen T5 is defiantly not the way. Unless old engine gets rebuild, one must find a new combo of engine and Trans.
As for buying at junkyard and rebuild has 100s combination and definitely not for me . LS1 T56 is good, but spending 7 to 8 k of 20 years old engine seems not a great idea. My budget of 5k simply will not do.. New combo I searched saying 13k & up of bare minimum.
Any one else has a better price of a new combo.
Joined: Apr 2000
Posts: 1,533
Likes: 322
From: South Windsor, CT
Car: '89 GTA
Engine: ZZ6TPI
Transmission: T56
Axle/Gears: Borg Warner 3.70:1
Re: Need New Engine
Orange Bird: Agreed.
As learning, T5 is only good with old similar HP engine. Any typical good new engine and thirdgen T5 is defiantly not the way. Unless old engine gets rebuild, one must find a new combo of engine and Trans.
As for buying at junkyard and rebuild has 100s combination and definitely not for me . LS1 T56 is good, but spending 7 to 8 k of 20 years old engine seems not a great idea. My budget of 5k simply will not do.. New combo I searched saying 13k & up of bare minimum.
Any one else has a better price of a new combo.
As learning, T5 is only good with old similar HP engine. Any typical good new engine and thirdgen T5 is defiantly not the way. Unless old engine gets rebuild, one must find a new combo of engine and Trans.
As for buying at junkyard and rebuild has 100s combination and definitely not for me . LS1 T56 is good, but spending 7 to 8 k of 20 years old engine seems not a great idea. My budget of 5k simply will not do.. New combo I searched saying 13k & up of bare minimum.
Any one else has a better price of a new combo.
I don’t think you’re going to find a decent engine/trans combo for $5K. I would stick with the GM Goodwrench crate 350/290hp swap. It has a 2 piece rear main seal so your original flywheel works and the 86’ and older cylinder heads, so your intake bolts up too. The 290hp advertised horsepower will probably be more like 275 with headers and full exhaust and accessories. 250-260 if you keep the stock HO exhaust manifolds.
Yes, it’s technically more than the T5 was rated for, but it’s not that much more and if you’re reasonably nice to it, it will last a while. Under 300hp on a T5, longevity has more to do with how it’s treated. I’ve seen 200hp motors destroy them quickly (5,000rpm clutch sidestep with drag radials, power shifting, etc.) and others that lasted a long time behind a 300hp motor because it was treated well. Eventually, they all seem to go, but it’s more often a slower progression of wearing out bearings and synchros.
The T5 will probably die eventually, whether it’s behind you stock motor or a 350. An 87’ or later world class T5 would be a little better and probably the least expensive option when it does eventually go. Or a T56 swap down the road.
Bottom line is I wouldn’t hold back doing a mild 350 because of the T5. Just be nice to it.
Thread Starter
Member
Joined: Dec 2011
Posts: 188
Likes: 1
Car: Transam, 85
Engine: 305 HO, 4bbl Carb, G Engine
Transmission: 5 Speed
Axle/Gears: 3.73
Re: Need New Engine
I am willing to go over 5k if it is a right combination.
If that be the case, what be the correct Trans that goes behind 'GM Goodwrench crate 350/290hp'.
If that be the case, what be the correct Trans that goes behind 'GM Goodwrench crate 350/290hp'.
Joined: Apr 2000
Posts: 1,533
Likes: 322
From: South Windsor, CT
Car: '89 GTA
Engine: ZZ6TPI
Transmission: T56
Axle/Gears: Borg Warner 3.70:1
Re: Need New Engine
If you’re asking what will handle the extra torque of the 350, a T56 6speed from a 93-97 LT1 F-body would be a good choice.
Supreme Member
Joined: Jan 2009
Posts: 2,313
Likes: 115
From: belle fourche,s.d.
Car: '82 z28
Engine: L83 5.7
Transmission: 700r4-1985
Axle/Gears: 3.42 posi
Re: Need New Engine
correct tranny: T56,T700...but reply #19 is right on-install suitable upgrade 350, then deal with the tranny if a problem develops.
Thread Starter
Member
Joined: Dec 2011
Posts: 188
Likes: 1
Car: Transam, 85
Engine: 305 HO, 4bbl Carb, G Engine
Transmission: 5 Speed
Axle/Gears: 3.73
Re: Need New Engine
When senior members of thirdgen suggests, some time it takes lots of reading and internet searches to digest what they meant. That is why thirdgen is awesome in learning.
Need for replacing engine (or trans) came out of necessity as they have worn out. I was successful in rebuilding rear end , and was very satisfied with its performance. Did not wanted to rebuilt engine, or T5, hopping to get newer replacement. As learning, it will not be an easy job. First I thought, I will only change engine of some good HP, found out I just cannot due to existing T5. Then reluctantly started to think of doing both engine and trans to remove the mismatch factors and made some progress on finding right combo. Today. I found out even if I do that, the new T56 must have very close gear ratio of T5 else 1st, 5th and 6th can be bad drive.
So any one of these 3 (motor, trans, rear) goes bad, either you find exact, or VERY similar replacement in terms of HPs, torques, gear ratio, or rebuilt the existing ones. Other choice is you must make plan to replace all 3 and do the home work ahead of time to marry all of them in a synchronize way, otherwise, all hard works will not give satisfaction with holes of $ks.
Putting back Kelly's photo and keep breathing !
Need for replacing engine (or trans) came out of necessity as they have worn out. I was successful in rebuilding rear end , and was very satisfied with its performance. Did not wanted to rebuilt engine, or T5, hopping to get newer replacement. As learning, it will not be an easy job. First I thought, I will only change engine of some good HP, found out I just cannot due to existing T5. Then reluctantly started to think of doing both engine and trans to remove the mismatch factors and made some progress on finding right combo. Today. I found out even if I do that, the new T56 must have very close gear ratio of T5 else 1st, 5th and 6th can be bad drive.
So any one of these 3 (motor, trans, rear) goes bad, either you find exact, or VERY similar replacement in terms of HPs, torques, gear ratio, or rebuilt the existing ones. Other choice is you must make plan to replace all 3 and do the home work ahead of time to marry all of them in a synchronize way, otherwise, all hard works will not give satisfaction with holes of $ks.
Putting back Kelly's photo and keep breathing !
Joined: Apr 2000
Posts: 1,533
Likes: 322
From: South Windsor, CT
Car: '89 GTA
Engine: ZZ6TPI
Transmission: T56
Axle/Gears: Borg Warner 3.70:1
Re: Need New Engine
When senior members of thirdgen suggests, some time it takes lots of reading and internet searches to digest what they meant. That is why thirdgen is awesome in learning.
Need for replacing engine (or trans) came out of necessity as they have worn out. I was successful in rebuilding rear end , and was very satisfied with its performance. Did not wanted to rebuilt engine, or T5, hopping to get newer replacement. As learning, it will not be an easy job. First I thought, I will only change engine of some good HP, found out I just cannot due to existing T5. Then reluctantly started to think of doing both engine and trans to remove the mismatch factors and made some progress on finding right combo. Today. I found out even if I do that, the new T56 must have very close gear ratio of T5 else 1st, 5th and 6th can be bad drive.
So any one of these 3 (motor, trans, rear) goes bad, either you find exact, or VERY similar replacement in terms of HPs, torques, gear ratio, or rebuilt the existing ones. Other choice is you must make plan to replace all 3 and do the home work ahead of time to marry all of them in a synchronize way, otherwise, all hard works will not give satisfaction with holes of $ks.
Putting back Kelly's photo and keep breathing !
Need for replacing engine (or trans) came out of necessity as they have worn out. I was successful in rebuilding rear end , and was very satisfied with its performance. Did not wanted to rebuilt engine, or T5, hopping to get newer replacement. As learning, it will not be an easy job. First I thought, I will only change engine of some good HP, found out I just cannot due to existing T5. Then reluctantly started to think of doing both engine and trans to remove the mismatch factors and made some progress on finding right combo. Today. I found out even if I do that, the new T56 must have very close gear ratio of T5 else 1st, 5th and 6th can be bad drive.
So any one of these 3 (motor, trans, rear) goes bad, either you find exact, or VERY similar replacement in terms of HPs, torques, gear ratio, or rebuilt the existing ones. Other choice is you must make plan to replace all 3 and do the home work ahead of time to marry all of them in a synchronize way, otherwise, all hard works will not give satisfaction with holes of $ks.
Putting back Kelly's photo and keep breathing !
If you do a T56 swap later, the gear ratios for the 94'-97' T56 will work fine with your 3.73 rear end. Stay away from the 93' T56 since it has the shorter 1st gear.
Thread Starter
Member
Joined: Dec 2011
Posts: 188
Likes: 1
Car: Transam, 85
Engine: 305 HO, 4bbl Carb, G Engine
Transmission: 5 Speed
Axle/Gears: 3.73
Re: Need New Engine
305 I have is Leaking coolant,,burning oil you can smell. Coolant switch doesn't work, even after troubleshooting wires and changing new switch twice. It comes on rarely when engine gets way too hot where coolant bubbles. Oil pan leaks, raw gas smell and a bit sluggish that I realized after rebuilding reared.
Thread Starter
Member
Joined: Dec 2011
Posts: 188
Likes: 1
Car: Transam, 85
Engine: 305 HO, 4bbl Carb, G Engine
Transmission: 5 Speed
Axle/Gears: 3.73
Re: Need New Engine
Transam GTA350: Guilty on over analyzing.
Yes I am now on the line of getting engine replaced with kind you suggested.
What year your T56 is, and are you happy with T56 and 3.70 performance?
Yes I am now on the line of getting engine replaced with kind you suggested.
What year your T56 is, and are you happy with T56 and 3.70 performance?
Joined: Apr 2000
Posts: 1,533
Likes: 322
From: South Windsor, CT
Car: '89 GTA
Engine: ZZ6TPI
Transmission: T56
Axle/Gears: Borg Warner 3.70:1
Re: Need New Engine
My T56 is from a 1995, so it does have the taller 2.67:1 1st gear. Should be a good match for the 3.70 rear, but I haven’t driven it yet. Still building the car.
Thread Starter
Member
Joined: Dec 2011
Posts: 188
Likes: 1
Car: Transam, 85
Engine: 305 HO, 4bbl Carb, G Engine
Transmission: 5 Speed
Axle/Gears: 3.73
Re: Need New Engine
Post: T56 behind a 305 Engine
I posted above to get some info. Some senior member had posted some valuable response and one of them even had experience of T56 with 3.7x like. In summary it appears the ultimate result is sub per. Thread Starter
Member
Joined: Dec 2011
Posts: 188
Likes: 1
Car: Transam, 85
Engine: 305 HO, 4bbl Carb, G Engine
Transmission: 5 Speed
Axle/Gears: 3.73
Re: Need New Engine
A T5 first is 2.95, then a 2.66 will degrade 1st gear pull...will it not?
Is it not the same theory that you do not want to put 3.3x on 3.7x in rear?
It is like interest rate in mortgage where 2nd decimal may not matter much, but first two digits matters.
Is it not the same theory that you do not want to put 3.3x on 3.7x in rear?
It is like interest rate in mortgage where 2nd decimal may not matter much, but first two digits matters.
Last edited by Sonny_T; Dec 30, 2020 at 02:10 PM.
Joined: Apr 2000
Posts: 1,533
Likes: 322
From: South Windsor, CT
Car: '89 GTA
Engine: ZZ6TPI
Transmission: T56
Axle/Gears: Borg Warner 3.70:1
Re: Need New Engine
With a 350, you'll have plenty of torque to pull that 1st gear no problem and won't feel like you have to shift too early. Also, the overall spread between 1st to 4th is closer, so your RPM drops for each upshift are less. It will all work together very well.
As a comparison, the 94'-97' 350 LT1/T56 combo had the 2.66 1st gear and a 3.42 rear gear, so the overall 1st gear ratio for those was even taller than what you will have. My 99' LS1/T56 also has the same 2.66 1st and 3.42 rear and it's also fine.
The old Muncie M21 and M22 close ratio 4-speeds had 2.20:1 1st gear ratios and were often paired with a 3.73 rear end.
Thread Starter
Member
Joined: Dec 2011
Posts: 188
Likes: 1
Car: Transam, 85
Engine: 305 HO, 4bbl Carb, G Engine
Transmission: 5 Speed
Axle/Gears: 3.73
Re: Need New Engine
2nd, 3rd may not matter much. 4th is 1 every where, but what about 5th and 6th. Is it even possible to have an useful 6th unless you are going 80 miles an hour.?
Joined: Apr 2000
Posts: 1,533
Likes: 322
From: South Windsor, CT
Car: '89 GTA
Engine: ZZ6TPI
Transmission: T56
Axle/Gears: Borg Warner 3.70:1
Thread
Thread Starter
Forum
Replies
Last Post