l69 305 h.o top end rebuild
Thread Starter
Member
Joined: May 2012
Posts: 126
Likes: 0
From: Ohio
Car: '86 Sport Coupe
Engine: 310"
Transmission: 700r4
Axle/Gears: Stock 10 bolt. 2.73's
l69 305 h.o top end rebuild
when i got this car the previous owner said it overheated i thought the cylinder head was cracked but thankfully it wasnt it ended up being a combination of things the radiator was junk, the fan didnt work, and the timing was way too retarded, so heres my build
the previous owner had a torker 2 intake on it witch is ridiculous, it didnt have enough vacuum to work the power brakes and it had NO bottom end power i ended up changing it to a performer intake witch helped it alot
theres the pics heres what was done
the cylinder heads got a valve job, put on dz 302 valve springs, and some porting
a new cam 272-282 adv. duration .442- .465 lift
edelbrock peformer intake
holley 650 spreadbore carb
accell distributor
weiand alm. water pump
and originally i put on a set of vintage mickey thompson valve covers but they didnt have a baffle inside for the pcv so i chanded them out for edelbrocks
the previous owner had a torker 2 intake on it witch is ridiculous, it didnt have enough vacuum to work the power brakes and it had NO bottom end power i ended up changing it to a performer intake witch helped it alot
theres the pics heres what was done
the cylinder heads got a valve job, put on dz 302 valve springs, and some porting
a new cam 272-282 adv. duration .442- .465 lift
edelbrock peformer intake
holley 650 spreadbore carb
accell distributor
weiand alm. water pump
and originally i put on a set of vintage mickey thompson valve covers but they didnt have a baffle inside for the pcv so i chanded them out for edelbrocks
Last edited by 86'sportcoupe; Oct 21, 2012 at 05:25 PM.
Member
Joined: Jan 2012
Posts: 294
Likes: 0
From: Milwaukee
Car: 1984 Z28
Engine: Vortec 350, hotcam
Transmission: T56
Axle/Gears: 3.73
Re: l69 305 h.o top end rebuild
Nice job. How does it perform now? Also in your last picture, what's the line coming out of the intake and over the valve cover for?
Moderator
Joined: Jan 2000
Posts: 20,981
Likes: 11
From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Re: l69 305 h.o top end rebuild
Looks like a capillary tube for a mechanical temperature gauge.
Joined: Dec 2005
Posts: 6,499
Likes: 31
From: Macon, GA
Car: 1992 Camaro RS
Engine: Vortec headed 355, xe262
Transmission: T56
Axle/Gears: 9-bolt 3.70
Re: l69 305 h.o top end rebuild
Why did you put dished pistons into a flat-top piston L69? The main difference between the LG4 and L69 was the L69 got a slightly better cam and flat top pistons for higher compression.
Regardless, the Torkers are a terrible match for a mostly stock engine, you did good by ditching it.
Regardless, the Torkers are a terrible match for a mostly stock engine, you did good by ditching it.
Last edited by InfernalVortex; Oct 22, 2012 at 01:03 PM.
Thread Starter
Member
Joined: May 2012
Posts: 126
Likes: 0
From: Ohio
Car: '86 Sport Coupe
Engine: 310"
Transmission: 700r4
Axle/Gears: Stock 10 bolt. 2.73's
Re: l69 305 h.o top end rebuild
Thread Starter
Member
Joined: May 2012
Posts: 126
Likes: 0
From: Ohio
Car: '86 Sport Coupe
Engine: 310"
Transmission: 700r4
Axle/Gears: Stock 10 bolt. 2.73's
Re: l69 305 h.o top end rebuild
Why did you put dished pistons into a flat-top piston L69? The main difference between the LG4 and L69 was the L69 got a slightly better cam and flat top pistons for higher compression.
Regardless, the Torkers are a terrible match for a mostly stock engine, you did good by ditching it.
Regardless, the Torkers are a terrible match for a mostly stock engine, you did good by ditching it.
Last edited by 86'sportcoupe; Oct 22, 2012 at 04:30 PM.
Supreme Member
Joined: Jan 2011
Posts: 1,932
Likes: 9
From: Lynden WA
Car: 84 Trans Am, 84 Fiero, 86 944
Engine: 5.0, 2.5, 2.5
Transmission: 5spd
Re: l69 305 h.o top end rebuild
great build so far, glad to see someone rebuild an l69 for a change rather the swap it for a "better" tree fiddy
Trending Topics
Thread Starter
Member
Joined: May 2012
Posts: 126
Likes: 0
From: Ohio
Car: '86 Sport Coupe
Engine: 310"
Transmission: 700r4
Axle/Gears: Stock 10 bolt. 2.73's
Re: l69 305 h.o top end rebuild
Thanks, i built the 305 because its my first car and my parents are just trying to keep me safe, plus this was a copo car and it was ordered with an l69 but my dad has enough parts to build a pretty sweet 355 down the road, but the 305 will do for now plus it will rev to like 6,000-6,300 rpm with those dz302 z/28 valve springs lol
Supreme Member
Joined: Jan 2011
Posts: 1,932
Likes: 9
From: Lynden WA
Car: 84 Trans Am, 84 Fiero, 86 944
Engine: 5.0, 2.5, 2.5
Transmission: 5spd
Re: l69 305 h.o top end rebuild
well that or your tach is wrong, mine says i do 6700 rpm on the interstate at 1/4 throttle and i dont think anyones factory tachometer is right given the failure rate of them
Thread Starter
Member
Joined: May 2012
Posts: 126
Likes: 0
From: Ohio
Car: '86 Sport Coupe
Engine: 310"
Transmission: 700r4
Axle/Gears: Stock 10 bolt. 2.73's
Re: l69 305 h.o top end rebuild
wow, i do have an aftermarket tach though and i haven't tested it yet but those old dz engines reved to like 7500 and the stiff valve springs had alot to do with it
Supreme Member
Joined: Jan 2011
Posts: 1,932
Likes: 9
From: Lynden WA
Car: 84 Trans Am, 84 Fiero, 86 944
Engine: 5.0, 2.5, 2.5
Transmission: 5spd
Re: l69 305 h.o top end rebuild
yeah that much i know, its a respectable (very) 5.0 but honestly you could probably save those dz 302 parts and sell them to someone doing a resto for big $$$$
Thread Starter
Member
Joined: May 2012
Posts: 126
Likes: 0
From: Ohio
Car: '86 Sport Coupe
Engine: 310"
Transmission: 700r4
Axle/Gears: Stock 10 bolt. 2.73's
Re: l69 305 h.o top end rebuild
well they went original they were an exact copy made by manely, but my dad has an original dz 780 holley carb and i think he used to have the intake too but i think he sold it
Moderator
Joined: Jan 2000
Posts: 20,981
Likes: 11
From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Thread Starter
Member
Joined: May 2012
Posts: 126
Likes: 0
From: Ohio
Car: '86 Sport Coupe
Engine: 310"
Transmission: 700r4
Axle/Gears: Stock 10 bolt. 2.73's
Supreme Member
Joined: Jan 2011
Posts: 1,932
Likes: 9
From: Lynden WA
Car: 84 Trans Am, 84 Fiero, 86 944
Engine: 5.0, 2.5, 2.5
Transmission: 5spd
Re: l69 305 h.o top end rebuild
i believe it was, but they called it the fleet program, and of course they caught on to the massive engines in muscle cars part of it lol anymore you cant even special order a vehicle form say Chevrolet with (i know there not around anymore) a Pontiac color option, you need at least 5
Thread Starter
Member
Joined: May 2012
Posts: 126
Likes: 0
From: Ohio
Car: '86 Sport Coupe
Engine: 310"
Transmission: 700r4
Axle/Gears: Stock 10 bolt. 2.73's
Re: l69 305 h.o top end rebuild
here is the est. power and torque numbers based on a engine building simulator
peak hp at the flywheel is 344 at 5500 and 415lbs of torque at 3000
peak hp at the flywheel is 344 at 5500 and 415lbs of torque at 3000
Thread Starter
Member
Joined: May 2012
Posts: 126
Likes: 0
From: Ohio
Car: '86 Sport Coupe
Engine: 310"
Transmission: 700r4
Axle/Gears: Stock 10 bolt. 2.73's
Joined: Dec 2005
Posts: 6,499
Likes: 31
From: Macon, GA
Car: 1992 Camaro RS
Engine: Vortec headed 355, xe262
Transmission: T56
Axle/Gears: 9-bolt 3.70
Re: l69 305 h.o top end rebuild
Your cam:
http://www.summitracing.com/parts/SUM-1103/
DZ302 cam (there are a few different versions around today, but this is one):
http://www.summitracing.com/parts/HRS-112192-14/
That cam is HUGE... MASSIVELY huge.
https://www.thirdgen.org/forums/tech...dz302-sbc.html
Go to the drag strip, just get down it at wide open throttle and see what your trap speed is. Your speed in the 1/4 and your car's weight (get on the scale at the track) will give you a very accurate estimate of real world horsepower. Use any one of the numerous online calculators that compute this, most are pretty consistent. Real world numbers are going to be a lot more accurate.
Your car likely weighs between 3400 and 3600 with you in it. Go find out how fast it will go. Trap speed is pretty consistent regardless of how bad you launch so dont worry about that.
Thread Starter
Member
Joined: May 2012
Posts: 126
Likes: 0
From: Ohio
Car: '86 Sport Coupe
Engine: 310"
Transmission: 700r4
Axle/Gears: Stock 10 bolt. 2.73's
Re: l69 305 h.o top end rebuild
The camshaft was what it had to do with.
Your cam:
http://www.summitracing.com/parts/SUM-1103/
DZ302 cam (there are a few different versions around today, but this is one):
http://www.summitracing.com/parts/HRS-112192-14/
That cam is HUGE... MASSIVELY huge.
https://www.thirdgen.org/forums/tech...dz302-sbc.html
Nothing special about any of that stuff. Z28 springs were all people had for yeras before the aftermarket began to offer a huge variety of more effective springs for every application. Nowadays it's better to run whatever spring the cam company recommends for their cams.
Go to the drag strip, just get down it at wide open throttle and see what your trap speed is. Your speed in the 1/4 and your car's weight (get on the scale at the track) will give you a very accurate estimate of real world horsepower. Use any one of the numerous online calculators that compute this, most are pretty consistent. Real world numbers are going to be a lot more accurate.
Your car likely weighs between 3400 and 3600 with you in it. Go find out how fast it will go. Trap speed is pretty consistent regardless of how bad you launch so dont worry about that.
Your cam:
http://www.summitracing.com/parts/SUM-1103/
DZ302 cam (there are a few different versions around today, but this is one):
http://www.summitracing.com/parts/HRS-112192-14/
That cam is HUGE... MASSIVELY huge.
https://www.thirdgen.org/forums/tech...dz302-sbc.html
Nothing special about any of that stuff. Z28 springs were all people had for yeras before the aftermarket began to offer a huge variety of more effective springs for every application. Nowadays it's better to run whatever spring the cam company recommends for their cams.
Go to the drag strip, just get down it at wide open throttle and see what your trap speed is. Your speed in the 1/4 and your car's weight (get on the scale at the track) will give you a very accurate estimate of real world horsepower. Use any one of the numerous online calculators that compute this, most are pretty consistent. Real world numbers are going to be a lot more accurate.
Your car likely weighs between 3400 and 3600 with you in it. Go find out how fast it will go. Trap speed is pretty consistent regardless of how bad you launch so dont worry about that.
And the edelbrock perfomer rpm is highly based on the old dz intake they are worth a crap load if original
Thread Starter
Member
Joined: May 2012
Posts: 126
Likes: 0
From: Ohio
Car: '86 Sport Coupe
Engine: 310"
Transmission: 700r4
Axle/Gears: Stock 10 bolt. 2.73's
Re: l69 305 h.o top end rebuild
also i cant take it to the strip yet as i only got my temps the other day but hopefully eventually i will make it to the track
Thread Starter
Member
Joined: May 2012
Posts: 126
Likes: 0
From: Ohio
Car: '86 Sport Coupe
Engine: 310"
Transmission: 700r4
Axle/Gears: Stock 10 bolt. 2.73's
Moderator
Joined: Jan 2000
Posts: 20,981
Likes: 11
From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Re: l69 305 h.o top end rebuild
No, then it would have come from the factory with matching VIN and all the documentation... not to mention you would have had to order about 100 of them at the same time as part of your COPO order.
Thread Starter
Member
Joined: May 2012
Posts: 126
Likes: 0
From: Ohio
Car: '86 Sport Coupe
Engine: 310"
Transmission: 700r4
Axle/Gears: Stock 10 bolt. 2.73's
Re: l69 305 h.o top end rebuild
Heres an updated pic, changed the air cleaner lid out for a jegs one that was in better shape then the edelbrock, and i painted the wing nut red
Thread Starter
Member
Joined: May 2012
Posts: 126
Likes: 0
From: Ohio
Car: '86 Sport Coupe
Engine: 310"
Transmission: 700r4
Axle/Gears: Stock 10 bolt. 2.73's
Re: l69 305 h.o top end rebuild
Forgot about this old thread, here is the update, got some miles on her now, performance is much better than expected. and the engine is not a true l69. Well it could have been, it was a reman 310 crate from napa. it has the dish pistons, but with 601 heads, either way it runs very good for what it is, here is a video of it running, cam lope sounds pretty intense in it. for how mild it is. this was an open y pipe, now has a race bullet in place of the flowmaster
(btw hardly any money was spent on this thing, and it is my first car, that is why we built the 305, my dad built race engines for years, thought of the 305 as a boat anchor. He was blown away by how this thing performs, great first hot rod engine)
(btw hardly any money was spent on this thing, and it is my first car, that is why we built the 305, my dad built race engines for years, thought of the 305 as a boat anchor. He was blown away by how this thing performs, great first hot rod engine)
Last edited by 86'sportcoupe; Mar 22, 2014 at 10:37 PM.
Thread
Thread Starter
Forum
Replies
Last Post
hectre13
Engine/Drivetrain/Suspension Parts for Sale
2
Dec 11, 2023 08:14 AM
3rdgenparts
Firebirds for Sale
0
Aug 6, 2015 09:03 AM
