Will this Work
Thread Starter
5th Gear
Joined: Nov 2006
Posts: 5
Likes: 0
Will this Work
Hope this is not a repeat of other post.
Ihave a 77 coup L48 all stock except have headers installed.
Looking to improve HP. to300-350hp. I would like to keep my
old 76cc heads. Here is what i was thinking.
1. Changing the pistons' with a set of dome style pistons
to raise the compession to about 62-65cc.
2. Port and polish the old heads for better flow
3. Replace the cam to?? (need suggestions)
4. Replace intake (need suggestions)
Every one seems to suggest replacing the heads and ofcourse
this would be best. But would a setup like above work and if
so, What HP. would I gain. There is 90,000 miles on the old
pistons and rings, so I thought this may kill two birds with one stone.
The rest of the engine is solid.
Ihave a 77 coup L48 all stock except have headers installed.
Looking to improve HP. to300-350hp. I would like to keep my
old 76cc heads. Here is what i was thinking.
1. Changing the pistons' with a set of dome style pistons
to raise the compession to about 62-65cc.
2. Port and polish the old heads for better flow
3. Replace the cam to?? (need suggestions)
4. Replace intake (need suggestions)
Every one seems to suggest replacing the heads and ofcourse
this would be best. But would a setup like above work and if
so, What HP. would I gain. There is 90,000 miles on the old
pistons and rings, so I thought this may kill two birds with one stone.
The rest of the engine is solid.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Have you done a compression test on the motor to see what you;re rings and seats are holding?
Another thin to consider is wear on your bearings. If your motor has worn a but the extra compression from domed pistons would put a strain on the rings and rod bearings.
Another thin to consider is wear on your bearings. If your motor has worn a but the extra compression from domed pistons would put a strain on the rings and rod bearings.
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
Hope this is not a repeat of other post.
Ihave a 77 coup L48 all stock except have headers installed.
Looking to improve HP. to300-350hp. I would like to keep my
old 76cc heads. Here is what i was thinking.
1. Changing the pistons' with a set of dome style pistons
to raise the compession to about 62-65cc.
2. Port and polish the old heads for better flow
3. Replace the cam to?? (need suggestions)
4. Replace intake (need suggestions)
Every one seems to suggest replacing the heads and ofcourse
this would be best. But would a setup like above work and if
so, What HP. would I gain. There is 90,000 miles on the old
pistons and rings, so I thought this may kill two birds with one stone.
The rest of the engine is solid.
Ihave a 77 coup L48 all stock except have headers installed.
Looking to improve HP. to300-350hp. I would like to keep my
old 76cc heads. Here is what i was thinking.
1. Changing the pistons' with a set of dome style pistons
to raise the compession to about 62-65cc.
2. Port and polish the old heads for better flow
3. Replace the cam to?? (need suggestions)
4. Replace intake (need suggestions)
Every one seems to suggest replacing the heads and ofcourse
this would be best. But would a setup like above work and if
so, What HP. would I gain. There is 90,000 miles on the old
pistons and rings, so I thought this may kill two birds with one stone.
The rest of the engine is solid.
andylmusic76, where he askes if he should use a set of 58cc chamber 305
heads. Then make up your mind if you want to port old heads.
Last edited by Little Mouse; May 17, 2007 at 09:01 AM.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
If you're going to replace the pistons, you'll need to measure the cylinders for taper and out of round. Then the crank rod journals for the same things. If everything is within tolerances, hone the cylinders to fit the new pistons and rings. At 90k miles, I'll bet there is more wear than you think, Not trying to be negative, just a look at reality. I'm reasonably sure you don't want to spend $$$ for new heads and pistons, then smoke like a chimney because the rings won't seat and then rattle becaust the pistons are too loose in the bores. It may be time to look at a crate engine or a full rebuild.
Thread Starter
5th Gear
Joined: Nov 2006
Posts: 5
Likes: 0
If you're going to replace the pistons, you'll need to measure the cylinders for taper and out of round. Then the crank rod journals for the same things. If everything is within tolerances, hone the cylinders to fit the new pistons and rings. At 90k miles, I'll bet there is more wear than you think, Not trying to be negative, just a look at reality. I'm reasonably sure you don't want to spend $$$ for new heads and pistons, then smoke like a chimney because the rings won't seat and then rattle becaust the pistons are too loose in the bores. It may be time to look at a crate engine or a full rebuild.
it was a stupid idea to try and take short cuts.
Thanks
