454 back together
Drifting
Joined: Jan 2002
Posts: 1,645
Likes: 11
From: Schaumburg IL
Hood
I added a dropped air cleaner bottom piece (K&N part 87-3549) to give hood clearance. It drops 1 1/4 inch so the wing nut would not hit the hood. The PO apparently forgot about clearance, since there are spider vein cracks in the paint where he slammed the hood on the wing nut. I had this setup when I had it dyno-ed last time. Even with the bb hood there is not enough room for a three inch thick filter with the intake I have.
Thread Starter
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
hood
long style big block hood similar to L-88
The PO installed an aftermarket hood that is a "long" style that eliminates the wiper door and has a raised center section similar to the L-88 hood. The attached dyno photo has the hood raised to show its shape.
Thread Starter
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
valve tool
BTW I've never seen that Moroso valve spring tool that checks pressures with the springs on the head and rocker arms still on, thats a handy tool I wouldn't mind having.
I need to check my spring pressure, (although I'm afraid to know).... I have about 17k miles on my springs now and I'm sure they are ready....
I need to check my spring pressure, (although I'm afraid to know).... I have about 17k miles on my springs now and I'm sure they are ready....
Thread Starter
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
final dyno run
68 corvette 454 after installing new valve springs to cure valve float
Awesome job man! Glad to hear its fixed. Hopefully the dyno treats you right..
As per our PMs, I've done the valve spring dance several times and I know how tedious it is but....it HAS to be right.
Good job on sticking with it and working through the issue.
Keep us posted on the dyno numbers.. I'm guessing it does 350 rwhp...
As per our PMs, I've done the valve spring dance several times and I know how tedious it is but....it HAS to be right.
Good job on sticking with it and working through the issue.
Keep us posted on the dyno numbers.. I'm guessing it does 350 rwhp...
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
At least it didnt happen in traffic know it doesnt make things any better.
Springs make all the difference in the world sounds like things are coming together on your end
Had mine compressed for well over a yr almost wonder if-dread it
Springs make all the difference in the world sounds like things are coming together on your end
Had mine compressed for well over a yr almost wonder if-dread it
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
68 corvette 454 after installing new valve springs to cure valve float
Took the car to the dyno today. Printout is attached. The car pulled strong right up to 6000 rpm for three runs. 338 rwhp and 359 ft lbs torque was a little less than I hoped for, but at least the motor is running properly now. I should have quit while I was ahead, however. The technician running the dyno suggested doing a fourth run -for free- so I said OK. At about 6000 rpm the water pump seized, the fan belt flew off and I got to have the car brought home on a roll-back. You just can't win. So I have my new Autozone water pump and new fan belt on my work bench ready for tomorrow's next adventure in Corvette restoration. Down but not out. RA
Well congrats on solving the RPM problem. I'm sure with some timing tweaking and playing with jetting, you could get another 10-15 rwhp out of it but...its definitely pretty close.
Pretty scary about the fan coming off, that would have been terrible if you or someone else had been standing beside it.
Out of curiousity, was this dyno pull with the air cleaner lid on?
So to recap, you went from 305 rwhp before the rebuild to 338 rwhp after? basically gained 33 rwhp from a head/cam swap. If that engine had about 2pts of compression more, you'd probably be much closer to 400 rwhp. Eitherway, you'll have a fun summer now tearing up the streets.
Thread Starter
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
Well congrats on solving the RPM problem. I'm sure with some timing tweaking and playing with jetting, you could get another 10-15 rwhp out of it but...its definitely pretty close.
Pretty scary about the fan coming off, that would have been terrible if you or someone else had been standing beside it.
Out of curiousity, was this dyno pull with the air cleaner lid on?
So to recap, you went from 305 rwhp before the rebuild to 338 rwhp after? basically gained 33 rwhp from a head/cam swap. If that engine had about 2pts of compression more, you'd probably be much closer to 400 rwhp. Eitherway, you'll have a fun summer now tearing up the streets.
Pretty scary about the fan coming off, that would have been terrible if you or someone else had been standing beside it.
Out of curiousity, was this dyno pull with the air cleaner lid on?
So to recap, you went from 305 rwhp before the rebuild to 338 rwhp after? basically gained 33 rwhp from a head/cam swap. If that engine had about 2pts of compression more, you'd probably be much closer to 400 rwhp. Eitherway, you'll have a fun summer now tearing up the streets.
"If that engine had about 2pts of compression more" Right- I gained about 30 HP (air cleaner off gained 5 hp on this run and also the last run). I considered bumping the compression with domed pistons but did not want to pull the engine to do the balancing act. Since the car is just a weekend cruiser, I am going to resist spending more $$$$ to add HP that I will never use. The car now has a more radical idle to scare off the Hondas and the aluminum heads look impressive. I also have the air cleaner sticker that boasts of 460 HP. Thanks for your help diagnosing the valve spring problem. RA
Thread Starter
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
"At least it didnt happen in traffic " My thoughts exactly. The car does not have A/C or power steering, so the water pump is easy to replace. I was surprised the new, not re-built, water pump was only $42 at Autozone for their heavy duty pump. Just one more repair to do.
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Le Mans Master
Joined: Mar 2001
Posts: 5,738
Likes: 644
From: Lincoln, CA
If you want a lighter one I'm using this one with no issues. Direct bolt on.
https://www.summitracing.com/parts/nal-19168602
https://www.summitracing.com/parts/nal-19168602
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
Don't forget, you'll also knocked about 80lbs off of the nose of the car.. that's good for a tenth and 1-2 mph.
Another place you can find some power if you want to put the effort in, is switch to an electric fan. My 7 blade clutch fan with the severe duty clutch cost me 15 rwhp on the dyno, same day A-B-A test. However, this will require an alternator and wiring upgrade. A bonus is it's not going to fly off and checking timing is much easier.
Another place you can find some power if you want to put the effort in, is switch to an electric fan. My 7 blade clutch fan with the severe duty clutch cost me 15 rwhp on the dyno, same day A-B-A test. However, this will require an alternator and wiring upgrade. A bonus is it's not going to fly off and checking timing is much easier.
Last edited by ajrothm; Mar 7, 2017 at 02:18 AM.
Thread Starter
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
Don't forget, you'll also knocked about 80lbs off of the nose of the car.. that's good for a tenth and 1-2 mph.
Another place you can find some power if you want to put the effort in, is switch to an electric fan. My 7 blade clutch fan with the severe duty clutch cost me 15 rwhp on the dyno, same day A-B-A test. However, this will require an alternator and wiring upgrade. A bonus is it's not going to fly off and checking timing is much easier.
Another place you can find some power if you want to put the effort in, is switch to an electric fan. My 7 blade clutch fan with the severe duty clutch cost me 15 rwhp on the dyno, same day A-B-A test. However, this will require an alternator and wiring upgrade. A bonus is it's not going to fly off and checking timing is much easier.
"switch to an electric fan" I had an electric fan on the alum radiator from the PO. I upgraded to a temperature relay so the fan did not run all the time. PO had it direct wired. I kept the Flex-o-lite fan that was there- not needed, but belt and suspenders type mentality. I have all of this stuff off to install the water pump, so I may just leave the fan on the work bench. (another 15 rwhp) BTW- the fan belt flew off, not the fan. I did not even notice it. One of the techs watching spotted it. RA
Thread Starter
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
If you want a lighter one I'm using this one with no issues. Direct bolt on.
https://www.summitracing.com/parts/nal-19168602
https://www.summitracing.com/parts/nal-19168602
Thanks. The pump I ordered today at Autozone is an aluminum one like this for about half the Summit price.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
Yeah I'd do the electric fan for sure since you already have it, IF its a good one... You don't want to create over heating problems you didn't have before.
I use a Lincoln MK8 fan and it works EXCELLENT..(I average 185-188* with AC on in the middle of summer and the fan cycling on/off)...I can manually override the fan to stay on and it will get into the 170*s on a 95* day with the ac on.
Dual 11" spal fans work pretty well also and pull less amps.
Thread Starter
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
I hope it turns out to be a short pump.
Yeah I'd do the electric fan for sure since you already have it, IF its a good one... You don't want to create over heating problems you didn't have before.
I use a Lincoln MK8 fan and it works EXCELLENT..(I average 185-188* with AC on in the middle of summer and the fan cycling on/off)...I can manually override the fan to stay on and it will get into the 170*s on a 95* day with the ac on.
Dual 11" spal fans work pretty well also and pull less amps.
Yeah I'd do the electric fan for sure since you already have it, IF its a good one... You don't want to create over heating problems you didn't have before.
I use a Lincoln MK8 fan and it works EXCELLENT..(I average 185-188* with AC on in the middle of summer and the fan cycling on/off)...I can manually override the fan to stay on and it will get into the 170*s on a 95* day with the ac on.
Dual 11" spal fans work pretty well also and pull less amps.
I installed the new water pump and just left off the fan blade. The old pump sounds like it has gravel in the bearing. Probably why it seized up. There sure is a lot more room without the old mechanical fan. The electric fan was on the car when I got it. Not sure what brand it is. I changed the PO direct wiring and added separate fused line and a temperature relay that comes on at 195 degrees. I think the electric fan was doing most of the air circulation even with the mechanical fan in place. Temp stays 180-195. I'm hoping to do some top down cruising the next couple days if the weather cooperates- tired of doing mechanical work on the car. RA
Racer
Joined: Oct 2010
Posts: 259
Likes: 3
From: Plano TX
Big Block Odyssey
Wow....it never ends sometimes, does it? Enjoyed your tale. Glad you go things sorted out.
Here is a thread from sometime back on my '73 with a "detuned" LS6 crate motor we installed in '77. '78?
https://www.corvetteforum.com/forums...e-on-dyno.html
Anyway, you mentioned the Pertronix ignition. This car is running the stock distributor with either the II or III. I can't remember, and it's night time and I'm sitting on my couch doing this and I really don't feel like getting up and double checking. Sorry. I'm not using the Pertronix coil, but not because I don't want to, I just found myself in need of one and grabbed an Accel coil...I think it might have been an 8145, but again, can't quite remember, and it's cold out in the garage. I'm old, and lazy. Sorry.
When the motor was installed, a high rise hood with an air box/ rear entry design was installed at the same time. During one set of runs (all runs I've done are without the screen set up), which are normally with the hood opened, I did one with the hood closed (just one....wasn't intending to do a definitive test) and it cost 3 hp. I didn't think that was so bad. I'm using a K&N 3" filter, which is stuck in the air box.
Good luck on your car.
Here is a thread from sometime back on my '73 with a "detuned" LS6 crate motor we installed in '77. '78?
https://www.corvetteforum.com/forums...e-on-dyno.html
Anyway, you mentioned the Pertronix ignition. This car is running the stock distributor with either the II or III. I can't remember, and it's night time and I'm sitting on my couch doing this and I really don't feel like getting up and double checking. Sorry. I'm not using the Pertronix coil, but not because I don't want to, I just found myself in need of one and grabbed an Accel coil...I think it might have been an 8145, but again, can't quite remember, and it's cold out in the garage. I'm old, and lazy. Sorry.
When the motor was installed, a high rise hood with an air box/ rear entry design was installed at the same time. During one set of runs (all runs I've done are without the screen set up), which are normally with the hood opened, I did one with the hood closed (just one....wasn't intending to do a definitive test) and it cost 3 hp. I didn't think that was so bad. I'm using a K&N 3" filter, which is stuck in the air box.
Good luck on your car.
Last edited by FlyLS6; Mar 8, 2017 at 11:03 PM.
Drifting
Joined: Jul 2013
Posts: 1,299
Likes: 93
From: Tri-Cities TN
68 corvette 454 after installing new valve springs to cure valve float
Took the car to the dyno today. Printout is attached. The car pulled strong right up to 6000 rpm for three runs. 338 rwhp and 359 ft lbs torque was a little less than I hoped for, but at least the motor is running properly now. I should have quit while I was ahead, however. The technician running the dyno suggested doing a fourth run -for free- so I said OK. At about 6000 rpm the water pump seized, the fan belt flew off and I got to have the car brought home on a roll-back. You just can't win. So I have my new Autozone water pump and new fan belt on my work bench ready for tomorrow's next adventure in Corvette restoration. Down but not out. RA
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
