425 Compression Question.
#1
425 Compression Question.
You guys have helped me solve a lot of stupid problems I've encountered on this, my first and seemingly never ending engine build, so I'm hoping someone can shed some light on what I'm trying to figure out now.
I built the 425 in my 66 Delta 88 with some help from a friend who owns a mechanic shop that works mostly on diesel stuff. He was kind enough to let me "borrow" one of his techs who basically helped me with assembly as you guys helped me with the olds specific stuff. The engine is all together and as I've posted before, it just lacks the performance that I know this engine is capable of producing. I've corrected several issues over the last few months with the information gathered from posts on this site, but I'm just disappointed with the way this thing performs. Block was bored 40 over, stock compression pistons, heads rebuilt stock + hardened seats and SK-247-SP springs. Put in a JM-22-25-10 cam and 555-HCR lifters. The cam, lifter & spring selection were all based on the information I got from Mondello after I told them how I wanted to build & use the engine.(and yes, I've since learned of the general consensus about "post-Joe Mondello on this site).
I've got a new Edelbrock 750 on top of the stock manifold. I have the Q-jet sitting in the Edelbox, but I don't know if I should rebuild it and ditch the Edelbrock. I went to Thornton and got there left exhaust manifold & ran them through an X and 2 flowmaster 40s. Just ask if I've left any valuable information out as I'm sure I have.
I realize that the information I have is limited and that "doesn't perform like I know it's capable of" is vague, but rest assured, this thing is LAZY.
I've double checked the cam timing. Overall advance is about 32(that seems to be where it runs best). Turbo 400 runs/shifts strong.
The thing that caught my eye and prompted me to post about this again was a recent post by J-(Chicago) on another thread where he said "Most 71' 455 motors had 40 cc dish in the pistons. Big ol' soup bowl like dish.
If you simply change head gaskets from stock factory to fel-pro, you will be at 7.8-1 compression if you don't have them milled." I don't recall off hand what gaskets were used. If this were the case, what kind of performance loss would I see? Could this be the problem?
Please, if my ignorance frustrates you, feel free to keep that to yourself(except Norm. Norm can say whatever he wants
I built the 425 in my 66 Delta 88 with some help from a friend who owns a mechanic shop that works mostly on diesel stuff. He was kind enough to let me "borrow" one of his techs who basically helped me with assembly as you guys helped me with the olds specific stuff. The engine is all together and as I've posted before, it just lacks the performance that I know this engine is capable of producing. I've corrected several issues over the last few months with the information gathered from posts on this site, but I'm just disappointed with the way this thing performs. Block was bored 40 over, stock compression pistons, heads rebuilt stock + hardened seats and SK-247-SP springs. Put in a JM-22-25-10 cam and 555-HCR lifters. The cam, lifter & spring selection were all based on the information I got from Mondello after I told them how I wanted to build & use the engine.(and yes, I've since learned of the general consensus about "post-Joe Mondello on this site).
I've got a new Edelbrock 750 on top of the stock manifold. I have the Q-jet sitting in the Edelbox, but I don't know if I should rebuild it and ditch the Edelbrock. I went to Thornton and got there left exhaust manifold & ran them through an X and 2 flowmaster 40s. Just ask if I've left any valuable information out as I'm sure I have.
I realize that the information I have is limited and that "doesn't perform like I know it's capable of" is vague, but rest assured, this thing is LAZY.
I've double checked the cam timing. Overall advance is about 32(that seems to be where it runs best). Turbo 400 runs/shifts strong.
The thing that caught my eye and prompted me to post about this again was a recent post by J-(Chicago) on another thread where he said "Most 71' 455 motors had 40 cc dish in the pistons. Big ol' soup bowl like dish.
If you simply change head gaskets from stock factory to fel-pro, you will be at 7.8-1 compression if you don't have them milled." I don't recall off hand what gaskets were used. If this were the case, what kind of performance loss would I see? Could this be the problem?
Please, if my ignorance frustrates you, feel free to keep that to yourself(except Norm. Norm can say whatever he wants
#2
I just remembered the other thing that has prompted me to post this thread.
I'm a body and paint man by trade, but I'm hungry for knowledge and try to learn and experience every aspect of a project that I possibly can. My second, and far more successful engine build was the 390 powerplant in the 66 Ford Galxie I'm building for my buddy. The fact that we just got his running and it absolutely BLOWS THE DOORS OFF of my 425 is just embarrassing.
If you can't help me make mine faster, how can I make his slower?
I'm a body and paint man by trade, but I'm hungry for knowledge and try to learn and experience every aspect of a project that I possibly can. My second, and far more successful engine build was the 390 powerplant in the 66 Ford Galxie I'm building for my buddy. The fact that we just got his running and it absolutely BLOWS THE DOORS OFF of my 425 is just embarrassing.
If you can't help me make mine faster, how can I make his slower?
#3
Piston specs ( http://www.harborfreight.com/cpi/cta...emnumber=99639 ) or part number?
Compression test (engine warm, no plugs, and WOT)?
Max? What RPM? What initial?
Be aware that the "azz dyno" is not very reliable, and timeslips show the most accurate data.
When you assembled it, did you verify that when #1 was at TDC, the timing mark was at "0"?
Nominal CR was 8:1 for all 455s. Lowest since '54 and went back up to 8.5 in '72. Not the best choice for a "performance engine".
The added .040" on the bore will compensate for some of it.
Not much and no.
Your check is in the mail.
Should be lighter and have lower rear gears than yours. Looks like an interesting challenge.
Norm
Compression test (engine warm, no plugs, and WOT)?
Be aware that the "azz dyno" is not very reliable, and timeslips show the most accurate data.
When you assembled it, did you verify that when #1 was at TDC, the timing mark was at "0"?
Nominal CR was 8:1 for all 455s. Lowest since '54 and went back up to 8.5 in '72. Not the best choice for a "performance engine".
Your check is in the mail.
Norm
#4
This is why the world needs Norm. Like I said, I've never done this before and I need someone to point(or shove) me in the right direction.
I did verify TDC of the #1 piston and timing mark at 0.
All I can tell you about the timing at this point is the over all.
I'll get post the results of the compression test & the initial timing along with the corresponding RPMs. May not have time until this weekend.
I did verify TDC of the #1 piston and timing mark at 0.
Thanks Norm.
I did verify TDC of the #1 piston and timing mark at 0.
All I can tell you about the timing at this point is the over all.
I'll get post the results of the compression test & the initial timing along with the corresponding RPMs. May not have time until this weekend.
I did verify TDC of the #1 piston and timing mark at 0.
Thanks Norm.
#6
I'd start simple with air intake and exhaust expulsion.
A stock air cleaner and small exhaust pipes makes for a bad day of racing.
My old stock 455 would go a second and a half faster at the track just by unbolting the exhaust and running open headers and no air cleaner.
I won't knock your manifolds,...yet.... because i've seen low 13 second cars running them.
Even if your motor had 40cc pistons, 7.8-1 compression and a thick head gasket.... properly tuned it should run a low 14 in your car with a stock open rearend and a 235 street radial.
A stock air cleaner and small exhaust pipes makes for a bad day of racing.
My old stock 455 would go a second and a half faster at the track just by unbolting the exhaust and running open headers and no air cleaner.
I won't knock your manifolds,...yet.... because i've seen low 13 second cars running them.
Even if your motor had 40cc pistons, 7.8-1 compression and a thick head gasket.... properly tuned it should run a low 14 in your car with a stock open rearend and a 235 street radial.
Last edited by J-(Chicago); July 7th, 2009 at 01:01 AM.
#7
Since this is a 425 in 66 they came in 2 versions, a low compression and high compression. You say you used stock pistons but what was the advertised CR of them? I am not up on those cam specs but are you running in the RPM range suggested? Possibly you need a little lower rear gear for the cam to operate in the proper RPM range. Most head gaskets these days are thicker than the factory steel shim type gaskets. I believe you must look hard and pay dearly for the thin head gaskets. You should be able to take that 390 Ford with your 425!
#8
It's the 4bbl high compression. I'm not going to be doing any racing, so I'm not looking to squeeze every last bit of horse power possible out of it. EVERY time I drive this car it will be farther than a 1/4 mile. I'd like to run this thing through the 1/4 mile one time just so I could give you guys a number, but if I had to guess, I'd say I'm somewhere above the 20 second mark(like I said, lazy lazy lazy on the low end)seems to pick up at higher speed. Gearing is something I need to check into also, because it's more than highway friendly. I'm going to gather as much concrete info as I can this weekend and come back with something solid that maybe can shed some light on this deal.
#10
#12
#13
#14
I hate to even come back to that, I thought I had ruled that out. Is taking measurements of the cam the only way to know if it's for the 39 or 45 degree?
I know that when I talked to them, we were very clear on the fact that it was a 66 with 45 degree bank. But again, didn't have it checked out before I put it in.
Norm, I had almost forgotten about that old thread. That was a little over a year ago. I can't believe it's been that long. Since then, I've moved and I also moved my business into a location that's better for business, but doesn't allow me the luxury of having lots of extra storage/work space to do my projects, so I've been putting a lot of things off. I also shifted my focus to paint, chrome and other things for a while because I had become so frustrated with the engine stuff.
I know that when I talked to them, we were very clear on the fact that it was a 66 with 45 degree bank. But again, didn't have it checked out before I put it in.
Norm, I had almost forgotten about that old thread. That was a little over a year ago. I can't believe it's been that long. Since then, I've moved and I also moved my business into a location that's better for business, but doesn't allow me the luxury of having lots of extra storage/work space to do my projects, so I've been putting a lot of things off. I also shifted my focus to paint, chrome and other things for a while because I had become so frustrated with the engine stuff.
#15
I'm going to put in some time on this thing this weekend. I'm going to return here with results of compression test, gear ratio, and timing info. I realize the importance of proper timing, but honestly I still don't have a firm grasp on the procedure from start to finish. Can someone point me to a thread(because I'm sure there is one & it would be easier than having people repeat themselves) that gives info about the various aspects of proper timing? i.e. initial, curve, max, etc. along with the rpm's I should be at when checking these things.
Man, I really enjoy learning things the hard way, but I sure will remember next time.
Man, I really enjoy learning things the hard way, but I sure will remember next time.
#16
One more thing I failed to mention in this post is that I did change the distributor to a Pertronix electronic set-up and I am running an MSD 6AL. Don't know if that changes anything or not.
#17
This is way beyond my technical knowledge so should probably keep quiet, but i was running the 750 edelbrock on my 65 425 (delta 88) and had the same "lazy" issue.
I've since spoken to loads of people who have had this carb in the past and most have changed it. I bought a rebuilt quadrajet from a 350 Cutlass and simply bolted it on without tuning and already it's a completely different car!
I've since spoken to loads of people who have had this carb in the past and most have changed it. I bought a rebuilt quadrajet from a 350 Cutlass and simply bolted it on without tuning and already it's a completely different car!
#18
You aren't the first to suggest that. I think I saw another guy or twelve on here that prefer the Q-jet. I still have the original Q-jet, but I'm sure it needs a rebuild. My budget is currently an issue, so my options are fairly limited at this point. I'll give that a shot after I verify that the compression and timing are ok.
I've rebuilt a couple of single barrels before, but from what I've heard, I don't know if I want to try and tackle the Q-jet.
I've rebuilt a couple of single barrels before, but from what I've heard, I don't know if I want to try and tackle the Q-jet.
#20
Qjets are a pain to rebuild the first few times. Once you've been into it a few times, you'll learn how to love the ol' junkers.
I suggest picking up Doug Roe or Cliff Ruggles' Rochester Quadrajet books to help you understand.
Don't learn the hard way like I did. Once I saw all the info the books contained I was mad that I didn't have them earlier.
I would have had to break 50 more Qjets teaching myself all of that info.
I suggest picking up Doug Roe or Cliff Ruggles' Rochester Quadrajet books to help you understand.
Don't learn the hard way like I did. Once I saw all the info the books contained I was mad that I didn't have them earlier.
I would have had to break 50 more Qjets teaching myself all of that info.
Last edited by J-(Chicago); July 8th, 2009 at 09:13 PM.
#21
#22
#23
#24
no cam card, the best I can do is what the specs are supposed to be. unless the cam was ground wrong or the part # on the box & invoice was wrong, this should be it.
JM-22-25-10 .512 intake, .523 exhaust, 274/280 adv. int/ex duration, 230 @ .050 int., 236 ex., 110 lobe sep. RPM rang 1400-6000
These are the specs Mondello lists for their(engle)cam. This was the part number on the box as well as the invoice, but I guess neither of those two things will open a valve very well.
The valve springs they sent me were also engle. And If I recall correctly, the box for the lifters was blank. It scares me a little bit because we order body parts twice a day and at least once a week we get a part that's boxed wrong. I like to think that someone doing something as critical as grinding a cam would be more careful. If the cam were wrong would there be any other tell tale sings or ways to possibly verify without removing it?
JM-22-25-10 .512 intake, .523 exhaust, 274/280 adv. int/ex duration, 230 @ .050 int., 236 ex., 110 lobe sep. RPM rang 1400-6000
These are the specs Mondello lists for their(engle)cam. This was the part number on the box as well as the invoice, but I guess neither of those two things will open a valve very well.
The valve springs they sent me were also engle. And If I recall correctly, the box for the lifters was blank. It scares me a little bit because we order body parts twice a day and at least once a week we get a part that's boxed wrong. I like to think that someone doing something as critical as grinding a cam would be more careful. If the cam were wrong would there be any other tell tale sings or ways to possibly verify without removing it?
#25
What numbers did you use to degree the cam?
Next to impossible.
Very likely.
Same with mechanical parts. It is why a competent machinist checks for accurate dimensions on every part when it is delivered.
You are making an assumption without knowing the facts. For all we know, the cam is the right one, and the "problem" is elsewhere.
Simply degree the cam, the same way you would, during assembly, except you will be doing both #1 and #2 [edit: #1 and #6] cylinders. Normally one only "degrees" the timing gear/chain, because the cam is accurate and the chain is a "crapshoot".
Hopefully I will have a copy of your card by tomorrow afternoon.
Norm
Next to impossible.
Very likely.
Hopefully I will have a copy of your card by tomorrow afternoon.
Norm
Last edited by 88 coupe; July 11th, 2009 at 12:41 AM.
#26
The ones that look like 2 dots...
Well, was feeling pretty competent, but I'm definitely no machinst, and my machinist didn't assemble the engine... I did. So I guess that puts us right back where we started.
I hope you are right. I'm fairly confident that you are.
What will that tell us?
What will that tell us?
#31
It was working. Looks like a reman that was not on there too long before the car was parked under a big oak tree for a few years. I don't know how well it was working. I've added that to the list of things to check this weekend. So now I should be coming back with the results of the compression test, the timing, the gearing & the carb swap.
If I decide to use it, Can I put an electric choke on it? Or just replace the original?
If I decide to use it, Can I put an electric choke on it? Or just replace the original?
#32
The way you did it works well. You quote the entire sentence or sentences, then reply. Instead of ".......several words taken out of context......"
Personally, I think that posting up the quote in it's entirety, then responding with several sentences or a paragraph is a clearer and easier way to dispute or reply to another post. But that's just me.
Last edited by captjim; July 10th, 2009 at 10:18 AM.
#33
Not the same as "degreeing it. Check the following links:
http://video.google.com/videoplay?do...95865478396890
http://video.google.com/videoplay?do...41611176015126
http://video.google.com/videoplay?do...69278091943082
In this case, you do not need the cam card. Use the degree wheel, as shown above, and note the "intake" numbers on #1 cylinder. Then turn the crankshaft 360° and compare those numbers with those on #6.
If they are the same, the cam is correct for that block. If they are off by 6° you have found your problem.
Norm
http://video.google.com/videoplay?do...95865478396890
http://video.google.com/videoplay?do...41611176015126
http://video.google.com/videoplay?do...69278091943082
In this case, you do not need the cam card. Use the degree wheel, as shown above, and note the "intake" numbers on #1 cylinder. Then turn the crankshaft 360° and compare those numbers with those on #6.
If they are the same, the cam is correct for that block. If they are off by 6° you have found your problem.
Norm
#34
#35
That is because it is the way it has been done since before algore invented the internet. It is still done that way for the same reason: To keep confusion at a minimum.
From: http://ezinearticles.com/?Twenty-Fiv...Tips&id=537856
This is done for brevity, it has nothing to do with "context".
Hard to lose context when the entire post is readily accessible by using that little blue button.
That is an accurate statement.
Norm
From: http://ezinearticles.com/?Twenty-Fiv...Tips&id=537856
Originally Posted by Forum Posting Etiquette Tips
#14. When replying to a post, do not quote more from the previous post than you have to.
Hard to lose context when the entire post is readily accessible by using that little blue button.
That is an accurate statement.
Norm
#36
IMO, you sacrifice clarity for brevity. IMO (and others here who find your posting style ineffective) if you added more than a brief phrase, it would be easier to follow.
BTW, the guy who made those videos is an idiot!
BTW, the guy who made those videos is an idiot!
#37
I'm a very jovial person by nature, so I guess my attempts at a couple of light hearted jokes about such a sensative issue may not have been the best idea. So I'd like to just get back to the issue at hand, if that's ok with everyone.
picked up a compression tester this morning. When I get home I'm going to run that first. Then I'll double check the timing numbers and the rear gears and post all of the info tonight.
picked up a compression tester this morning. When I get home I'm going to run that first. Then I'll double check the timing numbers and the rear gears and post all of the info tonight.
#38
And i hope it stays that way.
Well, I would have agreed with that statement until last night. I took it out yesterday and now I'm getting a pretty noticeable hesitation at part throttle(maybe 1/4-1/3 of WOT). Seems to be getting consistently worse. Going to check fuel pressure too and take the Olds experts' advice on the Q-Jet. A very nice, almost new Edelbrock 750 will be for sale very soon.
#39
#40
You (and your minions) have been beating the same dead horse for over two years. Isn't it about time you got the hint?
Norm