After all this - not what I thought .... - Page 4 - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #46 (permalink)  
Old 11-05-2008, 10:06 AM
DaSouthWon's Avatar
I put up the tools against$300
 
Last photo:
Join Date: Apr 2006
Location: Memphis,Tennessee
Age: 35
Posts: 683
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
From the point I read how much timing you had in your engine I was curious to know if you had an old balancer on it. Believe it or not they wear out, the rubber gets old and will flex. It may read correctly at 0 rpm but when you add centrifugal force and RPM's the outer band where the timing mark is could be anywhere. Additionally, the distance between 0 and 20 is shorter on a smaller diameter balancer obviously. Don't know if this is a problem or not on your car but I've seen 2 places in this post where you found the timing mark to be off, a different amount both times. One other thing, how did you figure your compression? What was the stock head chamber size and what is the cc size of the AFR's, I don't remember without going back and looking for it. Not to give you a hard time, but you said that you didn't know if the pistons were flush with the deck or if the sat down in the hole. This can have a bigger effect on your compression ratio than a head gasket. I'm wondering if your actual compression isn't a little lower than where you think you are.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #47 (permalink)  
Old 11-05-2008, 10:17 AM
Registered User
 
Join Date: Oct 2008
Location: Dasyton, Ohio
Posts: 13
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Hey Tomard, the 6.75 balancer is fine. Makes no difference what came on it originally. As a proud owner of a C3 vette ('74 coupe) I think you might be mistaken as to the weight of your shark. Me and mine weigh in at 3650lb. It is a heavy car. Also make sure your accel. pedal is putting you throttle to wide open. My pedal linkage needed to be bent back to the its original position. Also I ran a 274 cam in my 383 cu in with 9.0 to 1 and it suffered from low bottom torque but had great top end. Check that throttle.

peace Bud
Reply With Quote Quick reply to this message
  #48 (permalink)  
Old 11-05-2008, 10:40 AM
Registered User
 
Last photo:
Join Date: Oct 2008
Location: Alpharetta, GA
Age: 53
Posts: 43
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Responses

RG - I had my boy stomp on pedal and it is opening all the way (as far as I can manually open it anyway). The weight was a little less in the smog years, and I have removed some heavy components .... but with that said, I will get her weighed here soon

DaSouth - I measured it all when I changed headgasket this weekend .... .031" in the hole, .030" over pistons, 65cc chambers on AFR (I think the vette had 72cc stock chamber heads). Did I not attach the screen shot of compression calc?? Will do it here again.
Attached Thumbnails
Click image for larger version

Name:	Compression Ratio 9.39 with .015 gasket.jpg
Views:	62
Size:	100.4 KB
ID:	33927  
Reply With Quote Quick reply to this message
  #49 (permalink)  
Old 11-05-2008, 12:32 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 8,678
Wiki Edits: 0

Thanks: 17
Thanked 281 Times in 261 Posts
It sounds like something in the setup is giving you thr wrong timing readings. 50 all in a one hell of a lot of timing. Way too much for your setup. At minimum I'd say you're off about 12 degrees, maybe as much as fifteen. I believe you when you say it runs best where its at, I just don't believe you're getting the correct readings.
Reply With Quote Quick reply to this message
  #50 (permalink)  
Old 11-05-2008, 02:22 PM
carsavvycook's Avatar
My 2 cents worth
 
Last photo:
Join Date: Sep 2007
Location: Lakeside, CA
Age: 57
Posts: 2,855
Wiki Edits: 3

Thanks: 2
Thanked 2 Times in 2 Posts
Here is something to 'ponder' over.

In the past, I had a brand new 481 CID BBC engine, machined and assembled, by a engine builder. It took all night long to grind the valve reliefs in the pistons, and send the rotating assembly out for re-balancing. I was sleeping in the trailer during the final assembly.

I thought it should run in the high 120's, but it only ran 105 on the first pass, and 98 on the second pass, and this was with a dual stage nitrous system. The crank gear was off 1 tooth on the timing chain. It ran 128 on the first pass after fixing it in the pits, with only using the first stage of the nitrous system.

We went on to win the high points championship that year.

Could you possibly be off 1 tooth also?

Stephen
Reply With Quote Quick reply to this message
  #51 (permalink)  
Old 11-05-2008, 07:11 PM
Registered User
 
Last photo:
Join Date: Oct 2008
Location: Alpharetta, GA
Age: 53
Posts: 43
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Still grasping

What effect would it have if my distributor was "off" a tooth ? I did try to orientate it correctly (getting HEI electronics sitting at 3o'clock", with cyl 1 & 8 wires at 5 & 7 oclock positions)..... maybe I am "off" there and therefor my timing numbers are weird ?????
Reply With Quote Quick reply to this message
  #52 (permalink)  
Old 11-05-2008, 08:43 PM
Member
 
Last wiki edit: Calculating tire size
Last journal entry: Changes...
Last photo:
Join Date: Oct 2003
Location: Montreal
Age: 29
Posts: 532
Wiki Edits: 2

Thanks: 0
Thanked 2 Times in 2 Posts
The only problem putting a distibutor in one tooth off is that the distributor will visually be rotated a bit. The timing will still be whatever the timing light says.
Carsavvy is talking about the timing chain sprocket.

Try recurving your distributor, 20 initial and 36 total without the vacuum. Or even get a little twist-tie or zip-tie and lock out your mechanical advance and experiment to see what your engine wants.
Reply With Quote Quick reply to this message
  #53 (permalink)  
Old 11-05-2008, 08:50 PM
carsavvycook's Avatar
My 2 cents worth
 
Last photo:
Join Date: Sep 2007
Location: Lakeside, CA
Age: 57
Posts: 2,855
Wiki Edits: 3

Thanks: 2
Thanked 2 Times in 2 Posts
Quote:
Originally Posted by Tomard
What effect would it have if my distributor was "off" a tooth ? I did try to orientate it correctly (getting HEI electronics sitting at 3o'clock", with cyl 1 & 8 wires at 5 & 7 oclock positions)..... maybe I am "off" there and therefor my timing numbers are weird ?????
You can set a distributor in any way you want. This will not effect your timing numbers though. The distributor must have the rotor aimed at the post on the cap, where you place the #1 plug wire, with #1 cylinder @ TDC Compression.

What I was referring to is the Cam and Crank Timing. I don't have a crank gear, and do not remember exactly how many degrees of valve timing one tooth is. Maybe someone else can give this information.

If you have the crank gear off 1 tooth, it will not show up, even with the cylinder head off. Because your balancer will line up with '0' on your timing tab with #1 @ TDC.

What it changes, is the camshaft lift, and duration starting times.

We ran a locked 38* timing, with a 10* timing retard for the nitrous. The spark timing was set and looked correct at 38*, but it seemed 'down' on power. This is why we pulled the timing cover to verify that the Crank and Cam were timed correctly, by the marks.

When you design and build a engine that should come out to almost 1000 HP, and it runs a 105, you know something is wrong.

By the way, this was a Drag Boat, and I was the Crew Chief. I did have it dyno'ed after that first race, and it did come out to 981 HP, like we planned on. This was up from 867 HP from the previous engine.
Reply With Quote Quick reply to this message
  #54 (permalink)  
Old 11-05-2008, 10:41 PM
Member
 
Last photo:
Join Date: Jan 2005
Location:
Posts: 3,707
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
Fuel octane will also affect what amount of total timing will be needed. I once cocktailed an octane boost that required 50 degrees of total timing in a 355 engine with only 9.5-1 static compression. What fuel are you running? May need to try 87 octane and pull some timing out-and it may run stronger down low and through the entire rpm range. Bob
Reply With Quote Quick reply to this message
  #55 (permalink)  
Old 11-06-2008, 05:43 AM
Registered User
 
Last photo:
Join Date: Oct 2008
Location: Alpharetta, GA
Age: 53
Posts: 43
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Fuel

I am running straight 87 octane pump gas ...... I am very sure that my crank/cam gears are lined up (I was actually a tooth off before I put it all together, and caught it )

Let me go over what I am thinking, but before I do, could my MSD 8501 distributor just be hosed somehow?

This is what I was going to do:

1) Lock down the centrifugal advance weights with a rubber band or tie wrap, then check for initial timing at idle
2) My vac can (think it provides 16* advance) disconnected from PORTED vac source (no vac at idle) and plugged.
3) Curve (I did try different springs out of my Accel kit, but didn't change the
weights OR the one set of WHITE bushings (wasn't quite sure how the bushings went in). I tried different spring combo's and if memory serves me right, I am back with STOCK springs (have Heavy WHITE, Medium BLUE and light RED) Springs as well. Will try different spring combinations and see if there is any difference.

I did have it running before with BLUE springs but was still at 40* all in (before head gasket/compression change), so not sure what got hosed since then.
Reply With Quote Quick reply to this message
  #56 (permalink)  
Old 11-06-2008, 10:04 AM
Member
 
Last wiki edit: Calculating tire size
Last journal entry: Changes...
Last photo:
Join Date: Oct 2003
Location: Montreal
Age: 29
Posts: 532
Wiki Edits: 2

Thanks: 0
Thanked 2 Times in 2 Posts
I don't know about your msd distributor but there is usually more to limiting the advance than just changing the springs. The springs affect the rpm that it comes in at. You need to limit the travel somehow, maybe there is a bushing. Can you get a users manual for your distributor?
Reply With Quote Quick reply to this message
  #57 (permalink)  
Old 11-06-2008, 12:10 PM
grouch's Avatar
Registered User
 
Last wiki edit: How to document your project
Last journal entry: 1949 Olds -- Rotisserie, pt. 9
Last photo:
Join Date: Jul 2004
Location: KY
Posts: 1,143
Wiki Edits: 2

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by carsavvycook
I thought it should run in the high 120's, but it only ran 105 on the first pass, and 98 on the second pass, and this was with a dual stage nitrous system. The crank gear was off 1 tooth on the timing chain. It ran 128 on the first pass after fixing it in the pits, with only using the first stage of the nitrous system.

We went on to win the high points championship that year.

Could you possibly be off 1 tooth also?

Stephen
And at the other end of the scale...

I just ran into a similar situation with a 1.8L engine in a VW Fox. It's an interference engine so I decided to replace the timing belt before putting it back on the road after taking up space in my garage for over a year for painting. I've never tore into one of these engines before and know nothing about them except what's in the (non-factory) service manual.

What I saw after getting the cover off didn't match what the Bentley service manual said. I spent 2 days pondering and hand cranking that thing trying to figure out whether the manual had errors or the belt had been installed wrong. Finally said f- it and set the marks as the manual and installed the belt.

Results: Before, power topped at about 3200 rpm. (Redline 6500, but useless to go above 3200). Now, leaps to 4000 and still happy. Conclusion: Someone installed the previous timing belt a tooth or two off for at least one of the 3 sprockets.

If the mechanical timing is off, you can't make up for it with ignition timing. Maybe you can mask the symptoms with other things, but the loss from slightly off valve timing is still going to be there.
Reply With Quote Quick reply to this message
  #58 (permalink)  
Old 11-06-2008, 01:33 PM
Registered User
 
Last photo:
Join Date: Oct 2008
Location: Alpharetta, GA
Age: 53
Posts: 43
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
hmmmmm

I agree about the tooth being off would cause certain timing errors, but I am sure that I have that part right, as it WAS wrong, but I caught it and fixed it.

I have dilemma about where TDC is exactly, and since I had one of those nifty 14mm TDC tools, I put it in and I can crank motor by hand all the way around and it doesn't catch .... nice waste of $15 .... and a load of time!!!!

Going to Home Depot and getting a nice long 14mm bolt, grind the end smooth so I don't nick the top of piston and try it again ..... I have adjustable tab so will be happy when I get it right .....
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
last random thought by me of the winter (i hope) NamelessJoe General Rodding Tech 2 03-22-2007 11:30 AM
So, you thought you had seen it all? tfeverfred Hotrodders' Lounge 64 02-15-2007 10:37 AM
i thought i was banned ol'skool29 Off-Topic 9 07-26-2006 07:01 PM
Japan has thought about it. Gr8 '48 bow tie Hotrodders' Lounge 3 01-28-2006 09:08 PM
Thought I'd share my combo. 1971 Chevelle Engine 2 01-21-2006 11:32 AM


All times are GMT -6. The time now is 01:09 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.