Advice needed after rebuild
Thread Starter
Pro
Joined: Jun 2001
Posts: 528
Likes: 147
From: Palmyra NY
Advice needed after rebuild
I just put my rebuilt engine into my 75, and the car doesn't quite feel "right". About the build...
TrickFlow 62cc aluminum heads (195 intake and 75 exhaust runner volume)
Trick Flow Cam
Intake Duration at 050 inch Lift 212
Exhaust Duration at 050 inch Lift 216
Flowtech 1 5/8 in full length headers
MSD Street Fire Distributor
Stock mufflers
Edelbrock 1406 carb (600cfm)
Timing is set at 12 degrees initial, and the carb is set at factory calibration. Took the car out yesterday for about 120-130 mile round trip excursion. It went through an entire tank of fuel. The car does not idle real smooth, but I am not sure if it should with this setup. Power is not real impressive of the line, it almost feels like something is holding the car back. Once the RPM's get above 3,500 to 4,000, it comes to life and really takes off.
First question: Is the carb big enough?
Second question: What am I missing?
I am a little disappointed after the time and money that went into the engine that my diesel Jetta could probably take it in a drag race
Sorry for the long post, but any guidance on where to start is appreciated.
TrickFlow 62cc aluminum heads (195 intake and 75 exhaust runner volume)
Trick Flow Cam
Intake Duration at 050 inch Lift 212
Exhaust Duration at 050 inch Lift 216
Flowtech 1 5/8 in full length headers
MSD Street Fire Distributor
Stock mufflers
Edelbrock 1406 carb (600cfm)
Timing is set at 12 degrees initial, and the carb is set at factory calibration. Took the car out yesterday for about 120-130 mile round trip excursion. It went through an entire tank of fuel. The car does not idle real smooth, but I am not sure if it should with this setup. Power is not real impressive of the line, it almost feels like something is holding the car back. Once the RPM's get above 3,500 to 4,000, it comes to life and really takes off.
First question: Is the carb big enough?
Second question: What am I missing?
I am a little disappointed after the time and money that went into the engine that my diesel Jetta could probably take it in a drag race
Sorry for the long post, but any guidance on where to start is appreciated.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Proper timing for performance and making certain that your foot fully activates/opens the secondary throttle plates are the primary concerns. Your carb may also have a 'choke lockout' on the secondaries; that needs to release if the secondaries are to operate at all.
Thread Starter
Pro
Joined: Jun 2001
Posts: 528
Likes: 147
From: Palmyra NY
Not sure. I will have to check this when my helper (aka wife) will spend some time in the garage with me.
Throttle is opening all the way. I have checked timing several times, and it is consistantly at 12* with vacuum advance unhooked and plugged. I pulled the #3 plug out after a short little cruise this morning and it looked normal to me (not too white, no excess fuel, etc.)
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Burning Brakes
Joined: Dec 2005
Posts: 992
Likes: 56
From: Baldwinsville, NY
I have a similar cam with 114 degree LSA vs your 110, you should get a some what smooth idle. Mine is very smooth with 18" vacuum.
The power or torque should be strong to 2500 or 3000.
I would check the timing to be 36 at 3000 rpm with no vacuum connected to the distributor ans let the idle fall were it goes down to, about 18 degrees.
I do not use the secondaries often, just check to see if they work. Running on the primaries seems to have more then enough power for crusing and with 4K miles every summer, I try to keep the milage at 17 to 18 mpg.
The power or torque should be strong to 2500 or 3000.
I would check the timing to be 36 at 3000 rpm with no vacuum connected to the distributor ans let the idle fall were it goes down to, about 18 degrees.
I do not use the secondaries often, just check to see if they work. Running on the primaries seems to have more then enough power for crusing and with 4K miles every summer, I try to keep the milage at 17 to 18 mpg.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
More info.
Answer to second question: U don't list your compression ratio, cubic inches, idle vacuum, timing curve or even have your transmission type and gearing in your profile.
U have some nice parts but from looking for the important info your missing u still have plenty of loose ends to complete.
Too small carb would only affect top end rpm. But those 195cc runners may allow fuel mix to drop out of the intake charge at low rpm on only 350 c.i. - so even throttle response may be slow (like a VW). Big flow numbers are not so effective with big runners.
We don't know what u don't post. Well that may not be nice to say but it is hard to be truthful and not hurt feeling sometimes. I can tell u have a lot of work and $$$ in your effort and can sympathsize with that. But we need to get the word out that its too easy to get ahead of yourself with a full HP effort for your first overhaul.
Too steep learning curve and too many details. Most are overwhelmed by just getting the machine work right let alone an effective engine combo.
Ok, i'll stop preaching now,
cardo0
U have some nice parts but from looking for the important info your missing u still have plenty of loose ends to complete.
Too small carb would only affect top end rpm. But those 195cc runners may allow fuel mix to drop out of the intake charge at low rpm on only 350 c.i. - so even throttle response may be slow (like a VW). Big flow numbers are not so effective with big runners.
We don't know what u don't post. Well that may not be nice to say but it is hard to be truthful and not hurt feeling sometimes. I can tell u have a lot of work and $$$ in your effort and can sympathsize with that. But we need to get the word out that its too easy to get ahead of yourself with a full HP effort for your first overhaul.
Too steep learning curve and too many details. Most are overwhelmed by just getting the machine work right let alone an effective engine combo.Ok, i'll stop preaching now,
cardo0
Race Director
Joined: Sep 2002
Posts: 10,362
Likes: 5
From: San Diego - Deep Within The State of CONFUSION!
Two very good points. But you said the carb is all factory settings? That will never do. Get the car dyno tuned so the carb can be jetted properly for YOUR motor. Timing curve will also be set.
Thread Starter
Pro
Joined: Jun 2001
Posts: 528
Likes: 147
From: Palmyra NY
Sorry to dig up an old post. After vacation and other delays, I have finally had a chance to check timing. At idle, timing is set at 12 degrees. With the wife in the car increasing RPM, timing is all in between 2800-3000 RPM, but it jumps to (what I see) is approximately 48 degrees. Maybe I am doing this incorrectly (I am a newbie with this timing stuff). I have a paint mark on my indicator tab at 12 degrees so I can at least get back to where I started. At idle with my light set at "0", the notch on my balancer and the paint mark line up, indicating 12 degrees initial. When revved up, with my timing light dial set to 36, I am still at my paint mark. So 36 + 12 initial = 48.
What am I missing?
No hurt feelings here, I am asking the questions because I know the knowledge is available here.
Compression ratio: I am estimating at 10:1
Cubic inches: 350 bored .030 over
Stock gearing
TH400 Auto trans
Thanks everyone for your help.
What am I missing?
Answer to second question: U don't list your compression ratio, cubic inches, idle vacuum, timing curve or even have your transmission type and gearing in your profile.
U have some nice parts but from looking for the important info your missing u still have plenty of loose ends to complete.
Too small carb would only affect top end rpm. But those 195cc runners may allow fuel mix to drop out of the intake charge at low rpm on only 350 c.i. - so even throttle response may be slow (like a VW). Big flow numbers are not so effective with big runners.
We don't know what u don't post. Well that may not be nice to say but it is hard to be truthful and not hurt feeling sometimes. I can tell u have a lot of work and $$$ in your effort and can sympathsize with that. But we need to get the word out that its too easy to get ahead of yourself with a full HP effort for your first overhaul. Too steep learning curve and too many details. Most are overwhelmed by just getting the machine work right let alone an effective engine combo.
U have some nice parts but from looking for the important info your missing u still have plenty of loose ends to complete.
Too small carb would only affect top end rpm. But those 195cc runners may allow fuel mix to drop out of the intake charge at low rpm on only 350 c.i. - so even throttle response may be slow (like a VW). Big flow numbers are not so effective with big runners.
We don't know what u don't post. Well that may not be nice to say but it is hard to be truthful and not hurt feeling sometimes. I can tell u have a lot of work and $$$ in your effort and can sympathsize with that. But we need to get the word out that its too easy to get ahead of yourself with a full HP effort for your first overhaul.
Too steep learning curve and too many details. Most are overwhelmed by just getting the machine work right let alone an effective engine combo.Compression ratio: I am estimating at 10:1
Cubic inches: 350 bored .030 over
Stock gearing
TH400 Auto trans
Thanks everyone for your help.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Start by verifying the timing marks.
U need to make your own balancer marks and buy a timing light with adjustable advance. U verify TDC on #1 using a piston stop and u need then to mark and measure the balancer - diameter of balancer times pie then divide by 360 degrees = circumfrence distance per degree. U will need a good timing pointer also. Then we can help u set up a timing curve.
U need to work out your problems one at time and evaluate everything from mixture & timing to that auto trans to find out where the power loss is. Pleny of good reading on performance tuning here and even at your local library for free. But u really need to start doing your homework here as we can't tell if your dizzy is dying or your carb is choked let alone if the TH400 is slipping away with all your hard earned hp or even if your camshaft matches your compression ratio.
Hope to read from u soon,
cardo0
U need to work out your problems one at time and evaluate everything from mixture & timing to that auto trans to find out where the power loss is. Pleny of good reading on performance tuning here and even at your local library for free. But u really need to start doing your homework here as we can't tell if your dizzy is dying or your carb is choked let alone if the TH400 is slipping away with all your hard earned hp or even if your camshaft matches your compression ratio.
Hope to read from u soon,
cardo0
Thread Starter
Pro
Joined: Jun 2001
Posts: 528
Likes: 147
From: Palmyra NY
I just rechecked timing, and realized the last time I did it I never unhooked the vacuum advance. The new numbers (as set today) are:
Initial (idle with vacuum advance disconnected): 20 degrees
Total (2500-3000 RPM with vacuum advance disconnected): 36 degrees
Initial with vacuum advance (idle with vacuum hooked up): 41 degrees.
Car seems to run a little better, but still not great. Maybe I have too high of expectations ( my Z06 was much, much quicker and smoother).
Do these numbers sound about right? I was surprised that I am getting 21 degrees from the vacuum. I have it hooked to full manifold pressure, not ported. The idle is quite smooth now, but rather high (around 1,000 rpm in neutral) and 850-900 rpm in drive. I can not get the idle any lower with the advance hooked to manifold pressure. If I connect it to ported, the idle will drop as low as I want it until the car stalls out, but this configuration does not produce the smooth idle I have right now.
Thanks for the help so far
Initial (idle with vacuum advance disconnected): 20 degrees
Total (2500-3000 RPM with vacuum advance disconnected): 36 degrees
Initial with vacuum advance (idle with vacuum hooked up): 41 degrees.
Car seems to run a little better, but still not great. Maybe I have too high of expectations ( my Z06 was much, much quicker and smoother).
Do these numbers sound about right? I was surprised that I am getting 21 degrees from the vacuum. I have it hooked to full manifold pressure, not ported. The idle is quite smooth now, but rather high (around 1,000 rpm in neutral) and 850-900 rpm in drive. I can not get the idle any lower with the advance hooked to manifold pressure. If I connect it to ported, the idle will drop as low as I want it until the car stalls out, but this configuration does not produce the smooth idle I have right now.
Thanks for the help so far
Burning Brakes
Joined: Dec 2005
Posts: 992
Likes: 56
From: Baldwinsville, NY
Could you have a vacuum leak? What vacuum readings are you getting at idle?
I would think a cam like that would give 16 to 18 and be very smooth.
I hope that your avatar is not of your working conditions at home!
I would think a cam like that would give 16 to 18 and be very smooth.
I hope that your avatar is not of your working conditions at home!
Last edited by mikep3; Aug 26, 2010 at 03:40 PM. Reason: garage looked too clean and neat
Burning Brakes
Joined: Dec 2007
Posts: 889
Likes: 0
...Jetta TDi - yeah!
No hijac intended, but my wife just bought a 2010 TDi Wagon - and it's da'bomb. She loves the 'pickup' + the incredible milage!!! She has good, informed baseline to measure it - her last car was a 95' SS Impala that ran like a bat from he*l. She put 120K miles on that car and blew the doors off lots of unsuspecting BMW's, etc. I would really like to put an LT1 aluminum head engine in my C3. 
Is that possible???
Is that possible???
Drifting
Joined: Jul 2006
Posts: 1,871
Likes: 6
From: Sault Ste. Marie Ontario
Is the carb new or remanufactured?
I had a "reman" Edelbrock carb on my motor and it never ran right.
I tried all the jetting and metering rod changes with little imporvement.
As a test, I put an old Holley on and the motor came to life.
I've since changed to a new Street Avenger and found even more power.
I had a "reman" Edelbrock carb on my motor and it never ran right.
I tried all the jetting and metering rod changes with little imporvement.
As a test, I put an old Holley on and the motor came to life.
I've since changed to a new Street Avenger and found even more power.