Lazy off the line

Adger Smith · 04-12-2016, 06:50 AM

Why is the cam listed as 2 deg retarded with only 10.5 Comp?
Why such a high leave RPM?
Footbrake lower and hit the converter stall harder.
Might be loosing TQ multiplication of the converter.
I would put a little more timing in it before I re jet 2 lower.

bnsfmachinist · 04-12-2016, 07:26 AM

I retarded the cam 2* in order to have reasonable Piston to valve clearance.

Robert Simpson · 04-12-2016, 04:55 PM

I like your build but I have some questions. Have you taken a cranking compression yet? If so what is the psi? If not I suggest you do that, warm it up, remove the plugs, disable the Ing., and block the carb open. Check and see what the cranking comp is. If it is low say 150psi or under the cam is to big. If it is allot higher closer to 200psi then you have other issues. I believe that the cam and the heads are to big. What you are describing the engine does not have enough bottom end. A RPM intake would help some as would the rear gear, also if you could put in a lower gear in the trans that would help also. I am just suggesting this, I am not being critical of your build just trying to help. Let me know. Thanks

Robert

bnsfmachinist · 04-12-2016, 06:31 PM

I appreciate the suggestion! I'm new to actively participating in this sport and this is my first purpose built drag engine. The car is going together as a bracket car with the hopes to build it into a SS/GT car. I've got a long road ahead of me filled with successes, failures and setbacks! But I'm passionate about the sport, I've grown up in a weekend warrior family and I'm finally at a point in my life to where I'm able to participate!

Anyway back to technical aspects!

I will certainly do a cranking compression test, I'm interested in the points you bring up. I got the heads from my dad who had them ported back in the 80's by AFR, I don't have the flow chart in front of me but I want to say they flow in the neighborhood of 400cfm @ .700 on the intake and 350 on the exhaust? I haven't looked at that chart in a while but I know they're big numbers. So, I figured a big set of heads is going to want a lot of air and fuel, so thus picked out a pretty big solid cam. The rest of the build follows what seems to be a pretty typical 351c mild/moderate build based upon browsing 351c.net and other ford forums.

Again, I'm new into this world of engine building so I more than appreciate advice, pointers and suggestions. I'll get on that compression test when I get an opportunity. I'm a Union Ironworker 40+ hours a week, husband and father of 3 24/7, ain't always easy to get out in the garage these days!

Thanks again guys!

Hans Olsson · 04-13-2016, 07:35 AM

C6 transmission could be holding your car back some.

bnsfmachinist · 04-13-2016, 10:29 AM

Hans, I'm sure it is brother. I had read somewhere that a C6 will eat about 60-70hp vs. a C4 at 30-40?

This car was originally an F code 302 with a C4, I sold that pair to drop in the New combo. If I could go back I would have kept the C4 and had it prepped for this application rather than going with the C6....but, I'm not terribly concerned at this point. My aim is to bracket race this car and have some fun and learn along the way. Future SS build will of course, NOT include the C6

Mike Pearson · 04-13-2016, 03:17 PM

Not enough rear gear. Carb is too big. Cam needs to be advanced not retarded. That is killing the low end. Fix all of that stuff and it will run much better.

Hans Olsson · 04-14-2016, 10:56 AM

Pressure in the rear tires (10 psi) seems on the low side in my opinion.

n5ifi · 03-03-2017, 11:59 AM

Quote:

Originally Posted by Mike Pearson

Not enough rear gear. Carb is too big. Cam needs to be advanced not retarded. That is killing the low end. Fix all of that stuff and it will run much better.

Exactly.......
putting the cam in 2 retarded is going to guarantee you more retard running.

I remember Joe Sherman always telling everyone that you could run the intake clearance very close just spinning the motor around by hand. If it clears by .010 to .020 it will be fine running because the dynamic loading of the system would increase the clearances and retard the cam. The valve is chasing the piston down the hole too.

blasttime · 08-28-2016, 06:07 PM

Quote:

Originally Posted by Adger Smith

Why is the cam listed as 2 deg retarded with only 10.5 Comp?
Why such a high leave RPM?
Footbrake lower and hit the converter stall harder.
Might be loosing TQ multiplication of the converter.
I would put a little more timing in it before I re jet 2 lower.

X2 on everything

04-12-2016, 06:50 AM	#1
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: Lazy off the line Why is the cam listed as 2 deg retarded with only 10.5 Comp? Why such a high leave RPM? Footbrake lower and hit the converter stall harder. Might be loosing TQ multiplication of the converter. I would put a little more timing in it before I re jet 2 lower. __________________ Adger Smith (Former SS)

04-12-2016, 07:26 AM	#2
bnsfmachinist Junior Member Join Date: Feb 2014 Posts: 15 Likes: 0 Liked 0 Times in 0 Posts	Re: Lazy off the line I retarded the cam 2* in order to have reasonable Piston to valve clearance.

04-12-2016, 04:55 PM	#3
Robert Simpson Senior Member Join Date: Aug 2004 Location: Jacksonville, Florida Posts: 808 Likes: 7 Liked 20 Times in 12 Posts	Re: Lazy off the line I like your build but I have some questions. Have you taken a cranking compression yet? If so what is the psi? If not I suggest you do that, warm it up, remove the plugs, disable the Ing., and block the carb open. Check and see what the cranking comp is. If it is low say 150psi or under the cam is to big. If it is allot higher closer to 200psi then you have other issues. I believe that the cam and the heads are to big. What you are describing the engine does not have enough bottom end. A RPM intake would help some as would the rear gear, also if you could put in a lower gear in the trans that would help also. I am just suggesting this, I am not being critical of your build just trying to help. Let me know. Thanks Robert

04-12-2016, 06:31 PM	#4
bnsfmachinist Junior Member Join Date: Feb 2014 Posts: 15 Likes: 0 Liked 0 Times in 0 Posts	Re: Lazy off the line I appreciate the suggestion! I'm new to actively participating in this sport and this is my first purpose built drag engine. The car is going together as a bracket car with the hopes to build it into a SS/GT car. I've got a long road ahead of me filled with successes, failures and setbacks! But I'm passionate about the sport, I've grown up in a weekend warrior family and I'm finally at a point in my life to where I'm able to participate! Anyway back to technical aspects! I will certainly do a cranking compression test, I'm interested in the points you bring up. I got the heads from my dad who had them ported back in the 80's by AFR, I don't have the flow chart in front of me but I want to say they flow in the neighborhood of 400cfm @ .700 on the intake and 350 on the exhaust? I haven't looked at that chart in a while but I know they're big numbers. So, I figured a big set of heads is going to want a lot of air and fuel, so thus picked out a pretty big solid cam. The rest of the build follows what seems to be a pretty typical 351c mild/moderate build based upon browsing 351c.net and other ford forums. Again, I'm new into this world of engine building so I more than appreciate advice, pointers and suggestions. I'll get on that compression test when I get an opportunity. I'm a Union Ironworker 40+ hours a week, husband and father of 3 24/7, ain't always easy to get out in the garage these days! Thanks again guys!

04-13-2016, 07:35 AM	#5
Hans Olsson Member Join Date: Nov 2001 Location: Sweden Posts: 103 Likes: 0 Liked 0 Times in 0 Posts	Re: Lazy off the line C6 transmission could be holding your car back some.

04-13-2016, 10:29 AM	#6
bnsfmachinist Junior Member Join Date: Feb 2014 Posts: 15 Likes: 0 Liked 0 Times in 0 Posts	Re: Lazy off the line Hans, I'm sure it is brother. I had read somewhere that a C6 will eat about 60-70hp vs. a C4 at 30-40? This car was originally an F code 302 with a C4, I sold that pair to drop in the New combo. If I could go back I would have kept the C4 and had it prepped for this application rather than going with the C6....but, I'm not terribly concerned at this point. My aim is to bracket race this car and have some fun and learn along the way. Future SS build will of course, NOT include the C6

04-13-2016, 03:17 PM	#7
Mike Pearson VIP Member Join Date: Mar 2007 Posts: 2,470 Likes: 629 Liked 1,983 Times in 597 Posts	Re: Lazy off the line Not enough rear gear. Carb is too big. Cam needs to be advanced not retarded. That is killing the low end. Fix all of that stuff and it will run much better. __________________ Mike Pearson 2485 SS

04-14-2016, 10:56 AM	#8
Hans Olsson Member Join Date: Nov 2001 Location: Sweden Posts: 103 Likes: 0 Liked 0 Times in 0 Posts	Re: Lazy off the line Pressure in the rear tires (10 psi) seems on the low side in my opinion.