Changing from street strip to a cruiser.
#1672823
09/17/14 10:19 PM
09/17/14 10:19 PM
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Joined: May 2003
Posts: 148
Indian Hills, CO
mdurbahn
OP
super street
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OP
super street
Joined: May 2003
Posts: 148
Indian Hills, CO
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I have a 67 R/T with 440 and 727. I built it 15 years ago for street strip and never drove it much because the strip wasn't that exciting and it only got 5-6 mpg on the street. So I am planning on rebuilding it for more of a cruiser and would like to keep as many of parts I can but get better mileage (I have read of people online getting 20 MPG's with 440 b-body?!?)
My current drive train has less then 500 miles on it and includes:
Holley 4160 750 cfm carb - vac secondaries
Eddy Performer RPM Intake
Mild Ported 452 Heads
Adj. Rockers
Cam - Hydraulic Flat Tappet, Advertised Duration 300/308, Lift .480/.495 - eddy performer rpm
Hooker Comp 1 5/8" Headers
3" TTI exhaust
2800-3200 stall converter
5.1 kickdown/shift kit
3.91 sure-grip
FBO ignition kit
Items I am considering adding/changing to make it more of a driver and make this be able to take some longer road trips.
Briefly considered 6.1 hemi swap but would rather not
EFI Conversion or Six Pack Set up with vac secondaries
Gear Vendor OD
5 Speed MT Swap
Cam Swap?
Aluminum Heads?
Reinstall A/C - rebuild factory or use new kit?
Upgrade Sound/Heat Deadening beneath carpet and firewall
Any comments or suggestions??
Thanks, Matt
67 Coronet R/T
911 Turbo
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Re: Changing from street strip to a cruiser.
[Re: ademon]
#1672826
09/18/14 12:57 AM
09/18/14 12:57 AM
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Joined: Jan 2007
Posts: 7,664
IN
ahy
master
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master
Joined: Jan 2007
Posts: 7,664
IN
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With a couple of changes you should be able to double the mileage to the low 10's easy. Starting in the 5 ish range, it probably needs some tuning. I'd check timing marks first. They can be way off (mine were off ~10 degrees). Use the "positive stop" method to check/set true TDC and then set timing from there. I don't know that particular cam but it probably wants about 15 degrees or more initial and 34 or so total mechanical advance. Adjust the distributor accordingly. Use vacuum advance. If you don't have it now, get a vacuum advance distributor. 50+ degrees advance under light load cruise is good. Get the AF dialed in. If you are not an expert at tuning (I'm not) find a "dyno tune" shop that will help you dial in jet size, idle AF and other stuff. Or install a wideband AF meter and adjust as needed. I bet this helps a lot. Next step would be the rear gear. 3.23 or 3.55 with bigger tires would be a good balance between cruising and off the line performance. I'd do the above, at least tuning, first and see how much better it gets. As far as cam, there may be room for improvement with a shorter duration and higher lift cam... but may require beefed rockers/pushrods. It would help to post actual compression (and tire size) and current rocker setup. Beyond that, induction can help. A well tuned 6 pack is probably a little better than a well tuned 4 bbl and EFI better yet. Overdrive can help also with a torquey 440. I bet yours would be happy cruising in the low 2000 RPM range. It comes down to what you want and budget. My junk (496, EFI, 20% OD manual, 243@.050 cam) gets around 14 MPG highway @75 MPH and 10 or so around town driven "normally". If I ride it, less.
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Re: Changing from street strip to a cruiser.
[Re: ahy]
#1672827
09/18/14 02:31 AM
09/18/14 02:31 AM
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Joined: Sep 2005
Posts: 12,481
Chino Valley
RodStRace
I Live Here
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I Live Here
Joined: Sep 2005
Posts: 12,481
Chino Valley
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I agree, tune what you've got first.
Next step is taller gears. 3.55 would help, 3.23s or even 2.76 would be better, but would require a converter change.
Next, cam change. Something with less duration. The cam probably comes on at 2500 RPM and is lazy below that. Since a lot of street cruising is done with light throttle and lower RPM, optimize the cam for idle to 4500, not 2500-6000.
Gear vendors OD will help, but the rest of the drivetrain must be optimized as already outlined to take advantage of lower RPM.
Also, in any MPG seeking, look at the rest of the package. Weight, a true alignment, inflated tires, etc.
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Re: Changing from street strip to a cruiser.
[Re: ahy]
#1672829
09/18/14 01:24 PM
09/18/14 01:24 PM
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Joined: May 2003
Posts: 148
Indian Hills, CO
mdurbahn
OP
super street
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OP
super street
Joined: May 2003
Posts: 148
Indian Hills, CO
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Thank you, this is good info for me to start. The reason I am leaning towards a EFI swap is because I live in the foothills (7200' el.), work in Denver (5280' el.) and lots of the cruises go to the mountains or passes at 13000' el. It seems to me I would constantly have to be changing my tuning to make it run right, but since I have not had a carb'd car since I moved out here I am not sure. Quote:
With a couple of changes you should be able to double the mileage to the low 10's easy. Starting in the 5 ish range, it probably needs some tuning.
I'd check timing marks first. They can be way off (mine were off ~10 degrees). Use the "positive stop" method to check/set true TDC and then set timing from there. I don't know that particular cam but it probably wants about 15 degrees or more initial and 34 or so total mechanical advance. Adjust the distributor accordingly.
Use vacuum advance. If you don't have it now, get a vacuum advance distributor. 50+ degrees advance under light load cruise is good.
Get the AF dialed in. If you are not an expert at tuning (I'm not) find a "dyno tune" shop that will help you dial in jet size, idle AF and other stuff. Or install a wideband AF meter and adjust as needed.
I bet this helps a lot.
Next step would be the rear gear. 3.23 or 3.55 with bigger tires would be a good balance between cruising and off the line performance.
I'd do the above, at least tuning, first and see how much better it gets.
As far as cam, there may be room for improvement with a shorter duration and higher lift cam... but may require beefed rockers/pushrods. It would help to post actual compression (and tire size) and current rocker setup.
Beyond that, induction can help. A well tuned 6 pack is probably a little better than a well tuned 4 bbl and EFI better yet.
Overdrive can help also with a torquey 440. I bet yours would be happy cruising in the low 2000 RPM range. It comes down to what you want and budget.
My junk (496, EFI, 20% OD manual, [Email]243@.050[/Email] cam) gets around 14 MPG highway @75 MPH and 10 or so around town driven "normally". If I ride it, less.
67 Coronet R/T
911 Turbo
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Re: Changing from street strip to a cruiser.
[Re: mdurbahn]
#1672831
09/18/14 02:24 PM
09/18/14 02:24 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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First things first: Your build isn't that wild, as said above. Even the gear ratio isn't that wild.
No way would I tell you to spend the $2000+ on an overdrive or $5000+ on a 5-speed. You'll have a hard time ever getting that money back.
One thing that most posters here will not know about is living at altitude. It can really make a difference. Denver altitude reduces the air density by something like 20%. That also reduces fuel requirements by 20%. For example, on a 600 Holley I started out with 66 jets and ended up with 61s in the front. I probably could have gone smaller than that. Also thinner air means you need more compression. It also means your distributor advance curve can come in faster.
Keep in mind that your true compression ratio is probably nearly one whole point lower than advertised. That's a Mopar fact of life for bigblocks.
The Edelbrock Performer RPM cam is also hurting your efforts, especially with stock or near stock compression. It is your typical "chevy lobe" cam, meaning it has a lot of duration for the amount of lift.
Here's my shopping list:
1. Call Hughes and get a better camshaft. I'm guessing that it'll have an intake duration at 50 lift of around 218 - 220 degrees.
2. Keep the Perf RPM intake, it is perfect for your needs.
3. Leave the heads alone for the moment.
4. Get timing set to be all in at 2800 rpm, 38 degrees total with vacuum advance unhooked and plugged. You'll probably have to reduce the amount of mechanical advance in the distributor to be able to use enough static timing.
5. Use vacuum advance, as much as you can.
6. Find a chassis dyno and get your air-fuel right at altitude. If you get it to the lean side of acceptable at 5280, it will be a little rich at 7200 but not that bad.
After you have done these steps, you should be breaking 10mpg in town and 15 - 16 on the highway.
Another way to do it would be to pick a self-learning fuel injection setup that also has electronic timing advance built in. This would assure you that you are in really good tune wherever you go. The cam advice still holds, but it might work better with slight modifications to either intake duration or LSA to limit overlap. Again, between the cam grinder and the FI specialist, there should be a decent path.
Unless you get the engine tuned and optimized first, gearing changes won't make a whole lot of difference.
R.
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Re: Changing from street strip to a cruiser.
[Re: mdurbahn]
#1672832
09/18/14 02:26 PM
09/18/14 02:26 PM
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Joined: Jun 2008
Posts: 102
Colo
PJ68RT
member
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member
Joined: Jun 2008
Posts: 102
Colo
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My  MP resto cam 2.9x gears Stock convertor (2000-2500 stall) I'd remove the 5.0 kickdown lever while I was in the trans as well. Should cruise just fine. You can forget about 20mpg. The best imho will be 7/8 city 10/12 highway. You could probably do better if you went EFI/OD trans but that's going to be $$$.
Last edited by PJ68RT; 09/18/14 02:40 PM.
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Re: Changing from street strip to a cruiser.
[Re: dogdays]
#1672833
09/18/14 03:33 PM
09/18/14 03:33 PM
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Joined: May 2003
Posts: 148
Indian Hills, CO
mdurbahn
OP
super street
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OP
super street
Joined: May 2003
Posts: 148
Indian Hills, CO
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Quote:
First things first: Your build isn't that wild, as said above. Even the gear ratio isn't that wild.
No way would I tell you to spend the $2000+ on an overdrive or $5000+ on a 5-speed. You'll have a hard time ever getting that money back.
One thing that most posters here will not know about is living at altitude. It can really make a difference. Denver altitude reduces the air density by something like 20%. That also reduces fuel requirements by 20%. For example, on a 600 Holley I started out with 66 jets and ended up with 61s in the front. I probably could have gone smaller than that. Also thinner air means you need more compression. It also means your distributor advance curve can come in faster.
Keep in mind that your true compression ratio is probably nearly one whole point lower than advertised. That's a Mopar fact of life for bigblocks.
The Edelbrock Performer RPM cam is also hurting your efforts, especially with stock or near stock compression. It is your typical "chevy lobe" cam, meaning it has a lot of duration for the amount of lift.
Here's my shopping list:
1. Call Hughes and get a better camshaft. I'm guessing that it'll have an intake duration at 50 lift of around 218 - 220 degrees.
2. Keep the Perf RPM intake, it is perfect for your needs.
3. Leave the heads alone for the moment.
4. Get timing set to be all in at 2800 rpm, 38 degrees total with vacuum advance unhooked and plugged. You'll probably have to reduce the amount of mechanical advance in the distributor to be able to use enough static timing.
5. Use vacuum advance, as much as you can.
6. Find a chassis dyno and get your air-fuel right at altitude. If you get it to the lean side of acceptable at 5280, it will be a little rich at 7200 but not that bad.
After you have done these steps, you should be breaking 10mpg in town and 15 - 16 on the highway.
Another way to do it would be to pick a self-learning fuel injection setup that also has electronic timing advance built in. This would assure you that you are in really good tune wherever you go. The cam advice still holds, but it might work better with slight modifications to either intake duration or LSA to limit overlap. Again, between the cam grinder and the FI specialist, there should be a decent path.
Unless you get the engine tuned and optimized first, gearing changes won't make a whole lot of difference.
R.
Thanks, good info on your thread for me to go through and try. I understand from other reviews that my cam choice was bad as well and will be probably changing that out first then some high altitude tuning.
67 Coronet R/T
911 Turbo
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Re: Changing from street strip to a cruiser.
[Re: RSNOMO]
#1672835
09/18/14 05:39 PM
09/18/14 05:39 PM
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Joined: May 2003
Posts: 148
Indian Hills, CO
mdurbahn
OP
super street
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OP
super street
Joined: May 2003
Posts: 148
Indian Hills, CO
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What carb are you using? Right now I have both a factory carter 4327s and a holley 750 to use. Mid teens would be nice.. Quote:
I've been running a set-up similar to yours on the street for many moons...
A little less aggressive on the cam, but beyond that, real close...
I'll agree with what's been posted...
Dial it in, throw in 3:23's, you'll be fine...
Made many a long distance run over the years...
Mileage is mid-teens, sometimes a little better...
(Spike the sh%@ pump fuel with REAL 'gasoline'-as in 110)...
3:23's like 70-75 MPH...
(And above, but I will not endorse exceeding the posted limit)...
67 Coronet R/T
911 Turbo
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Re: Changing from street strip to a cruiser.
[Re: mdurbahn]
#1672839
09/18/14 11:20 PM
09/18/14 11:20 PM
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Joined: Jan 2007
Posts: 7,664
IN
ahy
master
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master
Joined: Jan 2007
Posts: 7,664
IN
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Quote:
Thank you, this is good info for me to start. The reason I am leaning towards a EFI swap is because I live in the foothills (7200' el.), work in Denver (5280' el.) and lots of the cruises go to the mountains or passes at 13000' el. It seems to me I would constantly have to be changing my tuning to make it run right, but since I have not had a carb'd car since I moved out here I am not sure.
Altitude (and fuel) compensation is one of the best features of EFI. I ran mine from IL to CA via Flagstaff and Phoenix and back via Las Vegas and Salt Lake in late summer. Overnight at Flagstaff (~7,500') was the first freeze of the season. She started right up and ran great. Later the same day, west of Phoeniz, was zero elevation and over 90 degrees. She still ran great. Similar comment on fuel... 10% alcohol or not she still runs fine.
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