Burning rubber
Thread Starter
Cruising
Joined: Jul 2015
Posts: 14
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Burning rubber
I have recently made an engine swap in my 78 to a 450HP 383 stroker. Although I'm very happy with the motor in not happy with the lack of preformance at the rear wheels. The car has lots of power but still wont burn the rear tires on demand. I'm sure this question has been ask before but should I change the rear gear?
Race Director
Joined: May 2006
Posts: 18,660
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Is the car an automatic or manual transmission?
If an automatic is the shift cable on the carburetor correctly adjusted?
What are the specifications of the camshaft?
If the camshaft is too radical and an automatic are you using a high stall speed converter?
If an automatic is the shift cable on the carburetor correctly adjusted?
What are the specifications of the camshaft?
If the camshaft is too radical and an automatic are you using a high stall speed converter?
Thread Starter
Cruising
Joined: Jul 2015
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Yes it's an auto. Not sure about the shift cable The cam is a 224/234 and no stall converter.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
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From: Great Plains Iowa
Le Mans Master
Joined: Apr 2011
Posts: 6,284
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From: Hermosa
With an auto and a 3.08 rear ratio through a Th-350 transmission you are going to need a stall converter to get that tire burning experience.
You engine may produce 450HP on the engine dyno with 3/4" open headers but many things installed on the car can rob you of power.
Intake and exhaust are big ones. Is the intake ingesting cool air or under hood air? What intake is being used? A dual plane is going to deliver better torque down low vs a single plane. Is there suffecient air cleaner/snorkel area for the intake to be unrestricted in getting air?
What kind of manifolds are being used? Size of exhaust pipes and are mufflers high flow? Dual exhaust at least?
450HP on the dyno can quickly turn to 350 or less on the car.
I use a 2600 rpm stall torque converter with my 380hp ish 350 with a Th-350 and a 3.08 rear. Th-350 also has a shift kit installed. Stall converter makes a huge
difference in launch capability. Shift kit makes a significant difference in shift firmness and time to shift.
A 3.55 ratio rear would really wake it up as would a 2004R or a 700R4, but those are the more expensive and involved mods.
You engine may produce 450HP on the engine dyno with 3/4" open headers but many things installed on the car can rob you of power.
Intake and exhaust are big ones. Is the intake ingesting cool air or under hood air? What intake is being used? A dual plane is going to deliver better torque down low vs a single plane. Is there suffecient air cleaner/snorkel area for the intake to be unrestricted in getting air?
What kind of manifolds are being used? Size of exhaust pipes and are mufflers high flow? Dual exhaust at least?
450HP on the dyno can quickly turn to 350 or less on the car.
I use a 2600 rpm stall torque converter with my 380hp ish 350 with a Th-350 and a 3.08 rear. Th-350 also has a shift kit installed. Stall converter makes a huge
difference in launch capability. Shift kit makes a significant difference in shift firmness and time to shift.
A 3.55 ratio rear would really wake it up as would a 2004R or a 700R4, but those are the more expensive and involved mods.
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Le Mans Master
Joined: May 2007
Posts: 5,007
Likes: 1,115
From: North tonawanda NY
Too often people only understand the HP number and nothing else resulting in a mismatched drivetrain setup. the difference between a good shop and a poor shop is this would have raised flags at a good shop and they would have explained it before the install...or course this could have been a situation where a couple buddies helped you with the swap in your garage... In that case its all on the "Engine Guru" in the group
I agree you NEED at the least a higher rpm stall converter.
Thread Starter
Cruising
Joined: Jul 2015
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Thanks for all the suggestions. I am quickly learning that there is a lot more to "to the ground HP" than I thought. A lot more to consider than just slapping a stroker motor in one. I do appreciate. Maybe I should have joined the forum before putting the new motor in.
Thread Starter
Cruising
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Melting Slicks
Joined: Feb 2006
Posts: 3,105
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From: Sunrise FL
Make sure the initial advance and mechanical advance are set and working. Go for more advance, but not detonation.
Did you mention what rear gear you have? What compression?
As said a higher stall will REALLY wake up a car with no low end.
Did you mention what rear gear you have? What compression?
As said a higher stall will REALLY wake up a car with no low end.
Le Mans Master
Joined: May 2007
Posts: 5,007
Likes: 1,115
From: North tonawanda NY
that cam has a fairly narrow powerband of 2,000 to 4800rpm... I would guess that a 2600rpm stall would be a good choice but I'm sure others could chime in that could better answer this.
I have a cam that starts making power at 1,800 rpm and I have a stock 2000rpm converter but wish I had gone bigger myself.
I have a cam that starts making power at 1,800 rpm and I have a stock 2000rpm converter but wish I had gone bigger myself.
Thread Starter
Cruising
Joined: Jul 2015
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Stock 3.08 rear gear and 10.1 compression.
Melting Slicks
Joined: Nov 2010
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From: Michigan
Le Mans Master
Joined: Apr 2011
Posts: 6,284
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From: Hermosa
This is what I found on that cam.
http://usaperform.com/street-fighter...ift-p-497.html
That's an old school grind. Low intensity ramps on those lobes. This means that the valves are open longer but not in a useful way.
Your over lap (time both intake and exhaust valves are open) is 71*. This is probably pared with a late intake closing. All boils down to less torque off idle but higher RPM capability.
The valve lift is normal for a flat tappet, but low compared to a roller cam. You will make power but it's gonna be later on. Maybe 2500-3000 +RPM range. A stall converter would definitely help here. Your stock 1800ish stall converter makes it a dog off the bottom.
That or different gearing.
Or....a different cam. Hmm. Depends on your mechanical aptitude.
http://usaperform.com/street-fighter...ift-p-497.html
That's an old school grind. Low intensity ramps on those lobes. This means that the valves are open longer but not in a useful way.
Your over lap (time both intake and exhaust valves are open) is 71*. This is probably pared with a late intake closing. All boils down to less torque off idle but higher RPM capability.
The valve lift is normal for a flat tappet, but low compared to a roller cam. You will make power but it's gonna be later on. Maybe 2500-3000 +RPM range. A stall converter would definitely help here. Your stock 1800ish stall converter makes it a dog off the bottom.
That or different gearing.
Or....a different cam. Hmm. Depends on your mechanical aptitude.