Sbc 355 swap help

Mike 86 regal

Not-quite-so-new-guy
Apr 17, 2022
22
1
Oklahoma
I recently bought a 86 regal limited, I did a chevy sbc 350 bored to 355 has cam(tappet) pistons,heads swap. Transmission is factory th200r4 amd the rear end is factory. I am new to this but the care isn't fast at all and I was told torque converter and rear end will fix this. I also have the 700r4 that came with it but I don't know what I need to put that in. Please help and input. Only did it because friend needed money so I got a great deal on the motor and transmission
 

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scoti

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Sep 5, 2019
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Texas
I recently bought a 86 regal limited, I did a chevy sbc 350 bored to 355 has cam(tappet) pistons,heads swap. Transmission is factory th200r4 amd the rear end is factory. I am new to this but the care isn't fast at all and I was told torque converter and rear end will fix this. I also have the 700r4 that came with it but I don't know what I need to put that in. Please help and input. Only did it because friend needed money so I got a great deal on the motor and transmission
A transmission & torque converter may or may-not be the 'fix' depending on the why it's not "fast". Parts within the engine combo can make a motor not be as powerful as a similar sized motor w/ a better combo of matched parts (not all 355's are the same). Gearing & a converter that matches the rpm range of the motor can definitely help a combo .

What are the long block specs?
What size cam does it have?
What is the current gearing in the rear-end?
Does it currently have a 'stock' converter?
 
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ssn696

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Jul 19, 2009
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What is your game plan? Will a budget control your build before you tire of this car? What is your emissions situation?

The 200-4R happens to have a bolt pattern for both families of engine blocks and will live behind a Chevy 350, depending upon how tired it is. You will have to figure out the torque converter lockup strategy. It has overdrive, but a similar first gear as a TH350, which means waking up your car might involve a gear change to 3.08-3.73 gears (and install a limited slip at the same time). If you want to race, be careful with the stock 7.5 rear.

If you dont plan on more than 300-350 hp, the 700-R4 may offer you an option to keep the rear gears you have, as it has a steep first gear. People rag on these, but for modest builds, they work just fine, especially if has already been rebuilt. You can replace the pinion gears within the differential with a Powertrax unit you can install yourself in the driveway.

The 700-R4 will also need a torque converter lockup solution. Painless, B&M, and others make a pre-computer kit to use transmission pressure and engine vacuum to engage the lockup. Check my profile for a link.

If you decide to ditch the 200-4R, let me know. I need another one for my Olds. If you currently have a 307, before you toss your computer/ECU, let me know; the same Olds needs a PROM change to go from 3-speed to 4-speed whether you sell me yours or not.
 
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Mike 86 regal

Not-quite-so-new-guy
Thread starter
Apr 17, 2022
22
1
Oklahoma
A transmission & torque converter may or may-not be the 'fix' depending on the why it's not "fast". Parts within the engine combo can make a motor not be as powerful as a similar sized motor w/ a better combo of matched parts (not all 355's are the same). Gearing & a converter that matches the rpm range of the motor can definitely help a combo .

What are the long block specs?
What size cam does it have?
What is the current gearing in the rear-end?
Does it currently have a 'stock' converter?
Fscarjunkie: Not sure on the long black specs, there is the information on the cam, stock rear end and stock converter
 

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Mike 86 regal

Not-quite-so-new-guy
Thread starter
Apr 17, 2022
22
1
Oklahoma
What is your game plan? Will a budget control your build before you tire of this car? What is your emissions situation?

The 200-4R happens to have a bolt pattern for both families of engine blocks and will live behind a Chevy 350, depending upon how tired it is. You will have to figure out the torque converter lockup strategy. It has overdrive, but a similar first gear as a TH350, which means waking up your car might involve a gear change to 3.08-3.73 gears (and install a limited slip at the same time). If you want to race, be careful with the stock 7.5 rear.

If you dont plan on more than 300-350 hp, the 700-R4 may offer you an option to keep the rear gears you have, as it has a steep first gear. People rag on these, but for modest builds, they work just fine, especially if has already been rebuilt. You can replace the pinion gears within the differential with a Powertrax unit you can install yourself in the driveway.

The 700-R4 will also need a torque converter lockup solution. Painless, B&M, and others make a pre-computer kit to use transmission pressure and engine vacuum to engage the lockup. Check my profile for a link.

If you decide to ditch the 200-4R, let me know. I need another one for my Olds. If you currently have a 307, before you toss your computer/ECU, let me know; the same Olds needs a PROM change to go from 3-speed to 4-speed whether you sell me yours or nohinest
 

Mike 86 regal

Not-quite-so-new-guy
Thread starter
Apr 17, 2022
22
1
Oklahoma
ssn696 no emissions in Oklahoma, budget egh always there with having a family.
The 700r4 already has a torque converter but it is to long for the drive shaft that's is in it, so what length would I need? As far as the computer, I will check on that for you and I will let you know on the 200r4
 

scoti

Royal Smart Person
Supporting Member
Sep 5, 2019
1,691
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Texas
That cam would be decent for a 355 w/flat top pistons & stock heads or dished pistons w/some some decent 64cc heads. If the long block has stock over-sized dished pistons & 76cc stock heads.... It probably sounds decent but would not offer much acceleration factor.

If it were my car, some 3.42 gears & a 2200-2600 stall converter would be a good start.
 
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bracketchev1221

Royal Smart Person
Jan 18, 2018
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I don’t remember what my 79 Malibu had in it for gears back in 1990, but it was a 267, t-350 factory car. But whatever it was I went to a 3.73 gear and picked up 1.18 seconds in et from 15.20 to 14.12 with nothing else.
 

scoti

Royal Smart Person
Supporting Member
Sep 5, 2019
1,691
113
Texas
I don’t remember what my 79 Malibu had in it for gears back in 1990, but it was a 267, t-350 factory car. But whatever it was I went to a 3.73 gear and picked up 1.18 seconds in et from 15.20 to 14.12 with nothing else.
My 305sbc 'Bu cruises the highway @ ~2k rpm/70mph w/a 1.00 final drive trans gear so that's 2.29 or 2.41's w/27" rear tires.

I recall the 7.5" housing options were 2.29, 2.41, 2.56, or 2.73's as standard stuff goes.
 
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bracketchev1221

Royal Smart Person
Jan 18, 2018
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I never checked it at the time but I always assumed it was a 2.73. It was only later on that I found it could have been worse.
 
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