87 v20

[John81287]

Hey guys,

I completely new to the square body. I have an 87 V20 that is going to be my project truck. I am looking at picking up an 85 C30 for the motor and front clip. The C30 has a manual trans in it. My V20 has an automatic. Can anyone offer some insight into what issues I may run into on doing this swap. I would like to keep the automatic transmission in the truck. Is it a direct bolt up to the new motor or do I need to make modifications to get it to link up. Any input is greatly appreciated. Thanks

 

[Jims86]

Hey guys,

I completely new to the square body. I have an 87 V20 that is going to be my project truck. I am looking at picking up an 85 C30 for the motor and front clip. The C30 has a manual trans in it. My V20 has an automatic. Can anyone offer some insight into what issues I may run into on doing this swap. I would like to keep the automatic transmission in the truck. Is it a direct bolt up to the new motor or do I need to make modifications to get it to link up. Any input is greatly appreciated. Thanks

You will definately need a different flywheel for an 85, as the balnce is different on the pre 86 engines due to the rear main seal setup from 2 piece to 1. Are you keeping the EFI too?

 

[John81287]

Yes I am doing a complete cab swap so all the electronics from the C30 will come over to the V20.

 

[John81287]

My mistake. I'm going to keep looking for a reg cab with a 454 model yr 1987. Truck doesn't have the throttle body any longer. But I'd like to get it put back in. Thanks for the input

 

[Jims86]

Yes I am doing a complete cab swap so all the electronics from the C30 will come over to the V20.

Ok, you know you are giving up around 50 hp/tq by using the 85 engine? Unless the c30 is a 454 of course.

 

[John81287]

It is a 454. That's why I want it so bad!

 

[Jims86]

My mistake. I'm going to keep looking for a reg cab with a 454 model yr 1987. Truck doesn't have the throttle body any longer. But I'd like to get it put back in. Thanks for the input

Ahh, ok, we posted at the same time. The trans in your v20 should be a TH400, so its a good one to put behind a 454.
I personally would recommend a 454 out of a 95. still TBI Like the 87, but you can run a4l80 later if you want. The fuel pump, pCM and harness are needed also. The 94-95 454s run 30-33 psi at the throttle body, opposed to the earlier ones, which run 9-13 psi fuel pressure.

 

[John81287]

Thanks for the info. I may just stick to the carb motor and be done with it. Haven't quite made a decision yet.

 

[Jims86]

Thanks for the info. I may just stick to the carb motor and be done with it. Haven't quite made a decision yet.

As long as its QJet or Holley, yer good.

 

[John81287]

Ok thanks. The truck is kind of a patchwork quilt. It's and 87 with a carb 305 in it. Engine was rebuilt/ replaced at some point. So this is why I'm leaning towards getting the carb 454 to put in it. How can I tell if the flywheel on my 395 will work with the 454? Or is it guaranteed that it won't? Thanks again

 

[John81287]

305* damn fat fingers!

 

[Jims86]

305* damn fat fingers!

Nope...different balance.

 

[John81287]

Am I going to have any issues with engine block length? Driveshaft lengths? Transmission location?

 

[John81287]

I assume ill have to relocate motor mounts which I fully expect.

 

[Jims86]

Ummm...i dont think youll have a problem with any of that stuff