i AM LOOKING AT PUTTING A BIG BLOCK 454 IN MY 86 GRANDPRIX, AND WAS WONDERING IF IT WILL BE A BIG DEAL TO DO SO. dO I GOTTA CHANGE THE SPRINGS AND OTHER FRONT END PARTS? iF SO WHAT AND WHERE DO I START? iS IT GONNA BE A PAIN TO WORK ON AFTER(MEANING IS THERE ANY ROOM LEFT UNDER THE HOOD)? I Have a low milage 454 and transmission coming out of my 83 coachmen motor home, good swap or stick with my mild built 350? Looking for a quick but reliable and streetable car to drive on the highway as in town. Thanks for any comments
BIG BLOCK SWAP ON AN 86 GP
- Thread starter GRANDPRIX350
- Start date
- Status
I bought my 81 Grand Prix with a 454 big block from a truck installed in it. The rest was stock. Car ended up getting stolen but anyways...
The front end was weighed down a bit, but not enough to be a critical concern. Still driveable.
Fitment -- I don't believe if there were any issues... there was a round hole cut out of the hood, and an air cleaner which stuck out of the hole about an inch. Could have easily used a different air cleaner (ie. an edelbrock) with no hood modifications.
It's a great addition to the Grand Prix. Gobs of torque. Fun to drive. You'll love it.
The front end was weighed down a bit, but not enough to be a critical concern. Still driveable.
Fitment -- I don't believe if there were any issues... there was a round hole cut out of the hood, and an air cleaner which stuck out of the hole about an inch. Could have easily used a different air cleaner (ie. an edelbrock) with no hood modifications.
It's a great addition to the Grand Prix. Gobs of torque. Fun to drive. You'll love it.
By the way I forgot to mention, you have to use low profile valve covers, in order to clear the stock heater box. So you can't use roller rockers, which require the taller valve covers.
Also in my case I was using exhaust manifolds, not headers, but there is enough room for headers if you want them.
Also in my case I was using exhaust manifolds, not headers, but there is enough room for headers if you want them.
the roller rockers fit fine on my big block, and i have used low profile valve covers. the biggest issue with a big block swap is not the actual swap itself but having to make sure the rest of the drive-train itself will handle the torque. The stock 7.5" rear axle is a bomb waiting to go off and the transmission is also not going to survive long in stock form.
If the car was originally a V8 car then you may not need to change the front springs unless it was a V6 car then you would have to. Also your driveshaft will have to be cut 1" to fit i believe. As far as room under the hood goes i have plenty of room with my 455 under the hood, the only thing was headers will be hard to fit on the drivers side due to the steering column but i used stock manifolds and haven't had a problem with them.
i took off the heater box and used 84 monte carlo solid mounts for a 350 and a th 350 trans a everthang bolted right in here check it out and a i had to use hooker super comp headers for bbc in a g body
Honestly its Not too hard a swap, but I personally wouldn't go through it for a stock motorhome big block, just my. 02... those engines have good torque, but no top end at all.... biggest draw back is the cam, heads, and the 8-8.5 compression ...mines originally out of a 80's pickup, but its much much different now
its not hard at all just a little on the expensive side
HKR 2241 headers new they are like 599.00
i got some for 300.00 used
almost everything from the SBC will work on the BBC just the brackets wont
if your wanting dual exhaust get the after market double hump crossmember for 209.00
but theres a few things that wont work
the shifter linkage from the column wont wrok due to clearaznce issues
power steering pump (need the one from the BBC
the front sprngs are iffy if you want to drive it you need to get some new ones if your just gonna drag strip it they are fine
also if you want the tall valve covers you can cut a notch out of the A/C box and redo it with some fiberglass
i have some pics up on here go ahead and take a look
and no you cant find a lower intake manifold unless you go with the stock cast iron intake
you will need to cut a hole in the hood for that
how i know ive tried many things and what you see in my pics is what you need to do
HKR 2241 headers new they are like 599.00
i got some for 300.00 used
almost everything from the SBC will work on the BBC just the brackets wont
if your wanting dual exhaust get the after market double hump crossmember for 209.00
but theres a few things that wont work
the shifter linkage from the column wont wrok due to clearaznce issues
power steering pump (need the one from the BBC
the front sprngs are iffy if you want to drive it you need to get some new ones if your just gonna drag strip it they are fine
also if you want the tall valve covers you can cut a notch out of the A/C box and redo it with some fiberglass
i have some pics up on here go ahead and take a look
and no you cant find a lower intake manifold unless you go with the stock cast iron intake
you will need to cut a hole in the hood for that
how i know ive tried many things and what you see in my pics is what you need to do
tHANKS ALOT FOR ALL THE HELPFUL HINTS. i PLAN ON TRYING TO GET ALL THE PARTS I NEED BEFORE STARTING THIS PROJECT. i WILL BE GOING THRU THE MOTOR AND COMPLETELY REBUILDING IT. WAS LOOKING AT DOING THE COWL HOOD ON IT. WOULD THAT HELP WITH HOOD CLEARANCE ISSUES? WHAT ABOUT THE transmission? I HAVE A MILD BUILT TH350? AND THE 400 OUT OF THE MOTORHOME BUT WOULD HAVE TO REPLACE THE SHAFT IT HAS THE EBRAKE ON IT. OR BUILD THE 200R4? WANT A QUICK BUT REAL STREETABLE DRIVER. THANKS AGAIN
- Status
