ive been reseaching this for about a year but still im not sure about big block swapping into Thirdgens. i know this is probably a popular theme but please moderators dont tell me to use the search feature cus iv tried and cannot get a clear cut answer. for awile i was sold on the fact that in order to swap a big block in a third gen some cutting and fabricating on the firewall and crossmember was needed to fit a big block. so i narrowed my idea of the biggest engine i could fit was a 400 sbc(w/o heavy mods in the engine bay). but after doing some more searching i realized many ppl r putin big blocks in their 3rdgens. so could someone give me the correct info please on whether swapping a big block requires modding the engine bay? for further specification i plan on doing a swap on my 92 firebird(v6 3.1L)

thanx,
tim

 

It will probably depend alot on what particular setup you'll be going with, such as headers, intake height, etc. I know of someone who had to pound back his firewall some and also had to do some grinding on a motor mount I believe. Find out who on here has done it and send out some pm's. You won't know for sure what will work or not until you try it yourself though. It can definitely be done.

 

The engine itself fits with no modifications.

You may have some clearance issues with the heater box or wiper motor depending on the valve covers you chose.

Just about any intake will require a small cowl hood but a drop base air cleaner can still fit under the hood with a typical dual plane intake manifold.

Standard factory type heads don't have any issues. Raised exhaust port heads move the headers higher and add to clearance problems under the car.

Headers are the biggest problems with the swap. The cheapest swap headers are Hooker Supercomps and they're the worst fitting. Minor sectioning under the car is required to get them to fit perfectly. You could simply run factory exhaust manifolds and have no exhaust issues other than having restrictive manifolds.

The block is longer than a SBC and all the length goes forward. Using a standard long water pump gets close to the rad but isn't impossible to use. Installing an electric water pump removes that problem.

My 540 has clearance problems but only because of how I installed it. I have it dropped down and moved back as far as it could go. With huge headers tubes, clearance is very tight. I've cut and sectioned the firewall to add clearance but still struggle to remove the bellhousing bolts. Having a tranny and flexplate shield don't help much.

You can do a search to find all the threads about doing a BBC swap but at the top of this forum in the stickies is a thread about what's required to do the swap.

A SBC upgrade is easier but using a 400 isn't as easy as it sounds. Since they haven't been made since 1979, they're getting harder to find. Going with an aftermarket engine, you'd jump right into a 434 SBC. These big SBC engines can be just as expensive as a mild BBC which also isn't as easy to find as it sounds. Although I have a bunch of 454's in my garage, my current engine has no factory parts on or in it.

 

thanx for the great info stephen87 iroc. i do have an after market hood i plan to install that has about a 3-4 in raise in the back center of the hood and if i were to drop a bbc in i definately would be putting headers on. so that may make things more difficult. someting else is that contrary to most ppl who drop in bigger engines for performance i want to still have air conditioning how will this factor into the swap b/c many ppl say the compressor gets in the way. anyone got more info?

 

There is this nifty sticky at the top of the forum. https://www.thirdgen.org/forums/engi...swap-info.html

 

ya thanks five7kid your small paragraph of info on swapping a newer(96 big block) engine which are probably very different from the big blocks of old which im requesting info for which were carbed not fuelys is pretty nifty.

 

Thanks for the praise regarding the sticky. Always love positive critiques of my work. . .

The majority of the information in the sticky is in links, not the text. Try again.

 

Why don't you go back and try reading the links in the sticky.

Then when you come back with specific questions to ask, you can be a little more civil about it so that you don't have get sent to the corner for a time-out.

 

ok i might have went a little overboard and i dont apreciate my post to be edited by someone other than me, but whatever. its just a build-up of anger and frustration against moderaters ever since entering this site. if five7kid wasnt a moderator then i probably wouldnt have reacted that way. its just that i would expect more from a moderator b/c one has to earn it to be a moderator. u dont know how many times moderators have told me to try the search feature or theres a sticky for that. there are 2problems i have with that.

first of all most stickys and other post are hard to find and most likely are not specifically about the same topic and responses to a new thread will be much more helpfull

2nd is that is the world gonna end if a certain # of threads are started, big deal if the same questions are asked over and over their are 3rdgen.org junkies out there that would answer the same questions over and over with no problems. if u are too lazy to answer the question again then dont and dont suggest a useless sticky unless its a sticky specifically for that persons thread i mean specifically. not a 96 454 when most ppl cant get and engine like that w/o spending an arm and a leg.

i know it may have been my fault for the detour in topic but lets bring it back to the orginal thread question.

ps i think it would be nice for the moderators to get off ppls back and get off their assses and make the links to good bbc swapping threads stickies and delete your own five7kid!

 

Since you have chosen to vent publicly, I'll respond publicly.

Let's get a few things straight:

1. You don't dictate how this Board is run. The Board owner does.
2. The Moderators don't dictate how this Board is run. They simply enforce the rules set up by the Board owners.
3. If you have an issue with a Moderator, Step 1 is to PM them. If that doesn't produce results to your satisfaction, then PM the Board Administrators.
4. If you have a suggestion for improving a sticky, PM a forum moderator and we'll consider your suggestions. This sticky in particular has been modified several times in an attempt to make it more user friendly. I wish I had more time to make it perfect, but I'm afraid I need to rely on others to help out a little here. If someone submits a comprehensive treatment of the topic, I'll be more than glad to replace the current one.

We're here to help each other out with technical issues. If you expect things to be handed to you just because you asked, regardless of what you asked or how you asked it, you're in the wrong place. We're grown-ups here, and expect members to act like it.

As for getting back to the thread topic and your last question, the Hot Rod magazine article linked in the sticky says this: "If you plan on keeping the air conditioning intact, the late model shorty compressor will require mount alterations to keep it properly positioned, and you'll need either a two-groove or three-groove big-block pulley to drive the accessories. The serpentine belt system on very late-model F-Bodies won't fit in this application."