454 Engine swap help needed

[derotoreut]

OK can someone give me the low down on swapping out my SB 305 with a 454 BB? I have a 69 C/20 TH350 with a 305 (was told it was a 350. WRONG!). I know someone that has a rebuilt 454, which includes oil pump, water pump, Edelbrock intake (less carb). I don't know all the details on the rebuild, but I will find out.

What are the pro's and con's about swapping out the SB for BB? I have seen some info on the motor mounts, but I don't fully understand the issues. I thought the thing about Chevy was it was easy to swap out these motors. I don't want to have problems with hitting the firewall; transmission mount problems; access issues, etc.

[gcburdic]

ttt

[specialtyretail]

I strongly recommend buying the big block engine stands. The big block will bolt up to your small block stands, but exhaust manifold/header clearance will be an issue. I know from experience. There are a couple of sets of bbc stands on the parts forum. If you want to see the clearance problems, check out my build thread under Project Cheap Bastard. Pics of the engine stand problems are there. Thanks and good luck.

[Shyguy]

Originally Posted by specialtyretail

I strongly recommend buying the big block engine stands. The big block will bolt up to your small block stands, but exhaust manifold/header clearance will be an issue. I know from experience. There are a couple of sets of bbc stands on the parts forum. If you want to see the clearance problems, check out my build thread under Project Cheap Bastard. Pics of the engine stand problems are there. Thanks and good luck.

Finally got around to reading your build thread, great info and pictures on there.

When we put the '73 454 in my '71 we used the motor mount and stands that came with the engine. The mounts worked great and allowed for clearances for the headers I had.

[specialtyretail]

Hey Danny. You going down to Memphis with your son this weekend. pretty good time, lots to see and do.

[Shyguy]

Originally Posted by specialtyretail

Hey Danny. You going down to Memphis with your son this weekend. pretty good time, lots to see and do.

Not going to make it his year. Hopefully we will next year.

Hope everyone has a great time. I think there will be 10 in my son's group.

[pillclinton209]

I did the swap BBC chevy parts are off the hook not as eazy to find and expensive to upgrade or replace. the manifolds and valve cover to booster issues of clearence then exhaust redone pulleys fan shrouds etc nickel and dime etc. I would stay sbc if I was going to do it over or get your self a vortex / ls1 / lq9 is the way to go if your gonna end up keeping the truck jmo.

[specialtyretail]

Originally Posted by pillclinton209

I did the swap BBC chevy parts are off the hook not as eazy to find and expensive to upgrade or replace. the manifolds and valve cover to booster issues of clearence then exhaust redone pulleys fan shrouds etc nickel and dime etc. I would stay sbc if I was going to do it over or get your self a vortex / ls1 / lq9 is the way to go if your gonna end up keeping the truck jmo.

He has a valid point. We are considering taking the big block out and building a mild small block to put in its place. A mild small block would be a lot more driver friendly than this wild ass big block we have,, therfore it would get driven more. But,, the big block does look good in there.. decisions,, decisions..

[derotoreut]

This is all good stuff. Reason for asking is I know someone who has a rebuilt 454 BB for $2,000. Trying to decide if it's worth it. It is a 1975 block with square port heads, honed the block, new rings and bearing and oil pump; new cam bearing and an off road cam not to much at all, maybe 2 steps up from stocks. New cower lifters and push rods with a roller timing chain all new, with a performer intake (no carb). The heads are all stock but they are very good heads the Bore is stock, the cam is not, the piston are stock.

This is all great, but I don't want to get nickel and dimed to death with other stuff. I may be better off just getting a different SB to replace the 305 small block I have. Here's my concerns:

I have 11" booster. Will it hit the valve covers?
Would need new headers. My SB headers won't fit. Prob translate into new exhaust too.
Would need new 4-core radiator I would assume.
What about TH350? I hear it would tear that up. Anyone?
I have heard not having high-hump is OK? Any clearance problems?

Looking at Summit or JEG's I could get a 350/290 HP long block for about $1500 and swap out my Edelbrock Performer intake and 600 CFM carb to replace the 305 cu in engine. Any thoughts are welcome.

[bartstoy]

As they say "when I did mine" this is what I ran into.

The bbc will fit, the 11 inch brake booster may hit your valve covers if you use the tall aluminum. I said may because mine clear about 3/4 of an inch. I did have to mess around with the mounts and needed a friend with a welder. You will most likely need a 4 core radiator, and the shroud.
Power steering and alternator brackets will be a @#$% to find, I still have the home made alternator top bracket rebuilt from the 350 block I replaced.

The drive shaft will need to be resized and rebalanced, (shortened). I did not suffer any transmission problems but I rebuilt the 350 with a shift kit etc. Exhaust system will need to be redone, enlarged etc. And if you want headers same circumstances. The distributor will be very close to the firewall and a @#$% to get to. I am not very tall so I layed on top of the engine alot.

Don't skimp on the carburetor or the brakes, you are adding a bunch of weight to the front end of the truck. Those of us with bbc don't talk much about the cost of gas, but you need to consider it while you have some of the options mentioned by others. For me I got it and I love driving it. Good luck.
Bart

[68 TT]

Originally Posted by derotoreut

This is all good stuff. Reason for asking is I know someone who has a rebuilt 454 BB for $2,000. Trying to decide if it's worth it. It is a 1975 block with square port heads, honed the block, new rings and bearing and oil pump; new cam bearing and an off road cam not to much at all, maybe 2 steps up from stocks. New cower lifters and push rods with a roller timing chain all new, with a performer intake (no carb). The heads are all stock but they are very good heads the Bore is stock, the cam is not, the piston are stock...

My big concern is if it really has rectangular port heads on it. I have had them on two different cars and they did well at the track with big cams & open headers but they suck on the street. They were designed for 7000+ rpm drag cars and were never intended for regular street use. At low RPM and low lift numbers they are not efficient and leave a bunch of torque on the table.

You really need a hefty stall converter to get the air flow velocity up in those huge ports. 4000 rpm is a good starting point. Fine for a drag car that really only works the trans for 20 seconds including the burnout but not street friendly or good on a trans due to all the heat buildup with continuous use.

I talked with John Lingenfelter in the 90's about my last rectangular port setup and he suggested I run a set of oval port heads punched out for the bigger valves on my car as it was a combination street / strip car. He said he made more torque up to 6000 rpm with the oval port heads on his street / strip type vehicles and they were faster that way.

He was right. My 70 Chevelle with a .630" solid cam 427 and rectangular port heads ran solid 11.70's at LACR's 2300 foot elevation. With a swap to a set of 049 casting oval port heads punched out to the 2.19 & 1.88 rectangular port valve size the car broke into the 11.40's. It was fast enough they wouldn't let me make another pass until I installed a roll bar. That's an 11.00 ET at sea level in a 3900 pound car. Not bad for my daily driver with full exhaust and DOT tires.

I have been running the big valve oval port heads on every big block I build ever since.

That being said I would not spend the money on either a small block upgrade or that rectangular port 454. Go get yourself a 5.3 LSx engine instead. Far better platform that is easy to get and makes amazing power with nothing but a cam swap. Replacements are all around you every day, the same can't be said of a 454 or even a gen-1 350 any more.

You can run it with the carb you have or keep the stock EFI depending upon what you want out of it.

I have seen complete engine, trans, wire harness & PCM packages sell for under $1000 so if you shop wisely you will come out ahead plus you will get aluminum heads, a hydraulic roller cam and a cross bolt main cap bottom end that will stand up to 600 rear wheel hp with nothing but a rod bolt swap.

I won't rebuild another gen-1 or LT1 small block or any big block again for a street car or truck. They just can't compare.

[68 TT]

Originally Posted by bartstoy

As they say "when I did mine" this is what I ran into.

The bbc will fit, the 11 inch brake booster may hit your valve covers if you use the tall aluminum. I said may because mine clear about 3/4 of an inch. I did have to mess around with the mounts and needed a friend with a welder. You will most likely need a 4 core radiator, and the shroud.
Power steering and alternator brackets will be a @#$% to find, I still have the home made alternator top bracket rebuilt from the 350 block I replaced.

The drive shaft will need to be resized and rebalanced, (shortened). I did not suffer any transmission problems but I rebuilt the 350 with a shift kit etc. Exhaust system will need to be redone, enlarged etc. And if you want headers same circumstances. The distributor will be very close to the firewall and a @#$% to get to. I am not very tall so I layed on top of the engine alot.

Don't skimp on the carburetor or the brakes, you are adding a bunch of weight to the front end of the truck. Those of us with bbc don't talk much about the cost of gas, but you need to consider it while you have some of the options mentioned by others. For me I got it and I love driving it. Good luck.
Bart

I have swapped big blocks into a small block 67 C10 and a straight six 69 C10 and in both cases didn't need to move the trans from the stock location. Neither had power brakes though. I never build enough vacuum to make them work right so I am better off with good working manual disc brake setups. Tall valve covers will require shifting things forward a bit if you want to get them off with the engine in the car.

Most headers don't clear the driver side 67-72 small block engine mount stand design but will work with square body small block stands and clamshell mounts so you don't have to find the 69-72 big block parts. Any V-8 square body will make a good donor.

[mud.man.rj]

I installed a 454 in my 71 4x4 with no fitment issues at all, distrib is a bit close but no big deal, I used B.Blk mounts though, all the rest fit easy, trans and all. A few things as mentioned are buggin me as mentioned the square port heads are basically crap on the street unless high RPM all day and far worse on a heavy truck over a car, the large port 781 heads work great, I used them on my 454, but the other big deal is if the pistons are stock that means a very low 8.3:1 ratio, not great with the small oval port heads but with the large square port, well just say I know why he is selling the motor, pretty much set up to be guttless, I would pass on it unless you have oval port heads and will still be low comp so not a good deal, stay small block, everything fits and way more power than that big block for sure.

[derotoreut]

You guys are a wealth of knowledge. I had no idea about the square port heads. This fellow runs a restoration shop in my area, and does some really nice work. I came across this engine when I responded to an ad that he placed for some tires. I bought some older 285/70-17's from him just to use for fitment tests with my 17" rims. He was really pushing the motor, plus offering to drop it in for me (charging me his restoration shop rate of course).

At first I was intrigued by the idea, but still apprehensive. I just didn't want to open a can of worms (or my wallet) for this. I'm not really looking for this type of swap in my truck. I have been just considering what I could do to maybe swap out the current 305 for some more power without going crazy. I thought maybe just another SB like a crate 350 or something where parts would be interchangeable and relatively easy to do. I'll be honest... I don't know any thing about the 5.3 LSx swap that 68TT is talking about, but I'd love to hear about it and learn more.

[mud.man.rj]

Nothing like a Big block, but not everybody needs one, more cost overall of course but in most cases asmall block especially a crate engine which their are a lot to choose from can't be beat, cheap to buy a 290-350hp motor with full warranty too, the LS swap is a beautiful thing but not cost effective at all in comparison to a basic small block which as you stated is sooo easy to swap and parts galor for it. Anyway stay away from the 454 it needs work on it to be useable first.

[derotoreut]

Thanks guys. I think I will stay away from this BB. Due to all the other projects I have going it would just add too much. I am planning on doing a front disc brake conversion and a Vintage Air install. All parts, for both projects, are on order and should be here soon. To do this BB swap would just be too much. However, I am really going to think about a SB crate engine swap. I am seriously considering a 355 crate motor. I can use my existing Edelbrock Performer intake and 600 CFM carb. I will also be able to swap over other parts as well.

[bartstoy]

That sounds like a good idea, I don't believe I would do it again.
I would be very interested in how you pull off the disk break conversion on the C20 I haven't tackled that one yet. Are you swapping out the complete front end?

[derotoreut]

Originally Posted by bartstoy

That sounds like a good idea, I don't believe I would do it again.
I would be very interested in how you pull off the disk break conversion on the C20 I haven't tackled that one yet. Are you swapping out the complete front end?

I decided to stay with the 8-lug set up. I am not swapping out the front end. I looked at both the CPP disc brake set up and Performance Online (POL) set up. After talking with others on the forum I decided to go with the POL disc conversion. After reading the disc conversion information posted, I thought about looking for existing '73 and up parts, but I figured I would need new rotors, calipers, brakes, ball joints, and more, so I decided on a new conversion set. I will see how it goes.