Big Block Conversion - 1975 Jimmy

[Mike Phillips]

Big Block Conversion - 1975 Jimmy 4x4





It's been a few years since I've removed a small block and replaced it with a Big Block, so tips and suggestions and reminders are welcome.


Starting with a stock but great running 454 removed from a good running and driving 1986 Suburban.  From what other's have posted, this is one of the last models for a carburetor.  At this time all I'm going to do is clean-up the engine, install it and get the truck back on the road.  I'll do the simple things like full tune-up but for right now I want to keep the stock intake, carburetor and distributor (if it fits).  As for the stock exhaust manifolds I'm leaning towards removing them and replacing them with some quality headers.  Truck currently has 350 Small Block with Doug Thorley Headers with Flowmasters and sounds real good.

This year had the serpentine belt system and I'd rather convert it back to the simple v-belt pulley system.  All it's going to have is a water pump, power steering pump and alternator.

I'm using the 4-core radiator form the Suburban.

Start



Oven Cleaner



Tips?  Suggestions?  Things to remember?

[choptop]

One thing to think about, I would replace the valve cover gaskets, and make sure the rear main and oil pan gaskets arent leaking. Now would be the best time to fix those issues. I usually change the valve cover gaskets because if they arent leaking at this time, they will.

[VileZambonie]

I would definitely run some good headers. I'd keep the serpentine belt system myself. The 454 still came available with a carb up to 1991

[Blazin]

x2 on the serpentine set up. If you have all of it you should run it.

[Mike Phillips]

Good tips.

I was planning on doing the simple things like gaskets, maybe a new water pump too, just didn't want to get into taking apart the core engine.  I'll do a compression check to to make sure there's no major problems. 

I have the complete serpentine belt system and all the brackets, is there a reason this is better than the old school system?  Seems like the old school system was simpler.


Mike

[Stewart G Griffin]

1) i don't have any real tips on SBC to BBC conversions as:
a) i've never done one.
b) it would seem to be mostly a bolt in conversion.  My only concern would be will the stock exhaust manifolds bolt up to the existing exhaust?

2) As far as serpentine vs. conventional V, i heard/read that each individual V belt is stronger than the one serp belt which means each v belt will last longer;  This difference is actually not a big thing if you carry a spare serpentine belt with you.  i prefer V belts primarly due to lower cost;  If the serpentine system were cheap enough, i would go with it due to the simplicity---one belt vs. up to three or four.

3) On the oven cleaner:  Does it work well?  And do you have to hose it off?

[Mike Phillips]

3) On the oven cleaner:  Does it work well?  And do you have to hose it off?

Works better than the engine degreasers you buy at the auto parts stores.  It works really well and you do have to wash/rinse it off.  I use any brush that fits the surface I'm trying to scrub and with time an repeated applications you can get right down to bare metal.

Not for everyone but work for me.

[Stewart G Griffin]

OK, just to make sure, when you say down to bare metal does this mean you've eliminated all the grease?   It(hopefully) does not mean the paint is removed too?


Also, should i degrease, hose it off, then run the engine so as to heat everything up and thus dry everything?  Is this a good plan?

[eventhorizon66]

Bare metal means the paint's gone too, at least to me it does.

[Mike Phillips]

OK, just to make sure, when you say down to bare metal does this mean you've eliminated all the grease?   It(hopefully) does not mean the paint is removed too?

Some comes off, some doesn't, I don't think I would use this on a engine installed and running, I only do it to things I've removed from vehicles and am going to do further work to.  It's a quicky, down and dirty way to loosen years of built up grime off an engine.

[choptop]

found a good mixture, 2 parts deisel, 2 parts water, 1part tide, or cascade detergent. Mix thouroughly, spray with chemical sprayer. Wash of with water hose.

[Mike Phillips]

I would definitely run some good headers. I'd keep the serpentine belt system myself. The 454 still came available with a carb up to 1991

Any recommendations?

I want to be able to change spark plugs easily and not have the boot on the spark plug wire melt, besides those little nitpicky things, a good flange seal against the head is important, being able to access the header bolts without complications would be a great assest, and of course performance.

I haven't bought big block headers for at least 15 years so I'm confident there's been improvements by all the manufactures.

[VileZambonie]

The better quality you want the more it's gonna cost. What kind of finish do you want?

[Mike Phillips]

The better quality you want the more it's gonna cost. What kind of finish do you want?

Hmmmm....

Best bang for the buck? 

[choptop]

I have had a set of Dynomax ceramicoated heaters on Oldyellers truck with the bigblock for about 5 years, and havent had any issues.Look great, and havent burned a spark plug wire since I got them But, I have heard that some have not faired so well. It seems most of them having issues are from the rust belt.