Experience with 400 SBC

by Iggy Fri Sep 13, 2019 10:37 am

For a while I thought I may have to sell the Laguna to save some family property, so far I have been able to work around that and keep the Laguna. I was planning on building a 383 for the car, already have a block that is bored but needs the rest of the work - clearancing for additional stroke, honing and deburring. Then I stumbled across a very good looking early 400 block with almost no ridge and still standard bore - it is at the machine shop for cleaning and crack checking.

I have had a lot of experience with slightly over stock builds of 400 small blocks in square body trucks and have not had any issues with over heating. Because these builds were for low end torque I kept the compression around 8.5:1 and they never saw anything above 4500 RPM. I know that the 400 SBC has an unearned reputation for overheating - my experience with that was others using head gaskets that did not have steam holes.

I like the idea of putting a 400 SBC in my 1975 Laguna, I would step up to a 6" rod and flattop pistons along with most likely AFR aluminum heads and keep the compression in the low 10:1 range. this would not be a hard core performance build - I would use a big block if I wanted to go that route. I would like to know what others experience is with a 400 small block in this chassis and any mods you would recommend. Thank you.

by bracketchev1221 Fri Sep 13, 2019 7:36 pm

There is nothing wrong with mild 400” engines. I haven’t really seen a difference in 5.7 vs 6” rods in a street motor. If it was me, I would go .030 over and keep stock stroke. If your budget can support it, I would go for a scat 9000 crank. 400’s only had cast cranks anyway, but by the time and cost of refurbishing a stock crank the scat isn’t much more for new. If you can swing it, the 6” rod will allow you to go internally balanced. I do like the 2 bolts over the 4 bolts in performance builds but if you already have a 4 bolt gonfor it. For 2 bolt blocks I like to put main studs. I could go on and on, let me know what you want to know.

by bracketchev1221 Fri Sep 13, 2019 7:57 pm

I would also use an oil pan designed for longer strokes with a scraper and windage tray. Doesn’t have to be anything special, summit I think has a package pan.

by jerry46765 Sat Sep 14, 2019 12:05 pm

Hello -

I think the siamese bore 400 got a bad rap for overheating, that wasn't warranted.

I never tempted fate by always using head gaskets with steam holes and drilling steam holes in non-400 heads.

The cast crank and production short rods don't like much over 5599 rpm.

The two freeze plug blocks were always two bolt mains from mid to late 70s.

In the last 10 years, a decent 400 block is tough to find.

It's an externally balanced engine so needs unique balancer and flywheel unless you internally balance.

The rest is super bulletproof small block Chevy.

With some clearance work, a 4.00 inch stroke crank will go to 434 cubes. Try that with a 350.

Thanks -

by Iggy Sat Sep 14, 2019 10:27 pm

It is a 2-bolt block and I have the studs already - once it checks out I will have it align honed and parallel decked. A new crank is defiantly in order because I already have 6" rods and would go internally balanced. I know I am jumping ahead, the block has not even been checked out yet! I have always looked at the 400 small block as a very good truck engine and have limited experience as a performance engine. I know a few dirt track racers that quit using the 400 because they put too many rods through the side - revved too high so they went back to 350. In my case I would see 6000 RPM with a max of 6500, just want to make sure it is a reliable build that will put a smile on my face!

by Iggy Tue Oct 01, 2019 12:53 pm

Well, it looks like I will go back to my original plan of a 383 - the 400 block has a crack in the lifter valley that is not repairable! Too bad as that was a 509 block with extra tin and nickel.

I might consider the 427 BBC I have laying around with 9.5:1 open chamber pistons, was trying to keep the weight off already front heavy Laguna so was looking at small blocks. I have a ZZ502 roller cam I could stick in it!

by thatfnthing Tue Oct 01, 2019 1:06 pm

Sorry to hear it, sounded like an interesting idea. Still, speaking from experience, the 383 won't suck. Smile

by Iggy Tue Oct 01, 2019 1:19 pm

Since I already have the block, a 350 block from a 1970 K20, I will most likely go the 383 route. The block is a 4-bolt main with extra tin and nickel - overkill! Cranks are not expensive at all and I already have 6" rods laying around so getting an internally balanced cast steel crank in a no brainer!

by 73ss Tue Oct 01, 2019 5:00 pm

Iggy wrote:Well, it looks like I will go back to my original plan of a 383 - the 400 block has a crack in the lifter valley that is not repairable! Too bad as that was a 509 block with extra tin and nickel.

I might consider the 427 BBC I have laying around with 9.5:1 open chamber pistons, was trying to keep the weight off already front heavy Laguna so was looking at small blocks. I have a ZZ502 roller cam I could stick in it!

Have you used the 502 cam? idle quality?
That should be a gen 6 cam, I think it is a little different set-up than a retro roller for a gen 4 block.

by bracketchev1221 Tue Oct 01, 2019 7:03 pm

Oh well. There’s nothing wrong with a 383. Just use the same approach with the longer stroke. Oil control and windage is important.

by Iggy Wed Oct 02, 2019 9:30 am

73ss wrote:
Have you used the 502 cam? idle quality?
That should be a gen 6 cam, I think it is a little different set-up than a retro roller for a gen 4 block.

The Gen VI roller cams will fit in the Mark IV or Gen V blocks using a stock type retainer plate, have to use a Gen VI timing set - blocks are already drilled and tapped, you have to use retro-fit roller lifters as the Gen VI lifters will not work.

by Iggy Wed Oct 02, 2019 9:35 am

bracketchev1221 wrote:Oh well. There’s nothing wrong with a 383. Just use the same approach with the longer stroke. Oil control and windage is important.

I have been looking at a Mildon 5 quart pan (plus filter) with baffling and windage already in the pan for a 3.75" stroke

by bracketchev1221 Wed Oct 02, 2019 10:52 am

This is for the later blocks, but something like this may work.

https://www.jegs.com/i/JEGS/555/50222/10002/-1

by Iggy Wed Oct 02, 2019 12:02 pm

This is the pan I am considering

https://www.summitracing.com/parts/mil-31503/overview/

by Iggy Wed Jan 22, 2020 11:35 am

Well, a push came to a shove, and the 1970 350 block went down the road. I am weighing my options - should I get a Dart SHP block and build a 400, or dust off the 9.5:1 compression 427 BBC in the corner of my shop?

One of the reasons I wanted a G3 is because of their handling and comfortable ride. My favorite car was a 1977 Monte Carlo that I put over 200,000 mile on. I have been trying to stick with a SBC to keep the front weight down, aluminum heads and intake to help reduce that weight. My other issue is I love the power from a BBC and I have a really nice .030" over 427 with open chamber hypereutectic dome pistons, moly rings and steel crank just sitting around (my son was going to install in a 1966 Caprice he no longer has). I have a set of mildly ported 049 Large Oval Port heads that are ready to bolt on and a 4L80E that someone wants me to take off their hands (for $$ of course)!

I sold the 350 block because I was going to pick up a 2002 LS1 from an F-body complete! I sold the block about the same time the other guy sold the LS1 - story of my life! So now I am back to which route to go:

Small Block with aluminum heads and intake and TH200-4R
or
All Iron BBC with 4L80E

I already own the TH200-4R and a complete 427 BBC, I do not own a 400 SHP block (though I do have a 1972 400 in unknown condition) or 4L80E

Just kicking around ideas because circumstances have changed since I bought the farm in the UP.

by bracketchev1221 Wed Jan 22, 2020 1:31 pm

Go with the 427. You have it all. Use it.

by thatfnthing Wed Jan 22, 2020 2:08 pm

That's what I was thinking. Built properly, the 200-4R will handle the 427.

by Iggy Wed Jan 22, 2020 3:41 pm

I am definitely leaning towards the 427! My daily driver for years was a 454 powered K2500 Suburban - went through three of them, wish I still had any one of them. I agree that the 200-4R should hold up just fine if properly built, I have a nice clean core from a 1987 Monte Carlo SS. I already "stole" the set of Hedman Elites' my son purchased for the 66 Caprice as they also fit the 73-77 Chevelle! Though the engine has been sitting for a few years (well oiled), until my son sold the Caprice I really did not consider it available. Now that it is available (and I am the one that paid for the machine work) I will most likely use it in the Laguna - I will put a milder cam, my wife needs to be able to drive the Laguna also.

by 73ss Wed Jan 22, 2020 7:00 pm

I've had a 200 behind a 454 since 09. It's held up well. It runs 12.80's in the 4000 lb chevelle, nothing too radical. My trans has a aftermarket direct drum which is a weak link. The weak link for me is the torque convertor. I've killed 2 of them. The trans builder said if this one fails, I'll need to step up to a billet unit $$$$. This one has been in the car 5 years and is doing well. It's a in-house convertor the trans builder supplied. 200 uses a 27 spline input shaft which makes convertor choices somewhat limited. Trans builder says the input shaft is good to 500 hp. Either way, you gonna pay, Controller unit for the 4L80 is $600~$1000, on top of what you have in a trans re-build.

I'll see if the 200 will live behind a 489 later this year. If it fails, I've got a 4L80 core. I'll never go back to a 3 speed.

by bracketchev1221 Wed Jan 22, 2020 7:08 pm

What cam is in it now?

by Iggy Thu Jan 23, 2020 7:31 am

The block currently has a Comp Xtreme Energy mechanical flat cam in it now, I would prefer not having to deal with adjustments, my son wanted the retro sound. I am leaning towards a hyd roller - have a ZZ502 cam that was a take out from a crate engine that was being used as a marine engine, also have a recommendation from Howards cam that has similar duration specs.

by bracketchev1221 Thu Jan 23, 2020 8:59 am

ZZ502 hydraulic roller would be perfect.

by Iggy Thu Jan 23, 2020 10:13 am

That is the way I am leaning, already have it on the shelf!

by bracketchev1221 Thu Jan 23, 2020 11:10 am

I guess you will need a set of Retro lifters to fit the rollers in the old block.

by Iggy Thu Jan 23, 2020 1:12 pm

That is correct on the retro roller lifters. You can use the Gen VI cam in the Mark IV block with the retainer plate.

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