Engine Choice 383/TH350 or 454/TH400

[kenm78]

I am rebuilding my 383 stroker but have a family member who has offered me a 454 and TH400 from a old 86 winabego RV camper. All I have to do is pull it out and rebuild it. Should I stay with my 383 or should I go ahead and fork a little extra cash and build the 454?

[ed2552]

the 383 is a better choice because it is cheaper to rebuild and you can make easy power w' it. but i would pull the th400 and use that if it fits, because it is stronger

[corn]

Id vote for the big block but its your choice, not mine. I say go get it anyway, even if you dont put it in its a good combo to have around...

[crazy longhorn]

That 383 is a runner for sure, I have one in my old truck. I will say one thing for sure tho.....if you dont give a chit about mileage, a well prepped BB will run soooooo much harder than the 383! I did run a 461 inch Olds in my old chev, & will say it was the "nutz" ! The only thing that Olds could not pass on the open road was a freakin gas pump! Its your "nickel".....spend it how you like, & have fun L

[cooters]

motor selection is entirely based on what the application is. Lots of pulling, a big block is good. Strokers are awesome but its harder to get low rpm torgue from them like a big block. For a daily driver they rock.

[68GMC454]

personaly i say the big block....but i got a 454 in my 84,,and i wouldnt get rid of it for nothing,,well maybe a 572,,but for pulling, hauling if i can get it on a trailer or in the truck i can take it with me...and is great for coming out of big hole with a load,,or that might be because of the granny tranny to..never had a stroker motor so couldnt say,,but i think strokers are more to say you got one..not trying to start anything with the stroker guys...

[arkracing]

I say get teh 454/400 anyway just to have it around. If you're already into the 383 keep going and finish it. If you have to start fresh with the 454 build - it will be more $$ out of your pocket.

save the 454 for your next truck

[piecesparts]

"There is no replacement for displacement" HOWEVER, if you have a lack of funds, the 454 will enhance that when it comes to purchasing parts. Once built, it will last a long time and pull hard, when needed.
I have a 383 and I love it, however it is a small block and has it's limitations. It is easy to work on and it is a high rev motor, in comparison to a BB, but the HP of the 454 will beat it in the long run.

[jeffspower]

If longetivity & how many miles you can clock before needing a rebuild again is taken into consideration, the 454 will last longer IMO. If they were both built to similar power levels, the 383 will need more go fast parts of course, & will work harder if you use it. FYI, every 454 motorhome engine I have been into from that era was a 4 bolt main.

[kenm78]

anyone know what year gm started using roller cams in there 454s

[jeffspower]

I believe it was 1996. That's what the cam was made for I used in my '88. Also required the cam retainer & timing set for a 96 also. I Used a Comp "96-up replacement grind" cam with retrofit lifters. Comp's tech line said I would have to drill holes in my block for the retainer and that the OEM threaded holes wouldn't line up- total BS. It all went together with no mods.

[mnunn454]

One thing to consider when (if) rebuilding the Winnie's 454....

If it's got heads with the infamous "peanut ports", they won't flow worth a flip. Plan during your rebuild to swap to some decent 781 castings or similar. Otherwise, above 3000 RPMs or so, your 454 will be sucking air through a straw, loose all it's real HP potential and worse, the 383 in your neighbor's truck you could have had will drive circles around you.

Breathing is everything for a BBC.

Keep the TH400 though. You'll need it regardless of which power plant you choose.

[jeffspower]

My '88 454 is mainly a driver & occasionally a trailer puller. It had the huge chambered low compression peanut port heads originally. I parted out an '88 454 propane power unit engine & used the heads off of it. I can't remember the casting number, and mortec didn't list them. They have smaller valves (but not as small as the propane heads of the 70's) and smaller combustion chambers than my OE heads, but large ports & stellite exhaust valves with hardened seat inserts. I used a Performer TBI peanut port intake. I know it may seem silly to have small runners going into large ports, but the runner dumps high into the port, which I think lets it flow past the short radius easier while keeping velocity up for the lower rpm range this engine lives in. The setup works for me- it picks up faster and pulls stronger with 3.21 gears than it did stock with 4.10's. I have another TBI unit to mess with, I'm going to send it off to have it opened up & bigger throttle plates installed. Curious to see how much that will gain.

[mnunn454]

Originally Posted by jeffspower

The setup works for me- it picks up faster and pulls stronger with 3.21 gears than it did stock with 4.10's.

jeffspower, I suspect the increase in pickup/pulling is due more to the numerically lower (3.21) gearing that the manifold/head ports/porting. The lower gears let the engine operate more in the torque range to which it's suited because of the smaller ports. 4.10's would require the engine to normally rev way above it's peak torque range.

You do bring up a valuable point though. And that's to try to achieve a 3-way match between the purpose of the vehicle (towing, daily driving/street/strip), the torque and HP curves of the engine once it's built, and the normal or average operating RPM.

In your case it seems your engine's torque curve and operating RPMs are now closely matched, which takes us back to the question about 383 or 454. My guess is the 383 would be the better choice if the gearing is numerically higher, and 454 if the gearing is numerically lower.

Food for thought.

[Livrat]

IMHO.. the only substitute for a Big Block is a bigger one!!

[LockDoc]

-
I have a 454/th400 in the white truck.... I don't know why, but when I go for a ride in that thing I never want to go home. It's a hoot to drive..... When I'm driving that truck I feel about 20 years younger than I am. (that still makes me an old fart though)....

LockDoc

[409biscayne]

454 / t400 is an awesome combo , the best . In my opinion our trucks look better with a bbc filling up the engine bay , they cost a little more but there worth it . 383's in a Nova or Camaro , big block in 4000lb trucks , just my .02 .

[mnunn454]

Originally Posted by 409biscayne

454 / t400 is an awesome combo , the best . In my opinion our trucks look better with a bbc filling up the engine bay , they cost a little more but there worth it . 383's in a Nova or Camaro , big block in 4000lb trucks , just my .02 .

I couldn't agree more.

[jeffspower]

Originally Posted by 409biscayne

383's in a Nova or Camaro , big block in 4000lb trucks , just my .02 .

I could pull the motor & tranny out of either one of my trucks and still weigh more than that

[droppedgmc]

i love my setup with the 454/400 and 4.11's in the ass. roll 45mph and light em up

[jeffspower]

Originally Posted by mnunn454

jeffspower, I suspect the increase in pickup/pulling is due more to the numerically lower (3.21) gearing that the manifold/head ports/porting.

I swapped the gears before the rebuild, so I have experienced just the engine improvement alone. I'm sure it would really scoot if I put the 4.10's back in. But I agree, even though it has alot more upper rpm power than the stock motor did, the real grunt is made down low now. I'd love to have a Gear Vendors overdrive, even with the 3.21's. It would be great for hwy cruising. I think there is enough grunt that it would pull a 6-7K trailer load in OD with ease, except in the hills of course. Drive for small hills, high side of second for moderate hills & 2nd for the nasty climbs. There isn't much for hills around here that are nasty though.

[kenm78]

How do I tell if they are the peanut heads??? any pictures of a peanut head and non peanut head.(we are talking about cylinder heads keep your minds out of the gutter) LOL

[FarmTruk]

Originally Posted by kenm78

How do I tell if they are the peanut heads??? any pictures of a peanut head and non peanut head.(we are talking about cylinder heads keep your minds out of the gutter) LOL

No pics here of the "peanut" heads, but I believe casting # was...346236. Started production in 1975.

[mnunn454]

Originally Posted by droppedgmc

i love my setup with the 454/400 and 4.11's in the ass. roll 45mph and light em up

You're singing my Tune, for sure!!!

Love it!!!

[mnunn454]

Originally Posted by kenm78

How do I tell if they are the peanut heads??? any pictures of a peanut head and non peanut head.(we are talking about cylinder heads keep your minds out of the gutter) LOL

Mortec.com says "Big block oval port cast iron heads were made in two different configurations. The large oval port heads found on many passenger vehicles and trucks and the small oval port heads (which are also sometimes called peanut ports or round ports or truck ports) found on many big block 454 truck engines made after '76. Each of the oval port head sizes used a matching intake manifold. If you are building a motor for pulling or towing on the street, the small oval port heads will make their power at low and mid range rpms, but run out of breath at rpms over 4500. If you are building a strong street performer or a bracket racer, the large oval port heads are the ticket up to about 6500 rpm if you do some bowl porting and add the 2.19"/1.88" valves. Some of the better performing cast iron large oval port castings are the open chamber designs like the "781" or "049" casting. You can get an aluminum version of the large oval port, open chamber head under casting number "391" from GM/Performance Parts. "

Underlining is mine

And "ignitionman" in a post at www.Chevelles.com says "IgnitionManApr 30th, 00, 11:49 PM

At this point, I think we should all get to agree with the port terminology of BB cylinder heads.

All dimensions are darn close if not right on, it's from memory. Rectangle is 2.125" tall x 1.240" wide, Oval is 1.900" tall x 1.065" wide, Square (peanut) is 1.065" tall x 1.065 wide. All refer to intake port configuration, not plug thread/jacket types used. Rectangle and oval were used from production inception in 1965 to 1974, then the only BBs were in trucks, and went to square (peanut) port heads, all of them past 1975. No peanut intake port heads were used or produced before 1975.

Large truck 366 and 427 tall deck engines all used Oval port heads, all years, all pickup 454's changed to square (peanut) port in 1975."

Hope it helps you ID your heads.