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383 or 455 1979 pontiac firebird t-top

  
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383 or 455 1979 pontiac firebird t-top

 
79KAC 79KAC
New User | Posts: 1 | Joined: 08/09
Posted: 08/05/09
10:28 PM

i have a 1979 pontiac firebird t-top and im needing to know if i should put a 383 or a 455 in it...and what is the big difference between proformance?  

Pontiac4 Pontiac4
User | Posts: 105 | Joined: 01/08
Posted: 08/06/09
11:38 AM

Is the 383 a chevy engine or a true Pontiac engine.
The 455 is a true Pontiac engine right?  
Professonal hi-performance engine builder

horsepower sells engines and torque wins races

gtomustang gtomustang
Enthusiast | Posts: 457 | Joined: 06/09
Posted: 08/06/09
12:07 PM

so now I'm curious...how do you make an original 383 cid Pontiac?  Their 350 already has a 3.75" stroke, and the bore won't go out to 4", will it?  
Just because you can't do it...doesn't mean its impossible

68scott385 68scott385
User | Posts: 51 | Joined: 07/09
Posted: 08/06/09
01:03 PM

cough it up pontiac4...not calling bs here...more interested in the method to the madness Grin
can it be stroked further?
i'm a sucker (sorta) for the road less traveled  
68scott385 68scott385 68scott385

Pontiac4 Pontiac4
User | Posts: 105 | Joined: 01/08
Posted: 08/06/09
06:30 PM

A Pontiac 350 bored .030 over and they use a 4.00" stroke which is basically and 428 crank that has 3.00" mains instead of 3.25" mains there are a couple of Pontiac parts places that sell these rotating assemblies to convert a 350 Pontiac into a 383 stroker but the dyno test results were not that impressive for the 383 pontiac for it to be worth the extra 1500 dollars and I have seen more power pulled from a Pontiac 350 using the stock configuration stock stroke crank.
Never count the Pontiac 350 out it can be built to be a potent performer.  
Professonal hi-performance engine builder

horsepower sells engines and torque wins races

68scott385 68scott385
User | Posts: 51 | Joined: 07/09
Posted: 08/06/09
10:41 PM

i haven't heard of people stroking the pontiac 350...i take it from what you (pontiac4) said that it isn't popular due to cost/gain ratio...

do the unimpressive gains stem from bore size/valve size restrictions/shrouding in this application?

just curious now that the subject (pontiac 383) has been brought up  
68scott385 68scott385 68scott385

Pontiac4 Pontiac4
User | Posts: 105 | Joined: 01/08
Posted: 08/07/09
01:24 PM

Most people probably have not heard of stroking a Pontiac 350 because there too busy downing the 350 and building a 455 mostly due to lack of Pontiac knowledge and how to pull power out of one a 350 pontiac that is.  
Professonal hi-performance engine builder

horsepower sells engines and torque wins races

gtomustang gtomustang
Enthusiast | Posts: 457 | Joined: 06/09
Posted: 08/08/09
02:06 PM

Actually, I had read about the 383 Pontiac, then forgot all about it until you explained it, b/c the idea of finding a 428 crank--much less wasting such a valuable engine to take that one part--was like landing a unicorn.  Doing a welded stroker seems closer to reality.

But still, the 350P has a bore and stroke similiar to an LS1 Gen 3 Chevy, 14 degree angle valves, 6" long connecting rods, an "air gap" style intake long before Edelbrock thought it up...the weak spots are those cast iron connecting rods (go use aftermarket or Chevy BB rods), lifter bores that need to be braced or supported or an aggressive cam will snap them off the side of the lifter valley, and they aren't a Y type or deep skirt style block, like the LS1 or Ford's FE or the Hemi or the 4.6 mods.

If you can figure how to run a cathedral style head port to push air into a small bore, long stroke engine like most 4 cylinder and new V8s are designed...you can engineer something fun out of the 350.  But everyone's gonna believe its a 400 instead, since the blocks are all the same like AMC's.

I'd love to see an article on one of these, but for magazines...if you can't bolt it onto an engine, it must not be a possible hot rod trick.  
Just because you can't do it...doesn't mean its impossible

Pontiac4 Pontiac4
User | Posts: 105 | Joined: 01/08
Posted: 08/08/09
02:47 PM

There was a article that CC did on a Pontiac 350 and B. Fulper got 670HP with a 125 shot of N.O.S.  
Professonal hi-performance engine builder

horsepower sells engines and torque wins races

Pontiac4 Pontiac4
User | Posts: 105 | Joined: 01/08
Posted: 08/08/09
02:50 PM

That cheap china made intake they call the tomahawk/hurricane did not help any it is probably why they did not get more power form the engine.  
Professonal hi-performance engine builder

horsepower sells engines and torque wins races

greymouser7 greymouser7
New User | Posts: 7 | Joined: 11/09
Posted: 12/01/09
05:02 PM

Forget the 350!!
Build the 455 for pete's sake!
It sounds like it might be cheaper if I follow the threads right.
You won't regret the performance of the 455. -That's my vote!  

Elsydeon Elsydeon
New User | Posts: 4 | Joined: 09/11
Posted: 09/18/11
01:42 PM

I gotta say 455, nothing says "this ain't another Chevy in a non-Chevy" like a 455.  

3836bbl 3836bbl
Enthusiast | Posts: 407 | Joined: 11/10
Posted: 09/18/11
02:05 PM

79 KAC welcome to the PHR forum...  Yep,  Keep it pure Pontiac either way, I would go for the 455ci for sure, parts are available & it's more cost effective in the long run, "there's no replacement for displacement"...  
"Fill Your Library Before Your Fill Your Garage"  3836bbl alias Budnicks

gtomustang gtomustang
Enthusiast | Posts: 457 | Joined: 06/09
Posted: 09/19/11
05:11 AM

Actually, if gas mileage isn't a consideration, grab a 400 block, drill it .030-over for 455 pistons (shorter skirts), then drop in a 4.5 inch stroke crank for 488cid...'cuz finding a 455 block of any manufacture is getting harder to find.  and that combo'll move a 4000lb turboturkey  Grin  
Just because you can't do it...doesn't mean its impossible

gtomustang gtomustang
Enthusiast | Posts: 457 | Joined: 06/09
Posted: 09/19/11
05:12 AM

Actually, if gas mileage isn't a consideration, grab a 400 block, drill it .030-over for 455 pistons (shorter skirts), then drop in a 4.5 inch stroke crank for 488cid...'cuz finding a 455 block of any manufacture is getting harder to find.  and that combo'll move a 4000lb turboturkey  Grin

but those T-tops...you may be finding out how good the spotwelds were in the roof back then. I think 1979 was the year there was a recall to redo the welds...?  
Just because you can't do it...doesn't mean its impossible