[xbazzarex]

alright so im dropping a pontiac 350 in to my third gen t/a. the swap itself does not appear all that difficult, however i could use advice on a cheap build for this motor. i also need some help with how to hook up all of my electronics. im used to working on newer cars and have never really dealt with an engine this old. the car is a 1985 trans am and the engine is a pontiac 350 from a 1972 firebird. the engine does not appear to have any work done to it other than valve covers. engine needs valve cover gaskets, carb works fine but id like to upgrade to a 4bbl carb. any help would be nice.

[importsmasher]

Sounds like a fun project! As for advice, on the 350 build, I suggest posting in the Street section; you'll likely get much more response.

Importsmasher

[ponyakr]

Yeah, there are a few guys who post in the street section who have built Pontiac 350's. They can answer your questions and probably post links to past threads with 350 info.

It would probably also be a good idea to ask about the swap into the 3rd gen. There use to be a vendor which sold the mounts and headers for the swap. But that vendor no longer exists. So, there will be some fabrication needed to make the swap. But it can be done. There are quite a few pontiac powered 3rd gen race cars.

This would probably be a real good swap thread, to help others who, like you, want to do a Pontiac powered 3rd gen.

[72blackbird]

A 350p into a 3rd gen Firebird or TA is definitely a cool idea- the 3rd gen F-body was actually designed to take a 301, which is essentially a short deck Pontiac V-8. Nunzi's Automotive in NY actually made adapter mounts to fit a 326-455 Pontiac into your car, so I would look into finding some of those mounts. If you can't, I'm sure some later clamshell frame mounts could be mounted on the crossmember, although it would take a bit of fab to make it happen.

As far as the 350p goes, it's possible to make 300-350 hp/ 400 ft-lbs. with just a head and cam swap. Look for no.11,17,18. or 47 heads- these may need to be upgraded to screw in studs, but the 1.96/1.66 valves should be fine. Forged pistons and rods are available for this engine, but aren't part of what most people call "cheap"- it all depends what your budget is. But forged 5140 I-beams can be had for $275/set.

Geno

[ponyakr]

"...I'm sure some later clamshell frame mounts could be mounted on the crossmember, although it would take a bit of fab to make it happen."



Yeah, I'll post some pics of a race car that used the late 2nd gen mounts. If I remember correctly, these pics came from the Angeles and McCarthy Pontiac book-not sure.

Also have a pic of what I think are GTO frame brackets, which somebody used for the swap.

I assume that most guys today would use motor plates for race apps. Hey, a rear plate, with the late 2nd gen side mounts, might be a good street set-up. Some say the plate transmits too much engine vibration. But I've read at least one post that said if you didn't know his car had a rear plate, you would not even notice it, from inside the car.

[ponyakr]

"... i could use advice on a cheap build for this motor..."


I'm with Geno on the forged rods. I'd also rather go with forged pistons.

BUT, you did say "cheap". The SP 357P cast pistons are cheaper. And, they may hold up, if you don't run too much timing, or do anything that results in detonation. Most cast pistons won't hold up to near as much detonation as forged pistons.

http://www.summitracing.com/parts/sl...w/make/pontiac

You didn't mention how much power you want from this engine. If you are content with 300hp or a bit less, you can go with 357P pistons, 6x-4 heads, cut down slightly, to at least 90cc, a Voodoo 256 cam, and thin 350P Cometic head gaskets . It's just 1 simple recipe, by no means the only one.

http://www.lunatipower.com/Product.aspx?id=1774

http://www.jegs.com/i/Cometic-Gasket...ductId=1288713

If your engine is indeed a '72 model, it should have heads without the end exhaust manifold bolt holes. The 6x heads have all 6 holes and better hardened seats. That's why I recommend them.

BUT, if, as Geno mentioned, you want a little more power, you can go with the earlier, higher compression heads. Those small valve 2-barrel heads can be used to build a real nice 350. But, they need a lot of work. The 6x head build will be a lot cheaper. IMO

Here's a stock '69 350HO rebuild.

http://www.hotrod.com/how-to/engine/...-engine-build/

Hey, you can even buy stroker assemblies for the 350 block to increase cubes to 383 or even a little over 400. Not cheap tho.

http://www.jbp-pontiac.com/products/...s.html#407_413

[xbazzarex]

i appreciate the responses thus far, this was originally posted in another section but was moved here(not sure why). the motor mounts are definitely an issue i needed some help with, i have mounts from a 3rd gen 305 but i dont believe they will work at all. as for the power out of the engine, 350 hp and torque. my local junkyard has a few older grand prixs from the 70's, just need to check out the engines for the intake manifold and a carb. another note for the build, the engine will not be requiring or using any emissions equipment. the engine has "custom" ****tily welded headers on it at the moment that will definitely need replacing. at this point, the carb going to a 4bbl, a cam, and possibly header swap is what im looking at. ive never really done a rebuild before mostly just bolt on work, so i dont have much clue on what im doing, having said that ill be following your guys advice on some of the internal pieces.

[xbazzarex]

some pictures of the project thus far, the engine was painted by previous owner(it appears to have some aftermarket items but i havent pulled anything apart yet, valve covers are moroso and the distributor i believe is accel, spark plugs are msd). the interior is still a work in progress but weve replaced our worn out 3rd gen seats with nicer 4th gen seats picked up off a nice fellow up in Delaware. had to also pull the front bumper and impact bar off as the car was in a low speed front end bump, frame is perfect, old impact bar was bent in slighty and had some rust.

[ponyakr]

"...as for the power out of the engine, 350 hp..."


Well, if you want 350hp, you'll have to go either the higher compression or the stroker route.

No problem at all with a stroker. Not too tuff with enuff compression and the right cam.

Some light Auto-Tec pistons will help. You can get 'em with the thin rings, and a different pin height. This will allow you to reduce the deck height to near zero, without cutting the block deck down. The lighter weight, smaller valve relief volume(3.8cc), and thin rings will also help make more power.

[xbazzarex]

ive found heads somewhat close by that i could pick up the guy has 11 and 6x and hes asking 25$ per head. im pretty sure this is a good price on these as ive seen them for much more. input on which would be better, im not entirely sure what the difference is of the numbers.

[ponyakr]

For $25 each, I'd buy all of 'em, quick.

The #11's are 1970 350 or 400 2-barrel heads. Several sites show these to have 80cc chambers. BUT, the ONLY way to tell exactly how big the chambers are on ANY head is to actually measure them. If the heads are 6x-8's, they came off '75-'78 400's. They have aprox 101cc chambers. If they are 6x-4's they came off '75-'79 350's or W72 400's. They have aprox 94cc chambers.

The 11's can be built to work. But they will cost more to build, because they'll need to have screw-in studs installed, and possibly have hardened seats installed. The 6x heads will be cheaper to build, but will have less compression.

This is all assuming the heads are rebuildable. Some are cracked.

And some have exhaust manifold bolts broke off in 'em. Each one will cost more $ to have removed.

[xbazzarex]

Originally Posted by ponyakr

For $25 each, I'd buy all of 'em, quick.

The #11's are 1970 350 or 400 2-barrel heads. Several sites show these to have 80cc chambers. BUT, the ONLY way to tell exactly how big the chambers are on ANY head is to actually measure them. If the heads are 6x-8's, they came off '75-'78 400's. They have aprox 101cc chambers. If they are 6x-4's they came off '75-'79 350's or W72 400's. They have aprox 94cc chambers.

The 11's can be built to work. But they will cost more to build, because they'll need to have screw-in studs installed, and possibly have hardened seats installed. The 6x heads will be cheaper to build, but will have less compression.

This is all assuming the heads are rebuildable. Some are cracked.

And some have exhaust manifold bolts broke off in 'em. Each one will cost more $ to have removed.

so the 11's, how would screw in studs need to be installed? would they have the be machined in? or could i just get a set.

[xbazzarex]

alright ive picked up the heads they are 6x-8's they definitely need to be rebuilt but after thorough inspection have no issues with bolt holes and appear to have no cracks anywhere visable. also picked up an intake manifold with a 4bbl carb. the carb isnt to dirty but is missing a few pieces and the manifold is in good shape just painted a hideous orange color.

if any one needs engines or other parts the guy is outside of baltimore and has tons of stuff i can put you in contact with him easily.



the body of the car is not to far from being finished, i just need to put in ttop weatherstripping, replace the front bumper cover and re attached the fenders and ground effects. while i have these pieces off ive been fixing any rust issues on the car, which it has very little of. only bad spot is where the battery was.

[b-man]

The 6X-8 heads are a great head for a street 455 build (101 to 105cc chamber volume typically), coming in at around 8.6:1 before milling.

Compression is a bit low using them on a 400, probably around 8:1 at best before any milling. For a 400 the 6X-4 (94-98ccs) would be preferred, and even then they take some milling just to get up to 9:1 compression.

For a 350 the 6X-8 is really not a usable head, compression will be way too low at around 7:1 with them. You can't mill them enough to get the compression up, same goes for the 6X-4 heads on a 350.

The #11 heads (low-80cc range) are a far better choice for a 350, even though you need to convert them to screw-in rocker studs.

With a Pontiac V8 you really need to choose your heads taking into consideration the chamber size. On a smaller engine you just can't use larger cc heads and come out with a decent compression ratio. You really don't want to resort to using domed pistons to 'crutch' a bad combustion chamber size choice.

You can use the smaller cc heads on the bigger engines, using a dished piston to keep the compression from getting too high. Dished pistons are a good way to go when trying to retain the original high-compression heads (like on '70 and earlier GTO engines) when adjusting the compression ratio for pump gas operation.

If you paid $50 for the 6X-8s you can't get hurt on them, you paid a very low price.

[xbazzarex]

Originally Posted by b-man

The 6X-8 heads are a great head for a street 455 build (101 to 105cc chamber volume typically), coming in at around 8.6:1 before milling.

Compression is a bit low using them on a 400, probably around 8:1 at best before any milling. For a 400 the 6X-4 (94-98ccs) would be preferred, and even then they take some milling just to get up to 9:1 compression.

For a 350 the 6X-8 is really not a usable head, compression will be way too low at around 7:1 with them. You can't mill them enough to get the compression up, same goes for the 6X-4 heads on a 350.

The #11 heads (low-80cc range) are a far better choice for a 350, even though you need to convert them to screw-in rocker studs.

With a Pontiac V8 you really need to choose your heads taking into consideration the chamber size. On a smaller engine you just can't use larger cc heads and come out with a decent compression ratio. You really don't want to resort to using domed pistons to 'crutch' a bad combustion chamber size choice.

You can use the smaller cc heads on the bigger engines, using a dished piston to keep the compression from getting too high. Dished pistons are a good way to go when trying to retain the original high-compression heads (like on '70 and earlier GTO engines) when adjusting the compression ratio for pump gas operation.

If you paid $50 for the 6X-8s you can't get hurt on them, you paid a very low price.

ill hang on to them as i plan to end up with another pontiac, having said that how bad are the heads on the 72-73 350p? ive looked up the code for the heads on my engine and they appear to be from 73, even though the engine was pulled from a 72.

[b-man]

Quite honestly the '68-'70 350 heads are the only ones worth considering out of all the 350 heads for use on a performance 350.

The compression is just too low if you're using any of the later 350 heads.

[ponyakr]

"so the 11's, how would screw in studs need to be installed? would they have the be machined in? or could i just get a set."


It can be done 2 ways. The holes can be tapped for 1/2" bottom ARP studs, made for this purpose.

Or, heli-coils can be installed, for 7/16 bottom studs. Then you can use BBC 7/16 studs.

Some Pontiac engine builders recommend the heli-coils--some recommend the ARP 1/2" bottom studs. So, I assume both ways will work, if done properly. I won't argue the point. Both methods have been used.

http://www.hotrodders.com/forum/mach...ds-232219.html

[ponyakr]

"...The compression is just too low if you're using any of the later 350 heads."



There is no doubt that a 350 will make more power, with more compression, as will most any other engine.

BUT, there are some Pontiac class racers who have proven beyond even a shadow of doubt that a low comp 350 can make quite a bit of power.

Bill Rink has had really good luck making power with his low comp '74 GTO. It ran good with unported #46 heads, as a Stocker. And runs much quicker in Super Stock form. The car always runs well under it's NHRA index.

The '77 350, which has 6x-4 heads, is a popular combo, for class racers. There have been lots of 'em running well under their index. Mike Morgan has a '77 Formula which can run in the high 10's, which is about .900 under his index.

http://www.dragracecentral.com/DRCSt...r2015#indextop

Bill Rink runs mid 10's with his '74 GTO. Here's a link to a race where Bill and Mike Morgan had the highest qualified Pontiacs, with their low comp 350's.

http://www.dragracecentral.com/DRCSt...er=30#indextop

No, a street 350 won't run 10's. BUT, with the correct combo of parts, a low comp 350 can make a reasonable amount of power. And, when used with the correct rear gear and converter, can provide very spunky performance. OR, you can go with the stroker assembly. There is no reason why a 350 can't provide decent power, without 10:1 compression.

But, if you try to run 7:1 comp, with a stock converter and 2.41 gears, you will definitely have a dog.

[b-man]

BUT, he's not building a class racer. So, he's not stuck using low-compression heads like a class racer. And he won't be using a trick racing cam, a high-dollar low-drag auto trans or ultra-high stall torque converter that a class racer uses.

He needs a street 350 that is a good runner, and it's more easily accomplished with a 9:1 350 instead of an 8:1 350.

For pretty much the same money you have a better street engine, that has both better power and better fuel economy just by choosing a head that has the most ideal combustion chamber size.

[ponyakr]

"...He needs a street 350 that is a good runner, and it's more easily accomplished with a 9:1 350 instead of an 8:1 350..."



It's even more easily accomplished with a 383 stroker. It will have a lot more low end torque, with the 4" stroke.

Of course, this conversation usually progresses to "You'd be a lot better off using a 455 or a 400 block stroker, instead of the 350. Everybody nowadays seems to want 400 + HP minimum--some much more. So, I reckin it all depends on what you want and have the funds to pay for. I'll stop now.