Author Topic: '78 T/A lots of good advice looking for some clarity for Torque and HP upgrades  (Read 7842 times)

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Offline raypfaff

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Hi Angelo, here are the pictures I took yesterday. Once I get home from work I'll check the back of the block behind the 8th cylinder for the casting code. These are the photos I have. The paint is confusing and it was my understanding pontiac's ha the dipstick coming up to the front from the passenger side like in the photos. Let me know what you think.

Offline Angelo

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No need for further pictures, the last picture shows a good view of the head, definitely a Pontiac motor. Based on the date code, it's not original to the car. This all makes sense now, a 75 Pontiac 350 may have had a smog pump depending on what car it came out of.
81' ex-Turbo Trans Am - Resto-mod

Offline raypfaff

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Okay, Great! Angelo thanks for the info I really appreciate it. How weird is it someone would paint it red and then paint it back to the pontiac blue? Its a real bummer the engine turned out to not be original motor. I was pretty happy thinking I bought an all original east coast survivor with the original order form laminated. Still glad it is in fact a Pontiac engine and I don't need to go behind the block to pull the block number right away. I know there are 2 block numbers for '75 350s. an early and late one. I'll get the number off the block this week for sure to confirm which I have but I guess now my question is... does this change anything? I know the 400 '78 had more torque and was set for 220hp (with the WS6/W72) and I was going to need D port heads for my plans. Anyone familiar with the 350 blocks and can shed some light in a direction I may need to go in now? Goals torque 375-400, HP 300-350 if possible.

Offline Angelo

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This changes things some, I'll leave it to engine building experts from this forum to go into detail and suggestions, but I know as recently as last year there was an article about a Pontiac 350 build up in High Performance Pontiac magazine, so there are options. From what you've had done so far, I think getting your quadrajet rebuilt and getting the distributor curve re-done now that the engine can breath better will help things.
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Offline Aus78Formula

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Canadian export vehicles had orange engine paint, if it look original, wild guess though.

Offline raypfaff

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That would be something. My East coast T/A from PA having a replacer Canadian 350. Wild to think about. More importunely though is a 350 worth sinking money into for my power goals? I know a lot of people are saying look for a 400/450. A friend of mine showed me a bunch of 400/450s he came across in his google search and the range seems to go from 3,500 to over 5,500 for a rebuilt engine. With Aluminum heads and a cam I am assuming I'll end up spending close to 3,000 for parts if I redo the 350. Anyone have an input on whether to throw money at this motor or rather to save a bit and go for a rebuilt engine? If so anyone have a recommended reliable company or someone they know? I have a few links so far would even like to get an assessment if any of these places seem legitimate.

Offline dgotterTA

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I just finished the build of my 79 TA 403. i went with a mondello setup. mondello in california specialize in olds motor. i went with the mondello aluminum heads which they paired up with a matching cam, roller rockers and comes with higher aluminum valve cover. i believe the cost was 2600.00 but you will need to install an electric fuel pump. the mondello heads are 75cc which is better than the edlebrock heads at 77cc.
added a performer manifold with holly 770 carb. 2400 stall converter and 3.73 gears. bored .025 over with flat top pistons added headers with super 44 flow master exhaust. upgraded with msd 10,000 coil. just had a dino completed at premier performace and i came in at 431 hp. very happy and the power differance from 185 hp to 431 hp is un believable.
TA

Offline 72blackbird

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More importunely though is a 350 worth sinking money into for my power goals? I know a lot of people are saying look for a 400/450. A friend of mine showed me a bunch of 400/450s he came across in his google search and the range seems to go from 3,500 to over 5,500 for a rebuilt engine. With Aluminum heads and a cam I am assuming I'll end up spending close to 3,000 for parts if I redo the 350. Anyone have an input on whether to throw money at this motor or rather to save a bit and go for a rebuilt engine? If so anyone have a recommended reliable company or someone they know? I have a few links so far would even like to get an assessment if any of these places seem legitimate.

Bolting on aluminum heads and installing a hotter cam will definitely wake up a 350P, but won't address worn rings or the fact the bottom end still has cast rods, a real liability and potential point of failure in any Pontiac V-8. IMO it's better to start with a 400 or 455 and start fresh, since it costs the same to build all three engines but the larger you go the more power you'll make. All of the well known Pontiac engine builders sell long blocks or crate engines, but be prepared to pay a premium vs. using a local builder. A healthy 400 or 455 can be built with forged pistons and rods and the factory crank for around $3500-4500 (iron heads- more of course for aluminum). Spend the extra money for balancing and honing with a torque plate- these are steps that no good engine builder skips.

If you decide to take this route, you'll need to set a budget, establish how much power you'd like to have, get a parts list going and then gather the parts for your build. Core costs vary from state to state, but internal parts can be sourced online.

Offline Angelo

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If she runs strong, test compression and it's within spec and you don't have any leaks or anything, I would just get the quadrajet rebuilt and getting the distributor curve re-done. Find out what quadrajet you have currently, it may be a great carb for a future 400/455 as well.

If you do swap out the motor, before you do the swap take video of your 350 running, then video testing each cylinder with a compression tester. When you go to sell it, show the buyer the videos and the compression results, you can easily sell the engine for 2x it's worth having this information, provided the tests and video show a strong runner.

81' ex-Turbo Trans Am - Resto-mod

Offline raypfaff

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Hello All Happy Memorial Day!

Okay, so here is my update along with some Qs. I took the info from Geno and Angelo did a little research and I think I found a great situation to get a 1970 455 or a 1971 400. Did some research and came across a company called S & J Engines in Washington. They 'remanufacture' blocks and look to sell them. The work listed as done on their cores include:
Installed precision milled cylinder head(s)
Installed Valve train: new valves, new valve seals, new valve seating
Leak tested Heads & Block
Milled Cylinder Head/s
New Main Bearings
New Oil Pump
New Pistons
New Rod Bearings
New Seals & Gaskets
New Timing Belt

Each block comes with a 7 year 100,000 mile warranty and even has trade in for your current core. Needless to say sounds great to me. Question being has anyone dealt with them before? Also if I do go this route what else should I be asking about their process and cores?

I want to go with the 455 but was wondering if there is anything I should know about compatibility of a 1970 455 and the setup of the 1978 T/A. For example:
Are the motor mounts the same?
Engine location?
Would my existing timing cover (off the 350) fit the 455?
Could I use the harmonic balancer or would I need a new one?
Flywheel?
Bolt to transmission a straight forward swap?
Any parts I haven't thought of that would need to be changed out for the 455?

Thanks for reading everyone I really appreciate all the advice and can't wait to get this block upgrade going.


Offline 72blackbird

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I've never dealt with S & J, but I'm sure they get some business with a 7 year/ 100k mi. warranty. Sounds like a nice warranty, but unless you're local to them you'll have to eat the cost of shipping a defective engine back to them- not a cheap or easy thing to do. I'd rather have a crate engine from a well known Pontiac builder or the build from a local build with a good reputation and current references- much better than a piece of paper.

As far as cores go I do know that if you don't have a 455 core to exchange for a rebuilt 455 they will charge you- 455's are somewhat rarer than 400's, being built only from 1970-1976, so expect to pay more for a 455 than a 400. I think they also have a local core service to save on shipping costs.

I'm not sure about the 70 9799140 455, but I do know the 71-74 485428 455's and 75-76 500813 455's have 5 mounting holes per side, and will bolt into a 76-81 F-body chassis with no mods. Your 350P timing cover will bolt on a 455 with no mods, but I would forget about trying to re-use your harmonic balancer- a 30+ year-old balancer can fail without notice due to the brittleness of the elastomer between the hub and outer ring. Get a new GM, Pioneer, or Professional Products balancer- these are all inexpensive and a must for any performance engine. Other upgrades that are also worth the expense are forged pistons and rods, as well as having the rotating assembly balanced- a 455 has much higher piston speeds than a 400 due to the long stroke crank and the factory cast rods are subjected to much higher loads at speed. So many 455 owners claim they don't race, but one thing leads to another and the next thing you know those cast rods are getting tossed out the side of the block or through the oil pan- a set of 5140 replacement rods are also very inexpensive, around $240/set. I would also plan on beefing up your trans- the 455 will bolt up to it,  but anything built for a 350P isn't strong enough to handle the torque of a hi-po 455, at least not for long.


Offline Angelo

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It's essentially a refurbished stock motor, most likely reusing parts that pass visual inspection. If you plan on running it beyond stock, I would not waste your time on refurbished short block. More than likely you will still need to pull it apart and put a modern rear seal on it, either a Viton 2 piece or a BestGasket "graphtite" rope seal so it doesn't leak.

Depending on the year 350P you have, your flywheel may not line up, I think either 75 or 76+ they changed the size of the register for the flywheel on the crankshaft. You will have this problem no matter what, a good engine builder is going to use a crank that has the more popular (older) flywheel register size.
81' ex-Turbo Trans Am - Resto-mod

Offline raypfaff

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Geno and Angelo thanks for the replies. I heeded your warnings and placed and call to pull up more information. After speaking with one of their reps I confirmed they replace the harmonic balancer and flex blade. They also replace the rear seal. He said all internal components going in are new. The pistons and rods are cast but are all new from Keith Black and are silicon treated. He said he believes if I made the request upon ordering they could probably get forged ones for me instead. They stick with cast to remanufacture the specs to as close to OEM as possible while still modernizing as much as possible. He gave the example of the silicon treatment and using hard seals for modern gas. Their warranty covers labor up to $1,200 in labor and they pick up shipping cost if you go with their premium warranty for a minimal difference in cost. They seem on the up and up. 

The cam they use is an Elgin E980P with specs of
Lift: .444/.466
Duration: 288/298
Duration @ .050": 214/224
Lobe Separation: 112 LC

They have other options upon request, not sure if those would be ideal specs for looking to use the 455 and maintain a certain level of street ability. Thought you guys might have thoughts about that.

As far as my trans goes I had the shop confirm it as the original so it was designed for the power of the 400. Do you think its best to replace or could it be modified to better suit a 455?

You guys are great! Thanks for everything thus far.

Offline 73Formula

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Hey there, I just got a rebuilt 400 from them. (Long block) I sprung for the 7 year warranty- The motor will go in the car in the next month or so. Right now, I just want reliability - plus I am having AC installed on my car. The shipping isn't a huge issue because they have a deal worked out with a shipping company- it cost 150 bucks to have my motor delivered from them to me here in Miami. I will let you know how it goes- I got the cam upgrade, plus I had them put in Clevite bearings, as this was recommended by my shop. (TA Specialties) Any questions. just ask :)

Offline Angelo

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That Elgin E980P cam sounds exactly like my Crower 60918 cam. Similar to the 068 HO cam with a lot more lift.

81' ex-Turbo Trans Am - Resto-mod