Chevy 350 or Pontiac 400

[hotrod_chevyz]

I need some opinions on what i should do next to my firebird. The motor in it is wasted now and i have to either rebuild the 350 block i have been sitting on, or put a 400 Pontiac engine and transmission i have already rebuilt in it.

Choice 1. Chevy 350.

The 350 is a T1027CKJ 3970014 block. 70-72 chevelle, monte carlo..ect block. The heads i would have to go with on it are a very clean very surfaced pair of 333882's. The pistons i have are forged flats at .040. A Competition 280 duration cam would be cleaned up and put in it. It would have a torker II intake with a carter AFB on it. VA HEI distributor, and a fresh 350 trans with a transgo shift it .It would run fairly stout and average around 10MPG. I have all the parts for it ready to go except the actual rebuild kit and new head bolts.

Choice 2: the Pontiac 400

The 400 would be coming straight out of the 72 Catalina transmission and all. The engine is a 30 over rebuilt by horton. It has around 30,000 miles on it now. The transmission was rebuilt at the same time the motor was. The heads have been surfaced twice wich added some compression, and the heads are 2.11-1.77's. The cam is stock and it has a 2 barrel carb. It averages around 17MPG in the Catalina. I have everything i need except a oil filter relocator and a few other minor things to put it under my hood and call it a day.

The gas milage is what makes one side of me want to put the 400 in it. I know how it runs with the 350 in it. Wich is great and all but the gas bill is high, i have to do somthing about the 10MPG, WITHOUT losing power.

question 1:

What would I have to do to the 400 without rebuilding it, in order to match the performance of the 350 if i put it together?

question 2:

Could it be possible the 400 will run as good as the 350 without any modifications, considering the entire car weight is 3,200 pounds with driver?

question 3:

Would the 400's gas mileage be as bad as the 350, by the time i was done trying to make it run as good as the 350 did?

question 4:

wich one will be faster.

Ive been stuck on this decision, waiting for the motor in it now to finish blowing up. Its time to decide I need to hear some opinions on this. I have the funds to do either engine i pick, but im not really sure what im going to do. Wichever way i go it has to be done by the end of next month.

[76ta]

the 400 will kill the 350 with torque.. also if its a pontiac block its the same size as a big block chevy, so it will weigh a considerable amount more then a chev 350, if ur car is a 350 car, the suspension may not be able to handle all that extra weight

[79Bandit]

and the 400 gas milage is not much better if you put a 4 barrel on wich i would imagine you would....i only get about 9 mpg...

[hotrod_chevyz]

Really they dont weigh a whole lot more and i plan on updating the front springs. An old AF member i talked to a time ago had one in his. He said the only reason he had to go back chevy is because the fan or somthing. Clearing the hood with the fan and alternator is the biggest pain of them all. I plan on relocating the oil filter to the firewall and fabricating brackets for the altenator to fit under the hood. The only hole i will have to cut is for the air cleaner to stick up out of the hood cause the engine is so tall. All electric fan will have to be used, no biggie it already has one.

The catalinas dual exhaust will drop in perfect. The exhaust will have a cross over just behind the transmission and the tubes will end up just in front of the rear springs, perfect. I want the crossover closer to the block but i will take what i can get, exhaust on these things is a trip. No mufflers involved just straight pipe duals, using stock cast iron manifolds.Thats all that will fit really. I have to get it about 3 inches higher in front so i dont mash up the exhaust tubing. That will actually sit the car back level, after i was done beefing up the rear suspension, it sits so high in back most of what you see out the back window is the factory spoiler. The entire front end has just been rebuilt so the stress on the car isnt of much concern. Im more worried about tweaking the body out of alignment.

Really I had planned on leaving it two barrel. I figure if the 400 gets 17MPG HWY AVG in a catalina, then a car a thousand pounds lighter might do even better. I just want to drive the T/A again. The 10MPG problem has turned it into a lawn ornament. Im in the crown vic all the time now cause it gets 17+ MPG HWY AVG.

I just want to make sure that if i go ahead with the 400, im not going to lose a bunch of power . If i have to get a high lift cam and 4 barrel for the 400 to hang with the 350, then im back to where i started. With a 10mpg lawn ornament.

[79Bandit]

also i was just thinking a chevy 350 is a very often used engine the parts are easier to find and probaly cheaper soo if money plays a role then hands down 350

[maxwedge]

Originally Posted by hotrod_chevyz

Really they dont weigh a whole lot more and i plan on updating the front springs. An old AF member i talked to a time ago had one in his. He said the only reason he had to go back chevy is because the fan or somthing. Clearing the hood with the fan and alternator is the biggest pain of them all. I plan on relocating the oil filter to the firewall and fabricating brackets for the altenator to fit under the hood. The only hole i will have to cut is for the air cleaner to stick up out of the hood cause the engine is so tall. All electric fan will have to be used, no biggie it already has one.

The catalinas dual exhaust will drop in perfect. The exhaust will have a cross over just behind the transmission and the tubes will end up just in front of the rear springs, perfect. I want the crossover closer to the block but i will take what i can get, exhaust on these things is a trip. No mufflers involved just straight pipe duals, using stock cast iron manifolds.Thats all that will fit really. I have to get it about 3 inches higher in front so i dont mash up the exhaust tubing. That will actually sit the car back level, after i was done beefing up the rear suspension, it sits so high in back most of what you see out the back window is the factory spoiler. The entire front end has just been rebuilt so the stress on the car isnt of much concern. Im more worried about tweaking the body out of alignment.

Really I had planned on leaving it two barrel. I figure if the 400 gets 17MPG HWY AVG in a catalina, then a car a thousand pounds lighter might do even better. I just want to drive the T/A again. The 10MPG problem has turned it into a lawn ornament. Im in the crown vic all the time now cause it gets 17+ MPG HWY AVG.

I just want to make sure that if i go ahead with the 400, im not going to lose a bunch of power . If i have to get a high lift cam and 4 barrel for the 400 to hang with the 350, then im back to where i started. With a 10mpg lawn ornament.

Great article in Hot Rod mag about a Pontiac 400 build up in stages.

[hotrod_chevyz]

Im not worried about the money of it. Im hoping that a mild 400 will end up as fun to drive as a built 350. I may not have to take it to far cause its a fairly light car .I want to avoid having to further reinforce the unibody wich a tweaked out 400 would require. And i dont want to twist the car up so the 400 cant be too radical. Really it shouldnt have to be.

The 350 cam i have now stacks extra power at high rpm but really kinda kills some of the bottom end. I think the engine it has in it now is dead because the cam expected more than the other hardware could take. If i stay mild and go with the 400 it might last a little longer than a modded out 350, while still ending up with with the same power.

The car has a 273 rear axle. If i cam the 400 just right i can keep the sweet spot somwhere in the middle like between 4000 and 5000 rpm's and still move the speedo around fairly quickly. I might be able to find a higher cfm 2 barrel carb to match a mild cam and still stay away from a 4 barrel . They do make some huge 2 barrels. I think if i let the low end torque of the 400 do its job and let the weight and aerodynamics of the car do its job it might run okay. Just hopin a mild 400 can match a wild 350. If it dont run mid thirteens its getting a cam and heads and more barrels even if it does eat gas.

I have however located a 1970 gto judge set of heads and intake as an emergency plan just in case i put the 400 in it and lose some get-up. A friend of mine who owns a shop has them and has had them for years. He wants 40 bucks for the intake and 300 bucks for the heads.

What did the 70 GTO's get on a 1/4 mile?

What would one get if it went on a major diet and lost 400 or more pounds?

[FormulaLT1]

If money isn't a concern I would go Pontiac motor but a 350 has a much larger aftermarket parts bin and parts are usually very affordable but the 400 has a nice aftermarket as well.

[MrPbody]

All things being equal, the 400 will STOMP the 350. This is not just an opinion. With the highway gears stated, the low-end torque of the Pontiac will make for a fun car to drive, reasonable on gas, and a top speed that would embarass any highway patrol car out there today... (:-

Much of what is said about the 350 Chevy is true. Parts are a bit cheaper. There is, however, no shortage of GOOD performance parts for the old Injun . If power and fuel economy are required, the Pontiac wins, hands down. The high-rev 350 will make very little low-end, as has already been stated.

Take a 400, throw in a Comp XE262H, Performer (or pre-'73 factory iron) intake, a well built Q-Jet, and 18-20 MPG is not out of the question, while delivering 250-275 RWHP. One must be careful when picking a combination.

Get Jim Hand's "How to Build Max-performance Pontiac V8s", and have many of the myths about Pontiacs dispelled. We have many out there going in the 10s on 93 octane. Many more, just cruising down the highway with that certain "look", like a karate expert, where they KNOW no one can do them harm...

Jim

[GTP Dad]

I have to agree with the 400 Pontiac over the 350. You can't beat cubes for power and the 400 will hold together just like the 350. Get yourself a 4 Barrel carb and you should have better mileage than with the 2 barrel since the front venturies are smaller and you have the secondaries if you need the extra power. Just be careful not to exceed the redline on the 400. They don't hold together very well if you go beyond it. A friend of mine had a 400 in a GTO quite a few years ago. It was quite strong and it was totally stock!

[79Bandit]

as for pricing my 400 block im rebuilding cost (after every part and screw ordered plus machine work) me about 5500 - 6000 buckaroos im sure you can build one for much cheaper put i went ahead and ordered all brand new chrome pulleys and pumps ect ect... i wanted to make sure it looks show quality the things that kill you on rebuilding an engine i have come to find are the things you cant do meaning the machining work...i got great deals on my machine work and i still cant belive it cost so much...but if you need some 400 engine parts i got just about all of them...

[MrPbody]

Bandit,

$6,000? That's a lot. That's the going rate for a complete 461 around 500 HP, not including the trinkets. Perhaps a little shopping is in order. Contrary to popular belief, Summit and Jeg's are NOT the only places to buy good parts. That's particularly true with non-small blocks.

Jim

[FormulaLT1]

PAW is like the best performance catalog out there. I hope you checked them out before purchasing anything Bandit.

[79Bandit]

Originally Posted by MrPbody

Bandit,

$6,000? That's a lot. That's the going rate for a complete 461 around 500 HP, not including the trinkets. Perhaps a little shopping is in order. Contrary to popular belief, Summit and Jeg's are NOT the only places to buy good parts. That's particularly true with non-small blocks.

Jim

hmm the cheapest i have seen them is 10.5k

[MrPbody]

You never asked me! There are more than two shops that build good Pontiacs. JBP and KRE are "high end" Pontiac shops. We're doing a 461 for a man in NC right now. The final bill, including "run-in" and SOME trinkets, is right at $6,400.

Jim