LoganMiller68

Hey Guys, some of you have seen my other post I posted recently. I didn't want to hijack that thread into an engine build thread since it was under general discussion.

I'll have my G block out and on a stand this winter and I know it's not a racing motor and never will be, but while it's out on the stand is there some things I can do to it make it perform better and make it a little more stable? Possibly solve some of the problems that plague these things?

P.S. I want to keep the 400 if I can because it is #s Matching.

chadman

What are your end goals? If you just want a cruiser then a stock rebuild with a nice little cam will suffice. If you are looking to make it a real street bruiser you would be better off setting the original 400 aside and replacing it with a built 455. This way you can keep it out of harms way in case you ever want to go totally original. Also the 455 is much easier to make power with not only due to the extra 55 inches but mainly due to it's bore size. The 400 G's have such a small bore it's tough to make alot of power with them.

Run to Rund

The G has a 3.87" bore vs. the 455 at 4.125. Otherwise the 455s tricks work on a 400. Have a good shop sonic test the bore thicknesses a number of places and thn either get custom pistons or find something standard that you can use with as much overbore as is safe. CP can custom make pistons for it, for example.

cutlassefi

No need for custom pistons. If you're just looking for a mild performance build and want to keep the original block in there then you can use readily available BB Olds 7.00" rod along with a Keith Black Icon SB Mopar piston and you're there. They're available in sizes starting at 3.910. Plus they're lighter, stronger, have better ring packs, uses the .984 pin which is also lighter than the stock Olds .980 pin, and are available off the shelf. This along with a good cam and tune and you'll see a noticeable difference.

gearheads78

This would be my exact thoughts.

LoganMiller68

Thank's for the advice guys. My end goal is just a nice street-rod motor. I don't really want to pay to completely over-haul a 455 block that I find. My 400 was just rebuilt last year. That's why I was thinking a cheaper approach with just adding/doing some things to the 400.

allyolds68

I wish I could find a link to Chili's 400G build on ROP but I don't see it. He's got it tweaked for the street with EFI. He'd also be the first one to tell you to dump the 400 and get a 455.

You've already committed to it. There's nothing you can really do to tweak it other than the basics.

I can tell you I've missed a couple shifts in my 455 that I don't think the 400 would have survived.

cutlassefi

Why? It's the same crank and rods, and both use cast pistons from the factory, so.....?

LoganMiller68

Well let me ask you guys this. What do you think a fair price would be for a 455 complete motor that I could rebuild off of? And what kind of money could I expect to spend on a project like building a 455 street motor

allyolds68

Mark,

I understand your point and it's a valid one. I think I'd be pushing the 400 a little harder to get the same performance I'm happy with in my 455. I'll be honest, I've never even driven a 400G to compare them.

I had both a 400G and a 455 block and I chose to build the 455. The 400G was not the matching engine for my car. I still have the block stuffed in a corner.

Just as a side note, both times I missed a shift (3rd) I cramped my right calf just as I was about to shift so I didn't let off when I dumped the clutch. I've got sciatica that causes it and it pisses my off. After it happened the first time I kind of watch out for it now. I can't tell the calf is cramped until it's too late...

droptopron

If your engine was redone last year do you know what was done to the heads? if redone stock some power can be found in some head work and a cam change. if you have the specs of what you have now you can get some more insight as to what you can do.

droptopron

Are you running a rev limiter on it? I have a Crane XR-i points conversion & it has one built in. I have an automatic but it is cheap insurance.

I am embarrassed to say but last weekend I was on my car and went to shift from 2nd to drive & threw it in neutral

allyolds68

Ron,

I've only had this completed for a year and it was on a tight budget for the entire process. I'm running everything in the ignition stock. In fact most everything except the carb and intake is from the 70 motor I bought. It was bored .030 over so it has new pistons. I try to do a little each year so maybe next year I'll sell enough spare parts to get out from the points and go to an HEI set up

LoganMiller68

Everything is to stock specs, including cam. I have C heads that are stock as well. A 750 cfm holley carb, which i'm going to replace. And an aftermarket Edelbrock intake manifold

Stevec

I recently pulled my 400 g block (80000 miles) due to bad valve guides. I decided to pull it because I got a severe case of the MAW's ya know MIGHT AS WELL! I changed the cylinder heads to large valve C heads
Roller cam and lifters
Timing chain
New oil pump
750 cfm carb
All new gaskets
Harland sharp roller rockers
2200-2400 stall converter
The car runs great smoked a 66gto,69gto and 71 chevelle and then lined up against my buddies 65 442 with a 455 and let me tell ya that 65 chewed me up and spit me out! I was just totally out matched from start to finish.

I am now in the process of acquiring parts for my new 455 build. The g block 400 just doesn't get it done mine is # matching so I'm going to pull it again and do a 455. If you want a nice stout street machine just build a 455....

LoganMiller68

Ha, wow. Well I guess if I'm going to spend the money MAW do a 455 lol

allyolds68

You asked how much. I spent $3500 for a stock rebuilt and the core engine cost me $400. You can probably get it done for less in an area where labor isn't so high. I had mine done in the Boston area.

LoganMiller68

Thanks so much for the info guys! Now it's time to just roll up my sleeves and get started.

I will make sure to post more as my project gets started

amesolds

Had to write to let you know that if you stick to your original plan, you can make a decent street machine with your 400G THAT IS A BLAST TO DRIVE. I pulled the 400 out of my '69 442 4-speed to do some upgrades. It is a .030 over block with a stock crank and rods, with Polydyne coated bearings. Did a mild clean-up of the bowls and a 3 angle valve job on the C heads. Blocked, but did not fill the crossover. Ported the stock cast iron intake. Jetted Q-jet up one size from stock. Running HEI from a '75 442. Added a 217/228 @ .050 Bullet cam (.485 lift I think) and Rhoads lifters. 3.23 rear axle ratio. Exhaust flows through the stock exhaust manifolds and Magnaflow mufflers. I run a high pressure oil pump, Amsoil, and beat on it any chance I can. At our last BOP shootout, it ran the quarter in 15.05 , the same as a friends' stock '70 455 powered 442 convertible with 3.08 rear gears and a Turbo 400. The suspension is stock and my 60 foot times are not great working the clutch, but I showed it could run with a larger engined car.

drjr56

Had the correct 400 in my 69 442.I had it rebuilt in the 90's,and used a HIT-282 CAM 226/234 and 491/518 lift,had a 3 angle valve job,with bowls cleaned up C heads,an HEI with an MSD 6al box,hedman headers,373 posi,2200 stall speed. Without beating the hell out of it because it was my ride home the car went high 13's @ 100 mph through the exhaust...This motor has never given me any trouble,would shift @ 5400rpm's,car has a 400 turbo trans with shift kit... also QJ Carb stage 2 rebuild by the original carburator shop...

LoganMiller68

Awesome! Thanks for the info!

Carsick

I am going to rebuild my 400G with C heads out of my 69 442.
Whats a good cam to go with ?
Im thinking of going with an aftermarket intake and possibly a carb but i want to keep the heads. What can i do to the stock heads to make them breath a little easier? Port polish?
Pistons?
Rods?

Im tempted to drop the 2k for a 471 stroker kit...or fk it and pick up the 512 stroker kit...

BangScreech4-4-2

Do a 100% stock rebuild on the numbers-matching G-block. Then put it on a stand in your garage, drop in the 512 stroker and have some fun.

Carsick

I think a well built 470 is the way to go. Ive been reading that the 512 kit uses really short piston skirts. My 65 Chrysler has a 440 and i love it..

Are the stock C heads any good?

If I went with the 470 kit with my C heads what would be a good Cam to go with? Rockers? Im thinking ill go with a hydr roller cam with around a .550 lift ...?

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Oldsragger

Do you know how much Hp and torque you got out of this 400g engine with this setup?

Stevec

I never had it on a dyno but if I had to guess it was prob 360-375 hp and maybe 450tq made 425 tq stock. It went pretty good till I spun a rod bearing.

BangScreech4-4-2

Factory rating was 440 lb-ft.

Stevec

It was a low compression 400 g, the car is a 68 turnpike cruiser 290hp/425tq.

Oldsragger

Oh, do you know on what rpm it has on 440lb-ft on stock and compression?

hm mine 69 407g block have 438,1lb-ft in 3750rpm, after rebuild and some porting heads and valvejob, and 381,1hp on 5000rpm with 750 edelbrock carb and 2151 performer intake, im not sure what compression it has yet, its 0.30" over stock and new pistons etc, but i can see they are not flat headed pistons. My tought was if the edelbrock intake that steals some torque vs the Iron intake maybe? Hmm

BangScreech4-4-2

Standard 4 bbl: 10.5 CR, 350 hp @ 4800 (325 hp with AT), 440 lb-ft TQ @ 3200.


W30: 10.5 CR, 360 hp @5400, 440 lb-ft TQ @ 3600.


Turnpike Cruiser (2 bbl): 9.0 CR, 290 hp @ 4600, 425 lb-ft TQ @ 2400 (Steve's car).


Coupla notes:


1) An engine rated for 440 lb-ft TQ by the factory is doing pretty well to dyno 438 lb-ft. The figure you got is about exactly what I'd expect.

2) Performance modifications won't "steal" torque, but they can certainly move it up the RPM scale (see W30 figures).

Oldsragger

Hmm,thats sound strange to me, how could it loose 2 lb-ft? And its 0.30" over from stock 400? (407) i have this results on the dynopaper, i think its only in motor and not Dyno on wheels. Unless the dyno shows wrong/less numbers then.

Cant wait to test the compression when i will crank it.

BangScreech4-4-2

Again, factory ratings are often optimistic, although torque is usually more reliably quoted than horsepower.

Oldsragger

Ah i understand what u mean now, ok so i will just be positive cause of the resaults then i guess.