Thread: 400 cid sbc timing/heads/carb

Tweet

okay i am a converted ford man , all i know about engines is sb ford. i have alot of questions about chevy sb engines. 1. i have a 400 cid in a 67 nova the timing seems to be advanced alot -maybe for the cam and large carb-but i don't have the typical setup on the distributor tower- no 3 & 4 facing front of motor-how is this possible? is there an old hot rod trick for relocating the distributor? 2.i have stock heads on the 400 now -what is a good choice head for this motor and i know i have to drill steam holes-how involved is this?3. the carb i have is a holley 12r10656 i'm not sure of the cfm but i think it is too much for this motor -any help would be appreciated.
any suggestions on the 400 cid set up (keep it driveable) would be helpful

wow- ok, Cheby's fire 18436572, and the dist. turns clockwise. I put # 1 facing #1 cyl. which is if your facing the engine- right side front.
As your facing the engine : 1,3,5,7, are on your right
: 2,4,6,8, are on your left
front to rear as numbered above.

You don't know what cam you are running makes it tough to make any suggestions to help you.
You not knowing the compression ratio same.

Brodix makes a good head for racing & street

Starter carb size formula I use is : cid x max rated rpm devided by 3456 = cfm.
Again, without the cam spec.'s it's going to be tough to use that one. I would only assume that the max rpm would be 7k, but read your plugs after you run it for 20 min.'s at normal useage to check for lean burn.
Good Luck

I used Vortec heads with dished pistons on my 406 with good result. Your choice will be driven by the type piston you have to keep the compression ratio within reason.

Three of the steam holes in the head have to be drilled at an angle. I just had the machine shop do it for $30.

I used an Edelbrock 750. I first tried a vacuum secondary Holley, but I couldn't get it to run correctly.

yeah- the plug wires do go to the correct cylinder as far as odd on right begining at #1 but the plug tower idoes not start withthe usual wire in front kind of hard to imagine but #3,#4 wires are in front - anyways the distributor works good so i guess there was some voodoo performed.
should the cam spec or any thing to identify it be visible on the front behind the timing gear?
I backed the timing off some and gained more power but the engine seems to run warmer but not overheating am i getting into the danger zone? i am kind of thinking the timing was advanced this much to keep up with fuel flow from the big carb on what i think is a stock motor (except the cam). as far as the carb i perfer edelbrock over holly also, so i am thinking of trying my 600 cfm off my f100 and see what that does.
thanks for all the info
a little about myself if you care to read-i am a louisiana boy,been around the world(usmc),and love old autos, i have 65 f 100 swb stepside with 302 great driver,67 nova 400 cid, 77 280z & 79 280zx stock- junky little cars but they do haul ass.

Originally posted by nasty nova
yeah- the plug wires do go to the correct cylinder as far as odd on right begining at #1 but the plug tower idoes not start withthe usual wire in front kind of hard to imagine but #3,#4 wires are in front - anyways the distributor works good so i guess there was some voodoo performed.
should the cam spec or any thing to identify it be visible on the front behind the timing gear?
I backed the timing off some and gained more power but the engine seems to run warmer but not overheating am i getting into the danger zone? i am kind of thinking the timing was advanced this much to keep up with fuel flow from the big carb on what i think is a stock motor (except the cam). as far as the carb i perfer edelbrock over holly also, so i am thinking of trying my 600 cfm off my f100 and see what that does.
thanks for all the info
a little about myself if you care to read-i am a louisiana boy,been around the world(usmc),and love old autos, i have 65 f 100 swb stepside with 302 great driver,67 nova 400 cid, 77 280z & 79 280zx stock- junky little cars but they do haul ass.

1. CAP AND WIRES---It doesn't matter which wires face where. That does not start the firing order. #1 wire pointed to #1 cylinder is a reference point only. It does make it easier to set timing and route wires though.
2. CAMSHAFT IDENTIFICATION---Unfortunately, the cam grind no. is on the back end of the cam and has to be pulled to see it.
3. BACKING OFF TIMING---Backing off timing should make it run cooler if anything. Advancing the timing will have a limited effect on a overcarbed engine. The exhaust will still burn your eyes and the plugs will foul if its rich. I don't know what size carb you have but a stock 400 will handle a 750 vac. sec. with ease.
4. HEADS---The 400 is a big small block. 200cc runner Dart or 190/195 runner AFR is a good all around choice for street/performance.

You would learn a lot from doing a cranking compression test on your engine. Just unhook your hot wire from the distributor and pull a couple plugs and check compression. If you have less than 150 psi your either overcammed or worn out. JMO JMO A properly set up street engine can run 200+ psi on 93 octane but you got to have your parts lined up right.

I would look into heads that have a port volume of around 170 cc.If you go much larger than that on the heads you will have to twist your engine a lot of r.p.m.'s. to really make the heads work right.If you plan on changing the cam out I would look for a cam that has less than 220 of duration at .050.

thanks for the good info i have more questions
i have a th350 trans , was wanting to go with overdrive 700r4-will it bolt right up to the 400 cid?will i have to change/modify my driveshaft?already did this in a 280z and it was not fun!!!
also i am putting on disc brakes ordered from ccp(classic performance parts) in socal, has anyone used this vendors setup and how well does it work?
last question for today- headlights- i like the looks of the headlights in the lowrider style impalas(not clear glass but reflective chrome sleeper look) does anyone know where i can get these lights for my 67 nova?

hey ray - seems you have learned from hands on and that is the best way
i am not really sure my engine came to temp any faster or ran any different temp because at the time i was not really paying attention, but i do feel i have gained power when i brought the timing back into the 8 degree btdc range which is close to stock. before i moved the timing it was pretty much vertical(center of the engine)when shooting with my light. originally the mark was not even close to the pointer-what is your opinion on this?