You'll find that your carb issue gets better now with more timing. Do yourself a favor, if you dont have a dial-back timing light, put a tape on the balancer and set it to give you 40 degrees total mechanical advance. Thats alot for a rat, but not for a low VE mismatched one. It will LOVE it. If the 40 is coming in north of 4000 rpm, you'll want to put somewhat lighter springs on the advance weights to get that to 3000( eg, if you buy a Mr. Gasket spring kit, use the heaviest ones first - the light ones will be too light). This will be a major change in driveability.

 

Thanks guys. Advanced timing as suggested by Beaumont. Major improvement. More to follow....

 

The 750 is not to big. You want the air flow but less fuel, you need to jet it down. Can you find out what cam the guy put in it? Other things are, check your dist to make sure it is working correct. The springs could be to strong and not letting the advance come soon enough like Mike F said. It could be frozen or tight and not moving like it should. Is the vacuum advance pod working? It sounds like the carb is to rich and the timing is to retarded. I think if you put the 750 back on lean it up and advance the timing it will wake up. Also make sure that your balancer has not spun on the rubber hub. If it has your timing mark will be off.

 

Try bringing the advance in much sooner. A low compression motor with too much cam can really be helped by bringing the centrifugal advance in very early. I have run them with full advance as low as 1500rpm and had good results.

 

No its not factory specs on the timing, but many guys find lots of initial timing works well with bigger cams. Check what the casting number is on the heads while the cover is off.

 

Of course you do realize if it is stock 8.5/1 CR with a big cam, one of those 177/174 mini blowers will pretty much take care of business

 

Guys - thanks for the input. BBB, is that factory spec on the timing? FYI, I pulled the covers and evrything looks good - no lagging rockers,etc. The motor is strong like I said over 2800 and appears in good order. I'm thinking it's just a matching problem - the last owner got all cam happy and didn't take into consideration the other stuff. Preliminary plan is to throw on a set of headers, 3K stall, go through the tranny (got a seal leak somewhere. if i'm dropping it might as well clean it up) and reset timing, etc. Doing compression check on Saturday to reconfirm no issues in the cylinders. If not, will proceed with plan. You guys think I might want to add a shift kit with the stall? Yeah I think I'm 16 again.

 

Florida,

Went through this with my 396, ended up putting earlier high compression heads on the motor, and a better exhaust and the car began to wake up. Will be going from 3.08 to 3.73 gears and a 3000 converter this year.

If your compression is stock 8.5-1 then you may have too much cam. A smaller cam will improve cranking compression and bottom end power. All depends on what you want. Also check your timing, 16-18 deg initial and 36-38 deg total by 3000 rpm is typical.

Do a search on 396 and 402 etc and you'll see lots of posts about this type of problem.

 

Biggest/easiest bang for your buck right now sounds like a 3000-3500 stall converter. If you feel the power kick in at 2800. Although, it may be over cammed as well, and rebuilding the engine to a proven combination would be the best in the long run.
My 2cents.

 

yeah, thats the only way to measure the cranking compression.

 

schurkey - not certain. Was told engine is 100% stock with exception of cam,intake,carb. After 33 years who knows. Can I measure it with a compression gauge?

 

DOn't have the numbers handy, but you would need to drop in the .300+ tall dome pistons in there. Look for the 396-375 pistons in the plus .030 or .060 size if you have to bore it to clean up the cylinders (which most likely you will want to do). Also, when you rebuild you can cut the deck as well as shave the heads to bring up the CR. First thing though, do as Schurkey suggested and get a reading on your cranking compression. For comparison, my 402 motor has 9.5/1CR and a hyd roller cam with 279/294 duration [230/242 @ .050, 113LSA installed at 108ICL]. Cranking compression is 165PSI. With 3000 stall converter I can literally boil the tires off the rims out of the hole if I wanted.

 

What is your cranking compression?

 

Stall converter is stock. Sounds like you guys think the cam is too big..? Would swapping the converter improve performance?

GRN69 - school me if you would. You say go to 10:1. Can I achieve that with the stock heads?

 

If the car is all original you should have 8.5/1 CR, about 1600-1800 stall and 3.31 gear. I would strongly consider a much smaller cam for starters. Even with the tight converter and 3.31 gears, an 8.5/1 402 motor will still spin the tires out of the hole. If you do decide to rebuild, you will get a major power increase by pumping the compression up to around 10/1 and reinstall with 2400 - 3000 converter.

 

You didn't mention what converter it has...I believe if the stall of the converter is too low for the cam the engine will feel doggy until you hit the cams power band.