Jump to content
73DATSON

Big Cam????

Recommended Posts

Ok I got a big cam 592, I’m also running 45mm dual side drafts and headers, But the car is losing power over 4000 RPM????? If I push it it’s like chokes, no popping just chokes. I need to let go of the gas pedal and then push on it slow, then it can creep over the 4000RPM. 

Edited by 73DATSON
Got answer for the first post already.

Share this post


Link to post

Big Cam dont mean anything to me. Lets get to the real meaning. Was this running ok before or is this a new set up your trying to get right.

Too me a 592 isnt near a street driving cam unless you got a real low gear ratio.

 

open the toppf the carb plate and see if the jets backed off out of their holders. Make sure its screwed down.

 

then put your finger in the funnel and make sure its not loose and wiggleing.

 

 

also make sure the choke plate is open

 

next check your distributor timming.

  • Like 1

Share this post


Link to post

What was the old set up?

 

If you did it once before you can do it again.

YOu just removed the head and install different head? make sure the timming on cam is correct and I guess to hope the carbs you got are goodif used)

was oil pump removed and installed off a tooth?

 

spark plug wires on correctly and not out of order. Rocker arm lash set correctly.

  • Like 1

Share this post


Link to post

I’m trying to post the pictures. I hope the pictures comes out?  But yes the carbs are brand new from   Percy manifold in California. I’ve check the timing with a timing light. 

https://share.icloud.com/photos/0JbBbcFS0jvUdU1g16umIXBYA#Home

 

https://share.icloud.com/photos/0DEccNLejBp1HJlz3BbaXiKVg#Home

 

https://share.icloud.com/photos/0DL_TMj5BXQpObRHoHlGw9wew#Home

Share this post


Link to post

The cam gear v notch is inline with the dash on the cam. My dizzy is line up to 11:28. Wires are in order. 

Share this post


Link to post

https://www.icloud.com/photos/#0DL_TMj5BXQpObRHoHlGw9wew

 

Could be the bad angle but this doesn't look lined up on the 0.

 

If it is lined up, the ignition and the cam timing are good enough to run.... if the valve lash is checked and the timing set  This leaves the carbs.

 

 

 

Are the carbs new.... by new I mean untried. Because that's a lot of area to cover right there.

 

Float height set?

Mechanical pump?

Change the fuel filter.

 

 

  • Like 1

Share this post


Link to post
33 minutes ago, datzenmike said:

https://www.icloud.com/photos/#0DL_TMj5BXQpObRHoHlGw9wew

 

Could be the bad angle but this doesn't look lined up on the 0.

 

If it is lined up, the ignition and the cam timing are good enough to run.... if the valve lash is checked and the timing set  This leaves the carbs.

 

 

 

Are the carbs new.... by new I mean untried. Because that's a lot of area to cover right there.

 

Float height set?

Mechanical pump?

Change the fuel filter.

 

Carbs are brand new  straight off the shelves 

 

Share this post


Link to post

If brand new off the shelf my guess is the jetting is not correct for your motor... 

Were they rejetted for your engine?

Are these webers? 

What fuel pressure are you running?

Also did you vacuum balance the carbs and set the air/fuel screw?

Not sure how much you have done to them, or did you just bolt them on?

 

I'm currently dealing with rejetting and tuning my single 40dcoe.... what I'm finding is every motor is different, so you might be close but because of your cam you need slightly different jets... so if trying to tune by yourself I would invest in a wideband o2 sensor and gauge or try find a dyno shop to help, preferably one that has jets and stuff available.... or you'll spend a bunch just trying different combinations to see what works....

 

 

Share this post


Link to post

If the distributor was removed and not installed correctly like off a tooth. it will still run if one has it cranked to one side to get running then once running and you gas it it will go out of time,

One way to kinda catch this if installed and the crank is lined up to ZERO you install the distributor in its center spot on the timming plate and the rotor pointds inbetween say plug wire 1 and 3 you know your way off.

 

as for the carbs if new I would say its most likely fine as I have always just bolted carbs on from DGVs to Mikunis40s and never had to jet them and they run fine . There is a basic basleine setting.

 

if your sure you got it right ask yourself what part is new. If from Pierce manifold then I assume new

 

If webers you need to know the baseline setting and fine what you need but I never understood the Weber numbers as they are not incremental when they mage them if I understand correctly how they did it back in the day

 

As for Crashd. I would scrap the single DECOE plan and go 2 carbs as its ezer set up. I alwasy seen more not running correctly with a single sidedraft. get2

 

 

Edited by banzai510(hainz)

Share this post


Link to post
31 minutes ago, banzai510(hainz) said:

 

As for Crashd. I would scrap the single DECOE plan and go 2 carbs as its ezer set up. I alwasy seen more not running correctly with a single sidedraft. get2

 

 

Not trying to post about my setup here but honestly I'm not having that much of an issue with my single side draft to say I need to add a second carb, that's just more money.

I think the biggest issue comes from the intake people run.... I do see alot who complain about their setup on the

cannon intakes.... those intakes pair 1/2, and 3/4.... I am running a lynx intake which seems to make the difference, they pair 2/3, and 1/4 ... something about the induction pulses.... everytime I check my plugs I have a consistent color across all 4... 

 

And yes I'm sure you can just bolt carbs on and run but if you want them right it takes some work.... not every engine is built the same.... if you had 4 l20b engines all built for different applications how could the same carbs be correct on all 4 engines..

Share this post


Link to post

Stock motors don't love dual side draft carbs. Even with a cam, you're likely going to have to spend a good amount of time tuning the carbs. The three basic functions of the carb that will need to be set are the choke or venturi size, the idle jets, and the air/fuel jets. There are also different pump nozzle sizes that can affect throttle response.  Webers have adjustable accelerator pumps which can make things even more confusing.

 

If this is your first rodeo with dual carbs, you may want to employ the help of a good tuning shop that is familiar with old cars. Being on the east coast, it shouldn't be hard to find a shop familiar with European cars like Alfa Romeos, etc.

 

Cam timing is uber important too and if you haven't degreed the cam, you may want to learn how to do that too. You can use the typical degree wheel method or the split overlap method. Both will require a dial indicator on an adjustable arm, but only the degree wheel method requires removing the crank pulley and setting up a degree wheel.

 

Not what you wanted to hear? Welcome to the world of high performance.

  • Like 2

Share this post


Link to post

This wkend I’ll hit it up again. I’ll play with the dizzy and check it a missing tooth? May old setup was a u67 head with 40mm dual side drafts Weber’s. It ran ok it was a lil too rich but I didn’t care cause the car might get 1000miles in a year. I’ve have a kit of jets and air corrector that I’ve been playing with.  I always play with cars so this is no bother for me. Gets me out the house on wkends. But I’ll keep everyone updated. Thx!!!!! For the inputs.  

Share this post


Link to post

if you put a timming light on the crank at idle are you having to put the dist in FULLY to one side side to say get 10-12deg BTDC. ???? try loosen the 8mm bolt on bottom side of the dist to recenter the timming plate. Or one can just remove the timming dist bolt and dial it to say 10-12degBTC and see if runs better by hitting the gas and see if the response is better or put a minni C clamp on there and drive it.

 

be hones one might need around 14 deg as My English 510 book with SUs said 14degBTDC for timming

 

Be honst I think 40mm carbs are best for the street, But my 44s on my other 510 I sold was OK also. but was geared lower

 

I really dont think your going to see a huge increase in power. Matter of fact you might be going backwards.

Share this post


Link to post

i Love the sound of the high cam! The car runs strong till it hits 4000rpm. I can spin the wheels in 3rd gear no problem.  like I said before this car is a once a month wkend car, I just want to have the power to pull in when I’m merge in a on-ramp.  Not looking to have a race with the local imports. But looking at my picture of the dizzy I think it might be off a tooth like u said??? I have a picture from someone that shows there top of there rod pass the Screw threads. 

https://share.icloud.com/photos/0COXG5Fkq4qJ4-14prczCDFjA

check our the picture.  Compare it to my ?  What you think?

Share this post


Link to post

I cant see your photos.

just do the timming like thing and youll know for sure.

Most times one can get the timming  youll see you can retard the motor to Zero and up past 25 deg by turing the dist then youl know your correct.

 

 

just remember most basic distributors start to cut out at 7 k anyways just due to slop in system and worn out so haveing a huge cam (590 is huge)and carbs might in effect be the best application. Keyon this is duration also.

But IM not a true expert on here I just know what I have seen work .  I have a 460/260 Schneider cam in my 521 and it shoulf have come stock in a L motor in my opinion

Edited by banzai510(hainz)

Share this post


Link to post
46 minutes ago, banzai510(hainz) said:

I cant see your photos.

just do the timming like thing and youll know for sure.

Most times one can get the timming  youll see you can retard the motor to Zero and up past 25 deg by turing the dist then youl know your correct.

 

 

just remember most basic distributors start to cut out at 7 k anyways just due to slop in system and worn out so haveing a huge cam (590 is huge)and carbs might in effect be the best application. Keyon this is duration also.

But IM not a true expert on here I just know what I have seen work .  I have a 460/260 Schneider cam in my 521 and it shoulf have come stock in a L motor in my opinion

Got u. I’ll try it. 

Share this post


Link to post

Who makes this '592' cam and what are the specs for it?

Share this post


Link to post

To make life easier. ... 

Screenshot_20181002-175131_Chrome.jpg

 

It's from Schneider cam but numbers look the same.... it's the biggest grind they do....

Who did the regrind?

Share this post


Link to post
5 minutes ago, Crashtd420 said:

To make life easier. ... 

Screenshot_20181002-175131_Chrome.jpg

 

It's from Schneider cam but numbers look the same.... it's the biggest grind they do....

Who did the regrind?

I’ve got this peanut head  and cam from Allen California Datsun

Share this post


Link to post

California Datsun???? ?

 

Measure the across the highest and the narrowest part of the cam lobe and subtract. Multiply this by 1.48 and that is the theoretical valve lift with zero lash.  O.592" is insanely high. Stock L20B is 0.413".

 

 

 

On 10/1/2018 at 12:38 PM, 73DATSON said:

I’ve pick up a peanut head and install the cam. 

 

Hopefully it has the correct lash pads and the wipe pattern is centered on the rocker. You'll need some stiff valve springs to follow that lobe... your stock L series springs will stack around 0.480", in fact maybe your valves are floating at 4K.

 

I would have kept the U67 head for better breathing.

Share this post


Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.