Jump to content

Updated: Carbs, Cams, Ignition, Etc... Geting The Mix Right.


jdeitch

Recommended Posts

I'm getting ready for a engine upgrade to Remy.  Your creative criticism and help would be greatly appreciated.

 

I'm currently running a weber 32/36 under a JAM adapter and stock air cleaner with the factory attached cold intake tube. I have a Bosch vacuum advance dizzy with a pertronix ignitor and blue coil. I have a Ireland ceramic coated shorty header mated to a dual down-pipe and factory exhaust system.  I rebuilt the head recently.  Stock piano-top pistons. (I assume stock C/R) This combination runs great and I'm going to keep all of the components in case I ever want to switch back.  ;)

 

I can no longer hold back the dual-carb itch... 

 

I have been doing considerable research here on the FAQ and the internet.  Like everyone else I'm trying to get the recipe right the first time.

 

I've purchased the carbs.  I decided to go with dual Dellorto DHLA 40.  Apparently very similar in design to the Weber, the Dellortos (Especially the later models A-H variants), purportedly are easier to tune, have better idle characteristics and transition better. Jets and such are also available in finer increments. (No flame please... This is what my research has told me.)

 

The carbs I bought are set up as follows: Any jetting comments and/or suggestions?

Main venturis (Chokes) 32

Main jets: 132

Air corrections: 180

Emulsion tubes: 7772.5

Idle jets: 45

Pump jets: 33

Stock 40mm velocity stacks.

 

post-39742-0-22491800-1376240777_thumb.jpost-39742-0-57398300-1376240804_thumb.j

 

Unless someone has a better suggestion, I am planning on  buying the Ireland intake manifold with Red-Line upper cross-bar linkage.

 

I am also researching a new dizzy.  Crank-fire would be cool but I'm trying to stay more 'period-correct' and use a old-fashioned dizzy.  I have upgraded to a CDI ignition in several of my other projects and it makes a dramatic difference.  I'm considering a custom Mallory Unilite dizzy like Fishhead or a MSD pro-billet modified by Terry Tinney. 6AL ignition box. Any thoughts/suggestions?

 

And the cam... SO many opinions. This is the one item for which I'm most uncertain.

 

At this point I think I will use a 292.  Not a regrind. Either a new Schrick or IE billet. I'm torn between the 292 and 284.  I don't want to lose the bottom end.  Anyone with a similar setup please chime in!

Link to comment
Share on other sites

I'm happy with my 284 Schrick...nice idle, still has good low end grunt (useful for a 5 speed conversion).  I'm running 9.5 pistons, a 32/36 Weber downdraft and a distributor that's curved for this setup. 

 

If you're going for dual sidedrafts, conventional wisdom seems to suggest a 292 cam to take advantage of those carbs, especially if you're using higher-than-stock compression pistons.

 

cheers

mike 

Link to comment
Share on other sites

I went from a stock cam (264) to a 292.  I noticed ZERO low end drop off during normal driving.  This actually surprised me as I was expecting it to be a dog, when actually now, I can dump the clutch and spin the tires.  I actually have done this many times on accident.  The only time I notice any difference is if I am in the wrong gear and am too lazy to downshift.  Then it will lug along and its slower to get into the powerband than a stock cam.  Easy solution, downshift and keep it in the powerband.  I have noticed considerably more punch at freeway speeds and above 4500 RPM.  For reference I have 9.5 pistons, a weber 38/38, Tii distributor with petronix, Ireland headers, 292 cam (Ireland), Ireland Header to a pretty much open exhaust.  My idle is a tad lumpy under 900 RPM, but I have my idle at 1000-1100 RPM and its pretty smooth.  The stock cam was smooth at 600 RPM.  I am going to a hotter spark setup (crane XR3000 and MSD blaster coil) and dual 40 sidedrafts soon.  

Link to comment
Share on other sites

I went from a stock cam (264) to a 292.  I noticed ZERO low end drop off during normal driving.  This actually surprised me as I was expecting it to be a dog, when actually now, I can dump the clutch and spin the tires.  I actually have done this many times on accident.  The only time I notice any difference is if I am in the wrong gear and am too lazy to downshift.  Then it will lug along and its slower to get into the powerband than a stock cam.  Easy solution, downshift and keep it in the powerband.  I have noticed considerably more punch at freeway speeds and above 4500 RPM.  For reference I have 9.5 pistons, a weber 38/38, Tii distributor with petronix, Ireland headers, 292 cam (Ireland), Ireland Header to a pretty much open exhaust.  My idle is a tad lumpy under 900 RPM, but I have my idle at 1000-1100 RPM and its pretty smooth.  The stock cam was smooth at 600 RPM.  I am going to a hotter spark setup (crane XR3000 and MSD blaster coil) and dual 40 sidedrafts soon.  

Thanks for the info!  Now if I could just find a IE 292 billet cam to purchase...

 

It seems no matter what I'm searching the FAQ for, I find a post from you.  Sounds like our cars will be very similar when/if I ever complete mine.  ;)

 

Hope to meet you at SoCal Vintage someday.

 

Cheers!

 

Jeffrey

 

PS Excellent website for your 2002!  (My blog here on the FAQ is slowly catching up to real-time.)

Link to comment
Share on other sites

Looks like a good build.  Where did you get your Dellortos?  I think they have not been produced for several years.

 

I recommend buying and reading one of the good books on tuning these carbs.  I know of (2):  HP Books Power tune series and CB Performance.  I had the CB book and it was very helpful with the downdraft 40's on my VW.  

Link to comment
Share on other sites

Hi Jeffrey , I just spotted you are using Dellorto carbs, I did have twin 40's but upped them to 45's

 

my recipe tuned with a wide band 02 sensor (highly recommended ) for the 45's is

  

36  Chokes

120 main jets

180  airs

50 idle jets

7580.1 holders

42 pump jets

7772.5 Emulsion tubes

 

292 Schneider cam , Tii disi with Pertronix, Crane Fireball HI6 ignition box, Crane LS92 coil, port matched 121 head. At the moment I am running with the stock 71 flat top piston bottom end. I am having a high compression, balanced & lightened block built to get the best out of my carbs & cam. I too use an IE stepped header. I love the performance now & still get 22 mpg. I run at Willow Springs big track too . Dellortos are my carb of choice, parts from Dellorto UK are quick & easy to deal with.

Link to comment
Share on other sites

Looks like a good build. Where did you get your Dellortos? I think they have not been produced for several years.

I recommend buying and reading one of the good books on tuning these carbs. I know of (2): HP Books Power tune series and CB Performance. I had the CB book and it was very helpful with the downdraft 40's on my VW.

Thanks for the comment/support. I believe I already have that HP Weber book.

After looking at numerous used (junk) carbs I found a nice used matched set (consecutive serial numbers). I added pics of the carbs to my original post.

The Alfa Romeo crowd is big into Dellortos. They were setup for a 2 liter engine so I hope I will be close on the jets, etc.

Link to comment
Share on other sites

Hi Jeffrey , I just spotted you are using Dellorto carbs, I did have twin 40's but upped them to 45's

my recipe tuned with a wide band 02 sensor (highly recommended ) for the 45's is

36 Chokes

120 main jets

180 airs

50 idle jets

7580.1 holders

42 pump jets

7772.5 Emulsion tubes

292 Schneider cam , Tii disi with Pertronix, Crane Fireball HI6 ignition box, Crane LS92 coil, port matched 121 head. At the moment I am running with the stock 71 flat top piston bottom end. I am having a high compression, balanced & lightened block built to get the best out of my carbs & cam. I too use an IE stepped header. I love the performance now & still get 22 mpg. I run at Willow Springs big track too . Dellortos are my carb of choice, parts from Dellorto UK are quick & easy to deal with.

Thanks for the detailed reply. It appears that I'm on the right track. Also good to know parts are easy to come by. (I order many parts from the UK for my 1962 Mini Cooper S)

Link to comment
Share on other sites

Well that didn't take long... I created a Parts Wanted post today and within a few hours I had purchased a NEW Schrick 292 cam!

 

Now for the ancillaries.

 

Although I've never had any issues, I don't want to risk the new cam with old rockers. As best I can tell the Heavy Duty IE and Korman rockers are the same.  Anyone have any info on this?  I don't plan on reving the engine like a F1 racecar so I don't think I will need dual springs. IE only has stock and dual springs listed in the online catalog. 

 

Korman has a complete kit:

"Includes Korman rocker arms, Schrick valve springs, and chrome alloy retainers.Valve springs are designed for performance cams, this kit is typically used in the Korman K300 and Schrick 284 and 292 camshaft installations. A/P# 1139 4 401" 

 

Any thoughts or suggestions?  What about shaft locks vs factory springs?

Link to comment
Share on other sites

You can use stock rockers. The IE's are hardly any more, though.  Neither will break in a street motor.

Stock springs will safely rev to 6800 with that cam- if you don't go past that, use stock.

And yeah, new rockers for new cam.

 

You MUST use something with a lot (1300+ppm) of ZDDP in it to break the cam in.  Really.  It's easy.  The consequences of not can be expensive.

 

Factory spring locks are fine at street driving.

 

Add a wideband air- fuel gauge to your budget, and a bung in the exhaust.  It saves a LOT of hassle when tuning.

 

hth

 

t

Link to comment
Share on other sites

You can use stock rockers. The IE's are hardly any more, though.  Neither will break in a street motor.

Stock springs will safely rev to 6800 with that cam- if you don't go past that, use stock.

And yeah, new rockers for new cam.

 

You MUST use something with a lot (1300+ppm) of ZDDP in it to break the cam in.  Really.  It's easy.  The consequences of not can be expensive.

 

Factory spring locks are fine at street driving.

 

Add a wideband air- fuel gauge to your budget, and a bung in the exhaust.  It saves a LOT of hassle when tuning.

 

hth

 

t

I have a portable Snap-On 5-gas analyzer I use for tuning but I do have a weld-in bung I was planning on installing. I've been looking at a AEM UEGO kt.  What are your recommendations on placement in the exhaust stream and which system to purchase?

Link to comment
Share on other sites

You can use stock rockers. The IE's are hardly any more, though.  Neither will break in a street motor.

Stock springs will safely rev to 6800 with that cam- if you don't go past that, use stock.

And yeah, new rockers for new cam.

 

You MUST use something with a lot (1300+ppm) of ZDDP in it to break the cam in.  Really.  It's easy.  The consequences of not can be expensive.

 

Factory spring locks are fine at street driving.

 

Add a wideband air- fuel gauge to your budget, and a bung in the exhaust.  It saves a LOT of hassle when tuning.

 

hth

 

t

+1 on all.

292 right choice.  good powerband and idles perfectly.  no lumpy idle at all at 850rpm (with dual 40 and then 45 dcoe's on my car)

 

Lucas makes a zddp additive for break in that is available at any auto parts store.  pour it on the cam and journals when building, add rest to oil.

 

installed WBO2 a must for tuning.  AEM is good.  i have been very happy with the Innovate LC-1 in my car.  put the sensor in exhaust just after the collector. 

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Upcoming Events

×
×
  • Create New...