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Caddy - Holley jetting question

One Eyed Gator

One Eyed Gator

Well-known member
I have a 70' 472 stock except for 10:1 pistons and a RV cam. Currently running a holley 600 2b on the stock manifold. A buddy who races car just gave me a fairly new 650 4b single line carb. He runs a lot hp the his car motors. I concern about how it is currently jetted.

Also as set-up It will turn a 72LXL38 2850 rmp on the water.

Just loooking for some starting point for the jetts.

One Eyed Gator

Can a one eyed man have double vision??
 
You may start at 92 , but it may be lean still. That is Max for a Holley. You can take the jets out and it won't help. Power valves on BOTH ends add an average of 5 more jet sizes but won't help at idle. The main body and blocks can be milled for more fuel. I'd try it but you may like the 2 bl better. DD I assume?
 
It is a DD, runs good now. Very flat under acceleration. It seems most people on this site are running 4b. I thought it might just give me a little more HP.

I also own a correct craft, 351 inboard w/ 4b. The motor is quick out of the hole.

Should I not expect that kind of snap out the hole from a 472? Also you said start at 92. Is that for primary's and secondary's


Agian thanks for the help. You guys are a wealth of knowledge.

One Eyed Gator
 
There are several things to look at with your acceleration. Are the weights in the dist. good and free so the mechanical part of the advance works? With out advance (proper advance) it'll be a slug. What is initial timing and what is total timing ? On a square bore mechanical secondary, there should only be 2 numbers different in jet sizes max. They should be even in theory. You need some way to gauge what you are doing either with exhaust temps or wideband 02 sensors. If the plugs have some tan color, you are probably OK, but there's really no way to tell if you have more power making capability w/o one or the other. Just leaning it out can and will cause harm to the engine (but it'll run really good til it pops!) Sometimes a bigger carb will kill lower end power because of poor carb signal.
 
Vacuum advance had a pin hole in it.
Ran on lake george this weekend. Much better out of the hole. Should check it before now.

What carb would be recommended for a basically stock 472 with piston and cam DD.

Distributor has points and condenser. Any one have any recommendations? Can I use the Accel HEI, real question is it a direct replacement?



Also I change out the radiator to a afco dual pass. Ran cooler 190-200 with a 180 thermostat. I got a set of 3 different size restrictor plates. I'm going to try those with the bypass plugged with a soft plug as suggested.



One Eyed Gator

Enjoying life on the water
 
an easy change for the points is the petronics conversion and it is inexpensive.and this is just my opinion but the stock quadrajet if done right is the best carb for the dd caddy.
 
The small cap stand alone from Accel has been discontinued. I have 2 left in stock. Parts will be available for them though. You can go to the CB7 site and get a used HEI. I make my own know and with a coil , it's $399 for a CDI unit. small cap, billet housing ect. Pretty, not cheap. Accel makes a stock replacement, with the big head, and I think Summit has em. You never know for sure though. At first, they made 5 and sent me one for a proto type to test and the other 4 to Summit. I rekon they'll have them. Bout 250 to 275 IIRC. Don't know if they made production run or not as they often advertise stuff that doesn't exist to gauge the market.
 
399.00 is half the cost of my msd set up and it has failed 2 times on me so 400. dollaros is not to bad.
 
Keep it simple! Just convert over to a stock caddy HEI dist! This will provide all the heat you need and you can get parts at any auto part store. You will need to change the springs and the weights to acheive the advance you are looking for. Don't use the vacuum advance and make sure you put silicom around the vacuum advance so water does not get under the cap. Drill a couple small holes in the bottom of the distributer on the down hill side so if you do get water in it, it will drain. I had water get in mine when it was raining and once the water level gets high enough it will travel down the shaft and get in the motor.

I also like the single wire 100 amp low idle alternator for your aplication. This will allow you to run all your electrical gear at low rpms with out killing your batteries. The best place to buy this is on ebay and it will run under 100 dollars.
 
Will any year stock HEI dist. fit a 70' 472 block?

What spring & weight combination should I try 1st.

Is there a special set for a caddy dist?



One Eyed Gator
 
distributor will fit,if it is used make sure it is in good shape.and the advance curve kit you get for gm at autozone or advance works.comes with advance stop bushings and springs and weights.i have heard the stock hei is lazy on advancing at low rpm so you might won't to try the light springs first.maybe 1 light 1 heavy depends.
 
One light and one medium spring worked well for me. I tried different springs and that combo seemed to work best for my particular setup.
 
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