Cam, Lifters, Headers In An Inline Six

[Jbesotes]

I am starting my new project on my 1970 shortbed Chevy Pickup . I am instaling a 260 hydro Cam with a spring rate of 370 lbs/in. With new hydraulic lifters.

I am also instaling a new 2bbl Holley 350cfm carbuerator on a clifford intake manifold and clifford headers. Attached to the headers I have exhost cutouts that will be welded inline and I havent decided what type of muflers I will be running yet.

I will have a few pictures in a few days. I am going on vacation for my birthday on the 16th so when I get back I will be tearing appart my motor and getting to work I will keep everyone updated who is interested.

Thank You

Justin

[culp7]

sweet! can't wait to see pics!

[Jbesotes]

Here are the parts finally got all of them even my valve springs that were on back order!!

Hope to get started soon!

[68Stepbed]

SWEET!!! This should be fun to watch.

[Shaky]

I've been waiting for this thread...

[RichardJ]

Have you considered changing the pedal to a '71-72 hanging pedal with factory style cable?
I found the pedal at a wrecking yard and gathered up four cables of different lengths. I ended up using the longest one, which was from a big Cad or Olds. The cable makes a loop over the valve cover and back over the intake to the side of the carb. I have a Carter 4bbl, but the same Clifford intake. The bracket to hold the cable end was from a Quadrajet. It had to be modified to work with the Carter, but the cable attachment hole is factory.
I mounted the pedal assembly when the engine was out. I think only one mounting hole was reused. Other holes had to be welded closed and new holes drilled with mounting nuts tacked in place.

http://http://67-72chevytrucks.com/v...ight=gas+pedal
I found this thread here where the guy did the same thing, but then made up and sold an adapter to compensate for the different bolt pattern between the '67-70 and the '71-72 style. This would be the easier way to make the change when the engine is still in place.

The factory cable is a quality piece and should not be overlooked. The success of any throttle linkage depends on how well you engineer the cable attachment points and the cable housing attachment. An expensive lokar will not make a poor design work better.

[Shaky]

This is good info. I used a '71-72 throttle cable on my '66.

[leddzepp]

I put a Clifford intake, a 4 barrel 390 Holley, and Clifford headers on all Jeep CJ's I ever owned. The difference in performance is night and day compared to stock....

[Jbesotes]

Now you said you used a 390 carbuerator on your jeep. I was looking into that and I was told that it would be too big of a carbuerator for the cam, and it would flood out the motor?

How did this set up work for you did you notice any flooding or problems? I am still considering the 390 because i kinda wanted a 4 barrel so that I would have more power when I get my foot into it but also get better mileage when I am crusing.

[Shaky]

I used that combo on my '66 with good results.

['68OrangeSunshine]

Originally Posted by Jbesotes

Now you said you used a 390 carbuerator on your jeep. I was looking into that and I was told that it would be too big of a carbuerator for the cam, and it would flood out the motor?

How did this set up work for you did you notice any flooding or problems? I am still considering the 390 because i kinda wanted a 4 barrel so that I would have more power when I get my foot into it but also get better mileage when I am crusing.

JB - You never stated what engine you're using, but I'm guessing you have a 250. I used to have a Holley 390 CFM 4160 -8007 on my 292 w/Offy intake, Clifford headers. The Holley would not set up right after 25 years and 250,000 miles on my new build so I went to the Edelbrock 1404 -500 CFM, but a 292 bored .030-over has 296 cubic inches. I have a Crane 260H cam on my new engine and it runs great. I admit, I don't know 250s, but I would guess 350 CFM on a 2Bbl would be too little.

[68Stepbed]

The 350 2-bbl will work great on a 250, especially with your cam choice. You will still have good throttle response, and the mileage won't make much difference between the 2-bbl and 4-bbl. If you were having some serious head work done, anything bigger than 400cfm is overkill.

[leddzepp]

Originally Posted by Jbesotes

Now you said you used a 390 carbuerator on your jeep. I was looking into that and I was told that it would be too big of a carbuerator for the cam, and it would flood out the motor?

How did this set up work for you did you notice any flooding or problems? I am still considering the 390 because i kinda wanted a 4 barrel so that I would have more power when I get my foot into it but also get better mileage when I am crusing.

I had no problems with flooding ever. I had a stock cam in them. AMC 258 cubic inch six banger. I also put in HEI units. Throttle response was instant, and I had power gains throughout the entire RPM range. I looked into the 500 Edelbrock, as I prefer them to anything else, but Clifford told me that would be over-carbing it. I bought all my stuff directly from Clifford at their shop here in Corona.

['68OrangeSunshine]

Originally Posted by leddzepp

I had no problems with flooding ever. I had a stock cam in them. AMC 258 cubic inch six banger. I also put in HEI units. Throttle response was instant, and I had power gains throughout the entire RPM range. I looked into the 500 Edelbrock, as I prefer them to anything else, but Clifford told me that would be over-carbing it. I bought all my stuff directly from Clifford at their shop here in Corona.

Carter used to make a 400 CFM AFB, but Edlebrock won't remarket it. They really only sell the 500 so you can put 2 of them on a double-carbed intake for a 502 or something bigger.
I asked an Edelbrock tech rep if I could jet down a 1404 to make 400 CFM. He said no matter how lean I jetted it, the carb would still flow 500 CFM.
One thing about the AFB vacuum secondary design is that you only draw as much fuel/air as you can use. I ran a Holley 790 CFM on a 350 for a while. That one was definitely overcarbureted. It would stall as soon as I got off the freeway.
I read in a Clifford catalog that they recommend the 2 Bbls because they think 4 Bbls will let in too much fuel and wash down the rings on cylinders 3 & 4. Since the diagnosis on my previous engine [ a '67 292 block rebuilt in '77] was that cyls 3 and 4 weren't functioning, maybe they have a point. It took me til 2002 to get there. I won't knock Clifford. I still run their long tube headers on my 2005-built 292 -- same ones I bought in '78-- just bead-blasted and hottanked and repainted w/ VHT 1200* cast iron grey.
I guess 250s and 292s are as different as apples and oranges. Or maybe tangerines and navel oranges?

[PanelDeland]

I want to watch this and see the results.One question is do the headers you're going to run miss the factory shift/clutch linkage?

[68Stepbed]

Panel, I know Clifford headers and Hedman headers clear the three-speed linkage. I don't have experience with the FlowTech headers like he has, but I would assume they would. Clifford also used to make a set of shorty headres that would NOT clear clutch linkage. They were primarily for A/T cars.

[292farmer]

i definitely want to see the outcome, as i plan on doing something like this one day, BTW maybe this is a stupid question but what is a hydro cam? does that mean a marine cam? thanks

[68Stepbed]

hydraulic flat tappet

[292farmer]

huh never heard hydro to describe that, thanks!

[Shaky]

I used Clifford shorty headers and they cleared the linkage. The y-pipe in the photo is a home made piece.

[LONGHAIR]

Ok,I had this "floating around" in my head, but it took a bit of searching to find documentation to back it up...and give better details than I could have remembered.

Comparing 4V carburetors to 2V is not an "apples to apples" kind of thing. The CFM ratings are based upon different levels of vacuum. The 2 barrel (ventri) carburetors are tested/rated at 3" of mercury. Somewhere back-in-the-day they decided that a 4 barrel equipped engines couldn't maintain 3" of vacuum at wide open throttle....so the testing vacuum level was dropped to 1.5" of mercury. It can make a pretty significant difference. The whole article here scroll down about half way to "CFM ratings"

[292farmer]

heres shakys old headers i bought installed on a 292 its a lot tighter to the clutch linkage about 1/16in but it works! sorry pic was with phone so not the best.

[RJGeister]

Subscribed. Interested in this one.

['68OrangeSunshine]

My Clifford long tubes cleared the stock L6 Z-bar OK. '68 292, SM 465. IIRC there was some minor ball pien adjustment.

[Jbesotes]

Hello everyone I have a question on my valve springs and how to break them in properly I have heard a fwe different ways to do it. Do I need to take out the second spring when I break in the springs? I have been told to take out the second spring to break it in and then go and put the second spring back in after it is broke in.