my built 4v 351c is a dog

[D.Hearne]

I've noticed several things here, that y'all have missed. One is the 4 bbl open chambered heads. THAT'S the cause of the detonation, not too much compression. Quench heads would help in the bottom end.And as far as I know, all the popups I've seen for Clevelands don't work with open chambered heads. And yea, the top end is lacing due to the 600 cfm carb. And the 3" exhaust doesn't help matters either.

 

[D.Hearne]

I'd never go with vaccum secondaries on a double pumper, but then again I don't build performance engines for fuel economy. In that car, with those gears, and a manual trans....perfect car for mechanical secondaries. With a proper tune, I don't see any reason for it not to get 13-14 mpg, assuming you drive like a mature adult most of the time.

Show me a vacuum secondary carb that's also a double pumper That would be a strange animal if one existed. I believe that's wishful thinking to get a 4 bbl open chambered headed, solid lifter cammed, 3.89 geared with no overdrive, 351 Cleveland to get 13-14 mpg. Unless it was downhill all the way between fillups. I'd be surprised if it got 10.

 

[Gud T.B. Blown]

what is wrong with vaccuum secondaries? i have also been told that a 750 on a cleveland is a little large for street driving, a 650 or 670 would be better suited. please educate me.

 

[pabear89]

I like my Properly set vac sec 750,
and I got 15.75 avg on the last car show run city/hwy
at 75

It would have gotten better but there was some catching up to get with the group which led to periods of high fuel consumption.

PB

 

[ddonaca351]

(imho)
Open chamber heads with pop-ups is a big no no. The o.c.h have no quench, and the flame front has to travel up over the dome, while its doing this temps and pressure are going thru the roof, I would bet that is causing a hot spot to cause your rattle... so you back off the timing, which kills your performance.

The edelbrock "performer" is anything but... it is ok on a mild street (read: "rv" cam) motor, but basically sucks for any performance build. You would be far better off with a Blue Thunder dual plane, or a new performer rpm thats been port matched.

I also feel the carb is WAY too small, a 750 or 780 Holley / Deamon would be my choice.

Sorry, not trying to bag on your motor, but it seems like it has multiple points holding it back.

DD

 

[milner351]

well, it sounds to me as if you have some opposing wants from this engine... and a bit of a mismatch set up currently. High rpm screamers are tough to get fuel economy out of. I agree, solid cams are most excellent, I've got one custom ground by cam research in colorado for my stroked W, but, hydraulics are more convenient for the street.
The open champer head / domed piston concern brought up previously is certainly a valid one that could be leading to your tendency to detonation, which is never a good thing. But, short of pulling the engine to make major changes, you're not going to fix that.

As with any project it depends on money and time, how much of each are you willing to put into improvements?

I think your idea to measure your current cam is a great place to start, at least then you'll know what you have and can decide where to go from there.

 

[DarkoStoj]

well, it sounds to me as if you have some opposing wants from this engine... and a bit of a mismatch set up currently. High rpm screamers are tough to get fuel economy out of. I agree, solid cams are most excellent, I've got one custom ground by cam research in colorado for my stroked W, but, hydraulics are more convenient for the street.
The open champer head / domed piston concern brought up previously is certainly a valid one that could be leading to your tendency to detonation, which is never a good thing. But, short of pulling the engine to make major changes, you're not going to fix that.

As with any project it depends on money and time, how much of each are you willing to put into improvements?

I think your idea to measure your current cam is a great place to start, at least then you'll know what you have and can decide where to go from there.

the most I'm going to change is the intake and carb. I'm going to measure the lift of the cam to get me in the ballpark to give me an idea of what kind of cam is in there. The only problem is the damn intakes for this sucker are super expensive.

Here is a picture of the shortblock when I pulled the heads last week

also, I was just curious if this whole is normal?

 

[stihl-066]

Yes I am curios if that hole is normal also. I have my intake off of car as well and noticed that hole on my cleveland as well.

 

[thumper460]

Vac secondary carb ( list 3310) the engine will use the secondarys as IT need it. Ign @ 38* TOTAL and have the curve come in as fast as possible ( total in at 1500-1800 rpm) install the cam in at 102 or 103 ICL and loosen the lash .003-.004 !! all the above will increase the low end !! Open chambers and pop pistons are OK!! Still the compression will be about 9.6 to 10.5 :1 ( depending on the piston!!) add a 50 CC front accel pump and then a 28-31 squirter and a more aggressive pump cam!! 45 power valve and rock!! the accel will be better and the cruise mileage should go up!!
Have fun..
Just me........... Thumper

 

[dodgestang]

Yes the hole is normal.

 

[A67StangMaster]

YES THAT HOLE IS NORMAL I HAVE THE SAME THING IN MINE IT Aids the engine in oiling....

 

[68RCodeConv]

I have a 4V Cleveland and have done a lot of research..

Your carb is too small and the intake is killing you. An Edelbrock Performer is good to about 5500 rpm and that's it. 4V Clevelands like LOTS of gas and do very well with a DP carb. Something in the 750 range if you plan on revving over 6000 with regularity.

Your gas mileage is going to suck, though.

 

[Hack]

There are some Cleveland gurus on the Corral. Check out this thread for instance.
http://www.corral.net/forums/showthread.php?t=764939

And here's another great place for Cleveland knowledge. Check out the engine builds link and the general automotive knowledge links. They are awesome!
http://www.network54.com/Forum/119419/