Im about to pick up my 69 tonight with a 427 BB. Need some advice on what single plane intake, what carb and what ignition I should get.

Right now its a holley 750 DP a dual plane intake and i believe an msd distributor (which i may just keep that not sure how he has it wired lol)


Anyway it seems like a power limiter with a dual plane and a 750 carb. Is this setup " just fine " or is there something that might make it come alive. Is 800-850 too big? Not sure what cam is in it, ill ask tonight.

He did say its a 9:1 comp ratio. (guess it was 11:1 but he got sick of adding octane boosters or something like that)

 

probably fine with that setup. if it is 9:1 cr

 

Agreed w/burnt should be fine

 

I agree it should be just fine but if you do want to swap to a single plane the first thing you need to know is what heads you have,oval port or rectangular.
Most likely oval,the rectangular ports were on the hi-performance engines like the L78 396 and L89 427 along with solid lifter cams and Holly carbs but who knows for sure what you have there without looking.

 

Hi perf gm heads, rect.

Ok update- on my way home from work i hear the dreaded sound thought i blew the motor, i got home pulled the valve covers and one of the rockers spun sideways. 4 others look dark like they werent getting oil.


SOOO since i have that problem to face, (probably gonna have to change the cam and lifters now, certainly the pushrods and rockers, found a bent pushrod so far) I am going to change the intake, carb and maybe the ignition while im there.


Probably just gonna keep the ign, seems fine. But the intake was a stock cast iron one not an edelbrock. (at a glance i thought it was, only had the car a couple days)


Gonna just stick with the 750 carb, but what intake will fit under the hood? Air gap maybe?

 

Are you sure they are rectangular port heads?
I'm pretty sure all the cast iron intakes were oval port.
You can bolt an oval port intake on rectangular port heads and it will work despite the port mismatch but it's certainly not optimal.
The carb is a 750? does it have an adapter plate from even bore to spread-bore?
All the 750's I've seen were even-bore and all the cast iron intakes spread-bore.
Are you sure the intake is iron,the stock even-bore intake that goes with the rectangular heads should be aluminum and made for an even-bore Holley carb if memory serves.

 

Hmmmm,were you revving it hard?
Miss a shift or anything like that?
I had the solid lifter cam in my 427 and it would bend pushrods and bust rockers if I over revved it.
Made a hell of a racket,thought sure I'd blown it up a couple times but a few new pushrods,rockers and pivot ***** later with a valve adjustment and I was back tearing up the pavement.
By the way if you don't have roller rockers and run stock bowtie stuff and you have a big cam like the solid lifer bowtie cam I had you need the special rockers with longer slots in them.
If memory serves they have an H stamped in them,with the standard rockers and the big cam it'll run fine till you run it hard and then they bind up and bend pushrods etc.

 

This cam is hydr. The rockers are comp cams roller tip, 1.72 ratio.

So you think the cam and lifters are ok then? Maybe just change our the pushrods and rockers? see what happens?

 

Oh by the way your right on the intake, once i had it off (felt light pullin it off lol) its a gm aluminum intake.


Question however, the long water pumps for BB out there dont all have the second port on them (short hose to the intake) is that needed? Can you just block that port on the intake?

Im thinking an edelbrock airgap intake. Any suggestions?

I want to order the intake at least today and if im just gonna do rods and rockers those too. Suggestions? I really want to get this thing back together.


I hate to not take the timing cover off at this point since im that far. I might as well check out the timing chain and change it while im this far torn down.

 

Boy I dunno,it's been a long time but my '69 had an Edlebrock intake with the short pump and the small hose and my '78 GMC's 454 also has a short pump and the short hose with an Edlebrock so I can't help ya there,might be later model stuff.
I'm not sure you'll gain a heck of a lot with the airgap intake but it's probably a good choice,I had the old twisted Torquer on my 427 and it worked great but it was pretty tall,gotta have a cowl induction hood or a scoop if you want an aircleaner on it.
For sure I'd do the timing chain or go dear drive while it's apart,good insurance IMHO.