The -781's are oval port, and will work well with the right pistons.

 

Get the Performer RPM for oval ports, I forgot the p/n but it's $196 thru Summit. And for a streeter I'd say an Edelbrock 750 vs. electric choke.

 

I have the Performer intake...just took it off a 396. $100+ shipping gets it. It's in exc cond. I just took it out of the car to put back to stock.

Pm me if interested.....

 

q-jets are a great street perf carb for a mild to fairly hot BBC if setup correctly which is very important or you will run into fuel delivery issues on top end.

Do what i have listed below and your q-jet if its a 1973 version or older and you will be good to go. If it newer it ok but the prim metering rods are different and i dont have the correct #s on hand for those.

* Remove small restrictive in carb fuel filter and install a larger inline hi flow filter. You could use the stock type large inline filter used for 1969 chevelle 396/325 & 350hp motors if you want to look stock.

* Many q-jets come with a .110" or .125" inch needle & seat which are not lrg enough (esp the .110") for some BBC perf motors putting out more power,rpm, etc. Have the carb rblt for a stage 2 rbld that includes a larger .135 or .145 high flow needle & seat. Also have 72-73 primjets & 45b rods along with AX or BG secondary rods installed. This is for 1973 oroled carbs. Sean (from SEAN MURPHY INDUCTION.COM) can do this for you,he is honest & does good work so check his site out if you need it done or want to buy the parts to do it yourself.

* Install a carter street f/pump rated for 6-7 psi max because anything over 7 psi is not good for q-jets.

* Even though its advertised that the lighter fuel pump rods are not required under 6k rpms dont believe it. I have run into mult times over the yrs where some perf pumps and esp stock pumps arms floated at above 4k rpms which results in fuel starvation issues so install one with the new pump.

Edelbrock makes a perf rpm manifold for q-jets.

scott

 

Thanks guys

Scott it did not come with a q jet just the manifold and stock dist.
I've had good luck with the Edelbrock carbs & intake for the street
so I will go with what Junkyard Dawg list's but thanks for that info,
its good for the carb on my nova.

I was still wondering about these heads as it looks like stock piston's
Are they still ok or should I look into different ones per mls48341's
post? I would like to do any mods while its out on the stand

Chuck

 

your heads are open chamber 118-119 cc chambers, most 396 engines are closed piston type, therefore your compression is likely 7.02 or 8.13 ,which is really low for a performance engine.. the heads are good but the power will be down because the low compression.. if you want like say 10.1 compression you will need trw forged part#l2287f...pistons.

 

A Q-jet setup correctly is a much better street perf carb then the edelbrock/AFB type carb IMHO.

Yes,with your heads and those large chambers you will need lrg domed pistons to get decent comp as mentioned in above post.

Maybe you should look at which is cheaper for you to do,piston swap or swap/sell your current heads for some 063's or 290's . Those are decent flowing closed chamber lrg oval port heads with approx 100 cc chambers that give you approx 9:6-9:8+ comp with LF2240 speed pro forged pistons & .184 domes depending on how much the block/heads are decked,quench,head gasket thickness,etc.

The 063/290 heads flow well for street use in the 305hp-450hp range (maybe up to 500hp if motor is setup well with right cam,carb,intake,) esp with mild porting,larger valves,and if you use something like Manley race flow swirl polished undercut valves for enhanced flow.

But if you decide to have the larger valves installed in 063's/290's make sure to take them to an experienced machinest thats aware of just how far to cut into valve seat area before breaking into the water jacket . This can & does happen from time to time when installing larger valves in thses heads resulting in coolent in the combustion chamber/s which is not a good thing. This is esp true if you install hardned ex valve seats along with the larger valves at the same time which is not a good thing to do.

You should either run the larger valves or install the hardened ex seats but never both at the same time,thats just asking for trouble with respect to cutting into the water jacket IMHO.

Scott

 

Thanks for the info guys:beers:

Chuck