Mark30

I was wondering if the RPM intake would be too much for a 1969 350 4 barrel?

The engine is stock but will have long tube headers. It is the 10.25 comp engine.

bdub217

olds 350? chebby 350? =/ need more info please!

Is this a stock motor? Crate?

thanks

based on the little info you gave me here's something to read.

Performer RPM Intake by EDELBROCK

like I said I can't be much help nor with others without some more information on the motor.

DoubleV

Being that this is an Olds site, I would assume he's refering to an Olds engine and he did mention it's stock with headers.

Mark30, you're going to get mixed responses as to whether an RPM intake would be better than a regular Performer ( or stock ), so be prepared. There are going to be some that will swear up and down the RPM won't do you any good ( or even hurt performance! ), but then others will swear it WILL make a difference, so it's going to be hard to make a decision based off the responses you're going to get.

From my own research on this, I have read of one guy who says the RPM intake didn't improve his ET's and was less responsive on the street. I have also read of a guy who was able to consistantly spin his tires up to a higher rpm than before the swap ( implying noticably more power ) and another guy who's ET's DID improve with one ( even on a stock 307 which he tried it on too! ). These were people with very mild/stock/stockish 350's.

I can tell you that when I put the RPM intake on MY very mild, dinky cammed 350, I may have noticed a LITTLE boost up top but I most certainly did NOT lose anything anywhere in the RPM range.

On another note, it is unlikely your CR is 10.25. Those engines are usually much lower than advertised ( more like highish 9's ).

So IMO, if you're planning on a bigger than the junk stocker cam down the road, I would go with the RPM all the way. If I wasn't going to touch the motor at all, then it's kind of a toss-up but maybe leaning toward the regular Performer intake ( because it's readily available used for cheap and it's lighter than the stocker ). Either way, I wouldn't expect too much from an intake swap unless you're planning on some other upgrades ( like bigger cam and maybe some head work ).

bdub217

my fault! got caught up in my response that i forgot about it being stock, just wanted more info as to what car and what carb what heads etc Bad habit of not reading everything in it's entirety sometimes.......glad I'm not that way when I work on stuffs =0

He didn't say anything about racing and what not so that would mean the intake he's asking about would be okay.

captjim

I did this several years ago,
http://www.realoldspower.com/phpBB2/...performer++rpm
However, I had a 9 to 1 355 with a 210/216 cam and 3.42 gears. It was right on the line. If you have the 6 cc pistons, the RPM is probably the better choice. If it was me, I would upgrade the came while you have it apart. Stock is very mild, somewhere around .400/194.

Mark30

The engine is a stock oldsmobile engine. I only quoted the compression ratio as thats all I have to go by and I wanted to make it clear it was the different 350.
As for what I am looking to do with the car, I am looking for a strictly street engine. I think I would prefer a performer but I have found someone selling a RPM for a very low price.

I currently own a Holley street dominator but I don't want to use it strictly because of its looks. I like the dual plane as they look more stock.

As for a cam, I was thinking of getting a W-31 style cam, but to be honest, I haven't really researched much for it.

Currently my car has a 350 transmission with a peg leg 2:56. I am looking to swap that for a set of 3:73 with a 200r4 to keep the same final ratio.

ah64pilot

Doesn't get any more definitive than a dyno so here ya go...Performer beats RPM Air Gap:

https://classicoldsmobile.com/forums...parison-4.html

oldcutlass

The only real difference is the the range in RPM and carb pad height.. If you had a little higher stall converter and a cam that will function with your setup, then the RPM manifold will perform fine.

cutlassefi

That's on a big block, not the same comparison. The regular performer for a small block is way smaller than the rpm both in runner size and plenum.
A big block performer actually has a larger plenum than the rpm does, that's why the big difference when using a carb that's essentially too small.

Use the RPM, you won't be sorry.

LX89mustang

That test was in no way accurate for 2 big reasons .

1. The dyno seemed to be malfunctioning due to the rpm reading on the sheet.

2. The motor had too small of a carb to start with .

Also , as Cutlassefi stated , that test was on a 455 .

bccan

I can't believe it - A thread w/ no nasty differences of opinion! Yet. We swapped RPM on to the red car from std Performer. 9:1 350, 202/212 x .5xx HR, 1 5/8" headers, 2 1/2" x pipe, 200-4R, 3.08, '68 OAI setup. Didn't hurt the low end at all, arguably helped top end. Carb did not need recalibrating, just an idle screw adjustment. I'm not sure if 1/4 mile performance changed or not. It runs 14.3 @ 96 like clockwork but I don't remember what it ran prior to that.

My opinion would be to run either one, you can't lose. Performer might be better presently but w/ some more gear & cam I would RPM it.

coppercutlass

I guess it comes down to what your future plans hold. I would go rpm for the fact that if he decides to build up that 350 down the road he can re use the intake on a future build.

ah64pilot

Yeah, it was late and I was skipping around. Totally missed that this was a small block. My bad.