RPM Intake on 350
 

So the 69 Lemans I acquired last month has a rebuilt NM 350 with 47 heads, unknown cam, unknown pistons. Unknown brand 4 tube headers, RPM intake, Holley List 2210 carb - I believe it’s a double pumper. It has BB Chevy rocker studs, roller tip rockers and poly locks - set screws are rather deep. The 8.2 rear gears are 4.33, TH 400 trans, unknown converter.

I haven’t started it up yet - I’m moving slowly due to lack of time. I have a 72 cast iron intake on the shelf and thought about installing it in place of the RPM but thought I’d ask here first - is the RPM intake OK for a 350 assuming it’s a mild cam or should I put on the cast iron intake and look for a Qjet?

The plan is to make the car a reliable driver and get the bodywork/paint done eventually - no rush as I have two other nice cars.

BTW, anyone know what this freeze plug on front of passenger side head is all about?

If i was in your shoes i would see how it does as is, make sure its all healthy, plugs, wires, no flooding carb no fuel starvation good oil pressure all that stuff then when you change a part you will have a good idea how you like the results

I'd do a compression test to see what's up there. I'd do all 8 cylinders, also to check on the general condition of the engine.

Rebuilders put that doo-dad, usually on a block surface. It's some kind of a tell tale that melts if the engine is ever over heated.

I'd also run it, as is, to see how it does.

If you are or are not planing on keeping the 4.33 rear gears you have motor important things to focus on.

In no particular order.

A 2210 is a Holley 2bb, not a 4bbl, maybe you have a 3310 Holley?

A 3310 out of the box is a vacuum secondary.
You have no photo of the passenger side of the carb for that to be confirmed

A 3310 can be converted to a double proper, and if that’s the case you have a common problem that I see because your drivers side secondary idle mixture screw has fallen out and is missing.

Either your rocker studs are too too short or your push rods are not the needed length, or maybe some of both, and that would make for the center poly lock Allen lock being set so deep in to outer nut.
If the center Allen lock is only engaging a few threads in the outer body then that’s a bad thing that may chew your Butt one day.


If your keeping those 4.33 rear gears then I hope the motor has forged rod’s in it , but I doubt that because that over heat tattletale stuck on that Freeze plug is a good sign that the whole motor ( block and heads )
is from a mass rebuilder.

In terms of the intake manifold, if your not keeping the 4.33 gears and going over to a street gear then I would install your 72 iron intake for better torque from off Idle conditions, and you will have no loss of top end power by doing such.

I see the motor has a nice duel oil filter set up on it, I hope the oil lines do not come off the motor with a leak prone screw on type adapter.
Hopefully the lines screw into a nice thick bolt on block which does away with the stock oil filter adapter totally, or the block itself has been drilled and tapped for 1/2” pipe.

Thanks, Steve- definitely not keeping the 4.33s - will do a street friendly gear - gotta see what’s available. The old fella who gave me the car cruised it a bit before the engine was rebuilt. it It has the original engine and after the timing chain went, he had it rebuilt by AHM Performance in Baltimore but of course they no longer have the build details. He said he had issues keeping it running so parked it - maybe the carb screw is the culprit?

I certainly hope the cam was broken in right. From what I’ve gathered the build has very low miles on it - like less than 10 when parked. He lives down the street from me and I only saw that car move under its own power once in 20 years. Seems someone talked the old fella into a performance build.

I pulled the water pump off yesterday as I anticipated it would leak and have a spare pump on hand. This is when I noticed the freeze plug - how difficult to pull that out and replace? BTW - all other freeze plugs are normal, albeit steel.

The oil filter lines have a screw in adapter to the factory adapter. Apparently due to the headers. I don’t plan to keep the headers or the oil filter relocation kit but not sure yet if an oil filter will fit in original location without touching the headers.

I failed to mention it has a Mallory Unilite dizzy (no VA) with Crane Fireball CD box and coil. Long term is to change to HEI and canister type coil. Below are additional pics including the carb list.

Looks like a 4777 Holley, 650 DP

Yes, to the above 650 statement, so yes your missing that secondary idle mixture screw which will have a big effect on the idle and just off idle running of the motor.

Is the passenger side screw gone also?

No need to remove that freeze plug, that sensor is not part of the plug so just leave it as is.

A Dizzy with no vac advance will not cut it on the street!

The first thing I would do is confirm that you have no fuel dribbling from the boosters which would indicate a bad power valve on that side of the carb.

Thanks - will check and advise re: the passenger side. Is it safe to assume the carb will need a rebuild after sitting for so long?


What is that sensor on the freeze plug for?

Interesting mixture of all kinds of 1980's ideas about building a performance engine. Quite a time capsule. The little melt tab your concerned about in the head freeze plug can just be left in place unless it really bothers you. They are generally just glued on to the freeze plug. You may be able to carefully pry it off it you don't want it there. Like other posts, I would get it running as is first to assess the mechanical condition of the engine before changing allot of parts. Sure, IMO it would run better, get better mileage and have better driveability with a proper Q-Jet and iron factory manifold but you have other more important things to assess first. If the engine is mechanically quiet, has good oil pressure and runs on all 8 cylinders, then you can change the induction, ignition, and rear end ratio with confidence. You also need to drive it a little and verify the transmission is OK and it doesn't have some kind of crazy high stall speed converter in there. Good luck with it.

If you decide on a q-jet at some point, I have a good '69 core that I was considering parting with.

That’s and interesting mix of parts. You must give us a report after you go for a test drive.

I think the RPM intake is going to be the least of your issues.

https://www.chevelles.com/threads/en...e-plug.862705/ Here you go. And also that older 650dp does not have four corner mixture screws. It only uses the front two. Rears will be blocked.

That carb is a poster child for a rebuild kit! Clean that up and figure out the rocker issue and run it

Thanks all - my original plan was to get it running first - easy to get off track so I appreciate the level set. Interesting about the freeze plug - explains why it’s in a concealed area behind the PS bracket too.

I have a spare 69 Qjet needing rebuild. If it comes to that may look for a newer model to rebuild. I also have a very nice TH400 with a 13” Continental converter on the shelf just in case- it was previously in the bird.

We used to run a `68 LeMans with a 350, Crane 310 cam [iirc], T1 intake, 750 DP Holley, 390 gears with an A1 2600 converter. N50`s in the back. So, I can`t laugh too much.


That car didn`t run half bad for those days. That intake was the worst we could`ve put. So, that rpm should be better than a single plane. Those low gears help in the city. I thought we were bad with the 390`s.:)


I did put that rear on my car to try. Didn`t stay long. Low rpm 455? I remember it being super snappy from light to light. I did manage not to put holes in the oil pan.;)

The #47 heads won't work with the 72 intake. The exhaust crossover is a different size, although an adapter can be made to make it work.
I agree with Jay S that the RPM is the least of the problems.
As 400 LM sez, early DPs did not have 4 corner idle screws.

Thanks Ken - I’m looking forward to hearing this thing. I also know the guy who installed the engine, he’s a full time mechanic and also does part time work at his house. Of course it’s been a long time but he said it was pretty radical and “fast”. I guess it felt fast with the 4.33s! The radical comment may be an over-cammed engine- who the hell knows but someone steered the old fella wrong on this. He said prior to the timing chain failure, he drove it as far as NC (from MD) so it must have had street gears in it.

3310 Holley does not have 4 corner idle mixture provisions. Nothing is missing or fell out, they're blocked off.

Just clean it up and rebuild the carb and run it like others have said. with those 4:33 gears, it should be a monster driving around town. There were 4.56's in my car when I bought it and it made for some impressive straight line acceleration.

Remember that tire size has an effect on how the 4.33:1 acts. If he had tall tire it will be different story than running some of the low profile tires everyone wants today.

Stan

I had a 65 GTO with 4.33:1 gear ratio and a 4-speed. It was that way when I bought it. My wife drove it as a daily driver for about a year. She didn't mind it around town and rarely drove it on the interstate. She hated the manual steering though!