Inliners International Forums General Discussion Hi Performance New Guy Here. 68 Camaro with an L6 250.

Not to be the doom and gloom guy, but I think I used that exact one you had and it couldn't keep up in mild 80-85ºF weather. It really needed a shroud to work effectively.

The cost and shroud of the HHR fan made it a very attractive replacement.

For some reason I cannot find a picture showing the previous setup (I know I took one...), but you can see it off to the side of this picture.

How many cores on your radiator? Mine is a 3 core. That might make a difference.

...or I can just use a piece of coated steel I have and make a shroud. I have a couple of sheets sitting in my garage along with various straps and bar stock.

I do like your HHR fan though. I'll have to look and see if it'll fit. The radiator is a big one!

This is a brass-copper 3-core. The car came with a 400 V8.

Found another picture.

Could be the same one.

I'll just have to put some miles on it first and see. If not you have a cheap fix.

Back to the carb: I loosened the nut on the adjustment bolt and my stumble is almost completely gone. Still a little dead up top. I think to get it exact I need to go up 3 sizes on the squirter and get a carb cam kit.

...or I'll leave it as-is until I get a big cam and do the had work then I'll fine tune it.

So that vid link I posted helped?

https://www.youtube.com/watch?v=k-Nx5HEzvlY

MBHD

Yep. It got through my thick skull.

I've found it in the past when I was trying to figure out what was wrong but I missed the key part somehow.

Thanks!

Mine had a small stumble at first...but after tinkering with it for awhile and adjusting here and there it seems to be happy through out the rang.

Oddball question: do you guys recommend silicone for the header to head seal or a gasket or both?

I was watching TV and a show mentioned using silicone for the header. That made me do some online digging. I'm seeing more opinions than posts on the subject.

So... using Langdon headers on a 250: metal gasket, silicone, or both?

I've always used just a gasket. IF I were to use a sealant of any kind it would be the copper RTV.

Don't use a metal gasket!!! It'll leak like a siv! Trust me. Get a good hard rubber gasket from Clifford Performance. Works great.

Hard rubber on a header?

I use the standard metal Felpro gasket on intake/exhaust. Use a bit of Ultra Black RTV on both sides just for the intake ports.

Care must be taken to get a good clamp for the intake and exh. Sometimes the clamps need to be offset (filed) to adjust for the different intake/ exh flange thickness.


A rubber gasket would burn from the exhaust in short order.

Yeah, works fine and doesn't melt either and seals up like a dream.

That's what I thought as well when I heard rubber. I'm using the fel-pro metal gasket as well but without RTV.

I've ground down the bridges to match the intake and exhaust. It has a good seal. I just saw RTV being used on CarFix and thought maybe I didn't do it right.

For now I'll leave it as-is since it's working.

So I decided to tidy up the engine bay a bit more.

Replaced the two mis-matched plugs on the t-Stat spacer and installed two brass plugs. I like the brass, silver, black and Chevy engine orange combo I have going and wanted to add some accents.

I also go around to doing the radiator filler panel. It's plasti-dipped black with a vacuum hose on the outside. I think it looks pretty good considering I made it in my garage.

Built is always cooler than bought.

Looks great! I like the braided fuel line. Adds a clean touch.

Thanks. That was more a product of necessity than style. Couldn't fit the stock fuel line around the HEI distributor. Tried bending a new one, gave up and bought that. Looks real but it's fake. No AN fittings.

I need new plug wires. Looking for advice:

HEI big cap
Standard 250.

Can I go with a 350 plug wire kit and will it reach the #6 plug?

Yes, the 350 kit will work. Buy one that you can cut to length.

Thanks Tom.

I'm also messing around with the carb squirter. Last night I stopped by a local speed shop with the car and we looked at the carb. I had a stumble at about 25% throttle (regardless of RPM). Checked timing, adjusted the power lever, and looked at what I need for the squirter. He suggested going from my 32 to a 35. Carb is the 8007 390 CFM carb. At 75-80% throttle it pulls like crazy. Over 80% there's no gain in power. At 90% it starts dropping off. He thinks I need to go up a bit in nozzle size. He didn't have any squirters on hand to try.

The squirter I have is a 32 without the tubes. I'm looking at this: http://www.jegs.com/i/Holley/510/121-35/10002/-1

Thoughts? I want to get this car 100% in the next month so my wife and I can take it on a trip for our 10 year anniversary.

I was doing some searching and found this:
http://www.oreillyauto.com/site/c/detail...5&ppt=C0261

It says the primary pump nozzle is a .025". Mine has a #32. Is it too big for the car?

ordered a #28 and a #35 along with a secondary spring kit. I'm hoping between the three I'll have what I need to get it right.

The 390 on our 243 ci Anglia works well with a #37.

The stock squirter is almost universally too small.

Squirter size question asked on pg 16 post #84394.

MBHD

Yeah, y3ah, yeah...

Pulled a plug and it's white. I hadn't driven it enough before to read them (or, rather, trust the readings).

Looks like I should have bought a 35 and a 37. Oh well... I can try to sell the 25.

Anything else I should change from stock? Don't hesitate to tell me. I don't mind extra parts if they're cheap.

TURBO!!!!

Eventually. My wife wants to move to a new house before dropping a couple grand into the car...

...but it's on my list.

New squirters should be delivered tomorrow or Saturday. Sunday is going to be a nice day so I should be able to tune it then.

Stupid USPS. Lost my squirters!

I had a 27 and 35 coming from ebay. They're in Baltimore. this is the second time that particular sorting facility has lost my stuff.

Luckily I bought a 37 yesterday on my way home (I wAntes to get a variety to try). Found a speed shop locally that has a ton of stuff. They've even built 250's before!

So I have my squirter, springs, new plug wires, and temp gauge. Today is going to be fun!

Maybe I'll finally get to see the full potential of my set up by the end of the day.

About the lump port head...I've been speaking with Larry at Cliffors for some time now about a build on mine and he tolf me not to waste my money on the lump port because all their builds make power at under 5,000 rpm and the lump ports are for above 6,000 rpm.He said to go with a stock head but with 1.94 intake valves and the standard 1.50 exhaust valves.The 1.60 exhaust valves rob power on their setups.Thought I'd relay that info to you.

Don't waste your time listening to Clifford.
If I had stayed with their suggestions I would have still been running 15"s in the 1/4 mile when I was naturally aspirated.

Having a better short turn radius (enter lumps) is going to help engine power at all engine RPMs', from idle to what ever your engine RPM's to.

Guys here on this forum could help you out with better informed decisions.

You need to talk with the other Larry (AKA Twisted6) about lump ported heads.
More current info with guys that run on the street & on the track.

Sissells, Mike Kirby, knows exactly what RPM's lump ported heads start pulling with authority over a stock head.
If he has time, he would be wealth of knowledge to receive.

MBHD

Thanks. I talked to him about 2 years ago right after I got the car.

His advice is based on his intake and exhaust. My exhaust flows a whole lot better than Cliffords. The Langdon headers are huge compared to tubular headers.


Back to the squirters: I plopped in the #37 squirter. It definitely runs better but it needs more gas still.

Since I can't get bigger squirters until Monday I took my #32 and opened it up with a 1/16" bit. I can't fire it up until my 2 year old boy wakes up. Then I think the big guy and daddy might take a little ride. I'll bring the #37, a screw driver and needle nose in case it's not driveable.

Any idea what number a 1/16" hole equates to?

1/16" hole is definitely too much but at least it's safe now. Not too lean. It's rich but not crazy rich believe it or not.

I'm done screwing with this thing. There's a machine shop around the corner that's highly respected. I met with the owner yesterday and he's an old car guy. He knows carbs and 250's. He's built a ton of them. He said $80-100 and it'll be running right.

He's getting the car. Problem solved.

Drove it a good bit today. getting closer on the carb.

Went back to the #37 squirter. Advanced timing just a bit to 12 degrees. Still have a slight hesitation and full throttle is not there but smoother.

Oh also lost the power steering belt about 10 miles from home. That kinda sucked.

Still trying to figure out the carb.

Using a 390 CFM Holley. I rebuilt it with everything new inside. No cracks or porous materials in the housings

Other bits:

HEI distributor with 8mm wires (new)
E3 plugs
timing: 10 degrees initial
new fuel filter and line.
Offenhauser heated intake
Chevy 250 inline 6

Stock I believe they come with a #25 squirter. mine had a #32 in it when I bought it. I ran it with the 32 but it was too lean and bogged tremendously. I put in a #37 and it seems to be running better now. Plugs look like they should. Not wet and not too white. Maybe a tad on the lean side but nothing too bad.

Smooth as silk at idle. I mean you can literally stand a nickle on the valve cover.

Slowly putting the peddle down power is smooth for first 50% throttle. Then gets a little squirly. A little surge, some bog as you go up to 100%. Around 80-90% it seems to run out of juice. No more power and actually seems to start to lose power.

When mashing the throttle it bogs. Badly.

It's definitely down on power from where it should be. Down low I have TONS of power (well... as much as can be expected from a 6. Actually more than can be expected truth be told. No problems lighting up a tire). From midway through to full throttle, though, I'm not gaining any power over 50% throttle.

At highway speed I'm experiencing surging.

Tried vac springs: Started with the plane spring and it was bad. Tried yellow (second to the most light) and it's better. Still surges and bogs but not as badly. I haven't tried other springs yet due to time (I don't have a quick change on it).

I'm guessing the vac secondary isn't putting out enough gas. How would I change that? Secondary metering plate? Something simple like the float level? Different spring?


Just for giggles I tried drilling out the #32 with a 1/16" bit. That made it a #62. Obviously too much but the limiting factor became the screw (not hollow) at that point so I figure effectively it was around a #40. She ran but ran rich and sucked down gas. Went back to a #37 after my experiment.

Surging can be too much timing at cruise speed. Can also be a lean condition at cruise.

Give us more info on the carb.
Main jets
Power valve setting (ie 5.5, 6.5,7.5 ect)
secondary plate size.

Do you know what the timing is doing?
@ 3500 rpm , no vac, what is it

It might be too much timing. That I can back off a bit.

I don't recall the power valve setting, main jet size and I don't know the secondary plate size. I'll have to take it apart for both.

I have a feeling this carb was screwed around with more than I realized when I bought it...

Larry at clifford doesn't know squat about nothing. All he knows is how to lure you in to buy his and only his parts. Been down the road with him. If yer gonna talk to him tell him you want certain parts and leave it at that. Don't even tell him what your project is. How the lump ports help is so obvious I'm surprised people even think they don't.

wrong thread...

gbauer,
With your carb troubles, I checked again what is in my 390 Holley.
Its a List 6390, a 4150 so it has both metering blocks. But the primaries would be the same. Not sure about the air bleeds as I don't know your List #### or what your bleeds measure.

I ran shootouts with my 390 Holley, stock 250, powerglide 3.08, both Clifford and Offy intakes. To get a good 60ft I would just STOMP on the 390 right at the line. If I hit a bad patch it would spin the right rear a little, no hesitation at all. Secondary opened up nearly all the way, and this carb won several of the carb/intake shootouts. It is well set up for sure:

Pri #51 main jets
Pri .028" PVCR (hole sizes in the metering block, you gotta know those!)
Power valve 6.5 or 8.5 not sure, that doesn't make much diff.
Squirters are .028 yup that's plenty for the stock cam.
You know the squirters have NOTHING to do with your full throttle or cruise mixture - they only operate like a squirt gun (actually like a mechanical fuel injection assist) while you are mashing the pedal. With the pedal in a steady position, the squirters do nothing at all.

Sec #52 main jets
Sec .031 PVCR
That is about equal to a 4160 plate with a .056 hole, a #3 plate has that size hole. Drilling them isn't quite the same but would be close.
Sec spring was either yellow or purple one.

If you can set your carb like this its gotta be close, except again I don't know how the air bleeds compare.

Timing was about 12 initial, 32-34 total at 3000-3500, somewhere in there.
Total timing cruising including vac was maybe 40-45 degrees, much more than that it will surge & buck as you describe.

Hope that helps, if not I'd try a different carb, you need a spare anyway!

I ran lots of carbs on that little 250: Autolite 4100s (440 and 500cfm), Autolite 4300 (440cfm), Carter 625cfm, Edelbrock 600cfm, Rochester 4GC 470cfm, Holley 390 and 450cfm. IIRC I even tried a Holley 600 on it, too big but it would run and cruise down the road ok. I rejetted some of them for the shootout but they would all run and drive right out of the boxes, not the kind of trouble you are having.