Hot Rod Forum banner

1 - 20 of 38 Posts

·
Registered
Joined
·
450 Posts
Discussion Starter · #1 ·
Here's the combo Im working with.

351c 4v in a 71 Torino (full interior, original body panels)
9" Rear w/limited slip
C6 automatic trans
hooker long tube headers, 3" dual exhaust w/h-pipe
KB hyper-eutectic pistons, Stock rods/crank
mildly ported 1971 4v factory heads
1.7 ratio roller-tip rockers
Hydraulic Flat tappet lifters, EDM pushrods
unknown aftermarket cam. Only specs known are gross valve lift: Intake is 0.5168" Exhaust is 0.5457"
Proform 650 Carb
aluminum dual plane intake
Wilson Manifolds 1" Tapered carb spacer


Its my buddy's street car He just bought it last year from someone who had no info on its history. He brought it over so I could go through the engine and replace gaskets and faulty/old parts. I found some damaged bearings, and the heads needed help, So i had the crank turned, put in new crank/rod bearings and the heads fully rebuilt w/hardened exhaust seats, valve job, and mild porting. I also fixed geometry issues with the pushrods/rockers, disassembled and cleaned all lifters. I installed all new hardware and components (head bolts, oil pump/pickup/pan, timing chain/gears, oil slinger, all gaskets, most bolts) I also disassembled/cleaned/painted the exhaust and also cleaned and painted the block/heads, new hoses and vacuum tubes, just a general refreshing of the engine, exhaust, steering. I added a 1" Wilson Manifolds tapered spacer.

Just got it all back together and had no problems on startup, no leaks or stalls or bad noises it fired up beautifully. I ran it for 20mins at 2200 rpm 50 degrees btdc just in case I reinstalled a hydraulic lifter wrong and it needed to re-seat. After 'break in' I set the idle to 800rpm, initial timing to 15 btdc. It starts and drives and turns off just fine. With no load, it has great throttle response and revs up to 6000 easy, as fast as you can bury your foot. It can go further but I havent felt the need to max it out. No stalls, no hiccups. It does smell very rich though.



Here's the issues Im having, both while engine is under load:

1) Engine stalls right after a sudden hard acceleration then quick release of gas pedal, (like sudden release of the gas after a burnout...) Starts right back up though

2) If you give it wide open throttle from a stop or while low speed cruising, the car accelerates hard and the rpms climb super fast up to 4000rpm, then its like it hits a flat spot and the acceleration slows down and the rpms climb very slow, like 100rpm every 1 or 2 seconds.


Now Im very unfamiliar with Holley carbs, and I have no idea where the initial and total timing should be at for this engine and by what rpm the timing should be in at. I was thinking I'd try 34 degrees total and see where the initial timing falls. I could use some guidance on where to start this process, and basic tuning on this carb, at least just to get it running a bit better. We plan on getting it fine tuned by a professional this summer. Thank you.




 

·
Registered
Joined
·
450 Posts
Discussion Starter · #3 ·
Thank you. I actually just ordered a fuel pressure gauge from summit with all the different style attachments. I also suspected fuel being the cause of it falling flat at 4000.
 

·
Registered
Joined
·
347 Posts
Initial timing depends on your total advance, 10-12 initial is fairly typical for Ford. It looks like you have your vac advance to venturi vac.. I have always run it to manifold vac.. That way it goes away under WOT, and you can run a little more initial.
38 is what I like for max total all done by 4000 or sooner.
If you have a timing lamp with an offset, set your initial to idle good, and turn the offset to zero out on crank. Then rev up to see what dist advance is limited to, that +initial+ vac= total.
Check your float levels close, if high or low can effect stalling after launch.
 

·
Registered
Joined
·
450 Posts
Discussion Starter · #5 ·
Ive been watching videos on float level adjustment. Looks like theres a few diff types of float set ups, some have removable float windows that you unscrew to check the fuel level, while others (like my carb) seem to have fixed float windows and the fuel should be 1/2 to 3/4 up the window. Im going to check/adjust those tomorrow.

Since there is a mixture screw on both sides of each metering block, does that mean I have '4 corner' idle system? im reading on how to adjust those along with the idle mixture screws. Ill also try doing that tomorrow. I will also check and see what my mechanical advance and vacuum advance are. 38 seems a tad high but again I dont know what its supposed to be. I just hooked everything up the way it was before I took it apart, thats why the advance is on ported.. I too run my distributors to manifold vacuum. Ill be changing his over too.

If im missing anything on float level adjustment please let me know. Im a little lost on the idle speed mixture adjustment as well. With an edelbrock I used a vacuum gauge and adjusted the screws until I had max vacuum.
 

·
More for Less Racer
Joined
·
19,950 Posts
Yes, 4 mixture screws, one on each corner, is 4-corner idle. You have it for the adjustment level.

Frequently with a parformance cam, you need to adjust a bit richer at idle....going to max vacuum is typically too lean for any cam that has a lope you really notice...once you find highest vacuum, turn each mixture screw back out richer 1/8 to 1/4 turn.
Remember that with an automatic it has to be rich enough to idle in gear.

Something that just hit me, probably one of the first three things you need to check and verify....you need to make sure you haven't opened tha main throttle speed screw too much and overexposed the transfer slots at the baseplate....should only be .020-.040" of the ends of the transfer slot showing BELOW the throttle plates.
You have to put the carb off the manifold to see it.
Have you got a List # for the carb?
Had it apart at all? I am curious if it had the idle feed restriction in the metering block at the low or the high position.
High position would be bad in your case, incorrect for cam and engine parameters.

The 4V Cleveland closed chamber is a pretty good design, it doesn't have detonation/octane sensitivity problems....Ford just ditched it back in the day because it was too dirty emissions-wise.....not because it didn't make power. It has a lot of quench pad area for good squish and a good spark plug placement. It'll be fine with a 38° initial + mechanical Total timing.
 

·
Registered
Joined
·
450 Posts
Discussion Starter · #7 ·
Thank you for coming over to this thread Eric. I have not had it all apart, originally I thought i'd just be putting gaskets on this engine. With the depth of work I ended up doing, I shouldve gone through the carb but I just wasnt familiar with it and wanted to get the car running. It's easy enough to pull it back off though. Ill take it off before I start with the adjustments tomorrow and get a picture and part number.

If I take the fuel bowls and metering blocks off, will I ruin any gaskets? I dont have any extra parts for this carb
 

·
RedLine Stage 4 ZL1 650rwhp
1971 BB Chevelle
Joined
·
574 Posts
Ive been watching videos on float level adjustment. Looks like theres a few diff types of float set ups, some have removable float windows that you unscrew to check the fuel level, while others (like my carb) seem to have fixed float windows and the fuel should be 1/2 to 3/4 up the window. Im going to check/adjust those tomorrow.
There's actually 3 different Holley set ups im aware off, the old Brass screw you take off and Adj Floats so it just trickles out, then the same with See Through Screws.

HOWEVER on the permanent fixed non removable windows you DO NOT adj past 1/2, amof you want less. I just went through this with my BB Chevelle and the car would run perfect in all conditions except WOT high RPM, it was like it threw up on itself when you jumped on it at speed. After some research I found out it belongs at half MAX but mine ran perfect when i went less like they recommended

615604
 

·
More for Less Racer
Joined
·
19,950 Posts
If I take the fuel bowls and metering blocks off, will I ruin any gaskets? I dont have any extra parts for this carb
Unfortunately, if it has been together a while and non-stick gaskets weren't used, it will likely peel either the metering block or bowl gasket somewhere, so you need to be prepared and have those on hand before attempting to take a float bowl off.
 

·
Registered
Joined
·
347 Posts
If you are taking fuel bowls and metering blocks off and have to replace gaskets, I always lightly coat the gasket with Vaseline, then if you have to go back in, nothing sticks. Helpful if jetting.
 

·
Registered
Joined
·
450 Posts
Discussion Starter · #11 ·
fiddled with the distributor timing, I have now got 38° total by 4,000 RPM, with 12° initial. I also switched my distributor to manifold vacuum.

I've got issues with the carb floats. They just will not stay where you set them. I spent half the day getting them to write below half, just to see a few minutes later that one of them is super low and the other one is high. They keep taking themselves out of adjustment. And when you shut the car off, the front float keeps letting gas in until it floods the engine.

Either my fuel pressures too high or, and this is what I suspect, the needles in the floats aren't seating properly, and the carb needs to be rebuilt.

There was no list number on the air horn and I could not find a number anywhere on the carb. I need to get a rebuild kit but I don't know which one to get
 

·
Registered
Joined
·
347 Posts
Go to Holley.com, there are pictures of how to find list numbers. I never liked the sight window carbs because of when you drop the level, you have to wait for it to suck out the gas to see what you have. The needle and seat is a unit and can be changed by itself, just screw it out. Start low and work up slow to set new one. I use a paint can lid, as a catch can, take one of the bottom bowl screws loose, and let fuel drip into lid to lower fuel level. Sometimes it will set just perfectly under the bowl and inside the runner. Fuel pressure doesn't need to be very high, you just need a quart in ten seconds for flow, 4-5 psi is plenty.
 

·
Registered
Joined
·
450 Posts
Discussion Starter · #13 ·
I bought a holley kit from parts store.

Put in new fuel bowl gaskets and float needles.

I adjusted the fuel levels to just below half. It was running great I took it out for a ride today.

I stopped in an empty parking lot and did a donut, the car turned off, the carb caught fire and bubbled some paint.
I put out the fire on top of the carb. I let it sit for some time. Every time I try and start it it just cranks wants to start then backfires or rather spits gas back out through the carb. I put the timing backwards and I put the timing forwards. If I put it backwards it will not start at all. If I put it forwards it will start but I have to give it a lot of gas to keep it running, and the second I put it in gear it will die. It feels like I have jumped a timing tooth maybe? Any ideas? I'm stuck in a parking lot
 

·
Registered
Joined
·
450 Posts
Discussion Starter · #14 · (Edited)
Even though it is spitting gas back through the carb, the fuel bowls are remaining at just below half through the sight glasses
 

·
Registered
Joined
·
450 Posts
Discussion Starter · #15 ·
it started barely. It ran extremely rough until about 4000 rpm. Kept my foot on gas and put it in drive. Made it 100' before I had to stop at stop sign, where it died and carb caught fire again. But this time I was ready and put it out immediately. I have no tools, I've called aaa...
 

·
Registered
Joined
·
1,180 Posts
it started barely. It ran extremely rough until about 4000 rpm. Kept my foot on gas and put it in drive. Made it 100' before I had to stop at stop sign, where it died and carb caught fire again. But this time I was ready and put it out immediately. I have no tools, I've called aaa...
Noooo!!!!
I'm glad you put it out.
 

·
More for Less Racer
Joined
·
19,950 Posts
Check the distributor gear and the roll pin that holds it....might have ground up the teeth or twisted off the roll pin.
I would not expect a timing chain jumping when it is a new set. They generally only jump when the chain gets old, stretched, and sloppy.
 

·
Registered
Joined
·
450 Posts
Discussion Starter · #19 ·
Well I realized quickly that I'd have to take the dizzy out to do that. I'm still in the parking lot. In summer clothes from this morning, freezing.... Triple a said 1 hour about 3 hours ago
 

·
Registered
Joined
·
450 Posts
Discussion Starter · #20 ·
I didn't hear any bad mechanical sounds, the car was running great and then halfway through the burnout it turned off. Then all the described symptoms happened. There was no bad noises or drop in oil pressure etc... And there is plenty of gas in the car.

After I get done with this nightmare and get it home I'll check the distributor
 
1 - 20 of 38 Posts
Top