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  #31 (permalink)  
Old 03-24-2008, 08:15 AM
Rambler American -69
 
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I found a vacuum leak from a broken hose to the intake. It's fixed now. However , it's still winter here and I took the engine out.

I'm installing those new internals to the tranny. I bought 2500rpm stall converter (HUP-GM25HD ) and aluminum radiator SUM-380328 .

I looked Summit catalog and found main cap studs. Should I buy those and install them? Right now I have main cap bolts. How much hp can bolts take? How about studs?

My future plans will be to upgrade e.g. AFR heads and let the engine rev up to 6500rpm, so it would be an easy job to change the main cap bolts into studs now that the engine is attached to engine stand.

By the way, this is great forum to find tons of information for a newbie like me

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  #32 (permalink)  
Old 03-25-2008, 01:40 PM
Rambler American -69
 
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Thanks for the answers. I was in a too hurry to buy the converter with 2500rpm stall. Luckily it was not that expensive part. Perhaps I will test it next summer and sell it if I'm not satisfied.
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  #33 (permalink)  
Old 03-25-2008, 05:50 PM
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Quote:
Originally Posted by jankinnu
I looked Summit catalog and found main cap studs. Should I buy those and install them? Right now I have main cap bolts. How much hp can bolts take? How about studs?

By the way, this is great forum to find tons of information for a newbie like me




ask machine shop tom, but I think leave it alone. studs change the torque clamping pressure over the bolts.

ask around B4 you change.

sounds like your doing real good with yer ported 76cc heads ect. I would like to see some dyno #s. as had a set of 76cc heads with 2" stainless intakes and 1 1/2 stock exhaust valves. The intake ports are gasket matched and the chambers have been polished. They have comp springs and retainers. The heads were clean and fresh as the valve job had only about 3000 miles on it. everyone said use a different head. so I ended up selling these 76cc heads and buying a fresh set of #187 64cc camel humps with acc holes and a set of vortec 062 heads. the camel humps are on a 400SBC we will see how they do next weekend.
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  #34 (permalink)  
Old 05-20-2008, 01:12 AM
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My entire project (14 pages) can be found here:
http://www.amccf.com/yabb2/YaBB.pl?num=1166690633

New modified headers sound nice I'll check the timing this week. If the timing is right and it still bogs around 4000-5000rpm, should I replace the power valve? What size main jets you would recommend for this kind of setup?

About the timing. When I remove the vacuum hose from the distributor during the timing measurement, should I plug the vacuum holes from distributor and carb?
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  #35 (permalink)  
Old 05-20-2008, 02:22 PM
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Plug the lead from the carb. The vacuum can on the distributor can stay open to atmospheric pressure.

Pat
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  #36 (permalink)  
Old 05-31-2008, 03:00 AM
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I'm still having trouble with engine bog at 4000rpm. After that I disassembled the carb, removed the choke tower and smoothened the sharp edges. I changed new gaskets and power valve, size 65 (earlier was size 50). Accelerator pump shooter size is 25. Is this too small? Primary jets are size 72. The check ball in the vac secondary housing was missing so installed new one.

After that I adjusted the float levels and idle circuit so that the idle is highest. The idle mixture screws are 1 1/4 turns open. I don't have vacuum meter.

I checked timing. It was 15deg at idle and 24@2000rpm with vacuum hose disconnected and plugged from carb. Maybe my distributor mechanical advance springs are too stiff? I'm gonna check the timing @3000rpm to see if it's changing. Maybe 36deg@3000rpm would be ok?

I try to do some tests today with the new setup. Will see how it works.
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  #37 (permalink)  
Old 06-01-2008, 06:15 AM
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Fuel pump is new, model Carter 4070 (electric). I have a decent grounding between the motor and the frame.

Ignition coil is new Accel super coil with new Accel high temp wires:
http://i130.photobucket.com/albums/p.../P1010238_.jpg

The distributor is old. I just bought a new original distributor cap and the rotating part. So this carbon cap center piece is still there. Just to make sure, is it the one in the picture with red circle around it?

Fuel line fits directly into 3/8" hose.

Here's some pictures of the distributor:
http://i130.photobucket.com/albums/p...u/P1010237.jpg
http://i130.photobucket.com/albums/p...u/P1010239.jpg
http://i130.photobucket.com/albums/p...u/P7270150.jpg
http://i130.photobucket.com/albums/p...u/P7270148.jpg
http://i130.photobucket.com/albums/p...u/P7270149.jpg

How much the gap in the magnetic pickup should be?
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  #38 (permalink)  
Old 06-02-2008, 12:58 PM
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I may have found the problem. If I rev the engine at neutral with partial throttle, it revs nicely up to rev limiter 6000rpm. When I push the pedal to the metal, it bogs and stays around 4000rpm.

I opened the hood and removed the air filter. The secondaries were all wet. Gas was also over the air filter. So the secondaries are flooding for some reason. I checked the float levels, they're ok. I have no idea why the secondaries are pouring way too much fuel.

I take a picture tomorrow of my carb. The previous owner had already made some modifications (choke removed, I removed the choke tower, the two pipes in the carb centerline coming out of main and secondary fuel bowls are shortened very short. I don't know why.
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  #39 (permalink)  
Old 06-12-2008, 11:06 AM
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I had courage to go underhood and rev it at neutral. With WOT it looks like the engine backfires from primaries. If I lift the gas pedal a bit, the engine revs up to 6000rpm rev limiter. Is the mixture too lean? I think I didn't see any flames, more likely just gas steam. The secondaries won't even open and I think they shouldn't open without load.

How do I know if I have vacuum leak? Maybe I gotta buy a vacuum cauge.

Last edited by jankinnu; 06-13-2008 at 10:43 AM.
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  #40 (permalink)  
Old 07-06-2008, 06:36 AM
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I finally bought a vacuum gauge.

Here's some measurements for warmed up engine (thermostat 82degC/180F):

I first measured the vacuum readings, with idle mixture screws 1 1/2 turns open:
14" , gear in P, 800rpm (engine temp was around 70degC/158F).
9-10", gear in D, 600rpm

Then I adjusted idle mixture screws until the vacuum reading was highest @ mixture screws 1 1/4 turn open (engine temp 82degC/180F):
15", gear in P, 800rpm
11-12 inHg, gear in D, 600rpm
20 inHg, gear in P, 2000rpm
19 inHg, gear in P, 3000rpm

I adjusted the timing to 20deg @ idle 800rpm with vacuum hose connected. What worries me is that the total timing with vacuum connected was 53@2000rpm and 56@2500rpm.

After these changes the car runs quite well at lower rpms, but backfire from the Holley 3310-2 carb primaries is still there.

I tried without vacuum. 15deg initial and 36deg total. Still after 4000rpm backfire during acceleration. I have to change new rear tires before the next tests Getting bored with symptoms.


- Can too much timing cause this backfire from the carb?
-How do I know if I have a vacuum leak? Maybe some leak detection spray?
-Is it possible that the camshaft is one tooth off from the correct position?

Last edited by jankinnu; 07-10-2008 at 08:22 AM.
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  #41 (permalink)  
Old 07-08-2008, 02:45 PM
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I didn't find any back and forth shaft play from the distributor. There is about 1.5mm clearance if I jerk the shaft up and down. Normal? I found this kind of serial number from the side of the distributor:

III2005 1F10

I think I'm gonna start saving to a new distributor. Any recommendations with the MSD 6AL ignition box?
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  #42 (permalink)  
Old 07-21-2008, 10:58 AM
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I got some suggestions from my friend for the cause of my engine symptoms. He said that either the head gasket is leaking to the intake manifold or one of the intake valves leak causing pressure to the intake.

I bought new intake gaskets and head gaskets. I'm gonna remove the heads to see if the head gaskets have markings of leaking. I will check the condition of the heads also. How do I see from the intake valves if they are leaking?
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  #43 (permalink)  
Old 07-21-2008, 12:15 PM
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Beg, borrow or steal a known good carb, put that on your car and see how it runs. You've got a carb on there that some yahooo screwed around with, cut pieces off of etc and you wonder why the car hesitates? You haven't thought to replace it yet???? Is the guy a tuner for Hendrick (sp?) Motor Sports in Nascar or maybe Kenny Bernstein? What the f$#& are you thinking man?
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  #44 (permalink)  
Old 08-10-2008, 09:40 AM
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I did a compression test for cold engine:

cylinders 1,2,3,5,7,8:
10.5bar/152psi. Spark plugs brown colored.

I couldn't measure cylinder 6 because my headers are modified so tight in the engine compartment.

Number 4 cylinder had only 5.5bar/80psi pressure. So I think either my intake valve is leaking or I have a leak between cylinders 4 & 6.

I'll borrow a dial indicator to check also the actual lift of the camshaft lobes. I didn't see any difference visually when I ran the engine without valve covers.
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  #45 (permalink)  
Old 12-08-2008, 01:39 PM
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I decided to disassemble the motor due to the low compression in one cylinder. Old iron heads will be replaced by some new aluminum heads. I just don't know which ones to buy. I am also replacing the pistons to flat tops, so I can use 64cc heads.

I have looked lots of heads and their flow numbers. At the moment, I have lift of 0.52" at the valve, so the heads should handle at least 0.6" lift for future modifications.

Car will have about 1000 miles a year in road trips so the new heads should last at least a couple of years without machine shop.

I have a budget of about 1200USD for the heads + seals, pistons, balancing, machining etc. Any suggestions? I have found a couple of used high flowing moderate price heads but don't have courage to buy used ones from abroad.
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