- Straight Eight Engine Specifications
- Straight Eight Casting Numbers
- Buick F-263 Head/Gasket Swaps, effects on compression
- 263 Head X-Sections
- Straight Eight Intake Manifold X-Sections
- 263, 2X2 Engine Mount Modification
- Compound Carburetion
- Buick Compound Carburetion
- Buick Fuel and Vacuum Pump
- Straight 8 speed secrets of Don Montgomery
- Looking to get rid of the torque tube 50 sedanette
- T5 Install on the '50 263
- Straight 8 sets two new Bonneville Records
- Building a High Performance Straight Eight
- Buick Straight Eight Lifter Adjustment
- Straight Eight Oil Supply Update
- Dual Points in a Buick Straight 8 Distributor
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Detonation ?
- Thread starter saltracer
- Start date
the plug readings don't show any definate signs of detenation............what does show is that the front four plugs look richer than the back four...........wich seam to mean that the carbs are not balanced but .but A/F ratio showed 13.4 on the LM1.................but number two piston had a hole right at the spark plug and a crack running over the top of the piston.........I run a rather large plentum with 1 7/8 inch runners.........and two 650 Holleys............and sence I first ask this post question, the motor is apart and number five looks as if it was getting hot.......I run pryometer in number eight and never got over 850 degree ?
I am beginng to think that reversion is a bigger deal in these motors than I thought...........never have any problems on dyno pulls or in the first 1 1/2 miles, but in the second mile all goes to hell................thinking about lower compresson ratio and adding water injection on top end ? strange things are happening on prolonged throttle and never lifting to let engine breath................has anyone ever tried to grind a can with "scattered" valve timing?
I run ERC 110K with a 115.5 (research method) octane rating
I am beginng to think that reversion is a bigger deal in these motors than I thought...........never have any problems on dyno pulls or in the first 1 1/2 miles, but in the second mile all goes to hell................thinking about lower compresson ratio and adding water injection on top end ? strange things are happening on prolonged throttle and never lifting to let engine breath................has anyone ever tried to grind a can with "scattered" valve timing?
I run ERC 110K with a 115.5 (research method) octane rating
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the plug readings don't show any definate signs of detenation............what does show is that the front four plugs look richer than the back four...........wich seam to mean that the carbs are not balanced but .but A/F ratio showed 13.4 on the LM1.................but number two piston had a hole right at the spark plug and a crack running over the top of the piston.........I run a rather large plentum with 1 7/8 inch runners.........and two 650 Holleys............and sence I first ask this post question, the motor is apart and number five looks as if it was getting hot.......I run pryometer in number eight and never got over 850 degree ?
I am beginng to think that reversion is a bigger deal in these motors than I thought...........never have any problems on dyno pulls or in the first 1 1/2 miles, but in the second mile all goes to hell................thinking about lower compresson ratio and adding water injection on top end ? strange things are happening on prolonged throttle and never lifting to let engine breath................has anyone ever tried to grind a can with "scattered" valve timing?
I run ERC 110K with a 115.5 (research method) octane rating
Is the piston dome on the side away from the spark plug forming a pocket around the plug area or just a symmetrical pop-up?
Would the rules allow you to inject alcohol rather than just water?
Have not worked with “scattered” valve timing. Some cams simply change timing between intake lobes for the cylinders that share an intake port. Other cams include a different duration for each lobe. Many hours of dyno R&D time. Since these timing variations only involve a few degrees you could try timing changes by varying the valve clearance. (Temporary dyno experiment)
Dale, I think I know what your problem is, almost exactly the same thing happened to my 248 once apon a time. About 30 years ago, I put a supercharger on my 248. I ran it around town for a while and it seemed fine. So I thought that it was time for a real run up to my cabin, about 100 miles away. Boy!, did that thing run!! But by the time I rolled in the drive, something was not quite right. By the time I managed to get back home, things were diffinatly not right. I pulled the head, partly melted pistons, holes in pistons and tops of pistons broken off the skirts up in the cumbustion chambers. The stock type piston certainly were not up to the job, but there was more going on. That was the end of the supercharging expierment, I just did'ent have the money or knowhow to make it work.
Over the years of expiermenting on my engines I have determined that at high levels of power, not sure exactly where, the str8 develops thermal distribution problems. The spark plug is way over on one side, actually over the deck, a really bad location, this makes the plug side of the piston much hotter than the far side. If there is a big dome in the way, it gets worse. There could be 2-300 degrees difference between sides. The piston can't take it. The only solution that I can come up with is to install oil squirters like the chevy LS engines have, aimed at the underside of the piston right at the hottest spot, and give it a good bath. And keep the oil cool. The next problem is that the front of the engine is always cooler than the back. The out put of the water pump must go into the engine at the center frost plug hole, then depending upon which block you are using, plug the coolant holes or drill new holes in the deck in order to warm the front and cool the rear. And, yes, there is a reversion problem with these engines. If the intake is too big or there is too much cam it's almost a sure bet. The way you can tell is if you are getting fuel stand-off above the carb/carbs or to a lessor degree, carbon tracking in the intake. Not a lot of fix other than less intake or cam. Have fun! alleycat
Over the years of expiermenting on my engines I have determined that at high levels of power, not sure exactly where, the str8 develops thermal distribution problems. The spark plug is way over on one side, actually over the deck, a really bad location, this makes the plug side of the piston much hotter than the far side. If there is a big dome in the way, it gets worse. There could be 2-300 degrees difference between sides. The piston can't take it. The only solution that I can come up with is to install oil squirters like the chevy LS engines have, aimed at the underside of the piston right at the hottest spot, and give it a good bath. And keep the oil cool. The next problem is that the front of the engine is always cooler than the back. The out put of the water pump must go into the engine at the center frost plug hole, then depending upon which block you are using, plug the coolant holes or drill new holes in the deck in order to warm the front and cool the rear. And, yes, there is a reversion problem with these engines. If the intake is too big or there is too much cam it's almost a sure bet. The way you can tell is if you are getting fuel stand-off above the carb/carbs or to a lessor degree, carbon tracking in the intake. Not a lot of fix other than less intake or cam. Have fun! alleycat
Alleycat brings up some good points. Piston domes should occupy the chamber space away from the spark plug. This pushes the fuel mixture around the plug for faster burn and keeps the piston aluminum away from the hot spot. Additional problems include the fact that the intake ports are nestled between two exhaust ports, with the already mentioned cooling problems and during prolonged runs (Salt Racing) the intake charge is getting heated enough to cause detonation. If you can inject alcohol into the intake ports it will help cool the intake air.
When you made reference to “Scattered valve timing” cams, I’m assuming you are talking about when one cylinder is robbing from the other during the time both intake valves are open in a common port (Cross-port interference). Some help can be found with cam timing. Installing a wedged dam at the back center of the intake port if you can remove some of the radius at the first turn will also help. A lot of work for small returns. Data logging all 8 exhaust gas temps really helps with fuel distribution and fuel mixture info and exactly when things go bad during a run.
We never leave home without it.
Paul
When you made reference to “Scattered valve timing” cams, I’m assuming you are talking about when one cylinder is robbing from the other during the time both intake valves are open in a common port (Cross-port interference). Some help can be found with cam timing. Installing a wedged dam at the back center of the intake port if you can remove some of the radius at the first turn will also help. A lot of work for small returns. Data logging all 8 exhaust gas temps really helps with fuel distribution and fuel mixture info and exactly when things go bad during a run.
We never leave home without it.
Paul
alleycat............I think it might be a little of everything you said and more, but I was thinking of running a "blower motor" class thinking forcing the air in might cure all, but guess not.
your right the spark plug in in the wrong place, was thinking about closing the combustion chamber up on the far side and running flater pistons?
and oil squirters.........I did install them this year, worked good on the bench, but at Bonneville the oil pressure dropped to low and had to un-hook them.............but now I know that it was the fault of too small of a "round" oil pick-up screen, ......(by the way I also installed a new HV Ford 351W oil pump this year and worked like a charm) so next time not only will I have squirters, but I can use them.
the cooling issue you talked about, I have taken care of that......I run a copper head gasket and did not open any of the water holes exceot the two in the back, I run the water into the front of the head so that it floods the entire head befor it goes into the block (at the back) and come out the front of the block. I have a 3/8 inch balance tube that ties the front and the back of the head to keep out any "hot spots or steam"and run a small 1/4 inch line mid way in the motor to keep the block even(works well I read temp in two places).......I only cool the top of the block due to having filled the bottom of the block in order tho keep the sleeves from moving around
but reversion is a big problem....and I think gets bigger at high RPMs.................was thinking today about at the end of the small intake splitter at the back of the runner , if adding about one onch of wire screen "gather" any reversion.......... give me your thought guys.
pmuller9 ........by injecting alcohol "at Bonneville" puts me in a "fuel class" that might be my easiest move, because that record is abut the same as the class I am running.........plus 80% alcohol+20%nitro+a shot of NO2 sounds interesting , but hell on the bottom end,
but also part of this is the valve timing..........before I spend the money grinding a "scattered " cam...........I am going to try and see what happens if I retard the timing , widen the rich cylinder valve lash and change the rocker ratio on the cylinder back to 1.5 to 1 and leave the lean one at 1.6 to 1...........and go to a .044 head gasket instead of the .032...........
and I know your right , but I only gather one EGT when racing but all eight on the dyno
but anyway guys it has been good for my brain to have you guys helping me figure this out........."it's a funny posion we picked for ourself"
again thanks..........Dale
your right the spark plug in in the wrong place, was thinking about closing the combustion chamber up on the far side and running flater pistons?
and oil squirters.........I did install them this year, worked good on the bench, but at Bonneville the oil pressure dropped to low and had to un-hook them.............but now I know that it was the fault of too small of a "round" oil pick-up screen, ......(by the way I also installed a new HV Ford 351W oil pump this year and worked like a charm) so next time not only will I have squirters, but I can use them.
the cooling issue you talked about, I have taken care of that......I run a copper head gasket and did not open any of the water holes exceot the two in the back, I run the water into the front of the head so that it floods the entire head befor it goes into the block (at the back) and come out the front of the block. I have a 3/8 inch balance tube that ties the front and the back of the head to keep out any "hot spots or steam"and run a small 1/4 inch line mid way in the motor to keep the block even(works well I read temp in two places).......I only cool the top of the block due to having filled the bottom of the block in order tho keep the sleeves from moving around
but reversion is a big problem....and I think gets bigger at high RPMs.................was thinking today about at the end of the small intake splitter at the back of the runner , if adding about one onch of wire screen "gather" any reversion.......... give me your thought guys.
pmuller9 ........by injecting alcohol "at Bonneville" puts me in a "fuel class" that might be my easiest move, because that record is abut the same as the class I am running.........plus 80% alcohol+20%nitro+a shot of NO2 sounds interesting , but hell on the bottom end,
but also part of this is the valve timing..........before I spend the money grinding a "scattered " cam...........I am going to try and see what happens if I retard the timing , widen the rich cylinder valve lash and change the rocker ratio on the cylinder back to 1.5 to 1 and leave the lean one at 1.6 to 1...........and go to a .044 head gasket instead of the .032...........
and I know your right , but I only gather one EGT when racing but all eight on the dyno
but anyway guys it has been good for my brain to have you guys helping me figure this out........."it's a funny posion we picked for ourself"
again thanks..........Dale
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Dale
Looks like you’ve done a ton of problem solving already. I prefer to see a racer totally destroy the record in the class they’re in before moving on but that’s just me.
You mentioned closing the combustion chamber up on the far side and running flatter pistons. When the valves are this deep in the chamber, any closing of the chamber creates too much valve shrouding. It is actually better to open the chamber up if you are over stock bore (You mentioned something about sleeves) use a stepped piston that’s high on one side and drops down to deck level where the plug is. Now there is minimum shrouding and some turbulence during compression.
There is a possibility of eliminating both reversion and cross-port interference but it is way outside of the box thinking and may not be legal. Would the class rules allow you to use an aftermarket crank with a different configuration?
Paul
Looks like you’ve done a ton of problem solving already. I prefer to see a racer totally destroy the record in the class they’re in before moving on but that’s just me.
You mentioned closing the combustion chamber up on the far side and running flatter pistons. When the valves are this deep in the chamber, any closing of the chamber creates too much valve shrouding. It is actually better to open the chamber up if you are over stock bore (You mentioned something about sleeves) use a stepped piston that’s high on one side and drops down to deck level where the plug is. Now there is minimum shrouding and some turbulence during compression.
There is a possibility of eliminating both reversion and cross-port interference but it is way outside of the box thinking and may not be legal. Would the class rules allow you to use an aftermarket crank with a different configuration?
Paul
Dale
Looks like you’ve done a ton of problem solving already. I prefer to see a racer totally destroy the record in the class they’re in before moving on but that’s just me.
You mentioned closing the combustion chamber up on the far side and running flatter pistons. When the valves are this deep in the chamber, any closing of the chamber creates too much valve shrouding. It is actually better to open the chamber up if you are over stock bore (You mentioned something about sleeves) use a stepped piston that’s high on one side and drops down to deck level where the plug is. Now there is minimum shrouding and some turbulence during compression.
There is a possibility of eliminating both reversion and cross-port interference but it is way outside of the box thinking and may not be legal. Would the class rules allow you to use an aftermarket crank with a different configuration?
Paul
Paul..........I thought about a crank with a different configuration, but have never looked into pricing. Also what about turning the engine around and running eight intakes and four exhaust ?
Dale
ps I hold the record in my class now , but the idea of more speed is just personal........but also know that it might be hard pushing a Model A Coupe much faster
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Paul..........I thought about a crank with a different configuration, but have never looked into pricing. Also what about turning the engine around and running eight intakes and four exhaust ?
Dale
ps I hold the record in my class now , but the idea of more speed is just personal........but also know that it might be hard pushing a Model A Coupe much faster
Dale
With an exhaust siamese port (With 180 degree crank separation) the first cylinder exhausting into the port sees the pressure pulse of the second halfway through its cycle and with long duration timing can actually see reversion back into the cylinder. The last cylinder using the port gets the benefit of exhaust scavenging from the exhaust header. So the first cyclinder suffers badly on two counts.
Glad to see someone looking at all the possibilities.
Do you have to stay with the stock head?
Paul
Paul.........thanks for the info on the exhaust.........I can either run 325 cu in with a after maarket head type head or 375 cu in with a "stock appearing" head...............this rule was actually thinking of the Wayne Twelve Port guys.
But a good after market head on a Buick would more than make up the 50 cu in handicap...................I have seen your post on the 16 port head, looks great but beyond my reach.
Dale
But a good after market head on a Buick would more than make up the 50 cu in handicap...................I have seen your post on the 16 port head, looks great but beyond my reach.
Dale
Dale
Thanks for the additional info. What displacement is your 320?
I have an Idea but I need more info on the 320 head. I only have 263s.
What is the diameter of your intake ports and what is the centers for the bolts that straddle the intake ports.
The bolt centers for the 263 is 2.122 inches and I’m hoping the 320 head is a lot more.
Paul
Thanks for the additional info. What displacement is your 320?
I have an Idea but I need more info on the 320 head. I only have 263s.
What is the diameter of your intake ports and what is the centers for the bolts that straddle the intake ports.
The bolt centers for the 263 is 2.122 inches and I’m hoping the 320 head is a lot more.
Paul
My 320 is over-bored to 356 cu in.........intake ports 1.680"........Dale
Thanks for the additional info. What displacement is your 320?
I have an Idea but I need more info on the 320 head. I only have 263s.
What is the diameter of your intake ports and what is the centers for the bolts that straddle the intake ports.
The bolt centers for the 263 is 2.122 inches and I’m hoping the 320 head is a lot more.
Paul
headbolts center to center 2.300"
ps.......... cleaned out my mailbox
Street Rod detonation
I need help! My engine is a '49 block with 3/4 cam by Elgin, 9 to 1 pistons by Ross, three carb manifold, headers, polished ports and combustion chamber, balanced, etc. The engine is installed in a 1940 Series 80 limited sedan. I plan to order a custom distributor from from Performance Distributors. They will tailor the advance curves to any specs I call for. The stock unit I have I know is tired and will be replaced. If I set the timing to stock specs, it is smooth at lower rpm and load and pings like mad under higher load and RPM. If I retard it to get rid of the ping, then it runs very rough at lower rpm. I am running with the vacuum advance installed and hooked up. It appears to me that the stock advance curve is just too aggressive for that compression ratio. I wonder if I need less machanical advance and somewhat greater vacuum advance.
What would you suggest as:
1. Initial Set point
2. Machanical advance curve
3 Vacuum advance curve
This is not to be a racing engine (can you imagine a black limo at the drags?) But I just wanted to have a good running engine with good power over a reasonable range and hopefully some decent mileage. Hope you can help me.
Regards,
Earle
I need help! My engine is a '49 block with 3/4 cam by Elgin, 9 to 1 pistons by Ross, three carb manifold, headers, polished ports and combustion chamber, balanced, etc. The engine is installed in a 1940 Series 80 limited sedan. I plan to order a custom distributor from from Performance Distributors. They will tailor the advance curves to any specs I call for. The stock unit I have I know is tired and will be replaced. If I set the timing to stock specs, it is smooth at lower rpm and load and pings like mad under higher load and RPM. If I retard it to get rid of the ping, then it runs very rough at lower rpm. I am running with the vacuum advance installed and hooked up. It appears to me that the stock advance curve is just too aggressive for that compression ratio. I wonder if I need less machanical advance and somewhat greater vacuum advance.
What would you suggest as:
1. Initial Set point
2. Machanical advance curve
3 Vacuum advance curve
This is not to be a racing engine (can you imagine a black limo at the drags?) But I just wanted to have a good running engine with good power over a reasonable range and hopefully some decent mileage. Hope you can help me.
Regards,
Earle
EarleI need help! My engine is a '49 block with 3/4 cam by Elgin, 9 to 1 pistons by Ross, three carb manifold, headers, polished ports and combustion chamber, balanced, etc. The engine is installed in a 1940 Series 80 limited sedan. I plan to order a custom distributor from from Performance Distributors. They will tailor the advance curves to any specs I call for. The stock unit I have I know is tired and will be replaced. If I set the timing to stock specs, it is smooth at lower rpm and load and pings like mad under higher load and RPM. If I retard it to get rid of the ping, then it runs very rough at lower rpm. I am running with the vacuum advance installed and hooked up. It appears to me that the stock advance curve is just too aggressive for that compression ratio. I wonder if I need less machanical advance and somewhat greater vacuum advance.
What would you suggest as:
1. Initial Set point
2. Machanical advance curve
3 Vacuum advance curve
This is not to be a racing engine (can you imagine a black limo at the drags?) But I just wanted to have a good running engine with good power over a reasonable range and hopefully some decent mileage. Hope you can help me.
Regards,
Earle
The 1949 320 Delco distributor (Part# 1110815) mechanical advance starts at 500 engine rpm and comes in at 23 degrees (Crank timing) @ 3000 engine rpm. Use this info to see if the springs are weak causing the timing to come in too soon. Since your engine has been modified you will need to test to see what the timing needs to be. First make a temporary tape with around 50 degrees of timing marks that can be attached to the harmonic balancer with a temporary pointer. Set the pointer to the first mark on the left side of the tape at TDC for cylinder #1. Disconnect the vacuum advance line and plug the line so vacuum won’t leak. Set your distributor to give the best WOT results from an idle and for various higher rpms while under load in different gears going down the road. You may have to play with springs in order to find the best rpm to bring in full timing. This should give you a base for the new mechanical advance curve. Put the vacuum advance line back on and work with it for best no load idle and various steady highway speeds. Stock vacuum advance starts at 5 to 7 inches of vacuum and adds 11 degrees of crank timing by 10 to 12 inches of vacuum. If you want, modify the stock distributor’s mechanical advance stops and springs to duplicate the new distributor specs and verify results before ordering a new distributor.
See reply #427 in "Anything new from the straight 8 hot rodders" by 39Cent for a reference to a very detailed article.
Paul
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