65 FI Performance Issues

[Mike R.]

I recently bought a 1965 FI roadster. It has a close ratio 4sp and 4.11 gears. It is 90% original but has things like modern spark cables, spin on oil filter etc. The car runs fairly well but not perfectly. The "issues" are:

Even with 38 deg of timing the engine is not pinging on pump gas (elevation 2100'). Do I have 11:1 compression?

The idle is somewhat erratic. It will idle OK then it wants to die. Could be ignition or FI. At high rpm (no load) the timing starts jumping around. The local guru attributes this to slop in the timing chain but I am not sure about this.

Acceleration is OK but not startling. My only other experience was a 69 with a built 468 engine and a Ford GT that I currently have. Both obviously have a lot more power. I expected that the fuelie would be capable of spinning the tires from a rolling start on a good surface. I have Dunlap 215/70 radial tires.


So far I have:

Removed the distributor. The bushings seem solid and I can get a .016" gauge under one side so I would guess that end play is about .010"

If I put my hand on the distributor cap with the engine running I get shocked but I do not see sparks in the dark and the engine is not obviously missing when driven. I will replace the boots.

I pulled one plug and it looked good.

I am wondering it my balancer could have slipped(???) and now the timing mark is off.

Any suggestions, observations or comments are appreciated.

Mike

[Jerry G.]

Re: 65 FI Performance Issues

The starting issue is probably caused by use of pump gas. The FIs have an issue with the fuel distribution spider(next to the intake,under the plenum) which heats the fuel and causes it to percolate.This causes hard hot starts. Use of aviation fuel or race gas will cure this. The issue of erratic idle can be caused by using the wrong vacuum advance can. The can needs to be matched to the 30-30 cam.assuming you still have the 30-30 cam. Someone else will be able to tell you which can you need or do a search of the archives. Jerry

[Mike R.]

Re: 65 FI Performance Issues

The starting issue is probably caused by use of pump gas. The FIs have an issue with the fuel distribution spider(next to the intake,under the plenum) which heats the fuel and causes it to percolate.This causes hard hot starts. Use of aviation fuel or race gas will cure this. The issue of erratic idle can be caused by using the wrong vacuum advance can. The can needs to be matched to the 30-30 cam.assuming you still have the 30-30 cam. Someone else will be able to tell you which can you need or do a search of the archives. Jerry

Thanks Jerry, There is no *starting* problem. I said that the acceleration is less than *startling*. After a few decades of listening to Jan and Dean, The Beach Boys and others, I was expecting more performance. Sorry for the confusion.

Mike

[Willard M.]

Re: 65 FI Performance Issues

I have owned five FI Corvettes in the past, from 57 to 65's. Currently I have a 64 FI with the same engine that you have. It has 4.11 gears and I run racing fuel after having all kinds of issues with lesser fuels. While it indeed is a great car and fast for it's time, it doesn't compare to some of the stuff we have available now. The torque and power of my C6 is much more impressive as many others have noted. While we all seem to believe that we went faster when we had more hair and less weight around the middle, the reality is that this is not the case. Your car appears to be in need of some tuning but it won't have the blistering performance of today's machines. Despite this, enjoy your fuelie for what it represents-the highpoint of technology and performance for it's time.

[Mike R.]

Re: 65 FI Performance Issues

Thanks this is what I suspected. Can you tell me if your 64 FI car had detonation issues with 92 octane fuel and book spark advance numbers? I have easy access to aviation gasoline and I will see if that makes a difference.

I have owned five FI Corvettes in the past, from 57 to 65's. Currently I have a 64 FI with the same engine that you have. It has 4.11 gears and I run racing fuel after having all kinds of issues with lesser fuels. While it indeed is a great car and fast for it's time, it doesn't compare to some of the stuff we have available now. The torque and power of my C6 is much more impressive as many others have noted. While we all seem to believe that we went faster when we had more hair and less weight around the middle, the reality is
that this is not the case. Your car appears to be in need of some tuning but it won't have the blistering performance of today's machines. Despite this, enjoy your fuelie for what it represents-the highpoint of technology and performance for it's time.

[William C.]

Re: 65 FI Performance Issues

With factory pistons in my '65, I have not had any detonation problems under hard acceleraton with current "Premium" unleaded gas. Owned many of these thru the years, none would break the tires loose from a roll, including 4.56 rear gearset models. The engine produces horsepower at high RPM by design, it will neve feel like a 468 bigblock.

[Willard M.]

Re: 65 FI Performance Issues

My major problem was fuel percolation with av gas or pump gas, something that has been written about in prior posts. I had a number of issues with my 64 when I first got it including having the wrong cam but it sure ran like crap with pump gas. I wish that there were some easy and cheap answers but it seems like racing fuel is the only way to make these cars run well-at least for me. Others have done OK with other fuels, as you can see by checking the archives. Jerry Bramlett has an informative website and I would encourage you to check it out.

[Jerry G.]

Re: 65 FI Performance Issues

One other issue is the close ratio transmission. It's first gear is "higher" that a wide ration. So it has less of a multiplier to the rear wheels. i have a 65 FI CR F40 TI car and it will break the rear radials loose fairly easily. I live a 5800 feet elevation. The car has 19000 miles and I've had it for 38 years so I know it's all original internally.

[George J.]

Re: 65 FI Performance Issues

I also have a '65 fi car. When having the engine rebuilt, I had the original style pistons put in and the actual compression ratio is about 10.2:1. I have had no problem getting it to run on pump gas (with 10% ethanol) once the mechanical and electrical issues were solved.
You MUST make sure the ignition system is functioning correctly. No "well it must be's". If there is any doubt, have the distributor rebuilt.
Use the correct vacuum advance can and verify it is functioning correctly.
Set the timing to come in early and use 38 degrees total advance.
Verify the idle speed by an electrical tune up device. Don't use the dash tach. Set the idle at what it likes. It might be 1100rpm. So be it.
Make sure the dwell is correct.
Don't use the ignition shields until you get it to run correctly. Then you can try and install them.

If these don't solve your problems, then I would look into making sure you have the correct cam and that it is timed correctly. After that, if you are still having problems, then I would get into the Fuel Injection unit.

Though not as fast as a new Ford GT (hell, what is?) they are still quite quick. I was dead even with a 2007 Mustang GT 500 from a twenty roll, up to about 90mph. And that is with a 3:36 rear gear. These cars move.

Good luck.

George

[Mike R.]

Re: 65 FI Performance Issues

Thanks everyone! Today I found that my timing mark on the balancer is not directly across from the keyway on the crank (tip from Jerry Bramlett's website). It appears to be 2-3 degrees off. I verified compression at 145psi which agrees with the book figure of 150psi (I am at 2100'). The distributor is solid. I filled the tank with Avgas and it idled smoothly at 900rpm (car tach, I will try the electronic tach on my timing light tomorrow) but I did not drive it around much. I am waiting for new distributor boots for the spark plug cables, I get shocked if I put my had on the them but they are not arcing to anything at idle.

It may be that my performance expectations were unrealistic. I wonder how much power is lost to the side exhaust vs under car exhaust?

[George J.]

Re: 65 FI Performance Issues

When I had my engine rebuilt we dyno'd it and with the dyno exhaust it pulled 333hp and just changing to the side exhaust it was down to 294hp. This was with no tuning. The shop said when they dyno'd a big block, those sidepipes caused a 100hp loss.

George

[Duke W.]

Re: 65 FI Performance Issues

George's lab dyno number with a dyno exhaust system (no mufflers) are about what I would expect with no head work. With some head work it would get closer to the advertised 375 SAE gross HP rating.

The best way to find out if engine performance is up to snuff is to get the car tested on a chassis dyno. With a "stock" 327/375 HP engine in good running order I would expect to see something on the order of 230-240 SAE corrected RWHP at about 6000 with the under the car exhaust. Side pipes will knock it lower.

If you do a dyno test start the pulls from 1500 and go to 6500.

Duke

P.S. George - Did your engine have the OE manifolds during the test or headers? What was peak torque @ RPM? If you have the printout or graph and can scan and post it that would be great.

I have a lab dyno test on another 375HP. It had some head work, but no flow numbers. Peak SAE gross HP (STP correction) with headers was 365 HP at about 6000 and 365 lb-ft @ 4800. Unfortunately, the test (as usual) was started at about 3700, so no low end performance data.

[Mike R.]

Re: 65 FI Performance Issues

Wow, this quite bad . I suspected a power loss with the side exhaust but not quite so much. I wonder how much loss there is with the standard under car system?

Mike

When I had my engine rebuilt we dyno'd it and with the dyno exhaust it pulled 333hp and just changing to the side exhaust it was down to 294hp. This was with no tuning. The shop said when they dyno'd a big block, those sidepipes caused a 100hp loss.

George

[Mike R.]

Re: 65 FI Performance Issues

Can you tell me what head gasket was used that resulted in the 10.2 CR? I can slide a .040 feeler guage between the block and head and I have read that a .020" shim gasket was originally used in these engines. Of course, I have also read (on these forums) that TWO .020" shim gaskets were used!

Mike

I also have a '65 fi car. When having the engine rebuilt, I had the original style pistons put in and the actual compression ratio is about 10.2:1. I have had no problem getting it to run on pump gas (with 10% ethanol) once the mechanical and electrical issues were solved.
You MUST make sure the ignition system is functioning correctly. No "well it must be's". If there is any doubt, have the distributor rebuilt.
Use the correct vacuum advance can and verify it is functioning correctly.
Set the timing to come in early and use 38 degrees total advance.
Verify the idle speed by an electrical tune up device. Don't use the dash tach. Set the idle at what it likes. It might be 1100rpm. So be it.
Make sure the dwell is correct.
Don't use the ignition shields until you get it to run correctly. Then you can try and install them.

If these don't solve your problems, then I would look into making sure you have the correct cam and that it is timed correctly. After that, if you are still having problems, then I would get into the Fuel Injection unit.

Though not as fast as a new Ford GT (hell, what is?) they are still quite quick. I was dead even with a 2007 Mustang GT 500 from a twenty roll, up to about 90mph. And that is with a 3:36 rear gear. These cars move.

Good luck.

George

[Duke W.]

Re: 65 FI Performance Issues

On SHP/FI small blocks, even with massaged heads, actual backpressure with under-the-car exhaust is only about 3 psi at peak revs, which is very good for a high performance engine with a reasonably quiet exhaust system. I don't have any hard data for sidepipe backpressure or power loss.

Backpressure increases with the square of flow (and power loss increases with the cube of flow), so SHP big blocks get up to 5-6 psi, which is basically what limits their output. As another point of reference the single catalyst SBs from the seventies generate about 10 psi backpressure, which is why trying to build these engines for more power is hopeless until you do something about the exhaust system.

Based on data I have the SAE net/gross conversion factor for SBs (with only the water pump, alternator, and clutch fan on the front end) is about 0.89, which is very good due to the free flowing under-the-car exhaust and the clutch fan. Nearly half of the loss is due to the lower air density used for SAE net. The rest is mostly the exhaust system.

So using George's SAE gross numbers, his SAE net at the flywheel is just under 300 HP.

Using a driveline efficiency of 0.85 his expected SAE corrected RWHP (air density is the same as SAE net at the flywheel) would be close to 250.

When testing on a chassis dyno it is critical to have sufficient external cooling to keep the fan clutch from engaging, which is why I also recommend testing in cool temperatures. Otherwise recorded output could be down by 15 lb-ft peak torque and 10-12 HP.

If the fan clutch remains "loose", the fan will only consume 1-2 HP.

Of the two "327 LT-1" configurations I system engineered, one made about 360 SAE gross HP on a lab dyno at 6500 with manifolds. A different, but identically configured engine made 278 SAE corrected RWHP on a chassis dyno, but that was on a 90 degree day with no external cooling and the fan clutch was "locked". If the fan had not engaged the RWHP number would have been about 290.

Duke