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choosing pistons and cam 327 FI its complicated

 
Old 03-14-2019, 03:48 PM
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ohpoppy
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Default choosing pistons and cam 327 FI its complicated

The block is at the machine shop.. I need to order internals for this original 64 375 hp FI,

I'm lost.. my thoughts are

I have marine gas stations nearby that sell ethanol premium. I wonder if I should go stock compression and cam or cut it down a little. This engine had a compression ratio @ 11 to 1.
If I cut it down to 10.5 to 1 it will run better on the available gas but the stock 300 hp 64 Corvette was running 10.5 to 1. Is there a way to get around 330 hp on 10.5 to 1. I guess the cam, FI, and heads I will bring it up.. will it? or should I cut the compression a little more?


I have the correct big valve heads and the original Rochester fuel injection. .

As far as a cam for it, I tend to go hydraulic since I hate adjusting valves on a hot running engine. I know little about these things.. do they make a hydraulic cam that can handle the redline on this car. (i think its 6000 rpm but need to look at the tech).

Savvy engine builders please weigh in on what you think is a best combination of pistons, rods, cam and lifters. Brands and a reasonable source would help, too. I am a parts changer, not a gifted engine builder. I would like prices to be on the reasonable side too if possible.. yes I understand the value of this car but want to do it smart and respectful.

don't be afraid to defy my thinking since I want whats best and I just don't know!
I will build it at a qualified engine builders shop but do it myself with a little help.

Last edited by ohpoppy; 03-14-2019 at 03:50 PM.
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Old 03-14-2019, 04:24 PM
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Originally Posted by ohpoppy View Post
The block is at the machine shop.. I need to order internals for this original 64 375 hp FI,

I'm lost.. my thoughts are

I have marine gas stations nearby that sell ethanol premium. I wonder if I should go stock compression and cam or cut it down a little. This engine had a compression ratio @ 11 to 1.
If I cut it down to 10.5 to 1 it will run better on the available gas but the stock 300 hp 64 Corvette was running 10.5 to 1. Is there a way to get around 330 hp on 10.5 to 1. I guess the cam, FI, and heads I will bring it up.. will it? or should I cut the compression a little more?


I have the correct big valve heads and the original Rochester fuel injection. .

As far as a cam for it, I tend to go hydraulic since I hate adjusting valves on a hot running engine. I know little about these things.. do they make a hydraulic cam that can handle the redline on this car. (i think its 6000 rpm but need to look at the tech).

Savvy engine builders please weigh in on what you think is a best combination of pistons, rods, cam and lifters. Brands and a reasonable source would help, too. I am a parts changer, not a gifted engine builder. I would like prices to be on the reasonable side too if possible.. yes I understand the value of this car but want to do it smart and respectful.

don't be afraid to defy my thinking since I want whats best and I just don't know!
I will build it at a qualified engine builders shop but do it myself with a little help.
You can easily build a 330 HP with 10.5 to 1 compression. Get some flat top pistons. Maybe get the heads worked on. Cam go with a 30/30, L79 cam grind would do the trick. Can run on premium gas and can always add some VP racing fuel. But then again not really would notice if you only had 325 HP... You are limited to the FI unit and intake... Even better get a set of trick flow heads with double hump castings on them:

https://www.hotrod.com/articles/smal...rns-tensema16/

Last edited by jimh_1962; 03-14-2019 at 04:32 PM.
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Old 03-14-2019, 04:35 PM
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My vote is to make it as stock as if it was coming off of the assembly line today. I'd get as close to factory specs as possible. What is the rub with the solid lifter cam? The valves don't need to be adjusted that often. It is your can and your choice but I believe it is worth more in stock condition. Aftermarket internals are OK but please don't change the potential performance...
I have a 327 in my 57 full size Chevrolet 150 car with Rochester FI on it. I will not use any gas that has ethanol in it so I use 100 LL avgas. I have 11:1 compression ratio and it runs very well with this set up. Some are using 93 non ethanol gas with some success also... Al
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Old 03-14-2019, 04:43 PM
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vettsplit 63
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Elthanol Fuel in stock FI motors run like sh** around town in warm to hot weather. Won't idle, hard starting. My experience anyway.
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Old 03-14-2019, 04:44 PM
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I want to avoid the aviation gas.
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Old 03-14-2019, 05:16 PM
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When I rebuilt my L76, which is basically the same long block as the L84, my only deviations from the stock specs were the cam, head machining (dual springs) and the head gaskets. The COMP XS274S solid lifter cam is a bit milder than the stock 30-30 and the FEL-PRO 1003 head gaskets are .041" compressed so compression is a little less than 11:1. The car is very drivable and has much better mid-range performance than stock but I do use a mixture of pump premium and 110 race gas. Cam lash is .016" on both intake and exhaust and though it's adjusted hot there is no need to do it running. I've never had the car on a dyno but if you do a little research you'll find this combination is claimed to put out 5 HP more than a factory spec build.
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Old 03-14-2019, 06:32 PM
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I would rebuild using stock dome pistons, update the rods and maybe the LT1 camshaft, maybe. I would also use the stock replacement valve springs, don't let anyone talk you into high volume oil pump etc. Keep it stock..
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Old 03-14-2019, 07:23 PM
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Donald #31176
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Originally Posted by ohpoppy View Post
I want to avoid the aviation gas.
As Vettesplit mentioned old model FI will not run well in 80* plus temperatures using ethanol gas as the boiling point is much lower than 60s style gas..New FI engines run well as the fuel pressure is much higher and vapor lock is a non issue.. If you run the stock FI racing gas ( higher boiling point) will be necessary for it to run well. on high temperature days

PS if the machine shop insist that the block needs to be decked to equalize the 2 sides DO NOT let them. You must preserve the passenger side engine pad ..where the assembly date and VIN are stamped.. Losing the pad will devalue your car considerable..
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Old 03-14-2019, 09:18 PM
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ohpoppy
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The o-rings in the rochester are not suitable for ethanol since it was rebuilt 20 years ago then shelved. I will not use modern gas. There are 2 gas stations that have ethanol-free premium here, I'm on lake hartwell, professional bass fisherman use the E-free gas. What compression ratio will handle this gas without additives... thats what I'm after.
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Old 03-14-2019, 09:42 PM
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Comp Cams Xtreme Energy 264 HR retrofit is a hydraulic roller with a power band from 1,200 rpm throigh 5,200 rpm. Torque monster throughout the range.
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Old 03-14-2019, 10:13 PM
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Be advised that a lot of the Comp Cams XE cams are designed to quickly fill the cylinders at low speed to produce great power in engines with no more than 9:1 compression. In a 10:1 engine or higher, they are detonators. Assembled a '65 Pontiac 389 for a friend with dished pistons (8.5 CR) and a Comp Cams XE 268 cam, and that car runs like a raped ape on 89 octane with no ping. That same cam in my 11:1 389 would need 110 octane to run. You are better off going a little light on static CR with today's fuels. Also, rear gear ratio matters. A car with a 4.11 rear gear will tolerate more compression with less octane than the same car with a 3.36 rear gear.
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Old 03-14-2019, 10:14 PM
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I need to find out the octane of the E-free premium here. and determine whether lead in gasoline is required for this engine regardless of compression rstio. I read somewhere lead is important but I remember back in the day Amoco premium was lead free. I used it sometimes. I will go look at the pump tomorrow. octane booster contains lead.





I know so little about these things
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Old 03-14-2019, 10:25 PM
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Lead is not needed unless you are pulling a heavy trailer or installing the engine in a ski boat. You are lucky you are able to get E free gas. I can't get any in CA.
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Old 03-15-2019, 01:36 AM
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I rebuilt my original engine ‘64 fuelie 2 years ago. Stock rebuild with .020 over stock domed pistons, stock 30/30 replacement cam (mechanical lifters) and .018 shim head gaskets. I drive it ~1K miles a year. I run 100LL. Runs good regardless the weather. Idles nice at 750 rpm. It does not miss a beat to 6500. It works for me and I love the sound of that high compression 327 with mechanical lifters and N11s. I add in some beach boys music and it does not get any better on an early Saturday morning out in the country.


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Old 03-15-2019, 08:34 AM
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what and where did you buy the parts.. I could not find a supplier of stock gm pistons and cam
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Old 03-15-2019, 09:09 AM
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jegs weighed..

Josh Quellhorst (JEGS Performance)

Nov 12, 2:00 PM EST

Bob,
I do apologize for asking you what combustion chamber size your heads have. Piston manufacturers advertise compression ratios based on the combustion chamber size of the cylinder head. Therefore my intent was to ensure the compression ratio with your heads would allow for pump gas and not race gas as you originally requested.
To answer your original question, "a full point of compression is worth roughly 3 to 4 percent of engine power". So 375 horsepower at 11.0:1 compression dropped to 10.0:1 (required for pump gas with those heads) would equate to roughly a loss of 15 horsepower and reduce power to 360.
see the following pistons that match closely to what you are looking for: https://www.jegs.com/i/United-Engine...6.030/10002/-1
I hope I am answering your question to your satisfaction. Please let me know if I can help with anything else.
JoshI told him my heads are stock, apparently he was able to determine the combus chamber size. does what he figured out seems right?? and does anyone think its the right way to go. 360 hp stock 30 30 cam on pump gas.
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Old 03-15-2019, 09:44 AM
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Originally Posted by Donald #31176 View Post
As Vettesplit mentioned old model FI will not run well in 80* plus temperatures using ethanol gas as the boiling point is much lower than 60s style gas..New FI engines run well as the fuel pressure is much higher and vapor lock is a non issue.. If you run the stock FI racing gas ( higher boiling point) will be necessary for it to run well. on high temperature days

PS if the machine shop insist that the block needs to be decked to equalize the 2 sides DO NOT let them. You must preserve the passenger side engine pad ..where the assembly date and VIN are stamped.. Losing the pad will devalue your car considerable..
Many shops have cnc programs these days to keep the stamp (QMP racing in Chatsworth Car for example)
Deck it do it right

Those werent a true 11:1 anyways, make yours one get the quench right..update the solid cam port the heads...it will feel like its a bigger engine period!!
Make it at least asquick as a Camry or V6 Mustang
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Old 03-15-2019, 10:15 AM
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If the decks are reasonably flat, for the life of me, I can't imagine what performance gain could ever justify decking a stock rebuild.
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Old 03-15-2019, 11:30 AM
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It's kind of late to be starting the planning process, but you can catch up. I recommend the LT-1 cam to replace the 30-30. If you want a hydraulic cam, go with the L-46/82 cam advanced four degrees. With proper setup of the '67-up OE ...068 valve springs (Sealed Power VS 677) the valve train limiting speed is 67-6800 with the L-46/82 cam and 7250 for the LT-1 cam. Install with the Cloyes OE truck replacement adjustable roller chain.

A true CR of up to 10.5 is okay with 93 PON fuel, but reduce by 0.1 point for each lower octane number, which would be 10.2 for 91 PON fuel. The KB157 piston with a relatively thin head gasket should get you in he range.

Search for threads started by ghostrider20 and Dave McDufford from about ten years ago to learn about the "327 LT-1" configuration. Also search for threads by me, download and study the compression ratio article, and you may find some other subjects of interest.

If the rods are stock they are the early, weak 327 type, so those need to be replaced and there are good low cost solutions like the Eagle SIR5700.

Stick with OE equivalent parts from Federal Mogul and Dana Corp. Avoid aftermarket hot rod cams and other aftermarket parts other than the con rods.

Duke
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Old 03-15-2019, 04:58 PM
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after some reasonable consideration I'm thinking forged.. Speed-Pro Forged Pistons L-2165F 30 are reasonable and will give me a little under 10 to 1. Summit or ebay around 300. anybody afraid of this brand?? yes they are made in ...

summit has a compression ratio calculator which is helpful.
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