Timing education

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Oct 8, 2006 | 09:19 PM

#16

krewat

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From: Long Island USA

Quote:

Originally Posted by pbear6969

You are right Carl. It is bored .30 over, heads shaved, block decked and .38 thick head gaskets. It is more like 10.62 to 1. I just rounded it up. I should have around a 34 quench and with running the 292H cam it gives me about a 8.59 dynamic. It will be close, but I think I can run high test gas without a problem.

This sounds close to my 390 build for my highboy. It was quite the animal, required 93 octane, and VERY creative vacuum advance and carb tuning. Manifold vaccum advance, OH, the HORROR!!!!!

I was close to 11:1, with TRW flat-tops.

I think the cam and other info is in my gallery.

Oct 8, 2006 | 09:30 PM

#17

pbear6969

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From: North Carolina

Quote:

Originally Posted by krewat

VERY creative vacuum advance and carb tuning. Manifold vaccum advance, OH, the HORROR!!!!!

I can believe the horror part. This whole thing has been very close to that already. I guess I will have to let my mechanic uncle do the vacuum and carb tuning. I haven't the first clue as how to tune a carb or vacuum. I can mess a little, but that is about all.

Edit: I just read my carb booklet and it told me how to do some carb tuning by using a vacuum gauge or tach. What would the best vacuum reading be? Is that something that is different from every motor or something someone could recommend for me? Should I set the timing first or adjust the carb first?

Last edited by pbear6969; Oct 8, 2006 at 09:41 PM.

Oct 9, 2006 | 11:24 PM

#18

Putt

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From: Colville, Washington

Set the timing first, then adjust the carb for the highest stable vacuum reading you can get at an acceptable idle speed. The carb will react to the timing changes much more than the other way around.

The vacuum reading will change from engine to engine, but "normal" is considered to be 17 to 20 inches of mercury(the proper vacuum unit of measure

) It takes about 12 or more in. hg. to run power brakes.

Oct 10, 2006 | 10:41 AM

#19

"Beemer Nut"

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From: "Islander"

Putt; with that 292H cam pbear will be lucky to see 12" at 900 rpm idle.

Oct 10, 2006 | 11:29 AM

#20

"Beemer Nut"

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From: "Islander"

With your build at 10.7 cr with stock 6090G heads and a standard flow single plane intake I came up with 164 BMEP, with a high flow single plane 173 BMEP, both at 4,500. You need a complete dizzy recurve with vacuum and mechanical as your close but shouldn't be detonating as bad as you said.

Oct 10, 2006 | 07:56 PM

#21

pbear6969

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From: North Carolina

Quote:

Originally Posted by Beemer Nut

They are not 6090G heads just C7AE-A heads. The 6090's were the high flow heads correct? The heads have been ported and polished. The intake is a Edelbrock Streetmaster that was ported and polished. Now when you say BMEP I am lost, have no clue what you are talking about. Same goes with the dizzy recurve, never messed with it. It might not be detonating as bad as soon as I tune the carb and set the timing. Right now the carb is at factory presets and the dizzy is lose so we can set it with an advance timing light. Maybe I shot off at the mouth too soon, but wanted some opinions just in case it was a big problem. Will a lead substitute help any?

Oct 10, 2006 | 08:55 PM

#22

"Beemer Nut"

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From: "Islander"

I used stock 6090G 427 LR heads as an example to give you the benefit of the doubt should you have ported heads, sorry I was trying to guess, will keep my mouth shut in the future. third generation speed "Nut" where good isn't the best you can get out of what you have to work with.

.....=o&o>.....

Oct 10, 2006 | 09:04 PM

#23

pbear6969

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From: North Carolina

Oh ok thanks for the correction. I read a little about the BMEP and I can't figure anything because I don't know what kind of HP/ft lbs I have. I can guess or go by what someone told me desktop dyno says. They said it should be putting out around 425 hp and like 450 ft lbs. Is this close to what you think or is it too high? I hope I at least have 400!!! :|

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Oct 10, 2006 | 10:00 PM

#24

"Beemer Nut"

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From: "Islander"

pbear, checking notes on my scratch pad your specs with 6090 G heads I came up with 448 hp @5,500 and 478 tq @ 4,000 rpm's. This is with cam advanced at 1 degree.

.....=o&o>.....

Last edited by "Beemer Nut"; Oct 10, 2006 at 10:03 PM.

Oct 10, 2006 | 10:09 PM

#25

pbear6969

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From: North Carolina

Quote:

Originally Posted by Beemer Nut

pbear, checking notes on my scratch pad your specs with 6090 G heads I came up with 448 hp @5,500 and 478 tq @ 4,000 rpm's. This is with cam advanced at 1 degree.

.....=o&o>.....

I guess that will do. I will find out what the rear wheel HP is after I get it all dialed in and get all the other loose ends tied up. Exhaust, interior, paint, etc..... That is the HP you go by anyway. Flywheel HP isn't any count if it can't get to the road!!

Oct 10, 2006 | 10:42 PM

#26

"Beemer Nut"

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From: "Islander"

The driveline will eat app 27%.

Oct 11, 2006 | 07:10 PM

#27

pbear6969

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From: North Carolina

Quote:

Originally Posted by Beemer Nut

The driveline will eat app 27%.

Yeah that's what stinks so bad. Is there a better alternative?

Oct 11, 2006 | 07:18 PM

#28

"Beemer Nut"

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From: "Islander"

More horsepower to recover your losses. Even a stick box and rear diff you lose a sizeable percentage. A well oiled chain is 97% efficient.

Oct 11, 2006 | 07:21 PM

#29

pbear6969

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From: North Carolina

Quote:

Originally Posted by Beemer Nut

More horsepower to recover your losses. Even a stick box and rear diff you lose a sizeable percentage. A well oiled chain is 97% efficient.

LOL I guess nothing is perfect. I think I can live with what I have now. It's never enough no matter what anyone has!

Oct 11, 2006 | 08:32 PM

#30

"Beemer Nut"

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From: "Islander"

My 'ex wife is perfect just ask her and me a POS, ask her again. I think I sent PM a photo of her to ya, the rattler.
Check with member Greg (GTEX) I think he had crank then dyno runs on his 446 motor. The driveline losses alone can haul a Toyota around, kind of sick.
They say you can gain a few HP to the tires with synthetic oils. This ain't NASCAR here just a FE powered jalopy right?

Remember, some is good, more is better and too much is about right!

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