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  #16 (permalink)  
Old 11-13-2012, 04:44 AM
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Wow thank you guys for all the suggestion. F-Bird I like the cam choice you suggested. Are the Summit lifters ok or should I get GM ones.

The rockers are Summit roller tip stock style with 1.6 ratio. I never got around to getting full roller rockers.

I originally had a 3,000 stall converter in it, and it launched great but my gas mileage was about 8. When I did the last rebuild, (I had one of the Edelbrock cams from China and one of the lobes went flat chewed the lifter up and flushed it through the motor) I changed to the XE268 and it ran great never had any problems with it. It just for some reason developed all these problems while sitting over the last 8 years.

I would much rather just change the cam and lifters and not pistons and rings.

And I will definately look at the timing curve. I may need some help on that though.

Bret

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Old 11-13-2012, 07:34 PM
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Detune 388 Stroker

Here is a good article to read before you start setting up your distributor. Listen to F-BIRD'88 on setting up your distributor. Your compression ratio is 10.792 and your DCR is 7.860. If the pistons are .010" from the top of the deck at TDC + .041" compressed gasket thickness your quench is .051". If you had set the quench to .040 your static compression would have been 11.097 and the DCR would have been 8.073. Is the Comp Cams valve springs you are using Part# 981-16? If so the installed height should be 1.700", 105 lbs. seat pressure at installed height, 1.250" open height, 273 lbs. open pressure. Stock pushrod length is 7.800" and Edelbrock recommends .100 longer than stock. But it would be best to measure with an adjustable pushrod after you have it set up correctly. The engine should run without pinging if you have the correct springs, pushrods, and the timing curve is right. What brand lifters are you using with the XE268H cam and have they been sitting 8 yrs. too. BTW Edelbrock recommends Champion RC12YC spark plugs for your heads. If you have any weird ignition problems thrash the ProComp distributor.
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Old 11-13-2012, 09:15 PM
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Detune 388 Stroker

Quote:
Originally Posted by bj383ss View Post
Wow thank you guys for all the suggestion. F-Bird I like the cam choice you suggested. Are the Summit lifters ok or should I get GM ones.

The rockers are Summit roller tip stock style with 1.6 ratio. I never got around to getting full roller rockers.

I originally had a 3,000 stall converter in it, and it launched great but my gas mileage was about 8. When I did the last rebuild, (I had one of the Edelbrock cams from China and one of the lobes went flat chewed the lifter up and flushed it through the motor) I changed to the XE268 and it ran great never had any problems with it. It just for some reason developed all these problems while sitting over the last 8 years.

I would much rather just change the cam and lifters and not pistons and rings.

And I will definately look at the timing curve. I may need some help on that though.

Bret
The summit cam 1103 will not work in your engine unless you plan on buying racing gas. The intake valve closes at 34 degrees ABDC and will raise your DCR to 9.471 which will not run on pump gas. To run pump gas you need a good DCR of 7.5-8.5.
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Old 11-13-2012, 10:14 PM
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OK, so currently we have 795.56 cc's in the cylinder, 2.12 cc's in the piston deck height, ~64 cc's in the chamber, 9.1 cc's in the gasket and 6.0 cc's in the piston crown. Total- 876.78 cc's. Less cylinder cc's- total 81.22 cc's. Divide 876.78 by 81.22 and find 10.795:1 static compression ratio. Intake valve closes at 42 degrees after bottom dead center, yielding a DCR of 9.143:1 on the KB calculator. So, yeah, I suspect it sounded like a coffee can full of marbles.

Keep the cam and all else except the pistons. Change 'em out for some 18cc dish pistons. SCR will be 9.70:1 and DCR will be 8.23:1. And everyone will live happily ever after.
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Old 11-14-2012, 04:53 AM
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Huh so the Summit cam won't work. Now its back to changing the pistons. I have looked at Summit and Jegs for pistons and they both only offer 12cc dish pistons in the Speed Pro range. Im not really wanting to spend $600 plus for pistons. Though I will if I have too. Where can I get 18cc dish pistons?

I also think my CR is a little bit higher because I had the Edelbrock heads resurfaced on the last rebuild, because they had been on 3 previous builds and my machinist recommended it.

Cdminter I bought the Comp K-kit. So I used the proper springs and lifters. I did check the install height and it was correct. I also am using .100 longer pushrods for the Edelbrocks. I remember when I put them on my stock 350 I was pissed because I didn't know about the pushrods and had to wait 5 days for them to come in the mail. And then 388 was run periodically during the 8 years just not everyday.

This engine ran perfect when I first installed it back in April of 2004. I did a full rebuild because I got promoted at work and was going to be driving more. But I went and bought an 02 Camaro SS in Nov of 2004, so the Caprice sat in the garage ever since. Its just frustrating that it has got to the point that I can't drive it anymore.

I also have a 64' Chevy stepside that I recently inherited. It sat for 10 years and with new gas, ignition and battery I got it running great. It has a stock 350 with a small RV cam in it. I am just enjoying the stock engine its much easier to tune. That's why I want to detune this engine as well. I guess my Hot Rod blood has thinned a little as I have gotten older.

Bret
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  #21 (permalink)  
Old 11-14-2012, 01:48 PM
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im confused here. it ran perfect 8 years ago with no changes its rattling after start up? Gas has gotten worse in the last 8 years but it should still be drivable.


Cam that will fix it if it was from cr is simple. Comp magnum 280H its a favorite of many hot rod guys its big its nasty but it should control knocking. But....

If it makes noise when cold its not detonation. its not easy to make an engine knock in the first minute of running unless you got something really wrong.

I am betting its a bent valve hitting the piston if I understand the problem right.

Knocking from high cr is between 1500 and 4000 rpm usally and only during hard acceleration usally. But if it was fine and now its knocking like crazy after setting for 8 years all the time then its not from CR it something much worse. Sounds like a valve got rusted open and bent when the engine was turned over.
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Old 11-14-2012, 03:37 PM
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Yeah I can see how you are confused. It did sit for the last 8 years except for the month of January in 2010 when I drove it to work due to my Camaro being down. When I stopped driving it that month it started running really bad and I parked it.

I have tried for the last 2 years on and off to find the problem. I started by changing out the original HEI dist(which was worse for wear) with the Procomp and that didn't fix anything. Next I readjusted the valves and that didn't change anything so I thought maybe the gas had gone bad.

I put off dropping the tank for the last year and I finally did it a couple of weeks ago and didn't realize how easy it was. So I started it up again hoping it would run better with new gas but it still has the same problem. Alot of detonation when I try to drive it. So I messed with the timing from 8* to 18* and no luck.

So I thought I would just detune it to more of a stock motor. So thats when I posted on here looking for a more tame or stock cam that would work with my existing parts and changing the pistons to lower compression. (even though I know this engine is a mild combo).

I do have a set of 882 heads I could put on and just change the cam, but I really like the Edelbrocks.

Sorry for the confusion.

Bret
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Old 11-14-2012, 04:35 PM
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Does it stop knocking if you go above 4500 rpm.

Have you changed the oil any metal in it. Do you have a magnet in the oil pan or drain plug. I would drain the oil and take the old filter and cut it in half and see if its filled with junk. Also see if the oil is filled with crap. You can strain it with a shop towel and see if any metal in the rag.

Are the plugs clean. All the same. I think you already said i will look back.

Did you put a full tank of gas in it. If you used just a few gallons go to the race track and buy 104 octane or something better and see if it runs right. I got a feeling its not going to change things. Either you have major oil on top of the pistons issue or a spun bearing making funny noise. A cam and detune might help if the cam is wiped but if it is the cam engine will be filled with scrap metal. I got a feeling exploratory surgery is in your future.

Yeah i cant see any reason it would start knocking like crazy just after it has been setting. A compression check might be a good idea before you take it apart. Seems like something is wrong. I think a cam swap and lower compression might fix the problem but i think you will find the problems when you take the pistons out and check over the heads. It is very possible that it spun a bearing or had some other oil related issue after being sitting for so long and starting up dry. But i cant say anything for sure with out crawling under the hood and hearing it first hand.
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Old 11-14-2012, 04:41 PM
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I hear what you are saying. I did change the plugs. Did a compression check this past week and all cylinders were between 180-190 psi. I havent changed the oil in a long time because the engine only has about 3,000 miles on it. As far as going above 4500 rpm it won't go that high in gear right now! And I only put about 3 gallons of gas in the tank. The tank looked really good inside I was really surprised for being 33 years old.

I will drain the oil and cut the filter apart as you said and see if there are any signs.

Bret
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Old 11-14-2012, 05:25 PM
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Quote:
Originally Posted by bj383ss View Post
I hear what you are saying. I did change the plugs. Did a compression check this past week and all cylinders were between 180-190 psi. I havent changed the oil in a long time because the engine only has about 3,000 miles on it. As far as going above 4500 rpm it won't go that high in gear right now! And I only put about 3 gallons of gas in the tank. The tank looked really good inside I was really surprised for being 33 years old.

I will drain the oil and cut the filter apart as you said and see if there are any signs.

Bret
5 gallons of race gas will up the octane enough so it should not knock. Still knocking after that something is up. Never seen an engine you could not drive easy and avoid it knocking. You cant put it in first gear and lightly touch the gas and let it rev up not going fast just higher rpm. It will kock right away?
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Old 11-14-2012, 06:57 PM
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When I put it in gear and hold my foot on the brake and push on the gas, that is when I can hear the valves rattling as I call it, or real bad detonation.

The weird thing is it does not blow any smoke from either tail pipe. The last time when my cam went flat in my last engine it was blowing smoke like a train and idling very rough.

When it is idling it runs fine and you can blip the throttle and it doesn't sound like there is any mechanical issues.
Thats one of the disadvantages to a lopey cam. Sometimes its hard to diagnose if you have a ignition, vacumn leak or what is wrong.

Bret
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Old 11-15-2012, 12:35 AM
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Rod

I don't guess it might have a rod starting to knock?? Just a thought, Is the old pressure steady? Does it drop when the engine warms up?? Just a thought , It sounds like its very loud, And some times you can here it on both sides?? I would drain the oil and cut the fiter open and just look,
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Old 11-18-2012, 10:32 AM
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Bodiebyes it has good oil pressure. 80psi when cold and about 60-65psi when warmed up.

I cut the oil filter open today. I didn't see any large pieces of metal in the filter media. However the oil at the bottom which was about a 1/2" deep had a metallic tint to it. Very small particles. I have never cut a filter open is this normal? The oil I drained out of the filter before cutting it open was fine just a little dirty.

Looking for advice from here. If the small particles are normal, then I am going to put a set of rebuilt 882 heads I have on and change the came to a small RV. Make it basically into a stock engine.

Bret
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Old 11-18-2012, 11:37 AM
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Heads resurfaced

How much did you take off the heads? Did you use a pushrod checker to check what length you need? Too long , wrong angle, Nosiey? Just a thought? Man I have been there chasing Gremlins!!! Taking the performance out of the is not the awsner. It has to be timming related. Take the plugs out. take the valve covers off. Turn the engine over by hand untill you get to top dead center. It will push air out the number one plug. Both the rockers on number one will be loose. Number 6 they should have tension on them. if Number one has tension . you are on Number 6. Rotate 180 degrees. Balanance should be on zero. Rotate it to 20 degrees before. Check where distubter is pointing. Line it to # 1. put evrything back together and crank it. Timming should be set. Thats how I do it. and It should crank and run. You might have to play withthe timming,But it should be close. I like to set the valves on cynder at a time. Just how you got # 1 up turn the engine by hand, keep the plugs out . When the exhaust valve stats to open. Set the intake, Back it off till loose , the tighten till you feel Zero play the turn it a half a turn. Exhaust valve, Rotate the engine untill the intake valve stats to close. Then set the exhaust the same way. I know its time consuming, But it will be right. I only run soild cams so it set the lash like this. An Old timer showed me this way and its the only way I do it. I works evrytime. Check the push rods and Balancer first, You'll get it. Don't go back stock!! It sucks!! If you are worried about compression try a thick headgasket first, I would. As long as you are under 10-10.5:1 you should be ok. Especally if you have alumnium Heads. Just a thought. Good luck!!
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Old 11-18-2012, 12:22 PM
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Quote:
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If you are worried about compression try a thick headgasket first, I would.
Generally speaking, a thicker gasket will make the situation worse due to a wider squish.
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