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Old 08-15-2007   #81
george88gta
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Re: hard start and intermittant miss

Update. Vacumn tester showed up last night, as well as my new leakdown tester. All I had time for now was to do a quick vacumn check. Could not find any leaks with the carb cleaner. However, I hooked up the vacumn tester to the Holley fuel pressure regulator, and it wont hold vacumn. If I pump the vacumn down to about 15 inches, the vacumn bleeds right off, nice steady drop, almost immedialtely. This doesnt sound right to me. I am thinking a defective diaphragm in the regulator. I dont think the diaphragm is replaceable so it is probably time for a new regulator. I will wait until I do the leakdown test before replacing. No sense in going in there twice, incase I need valve/head work.
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Old 08-24-2007   #82
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Re: hard start and intermittant miss

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Originally Posted by george88gta
Update. Vacumn tester showed up last night, as well as my new leakdown tester. All I had time for now was to do a quick vacumn check. Could not find any leaks with the carb cleaner. However, I hooked up the vacumn tester to the Holley fuel pressure regulator, and it wont hold vacumn. If I pump the vacumn down to about 15 inches, the vacumn bleeds right off, nice steady drop, almost immedialtely. This doesnt sound right to me. I am thinking a defective diaphragm in the regulator. I dont think the diaphragm is replaceable so it is probably time for a new regulator. I will wait until I do the leakdown test before replacing. No sense in going in there twice, incase I need valve/head work.
Ran the leakdown test this morning. Not good news. Cylinders 4 and 6 leak past the exhaust valve, about 25-30% leakage. Cylinder 2 leaks about 20% past the rings. All remaining cylinders had about a 5- 10% leak past the rings. I ran this test on a cold engine, could not see burning myself trying to get the plugs out of a hot engine, so hopefully, the ring leakage isnt as bad as it looks. Now the choices are valve job or a set of aluminum heads. Aluminum heads present a bit of a problem, I havent yet seen a set with the exhaust cross over ports for the EGR. Does leaving the EGR blocked destroy the catalytic converter? Does anyone know of an external EGR setup that will work with the stock TPI intake? EGR has to at least be there for inspection, no emissions testing yet for this vintage car.
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Old 08-24-2007   #83
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Re: hard start and intermittant miss

all heads that are designed for the firebird/camaro will have EGR cross over passages.

The ones for the corvettes will not.

So when you are shopping around for heads, look for a set that is emissions legal. For example, the Edelbrock performer series of aluminum L98 heads, fully assembled PN: 60859 out flow the aluminum L98 vette heads and have crossover passages for the EGR.
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Old 08-24-2007   #84
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Re: hard start and intermittant miss

Quote:
Originally Posted by merc3065
all heads that are designed for the firebird/camaro will have EGR cross over passages.

The ones for the corvettes will not.

So when you are shopping around for heads, look for a set that is emissions legal. For example, the Edelbrock performer series of aluminum L98 heads, fully assembled PN: 60859 out flow the aluminum L98 vette heads and have crossover passages for the EGR.
Thanks, for the tip. I looked at the Edelbrock design and they are using a small port for the egr. I am used to the big exhaust cross over port. I have seen some heads that have this small port ( Dart e.g.). Before I jump in to a new set of heads, I want to run a compression check to see what is happening with cylinder #2. I know it isnt leaking past the valves and it is hard to believe that an engine with less than 20,000 miles could have bad rings. Not ready to tear it down just yet, hoping to save that for a winter project. Depending on what is wrong with #2, it could be an engine removal.
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Old 08-24-2007   #85
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Re: hard start and intermittant miss

OUCH!! Sorry to hear that. Hopefully it wont be nothin more than just the top end.
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1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 08-24-2007   #86
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Re: hard start and intermittant miss

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Originally Posted by fearthisgta
OUCH!! Sorry to hear that. Hopefully it wont be nothin more than just the top end.
I'll know more next week. My assistant (flyboy son) is away on a mission. When he gets back we will do the compression test. Maybe I will ask him about the rumor I heard that he had done a few burnouts with the old girl, maybe not. He was driving the car a lot when it was a 305. I took the car to work and on the way home,the engine let go. I kept the 305 and if I need to replace the lower end, I may take the 305 to a local race shop. He runs 305's exclusively and has set several NHRA records with them. He swears by the 305, doesnt want anything to do with the 350's. More to follow. It just gets better and better. Anyone heard anything bad about the GM crate engines?
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Old 08-24-2007   #87
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Re: hard start and intermittant miss

They are expensive I know that lol

Other than that they look pretty decent for what they are.

My club mechanic runs a 305 into the 11s n/a and low 10s with the bottle. So he swears by em too.
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Old 08-25-2007   #88
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Re: hard start and intermittant miss

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Originally Posted by merc3065
They are expensive I know that lol

Other than that they look pretty decent for what they are.

My club mechanic runs a 305 into the 11s n/a and low 10s with the bottle. So he swears by em too.
If I have the 305 rebuilt, I wont be going for a race version. Maybe have it bored out .030" ( if it needs it), GM LT1 (LT4?) cam, have the heads modified to accept the new style valve seals and thats about all. This guy runs a carb'd Camaro and he is consistantly in the low 10's, no bottle.
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Old 08-25-2007   #89
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Arrow Re: hard start and intermittant miss

A friend stopped by this morning and we did a compression test. Only did 4 cylinders. #1 165 psi, #7 170 psi, #2 155 psi, #8 160 psi. Numbers look good. Since the numbers were that close , I did not bother to add oil to #2 to see if it went up. Sure looks like there is something wrong with the right side head. So its time to put it back together and go shopping for some street legal heads. Anyone know what the combustion chamber size is on the original 305 heads? I think it is 58CC, but not sure. If they are 64CC, then if I cant find a reasonable set of aluminum heads, I may have the 305 heads redone. Assuming they are not 58cc.
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Old 08-25-2007   #90
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GTA Year: 1987
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Re: hard start and intermittant miss

if you spend all that money rebuilding a 305 i'm going to cry...
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11.16 at 123 mph.
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Old 08-25-2007   #91
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Re: hard start and intermittant miss

Quote:
Originally Posted by MunsonGTA
if you spend all that money rebuilding a 305 i'm going to cry...
Well, I hate to see a grown man cry. Right now the plan is new or rebuilt heads and leave the 350 in place. It has a decent cam and it only has 20,000 miles on it. I am amazed at how clean it is ( I removed a valve cover) guess that Mobil 1 really works. Only thing that would make me consider the 305 is if I find any serious damage to a pistion or the block. So far there is no indication of that. You would be surprised how stout that original 305 was.
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Old 08-25-2007   #92
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Re: hard start and intermittant miss

Quote:
Originally Posted by george88gta
Well, I hate to see a grown man cry. Right now the plan is new or rebuilt heads and leave the 350 in place. It has a decent cam and it only has 20,000 miles on it. I am amazed at how clean it is ( I removed a valve cover) guess that Mobil 1 really works. Only thing that would make me consider the 305 is if I find any serious damage to a pistion or the block. So far there is no indication of that. You would be surprised how stout that original 305 was.
305 motors aren't really that bad in my opinion. i just don't see why people looking for power put money into them. a stock 350 with minor work or bolt ons runs as good as a highly modded 305 for 1/4 of the cost. i have a local buddy that is driving me crazy. he keeps looking for more power in his rs camaro. it had the tbi 305, he converted it to tpi. instead of dropping in the whole roller 305, he just put the intake setup on his tbi 305. and instead of buying a 350, he spent 400 bucks on a c4 brake conversion so he could stop a little faster. i mean it's his money, but it drives me nuts when he sits there and talks about how his car isn't fast enough.
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87 GTA: Forged 408 LSX short block, TEA stage 2 cnc ported 243 heads, BTR Stage 3 stroker cam, Fast 102 intake, NW 102 TB, Longtube headers, custom 411 ECM, custom harness, custom tuned, Performabuilt stage 2 4l60E with PTC 2800 stall, 9 bolt rear with 3.70 gears and TAP girdle.

11.16 at 123 mph.
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Old 08-25-2007   #93
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Re: hard start and intermittant miss

Quote:
Originally Posted by MunsonGTA
305 motors aren't really that bad in my opinion. i just don't see why people looking for power put money into them. a stock 350 with minor work or bolt ons runs as good as a highly modded 305 for 1/4 of the cost. i have a local buddy that is driving me crazy. he keeps looking for more power in his rs camaro. it had the tbi 305, he converted it to tpi. instead of dropping in the whole roller 305, he just put the intake setup on his tbi 305. and instead of buying a 350, he spent 400 bucks on a c4 brake conversion so he could stop a little faster. i mean it's his money, but it drives me nuts when he sits there and talks about how his car isn't fast enough.
I agree, if you want to go fast, there is no replacement for displacement. If I were to rebuild the 305, it would remain basically stock. The LT4 hot cam idea is just because the block has around 60,000 miles on it and I wouldnt reuse the old cam. It is already set up for roller lifters and I would have to buy new lifters, again not something I would reuse. After that, rebuilding either block would be about the same cost ( except my 350 doesnt have roller lifters). Cleaning, boring and honing are the same for either engine. One other thing that comes in to play, if I rebuild the 305, I can still drive the car while I am waiting for the new engine. At any rate, the 350 stays for now unless I find some real problems when I pull the heads.
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Old 08-25-2007   #94
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GTA Year: 1991
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Re: hard start and intermittant miss

While you have it down I would ck the rings as well and make sure thats not your problem. Even with that low of mlg anything is possible.
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Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 08-26-2007   #95
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Re: hard start and intermittant miss

Quote:
Originally Posted by fearthisgta
While you have it down I would ck the rings as well and make sure thats not your problem. Even with that low of mlg anything is possible.
Not sure how to check the rings, with out removing the pistons. I plan to leave the engine in the car. If I have to remove the engine, then I would plan on a complete rebuild, or rebuild the 305. Shouldnt the leak down and compression tests have shown defective rings?
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Old 08-26-2007   #96
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GTA Year: 1991
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Re: hard start and intermittant miss

Well, with the leak down it can be either rings and/or valves. If you pull the heads then you can take them to a machine shop and they can tell you if the valves a re seated and sealing properly and if they are then you have some bad rings.

I guess I shoulda been more specific.
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Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 08-26-2007   #97
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Re: hard start and intermittant miss

Quote:
Originally Posted by fearthisgta
Well, with the leak down it can be either rings and/or valves. If you pull the heads then you can take them to a machine shop and they can tell you if the valves a re seated and sealing properly and if they are then you have some bad rings.

I guess I shoulda been more specific.
You have to realize that you are dealing with an "old guy" here. I started this stuff back in the late 1950'. Back then we didnt have none of them there fancy gauges and tools. When I did the leakdown test, I actually followed the instructions. I removed some parts so I could hear the air leaking. I brought each cylinder to TDC and applied the air. I then went around the car listening for leaks. 4 & 6 were leaking air thru the tailpipes. #2 indicated a leak past the rings, air was coming thru the dipstick tube. Just to be sure, I tested each cylinder more than once and moved the crankshaft to be certain that the valves were closed ( or at least had the ability to close, stems could be bent,etc.). When I did the compression test, #2 came well within limits. All tests were done with a cold engine, so the results may not have been as good as they could have. Anyway, that is a good tip to take the heads to the shop and I will do that, unless I find something obvious (bent stem, burned valve, e.g.). Still at a loss as to how the engine got this way. Always been a cruiser, lots of oil changes. The only thing I know that was done wrong is that the 1997 GM Perfomance catalog, had a misprint. It spec'd a hotter plug and a .060" gap. After running this way for a few years, I found a newer catalog and it showed the correct plug with an .045" gap. The hotter plug spec was for a different engine. Other than that, this is a mystery. I am actually looking forward (well maybe not really) to pulling the heads to see what is going on.
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Old 08-30-2007   #98
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Re: hard start and intermittant miss

Update. I ordered a set of Vortec aluminum heads today. Going to take my chances with the emissions testing. I will be able to reuse the stock TPI intake and exhaust manifolds, so the engine will look basically stock. Should be able to the swap in a few weeks. Actually looking forward to see how the old girl runs with new heads.
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Old 08-30-2007   #99
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GTA Year: 1991
GTA Engine: 350 TPI Automatic
Re: hard start and intermittant miss

Congrats George.
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Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 08-30-2007   #100
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Re: hard start and intermittant miss

I have a funny feeling you might be in for a surprise when those vortec style heads don't bolt to your TPI intake...

The Vortec style bolt pattern is completely different than the stock SBC gen 1 bolt pattern.

Also, the vortecs are not emissions legal on a thirdgen. You need to have an external EGR.

Check out this article...

Chevy Hi Performance Article on SD TPI Vortec Intake manifold
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