Chevy 350 marine engine with 4 barrel Holly Carb

Hello all,

first er time boat owner and first time forum poster. I am having a little trouble with my '89 donzi. It has a high performance Chevy 350 marine engine with a 4 barrel holly carb. Here's what happened: out on the water and when I would gun it to get on a plane there would be like a gap in the throttle where it would die then pick back up. So I would gun it, it would putter, then it would get back on it. I then did so slow towing, and puttering and it died all together. I couldn't get it back up and running, and had to get Towed. Any advice??? Thank you!!

sounds like a fuel issue

Change all fuel filters, and water separator filter ( if installed ). If your still having problems afterwards, pull and rebuild the carb. That's my best guesses with limited info. Good luck.

There needs to be some questions answered first.

1. what is this "high performance" 350?

2. What is the Holley, a marine carb or a street carb?

3. What ignition? Mercury or aftermarket?

Without some basic info it is hard to figure out what is going on.......

could be fuel pump, issue with the fuel pick up, maybe clogged fuel filter, maybe a shift cable issue (stalled could not get it started), did it over heat?


I know from experience if this is a holley carb and is not set up right it can reak havic, a lot of tunning can be done and if done wrong all bets are off.......

Maybe some pictures to tell what is what........

Thanks for all your help guys. I have a little problem. My engine is clean as hell, the guy that owned it prior dropped in this beautiful engine. But when I am in idle then hammer down I hear a click from the engine, and a hesitation like it wants to die, then i either power through it or let up then keep going. What could this problem be? Also when I get it up to about 4000 rpms I feel like it isnt running as smooth and it isnt giving as much power as it should. What do you think the problem is? Thank you for all your help!

Danthedonziman said:

Hello all,

first er time boat owner and first time forum poster. I am having a little trouble with my '89 donzi. It has a high performance Chevy 350 marine engine with a 4 barrel holly carb. Here's what happened: out on the water and when I would gun it to get on a plane there would be like a gap in the throttle where it would die then pick back up. So I would gun it, it would putter, then it would get back on it. I then did so slow towing, and puttering and it died all together. I couldn't get it back up and running, and had to get Towed. Any advice??? Thank you!!

Click to expand...

First off.... I'd not be "gunning it" upon take off. I'd want to avoid these heavy loads by starting off more gently.... particularily if this is an A drive.

Secondly.... it would help to know what is meant by "high performance Chevy 350 marine engine"!
Incorrect internal engine components can lead to issues when used for Marine purposes.

Thirdly..... it would help to have info re; the ignition system and fuel delivery system.

Lastly...... it would help to know what boat this is in. Large hull... small hull... etc?





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Thanks for your input. It's a edelbrock engine with a 4 barrel holly carb. It's in a deep v 21' 1989 Donzi.

i tried uploading a picture.

RicardoMarine said:

First off.... I'd not be "gunning it" upon take off. I'd want to avoid these heavy loads by starting off more gently.... particularily if this is an A drive.

Secondly.... it would help to know what is meant by "high performance Chevy 350 marine engine"!
Incorrect internal engine components can lead to issues when used for Marine purposes.

Thirdly..... it would help to have info re; the ignition system and fuel delivery system.

Lastly...... it would help to know what boat this is in. Large hull... small hull... etc?





.

Click to expand...

I had a persistent hesitation that suddenly started in my 5.7L carbed 260HP engine when I first opened the throttle after shifting into gear. It would often stall. I eventually traced it to a slop in the linkage between the throttle arm and the accelerator pump lever. When MERC made the engine, the carb was painted after assembly and the paint on the carb formed a zero clearance bearing on the linkage for the accelerator pump. I had removed the top of the carb to clean out some "gift of ethanol" deposits prior to the problem and broken off the paint that formed the zero clearance bearing. Per advice that I got from this forum, I was told that the zig-zag in that linkage is there partially to provide a means to bend (straighten out) the linkage so as to remove free play, i.e., the accelerator pump lever moves as soon as the throttle lever moves, not later after the slop is taken up.

To paraphrase Rick.... marine engines are often high performance engines, but high performance "street" engines (including HD "truck" ones) are not usually suited for marine use.

Unfortunatley it is not the same with a HOLLEY.

The holely 4 barrel uses accelerator cams on the throttle shaft. The pluse amount and duration is controlled by the cam shape and is color specific, (pink,clear, red, blue...etc). Also the size of the accelerator pump discharge nozzles alter the issue (size and length).....The acceloreator pump also comes in several sizes such a 15 cc or 30 cc and I think higher so the amount of gas can be increased over the duration of the cam movement so the pump will not run out of gas.

All these play a roll in the tuning of a holley..........

There are many reasons a holley may hesitate.......we dont even know if it is a vacuum secondary or mechanical secondary.
We dont even know what size it is.

It could be a 600 cfm square bore vacuum secondary, or a 650 spread bore vacuum secondary or even a 750 doulbe pumper with mechanical secondary and the list goes on for possabilities.....

I have tuned and played with many holleys and they can be a bitch to get right. The are great for race track off the line as it just dumps fuel into the motor.........ask me how i know........lol
But off idle hesitation can be caused by many contributing issue, Vacuum leak, bad float setting, loose throttle shaft, bad accelrator cam timing. It also can be a timing issue witht he iginition as we dont know what that is either..

So in the end until we get more specific info and pictures it is a crap shoot...........

Ahhhh, yes..... the Holy Grail of "specific info"

While I've played with Stromberg WW s, Zenith downdrafts, Carter AFBs and now a MERCARB, never played with a HOLLEY. Thanks for the info! Those cams sound like a better system with more options, but I guess with more options comes more ways to get it wrong.

....also....if there have been a few backfires....that will wreak havoc on a standard holley power valve. that will cause a very poor transition from the idle to the power circuit. also the float levels on those must be addressed to start with.....(while running....trickle out the side sight hole on float bowl)......

crankbait said:

also the float levels on those must be addressed to start with..... (while running.... trickle out the side sight hole on float bowl)......

Click to expand...

To the best of my knowledge, the Marine version Holley is no longer equipped with the float level peep-sight holes..... and only certain models are equipped with the external needle/seat adjustment.

Those that were equipped with the float level peep-sight holes, were automotive... and were from back before USCG regs put restrictions on the usage.

Here's a current Marine Holley.


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Ayuh,.... Why would ya run a Holley, on a Mercruiser,..?? Volvo I could understand,....