Installed New Head Gaskets, Reassembled Engine -- Cranks but Does Not Fire??

[nscottschafer]

Hello, I have a 1995 Volvo Penta 7.4 GL PHUS with a DP-D1 Lower Unit. The VP has always ran great since I purchased it four years ago, however I do all my boating on a river which has lots of sandbars and the VP does not like sand or should I say loves sand and gulps it up every chance it can. This causes lots of overheating issues so i am constantly watching my temp guage and cleaning sand out of coolant hoses. I usually shut engine down before it gets to 200 degrees. About a month ago I decided to change the Head gasket and all other corresponding gaskets due to problems at the end of last season.

Here is what I did to my boat (1995 Larson 280 Cabrio) and the problem I am having. I replace the head gaskets, intake gaskets, exhaust gaskets, Manifold riser gaskets, cleaned the cylinder heads and Valves to a smooth shine and also surrounding areas and parts. I made sure to install valves back in to the same place they came from and lapped the valves also. I assembled everything back together and decided I wanted to install a new distributor as my old prestolite distributor was looking pretty rough. I purchased a Pertronix D200801 Flame Thrower with a 45001 Coil, installed and set engine at TDC. I have everything torqued down and Distributor at TDC and set initial timing.

Here is the problem I am having, The engine turns over but every now and then I get a loud almost like a vapor lock noise like the compression is too much and the engine doesn't want to turn over. When it does crank it sounds good but simply won't fire almost like it's getting no gas. I took fuel pump off and it is working fine. I siphoned gas and replaced with fresh gas. I just took the carb off and it was full of gas and lots of gas resting on top of the intake under the carb. I am all out of ideas and if anyone would like to share there words of wisdom I would sure appreciate it greatly.

Please let me know if there is any more information you need from me to help diagnose this problem. This is my first post in a foru and I look forward to hearing ideas form my fellow iboat members!!!

NSS

 

[dennis461]

I'll take some guesses, do not be insulted, I'm working from my own experiences.
1. Are the push rods installed correctly>
2. Was timing chaine moved-reinstalled.
3. is distributer drive installed and turning
4. did you put two gaskets (or wrong thickness) on each head
5 did you check compression pressure
6. is firing order all out of whack
7. did you check ignition with timing light (to see if coil is firing)

 

[Lou C]

Well for sure if you did not get the engine set at the compression stroke for #1 cyl and get the dist installed correctly then it would either not start or seem to be fighting itself (as if you mixed up the plug wires) so go back over that step and make sure the plug wires are set up according to the proper firing order. When you said you set the engine at TDC, are you sure, it was TDC on the compression stroke of #1?

 

[nscottschafer]

Dennis, First of all you won't offend me and thanks for the reply.
1) All pushrods went in the same spot as they came out of... However, I will admit that I may have inadvertently mixed up some of the springs and rocker arms? Will that cause problems?
2)Timing Chain was not touched
3) Distributor was installed in to engine with the rotor pointing towards #1 cylinder then distributor cap installed with the #1 wire in line with the rotor and #1 cylinder.
4) I used one gasket on each side and it was a marine Felpro 17042 Head Gasket, Marine, Steel Core Laminate, 4.370 in. Bore, .039 in. Compressed Thickness. No gasket sealant or RTV used
5) Did not check compression. Performed a leakdown test and all cylinders seemed to be consistent and were good to great.
6) I believe the firing order is correct and starts with 1,8,4,3,6,5,7,2. After cranking a few times i checked the plugs and they were completely dry.
7) Yes ignition checked with timing light.

Thank you

NSS

 

[nscottschafer]

Lou, I set TDC with the #1 cylinder all the way to top and both valves closed.

 

[Scott Danforth]

puff out the intake normally would indicate improper timing, however if the plugs are completely dry, you may have a fuel issue. are there two streams from the pump nozzles when you open the throttle? if not, go thru the carb, free up the two check valves for the accelerator pump circuit.

cranking compression will be about 150psi or higher

nearly impossible to mix push rods around. the short ones wont reach the rockers if in the wrong hole

 

[nscottschafer]

I have it running now and timing was off by 180. My next question is how do you adjust valve lash? I had it all adjusted but when it was running all the rocker arms loosened up? Do you use alot of locktite to keep them in place? I also have a few push rods, when adjusting the lash, you can tighten them down as far as you can go and there is still a little play in the pushrod.

I appreciate all the help guys thanks!!

NSS

 

[Lou C]

You need to find GMs procedure for setting the lifters, normally you are setting it with each cyl at TDC of the compression stroke and both valves will be closed. You back off the adjustment till you can move the push rod up and down slightly. Then tighten it till you can no longer move it up and down. This is the zero lash position. Then go one full turn more. If your rocker arm nuts will not hold the adjustment you should replace them.

 

[Scott Danforth]

there must be 10,000,000 videos on setting valve lash on a BBC.

each cylinder must be at TDC when setting, start with cylinder #1, then follow the firing order and turn the crank 90 degrees for each cylinder change

lash is the amount of up/down slop you get with your fingers. you set that to zero, then turn the nut 1/2-3/4 turn

if the nuts are backing off, get new nuts. they are a prevailing torque nuts and generally should be changed at a rebuild. or upgrade to roller rockers (need a valve cover spacer) and use the set screw.