ok everyone this is REALLY frustrating lol

i bought an 87 TPI 305 car last yr
i began a swap to the 355 its a 1974 chevy block that was originally carburated

so i stripped the block down to just the pistons and the crank were left in, i changed the cam to a hydraluic cam .476 int/exh

i then got all the things required to make the carb block work for a tpi harness, (knock sensor, 350 PROM etc...) and i put the motor in and the center bolt heads which were not the 305 ones but they are compatible. i used the TPI intake and the plenhams and all that.

i am using roller tip rockers aswell.


now that i am at the stage where im trying to get the engine to fire, it just wont go.
i set the distributor to point at piston one on TDC and then i begin the set the timing on all the valves i tighten the bolt until the push rod has resistance then i turn half a turn and lock them in and do that for all of them.

then for some reason i cannot start the car by turning the key i can only start it by hooking a wire to the start and thento the battery
DO i have the wires backwards for the starter??!?!!!?

anyways i try to start the car now all my ignition cables are in the correct spot, and i have tried my distributor in both 180 degrrees in and out so like set to both ways. set to one way the engine just turns over and voer but doesnt fire. the other way( which i think is proper) the engine just backfires out the intake.

the engine will always just backfire out of the intake it even blows air out of the intake when i try to start it. i check my compression and i have no compression once and a while it says i have 70 on the scale but its a 12:1 motor it should be like 110.

its always backfiring out of the front of the intake why does it never backfire out of the tail pipe atleast. it could be a fuel problem because my #1 spark plug is hardly wet. but the fuel pump is working because i had a blow o ring earlier and it leaked fuel everywhere, the car does have gas btw haha.

do you think my cam shaft is out by a tooth or two?
is this a timing problem?
i am so confused.

all help is appreciated!!!!!!!!!!!!

 

If you adjusted the lash on all the valves just as you described then they are not properly adjusted. Some are to loose and probably some are not opening at all. the backfire you hear is most likely a cylinder firing against a closed Exhaust valve. The proper procedure has been posted many times.

 

Here are step by step instructions:

1. Remove the valve cover.
2. Identify the number one cylinder. Turn the engine over until you see the number one cylinder exhaust valve rocker arm JUST START to move from the closed position to open. You may need to turn the motor over a couple of times to reach this point, but do not turn any further.
3. Locate the intake valve.
4. Loosen the rocker arm adjustment nut until you feel some obvious lash or clearance in the adjustment.
5. Using the thumb and index finger of one hand, grasp the intake push rod below the rocker arm, and rotate it back and forth (clock-wise and counter clock-wise successively to be sure there is no remaining pressure on the push rod from the rocker arm as you loosen the rocker arm adjusting nut.
6. Using the other hand, while continuously performing step 6, with a 5/8 socket and ratchet, tighten the rocker arm adjustment nut slowly until you feel a resistance of motion on the push rod.
7. This will be the zero lash adjustment point. For hydraulic lifters, tighten the rocker arm adjustment nut 3/4 of a turn. For solid lifters, back off the rocker arm adjustment nut until your feeler gauge just fits under the contact point between the valve stem and the rocker arm. Fine tune the adjustment by checking it with a feeler gauge just slightly thicker than the preferred clearance to be sure the clearance is not greater than it should be. If the larger feeler gauge will fit, it needs to be re-adjusted. A lash tolerance of 1-2 thousandths of an inch in the valve adjustment for solid lifters would be acceptable since it may be difficult for someone who is in-experienced to be more precise than that.
8. Turn the engine over until the intake valve opens and then is almost closed.
9. On the exhaust valve, repeat steps 5 through 8 for the exhaust valve adjustment.
10. Repeat this procedure for each cylinder. Be sure to do each cylinder sequentially, either following the firing order, following the cylinders numerically, or in the case of a V8 doing one side of the engine at a time. I prefer to do one side of the engine at a time.
11. make this a sticky, i post this about evry other day for diffrent people, this is hands down the best way to do it......

 

ok everyone i figured out the problem , it turns out (thought i never had it running so i didnt do any real damaged) on all exhaust valves the pushrod seems to have hit the piston, bent the pushrod and caused the rocker stud to be actualy ripped out of the head. so everytime i would tighten all the rocker nuts down, when iturned it over, on all exhaust valves they would pop up again mean the valves wouldent open or close at all, explaining why i have no compression....

now what lol

 

Well, bent pushrods are definitely "real" damage. Am i reading this correctly, the piston struck the exhaust valve while it was open and bent the pushrods?
Did your valve springs match the existing cam, or did you just put the cam in without checking?

 

i put the cam in without checking the valves springs i had no idea

 

Valve springs need to be matched to the cam. If the heads are all stock, including the springs, you will have to change them in order to prevent damage to your cam and valvetrain. So, did the pistons strike the exhaust valves?

 

the piston only hit exhaust valves not the intake ones

 

When the cam & crank gear were installed, were the dots lined up correctly--

cam gear dot straight down { 6 o'clock position }
crank gear dot straight up { 12 o'clock position }

The dots would be lined up.

12:1--
hi-dome pistons?

 

yes i lined the dots coreectyle

the pistons are flat tops at 0 deck that are all dished for valve clearance

 

Although you didn't post all the cam specs, a 12.0:1 engine should pump a lot more than 110 psi based on what cam specs you DID post.

The piston is always chasing the exhaust valve, so it's not surprising that it caught up with and hit the exhaust valves.

I sure wish you had posted here BEFORE you began your setup because you made some serious mistakes. Once you begin the repairs BE SURE to walk everything you plan to do by us first. We can save you future damage, work and expense.

Jake

 

soory its an 11.1 engine and i just pulled the heads off and there was no damage the valves did not hit the piston so it only leaves the problem to be that i had coil bind and my springs caused this to happen. so happy i didnthave internal collisions