Yippers what heat riser,s do is they allow exhaust too circulate thru them too keep intake manifold from freezeing up in winter . << Note tho that they do not allow exhaust gas intoo the manifold itself . But commonly these riser,s plug up both on intake manifold and the exhaust . Now as ya fail too mention wether or not your talkin dual port head,s or single port head,s here im gonna go with the single port head,s frst . Ok couple of reasons on SP heads that can cause a badd fit ? most common one is the o-ring gasket they smash intoo the head port and actually look like part of the head ? Then you come along look at it clean it up real nice add another o- ring gasket ontop of the one allready in there ??? <<< LMAO some day,s im just down right good at this sht ! << Most likely scenario gonna require gettin old o-ring out with a pen knife with out gougin the head port gasket seating surface >> continuing on too dual port now on dual port ya have 2 different sized manifold,s one size is for 30 pict series carbs and other size is for 34 pict series << Meaning make sure both end castings and manifold are the same size ?? Now for problem,s that affect both DP and SP motor,s or head,s ? Most common being aftermarket exhaust system,s made in Taiwann << Simply put they dont f---n fitt . << Probably your problem here ? Hell i dont even stress China And Korea havin nuke capability,s << Cause i know there s--t dont work any how ? LMAO German exhaust here is the answer or a header that will flex if you insist on usin an aftermarket exhaust >> Brazillian for example or Mex ? You will strip stud,s out of the heads , flex head,s too leakin on cylinders etc etc or worse will break somethin . << German exhaust fitt ! others dont Fit ! << Now ifn none of these situation,s apply,s too you i would check head bolt,s for loosenes under valve covers <, Meaning that if the motor is pounding apart here it,s growin in width and another thing ive seen kinda rare is on supposed newly rebuilt motors i once found a deck height in excess of 250 thousandths wich actually added a 1/4 inch in width too the motor . Now as for intake manifold leaking << Badd Badd Mojo a lean condition will smoke the motor fix this above all else will cause over heating resulting in motor failure ! << Gett this right above all else >> In summer month,s you can hack off heat riser,s ? <, Just cut um off then for like 10 buck,s ya buy block off plates for the exhaust heat riser port,s . <<< If it makes manifold fitt properly do it wont hurt nothin till winter , and wouldnt be first time i seen a bent heat riser on a manifold causeing a badd fit . Note >> but back too exhaust if it,s Kadron Brazillian etc Taiwann garbage that doesnt fitt gett rid of it buy a German exhaust there spendy like 100 buck,s there about,s Now back too dip stick test << This is indication your runnin way too hot ! So fix intake leak immediately then check dip stick again still runnin hot time dizzy too the proper mark on the proper crank pulley as the dizzy and crank pulley are a matched sett ! Lett me know how ya come out . Sean